Title of invention: secondary battery for internal short test, secondary battery internal short test method and apparatus using the same
Technical field
[One]
The present invention relates to a method and apparatus for evaluating the safety of a secondary battery, and more particularly, to a method and apparatus for testing an internal short circuit of a secondary battery. This application is an application for claiming priority for Korean Patent Application No. 10-2018-0089876 filed on August 1, 2018, and all contents disclosed in the specification and drawings of the application are incorporated herein by reference.
Background
[2]
As technology development and demand for mobile devices, electric vehicles, power storage devices, and uninterruptible power supply devices increase, the demand for secondary batteries as an energy source responding to high output and high capacity requirements is rapidly increasing.
[3]
Among the secondary batteries, lithium secondary batteries are representative. The secondary battery includes a separator between the positive electrode plate and the negative electrode plate. This separator has the property of being easy to shrink. For this reason, when the secondary battery is kept in an extremely high temperature environment for a long time, the positive electrode plate and the negative electrode plate physically contact each other, and an internal short circuit may occur. In addition, the separator is destroyed by conductive powder adhered to the surface of the positive electrode or negative electrode plate or lithium metal deposited on the negative electrode plate, and as a result of electrical conduction between the positive electrode plate and the negative electrode plate, an internal short circuit may occur. Also, an internal short circuit may occur due to an impact from the outside of the secondary battery.
[4]
Once the internal short circuit occurs, the short-circuit portion is further expanded by Joule heat accompanying the short-circuit current, causing abnormal heating, and thus the secondary battery may be destroyed. When an internal short circuit occurs, the high electrical energy stored in each electrode plate is instantaneously challenged, and thus, unlike other safety accidents such as overcharging or overdischarging, the risk of explosion is very high. For this reason, the internal short circuit must be carefully managed in terms of safety, and it is important to prevent the internal short circuit from occurring in the secondary battery. It is important to ensure that. Accordingly, it is becoming more important to correctly evaluate whether or not to secure safety by performing an internal short-circuit test after the secondary battery design stage or manufacturing, as well as a technology to increase the safety during internal short circuit of a secondary battery.
[5]
Conventional internal short circuit generation technologies include nail penetration and ISC (Internal Short Circuit) devices. Nail penetration is a method of inducing an internal short circuit by passing a nail through the inside of the secondary battery, and is the method of generating an internal short most easily. However, it is not possible to completely simulate the internal short-circuit issue occurring in the actual field (filed), and there is a limit because excessive internal short-circuits are generated more than necessary. The ISC device was developed by researchers belonging to the National Renewable Energy Laboratory (NREL) under the Department of Energy (DOE), and the related patent is US2013-020984.
[6]
1 is an exploded perspective view of an ISC device, and FIG. 2 is a cross-sectional view showing a method of inserting such an ISC device into a secondary battery.
[7]
Referring to FIG. 1, the ISC element 1 has a wax layer 30 between a copper disk 10 and an aluminum disk 40, and a copper puck between the copper disk 10 and the wax layer 30. A polyethylene or polypropylene film 20 having 15) in the center is also included. As shown in FIG. 2, the ISC element 1 is inserted between the positive electrode plate 110 and the negative electrode plate 120 of a secondary battery and used. First, after making a hole (H) in the separator 130 between the positive electrode plate 110 and the negative electrode plate 120 in the secondary battery, the copper disk 10 of the ISC element 1 contacts the negative plate 120 and the ISC element The ISC element 1 is inserted into the hole H of the separator 130 in the direction of the arrow so that the aluminum disk 40 of (1) contacts the positive electrode plate 110. When the secondary battery in which the ISC element 1 is inserted between the positive electrode plate 110 and the negative electrode plate 120 is exposed to a high temperature to melt the wax layer 30 of the ISC element 1, the copper disk 10 of the ISC element 1 ) And the aluminum disk 40 are energized to cause an internal short circuit in the secondary battery.
[8]
However, since the ISC device 1 operates only at a specific temperature or higher to melt the wax layer 30, there is a limit that it is impossible to generate an internal short circuit at room temperature. And, since the wax layer 30 generally melts at a high temperature (60°C or higher), in the case of a pouch-type secondary battery manufacturing process in which a lamination process involving high temperature heat is included during the manufacturing step, the ISC device 1 It is difficult to manufacture a secondary battery by inserting ), and there is a disadvantage that the manufactured secondary battery must be disassembled and inserted. And, even if the secondary battery is tested by generating an internal short after a long cycle or after high-temperature aging, the wax layer 30 may melt before the test and the intended test becomes impossible. have.
Detailed description of the invention
Technical challenge
[9]
The present invention is invented to solve the above problems, and is not affected by the test temperature conditions, and is a secondary battery for internal short circuit test capable of performing an internal short test in a desired state, such as after a long cycle of the secondary battery and high temperature storage. It aims to provide.
[10]
Another object of the present invention is to provide a secondary battery internal short test method and apparatus capable of performing an internal short test in a desired state, such as after a long cycle of a secondary battery and after high temperature storage, without being affected by the test temperature conditions.
[11]
Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by examples of the present invention. In addition, it will be readily understood that the objects and advantages of the present invention can be realized by means and combinations thereof indicated in the claims.
Means of solving the task
[12]
A secondary battery for an internal short circuit test according to the present invention for achieving the above object includes: a positive electrode plate having a positive electrode active material layer formed on a positive electrode current collector; A negative electrode plate having a negative electrode active material layer formed on the negative electrode current collector; And a separator interposed between the positive electrode plate and the negative electrode plate; and in any one of the unit cells, one end is positioned between the positive electrode plate and the separator, and the other end is external to the unit cell. A positive electrode side metal terminal that comes out; And a negative metal terminal in which one end portion is positioned between the negative electrode plate and the separator and the other end extends to the outside of the unit cell in the unit cell having the positive metal terminal, and the other end of the positive metal terminal and It is used for the purpose of causing an internal short circuit of the unit cell by contacting the other ends of the negative metal terminal with each other.
[13]
In a preferred embodiment, the secondary battery for the internal short test comprises: a positive electrode tab formed on the positive electrode plate and a positive electrode lead connected at one end to the positive electrode tab; A negative electrode tab formed on the negative electrode plate and a negative electrode lead having one end connected to the negative electrode tab; And a pouch-type battery case accommodating and sealing the unit cell and the electrolyte, wherein the positive electrode lead, the negative electrode lead, and the other ends of the positive electrode-side metal terminal and the negative electrode-side metal terminal are exposed to the outside of the battery case.
[14]
In this case, the anode-side metal terminal and the cathode-side metal terminal, or between the anode-side metal terminal, the cathode-side metal terminal, and the anode lead and the cathode lead may be formed to be visually distinguishable.
[15]
The positive-side metal terminal is at least one of a positive-side first metal terminal having the one end on the positive electrode current collector and a positive-side second metal terminal having the one end on the positive electrode active material layer, and the negative-side metal terminal May be at least one of a negative electrode-side first metal terminal at one end of the negative electrode current collector and a negative electrode-side second metal terminal at the one end of the negative electrode active material layer.
[16]
For example, there may be several unit cells, and only one of the unit cells may include the anode-side metal terminal and the cathode-side metal terminal.
[17]
For another example, there are several unit cells, one of the anode-side first metal terminal and the anode-side second metal terminal, and the cathode-side first metal terminal and cathode-side second metal terminal in one of the unit cells. Any one of the metal terminals is included, and the other unit cell includes the other one of the positive first metal terminal and the positive second metal terminal, and the other one of the negative first metal terminal and the negative second metal terminal I can.
[18]
One end of the positive-side metal terminal and the negative-side metal terminal are aligned at the same position in the vertical direction inside the unit cell, and the other end of the positive-side metal terminal and the negative-side metal terminal are horizontally aligned outside the unit cell. It is preferable that they are formed to be spaced apart from each other.
[19]
To this end, the positive-side metal terminal and the negative-side metal terminal may be provided in a form bent on a plane.
[20]
A secondary battery internal short test method according to the present invention for achieving the above other object includes: a positive electrode plate having a positive electrode active material layer formed on a positive electrode current collector; A negative electrode plate having a negative electrode active material layer formed on the negative electrode current collector; And a separator interposed between the positive electrode plate and the negative electrode plate, for a secondary battery including at least one unit cell including: Providing an anode-side metal terminal protruding from the outside of the unit cell; (b) in the unit cell having the anode-side metal terminal, providing a cathode-side metal terminal having one end positioned between the anode plate and the separator and the other end extending out of the unit cell; And (c) causing an internal short circuit of the unit cell by contacting the other end of the anode-side metal terminal and the other end of the cathode-side metal terminal.
[21]
The step (c) may include: connecting a short circuit including a switch and a resistor to the positive metal terminal and the negative metal terminal in a state in which the switch is off; And turning on the switch to cause an internal short circuit of the unit cell, and measuring a current flowing through the short circuit.
[22]
In addition, the secondary battery includes: a positive electrode tab formed on the positive electrode plate and a positive electrode lead having one end connected to the positive electrode tab; A negative electrode tab formed on the negative electrode plate and a negative electrode lead having one end connected to the negative electrode tab; And a pouch-type battery case accommodating and sealing the unit cell and the electrolyte, wherein the other ends of the positive electrode lead, the negative electrode lead, the positive electrode-side metal terminal and the negative electrode-side metal terminal are exposed to the outside of the battery case. And measuring a voltage between the positive lead and the negative lead while causing the internal short in step (c).
[23]
In addition, depending on the test method, while discharging the secondary battery by connecting a power source between the positive lead and the negative lead to charge the secondary battery or by connecting a load between the positive lead and the negative lead, the (c) You can also perform steps.
[24]
In particular, the positive-side metal terminal is at least one of a positive-side first metal terminal having one end on the positive electrode current collector and a positive-side second metal terminal having the one end on the positive electrode active material layer, and the negative electrode side The metal terminal may be provided such that the one end is at least one of a negative electrode-side first metal terminal disposed on the negative electrode current collector and a negative electrode-side second metal terminal disposed on the negative electrode active material layer.
[25]
The secondary battery internal short test method according to the present invention can be easily performed by using the secondary battery for internal short test according to the present invention.
[26]
The present invention also provides an internal short test apparatus suitable for carrying out the internal short test method according to the present invention. The apparatus includes: an explosion-proof chamber capable of loading a secondary battery for an internal short circuit test according to the present invention; A short circuit connected to a positive metal terminal and a negative metal terminal of the secondary battery for internal short test, and including a switch and a resistance; A measuring instrument measuring the current flowing through the short circuit; And a controller controlling on-off of the switch.
[27]
The device includes a power source or a load connected between the positive lead and the negative lead of the secondary battery for internal short circuit test; And a measuring device measuring a voltage between the positive lead and the negative lead.
Effects of the Invention
[28]
The internal short test method of the present invention is not a simulation of abnormal conditions such as the conventional nail penetration test. According to the present invention, an internal short-circuit issue occurring in an actual field can be completely simulated, and the safety of a secondary battery at that time can be evaluated by causing an internal short-circuit under conditions that do not cause excessive internal short-circuits more than necessary.
[29]
The internal short-circuit test method of the present invention can be used in the secondary battery design stage or post-assembly verification stage. By evaluating the state of the secondary battery in a state that accurately simulates the internal short-circuit situation of the secondary battery, it is possible to conduct a practical safety evaluation for the design of the secondary battery, and can be used for verification and correction of new design standards.
[30]
According to the present invention, one end of the positive-side metal terminal and the negative-side metal terminal, which may cause an internal short circuit, is located in the unit cell and the other end is located outside the unit cell. By causing an internal short-circuit by contacting the other end of the positive-side metal terminal and the negative-side metal terminal with each other, it is possible to control an accurate short-circuit timing outside the unit cell. If a resistor is connected to the other end of a metal terminal that can cause an internal short, and the current flowing through it is measured, short-circuit current and short-circuit resistance measurement according to each internal short type becomes possible.
[31]
According to the present invention, since it does not use the same wax layer used in the conventional ISC device, it is not affected by the test temperature conditions. Since it is not affected by the test environment, it is possible to generate an internal short even at room temperature, and it is also possible to simulate an internal short in a desired cell state, such as after a long cycle and high temperature storage.
[32]
According to the present invention, the metal terminal located at the other end outside the unit cell may cause an internal short circuit in the secondary battery in a continuous and controllable manner. One end of the metal terminal can be placed in any position inside the unit cell. Accordingly, in the secondary battery, all four types of internal short circuits, such as a positive electrode current collector-a negative electrode current collector, a positive electrode active material layer-a negative electrode current collector, a positive electrode active material layer-a negative electrode active material layer, and a positive electrode current collector-a negative electrode active material layer, can occur.
Brief description of the drawing
[33]
The following drawings attached to the present specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of ​​the present invention together with the detailed description of the present invention to be described later, so the present invention is described in such drawings. It is limited to and should not be interpreted.
[34]
1 is an exploded perspective view of a conventional ISC device.
[35]
2 is a cross-sectional view illustrating a method of inserting a conventional ISC device into a secondary battery.
[36]
3 is a diagram for explaining an internal structure of a unit cell and types of internal shorts.
[37]
4 is an exploded perspective view of a unit cell part in a secondary battery for an internal short test according to the present invention.
[38]
5 is a top view of the unit cell of FIG. 4 in a state in which the unit cell of FIG. 4 is housed and sealed in a battery case.
[39]
6 is a partial cross-sectional view of VI-VI' of FIG. 5.
[40]
7A to 7D are diagrams illustrating implementation of each type of inner short, and are cross-sectional views along a length direction of a metal terminal.
[41]
8 is a circuit diagram of the secondary battery for an internal short test of FIG. 5 during an internal short test.
[42]
9 is a circuit diagram for explaining a comparison between an external short and an internal short.
[43]
10 is a schematic diagram of a secondary battery internal short test apparatus according to the present invention.
[44]
11 is an exploded perspective view of a secondary battery for an internal short test according to another embodiment of the present invention.
[45]
12 is an exploded perspective view of a secondary battery for an internal short test according to another embodiment of the present invention.
[46]
13 is a photograph of a secondary battery for an internal short test according to an experimental example of the present invention.
[47]
14 is a photograph of an element implementing a short circuit used in an experimental example of the present invention.
[48]
15 is a schematic diagram of a state in which a secondary battery for an internal short test and a short circuit implementation element are connected according to an experimental example of the present invention.
[49]
16 shows the full cell voltage drop measured by the internal short test in the experimental example of the present invention.
[50]
17 is a graph showing changes in short-circuit current by performing an internal short-circuit test on two secondary batteries for internal short-circuit tests having different positive electrode active material layers according to the experimental example of the present invention.
Mode for carrying out the invention
[51]
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the embodiments according to the present invention may be modified in various different forms, and the scope of the present invention should not be construed as being limited to the following examples. The embodiments of the present invention are provided to more completely describe the present invention to those of ordinary skill in the art.
[52]
The terms or words used in the specification and claims should not be construed as being limited to their usual or dictionary meanings, and the inventor may appropriately define the concept of terms in order to describe his own invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of ​​the present invention based on the principle that there is.
[53]
Accordingly, the embodiments described in the present specification and the configurations shown in the drawings are only the most preferred embodiments of the present invention, and do not represent all the technical spirit of the present invention, and thus various It should be understood that there may be equivalents and variations. In the drawings, the same reference numerals indicate the same elements.
[54]
In the embodiments described below, the secondary battery refers to a lithium secondary battery. Here, the lithium secondary battery refers to a secondary battery in which lithium ions act as operating ions during charging and discharging to induce electrochemical reactions at the positive and negative electrodes.
[55]
On the other hand, even if the name of the secondary battery is changed depending on the type of electrolyte or separator used in the lithium secondary battery, the type of the battery case used to package the secondary battery, the internal or external structure of the lithium secondary battery, etc. Any secondary battery used as should be interpreted as being included in the category of the lithium secondary battery.
[56]
The present invention can also be applied to other secondary batteries other than lithium secondary batteries. Therefore, even if the working ions are not lithium ions, any secondary battery to which the technical idea of ​​the present invention can be applied should be interpreted as being included in the scope of the present invention regardless of the type.
[57]
3 is a diagram for explaining an internal structure of a unit cell and types of internal shorts.
[58]
Referring to FIG. 3, the unit cell 101 includes a positive electrode plate 110, a negative electrode plate 120, and a separator 130.
[59]
The positive electrode plate 110 includes a positive electrode active material layer 114 formed on the positive electrode current collector 112, and the negative electrode plate 120 includes a negative electrode active material layer 124 formed on the negative electrode current collector 122. 3 shows an example in which a positive active material layer 114 is formed on one surface of the positive electrode current collector 112 and a negative active material layer 124 is formed on one surface of the negative current collector 122, but the positive active material layer 114 is It may be formed on both sides of the positive electrode current collector 112. The negative active material layer 124 may also be formed on both sides of the negative current collector 122.
[60]
The positive electrode plate 110 is coated with a positive electrode active material layer 114 including NCM, a lithium metal oxide containing Ni, Co, and Mn, as a positive electrode active material on a positive electrode current collector 112 such as aluminum (Al), and dried. And what was produced by rolling can be used. The negative electrode plate 120 may be prepared by coating a negative electrode active material layer 124 including graphite as a negative electrode active material on a negative electrode current collector 122 such as copper (Cu), drying, and rolling.
[61]
The separator 130 is interposed between the positive electrode plate 110 and the negative electrode plate 120 to separate the two. The separator 130 is a porous insulating film for electrically insulating each of the electrode plates 110 and 120 while allowing lithium ions to move. The separator 130 may be a sheet or nonwoven fabric made of, for example, an olefin-based polymer such as polypropylene having chemical resistance and hydrophobicity, glass fiber or polyethylene, but is not limited thereto. Preferably, inorganic particles may be coated on the surface of the separation membrane 130.
[62]
There are four types of internal shorts in the unit cell 101. It includes an inner short (S A ) between the positive electrode current collector 112 and the negative electrode current collector 122, an inner short (S B ) between the positive electrode current collector 112 and the negative active material layer 124 , the positive active material layer 114 and It is an internal short (S C ) between the negative electrode current collectors 122 and an internal short (S D ) between the positive active material layer 114 and the negative active material layer 124 . The secondary battery for an internal short test according to the present invention allows these four types of internal short S A to S D to be distinguished and tested.
[63]
4 to 6 are schematic diagrams of a secondary battery for an internal short test according to the present invention, FIG. 4 is an exploded perspective view of a unit cell part included in the secondary battery for an internal short test according to the present invention, and FIG. 5 is a unit cell of FIG. Is a top view of the battery case in a state where it is housed and sealed. 6 is a partial cross-sectional view of VI-VI' of FIG. 5, corresponding to a cross-sectional view along the length direction of the metal terminal, some elements are omitted, and only minimal elements necessary for description are illustrated.
[64]
The secondary battery is originally based on an electrode assembly including a unit cell 101 as shown in FIG. 3, for example, a unit cell manufactured by disposing a separator between a positive electrode plate and a negative electrode plate. Hereinafter, in the embodiments described with reference to FIGS. 4 to 6, a case where the electrode assembly includes one unit cell is exemplified, but the electrode assembly may include a plurality of unit cells, preferably, at least one of the plurality of unit cells One has the structure as described with reference to FIG. 3. Such unit cells may be simply stacked, stacked and folded, or manufactured as an electrode assembly in the form of a jelly roll. Since a method of manufacturing an electrode assembly in various types is widely known, a detailed description will be omitted.
[65]
4 to 6, the secondary battery 200 for an internal short circuit test according to the present invention may basically include a unit cell similar to that shown in FIG. 3. The secondary battery 200 for internal short test includes a unit cell 101' including a positive electrode plate 110, a negative electrode plate 120, and a separator 130.
[66]
A positive electrode tab 116 is formed on the positive electrode plate 110, and a negative electrode tab 126 is formed on the negative electrode plate 120. The positive electrode current collector 112 and the negative electrode current collector 122 include a portion (uncoated portion) to which an active material layer is not applied, and each electrode tab 116 and 126 may be formed therein. As shown, each of the electrode tabs 116 and 126 may protrude in one direction so as to be formed side by side with each other on one side of the unit cell 101 ′, or formed on one side of the unit cell 101 ′ and the other side opposite to each other so as to face each other. It can also be projected in both directions.
[67]
In the secondary battery 200 for internal short-circuit test, the unit cell 101' includes a positive-side metal terminal 210 and a negative-side metal terminal 220. Specifically, in the unit cell 101', the anode-side metal terminal 210 has one end positioned between the anode plate 110 and the separator 130, and the other end extends outside the unit cell 101'. The negative electrode-side metal terminal 220 has one end positioned between the negative electrode plate 120 and the separator 130 and the other end extending out of the unit cell 101'.
[68]
Here, the anode-side metal terminal 210 may be formed between the positive electrode collector of the positive electrode plate 110 and the separator 130, or may be formed between the positive electrode active material layer of the positive electrode plate 110 and the separator 130. . Of course, a positive metal terminal may be formed between the positive electrode current collector of the positive electrode plate 110 and the separator 130, and a positive metal terminal may also be formed between the positive electrode active material layer and the separator 130. In particular, referring to FIG. 6, in the present embodiment, an example in which the positive electrode-side metal terminal 210 is formed between the positive electrode active material layer 114 of the positive electrode plate 110 and the separator 130 is described.
[69]
The negative metal terminal 220 may be formed between the negative electrode current collector of the negative electrode plate 120 and the separator 130, or may be formed between the negative electrode active material layer of the negative electrode plate 120 and the separator 130. Of course, a negative metal terminal may be formed between the negative current collector of the negative electrode plate 120 and the separator 130, and a negative metal terminal may also be formed between the negative active material layer and the separator 130. As shown in FIG. 6, in the present embodiment, an example in which the negative electrode-side metal terminal 220 is formed between the negative electrode active material layer 124 of the negative electrode plate 120 and the separator 130 is exemplified.
[70]
The anode-side metal terminal 210 and the cathode-side metal terminal 220 are preferably formed at positions that do not interfere with each of the electrode tabs 116 and 126. The anode-side metal terminal 210 and the cathode-side metal terminal 220 may be provided by contacting one end of each of the electrode plates 110 and 120 and exposing the other end to the outside of the unit cell 101 ′. It is preferable that one end of each of the metal terminals 210 and 220 in contact with each of the electrode plates 110 and 120 is aligned in the vertical direction or in the vertical direction based on the wide surface of the unit cell 101 ′. Therefore, if the path where the plane orthogonal to the plane on which the wide surface of the unit cell 101' is placed is indicated as CC, for example, on the CC as shown in FIGS. 4 and 5 It is preferable to insert one end of each of the metal terminals 210 and 220 so that one end of each of the metal terminals 210 and 220 is aligned at the same position when viewed from the top of the wide surface of the unit cell 101 ′ so that one end of each metal terminal 210 and 220 is placed. This is because if the alignment is misaligned, the electrode plates 110 and 120 facing each metal terminal 210 and 220 act as a non-reactive area, resulting in a decrease in capacity and a possibility of Li-plating. Therefore, it is preferable that one end of the anode-side metal terminal 210 and the cathode-side metal terminal 220 is placed along the CC, so that they are aligned at the same position in the vertical direction or in the vertical direction inside the unit cell 101'. .
[71]
In addition, in order to prevent an unintended short circuit due to contact between the metal terminals 210 and 220, each electrode plate 110 at each metal terminal 210, 220 excluding each other end to be contacted to cause an internal short circuit. , It is preferable to insulate the parts that are not in direct contact with 120). For example, an insulating tape can be attached to the area.
[72]
On the other hand, in handling other than the internal short test, in order to avoid unintended contact between the metal terminals 210 and 220 due to external physical factors in the vertical direction or the vertical direction, the positive metal terminal 210 and the negative metal It is preferable that the terminals 220 are formed to be spaced apart from each other on a plane on which the wide surface of the unit cell 101 ′ is placed. In other words, it is preferable that the other ends of the anode-side metal terminal 210 and the cathode-side metal terminal 220 are formed to be spaced apart from each other in the horizontal direction outside the unit cell 101'. This is to prevent inadvertent contact with each other before the internal short test.
[73]
Therefore, in this embodiment, each metal terminal 210, 220 is provided in a predetermined bent shape as shown, and is arranged in the same position in the vertical direction inside the unit cell 101', but the unit cell 10' Externally, it can be formed to be spaced apart from each other in a horizontal direction. The planar shape of each metal terminal 210 and 220 itself may be folded twice in the direction of 90 degrees, or the metal terminals 210 and 220 in the shape of a strip may be folded twice in the direction of 90 degrees. In either case, the positive-side metal terminal 210 and the negative-side metal terminal 220 may be provided in a shape bent on a plane. In this embodiment, each of the electrode tabs 116 and 126 is formed side by side on one side of the unit cell 101 ′, and the anode side metal terminal 210 and the cathode side metal terminal 220 are formed side by side on the other side of the unit cell 101 ′. Although an example has been given, the present invention is not limited to these formation positions.
[74]
In the secondary battery 200 for internal short circuit test, one end of the positive electrode lead 118 is connected to the positive electrode tab 116, and one end of the negative lead 128 is connected to the negative electrode tab 126, and such a unit cell 101' The excess electrolyte is accommodated in a suitable battery case, such as a pouch-type battery case 230, as shown in FIG. 5 and sealed by heat fusion. In this way, the other ends of the positive lead 118, the negative lead 128, the positive metal terminal 210, and the negative metal terminal 220 are exposed to the outside of the battery case 230. In order to increase the sealing force, a sealing tape S may be interposed between the positive electrode lead 118, the negative electrode lead 128, the positive metal terminal 210, the negative metal terminal 220 and the battery case 230. As a manufacturing method, a positive electrode lead 118 with sealing tape (S) attached to the positive electrode tab 116 is connected, and a negative electrode lead 128 with sealing tape (S) attached to the negative electrode tab 126 is connected. As the side metal terminal 210, a metal strip with a sealing tape (S), for example aluminum, may be used, and as the negative metal terminal 220, a metal strip with a sealing tape S, such as copper.
[75]
The positive-side metal terminal 210 and the negative-side metal terminal 220 do not need to be bonded or welded to the unit cell 101'. After simply inserting one end of the positive metal terminal 210 and one end of the negative metal terminal 220 into a desired position between the positive plate 110, the separator 130, and the negative plate 120, a conventional method for manufacturing a secondary battery Depending on, for example, lamination, etc., may be fixed to the inserted position.
[76]
If the secondary battery 200 for internal short-circuit test further includes a unit cell other than the unit cell 101', several positive tabs are collected and connected to one positive lead, and several negative tabs are collected and connected to one negative lead. do. Except for this point, you can follow the instructions previously described.
[77]
The positive-side metal terminal 210 and the negative-side metal terminal 220 may be formed to be distinguishable with the naked eye. For example, a difference in color between the anode-side metal terminal 210 and the cathode-side metal terminal 220, marking, different size (thickness or width), or the length exposed to the outside of the unit cell 101' It is good to make it possible to distinguish between each other by a different method. When aluminum is used as the anode-side metal terminal 210 and copper is used as the cathode-side metal terminal 220, a color difference naturally occurring due to a material difference can be used. It is also possible to paint the other ends of each of the metal terminals 210 and 220 with a means such as ink (which is better if it is electrically conductive) to make the difference in color intentionally. A distinct mark may be made on each of the metal terminals 210 and 220 with a marking means such as laser marking.
[78]
In addition, if the positive-side metal terminal 210 and the negative-side metal terminal 220 are distinguishable from each other, and they are formed so as to be visually distinguishable from the positive lead 118 and the negative lead 128, each of the terminals for internal short test Since the metal terminals 210 and 220 can be distinguished from the respective electrode leads 118 and 128, which are terminals related to the current input/output (I/O) of the secondary battery, there is no fear of misunderstanding or confusion during handling. desirable.
[79]
As shown in FIG. 6, in this embodiment, the positive electrode-side metal terminal 210 is formed between the positive electrode active material layer 114 and the separator 130, and the negative electrode-side metal terminal 220 is a negative electrode active material layer 124 ) And the separation membrane 130. These internal short-circuit test secondary battery 200 as in the other secondary battery, if used as a normal usage by an external conductor (not shown) connected to the anode lead 118 and cathode lead 128 is related to the charge and discharge electronics (e - ) Will move and lithium ions (Li + ) will move between the positive electrode plate 110 and the negative electrode plate 120 through the separator 130 according to the secondary battery operating principle (for example, in the direction of the arrow).
[80]
With further reference to FIG. 6, the principle of internal shorting by the metal terminals 210 and 220 will be described. When the other end of the anode-side metal terminal 210 and the other end of the cathode-side metal terminal 220 contact each other in the internal short test step, between the anode-side metal terminal 210 and the cathode-side metal terminal 220, a dotted arrow As a result of the direct electron (e − ) movement path, as shown in FIG. 2, the internal short-circuit condition of the unit cell 101' is simulated. In particular, in this case, S D (see FIG. 3 ), which is an internal short between the positive active material layer 114 and the negative active material layer 124 , is simulated.
[81]
7A to 7D are diagrams for explaining the implementation of each type of internal short circuit and correspond to a cross-sectional view along the length direction of the metal terminal, as in FIG. 6.
[82]
7A is an internal short (S A ) between the positive electrode current collector 112 and the negative electrode current collector 122 , FIG. 7B is an internal short (S B ) between the positive electrode current collector 112 and the negative active material layer 124 , 7C shows an internal short S C between the positive active material layer 114 and the negative current collector 122 , and FIG. 7D shows the positive active material layer 114 and the negative active material layer 124 as already described in FIG. 6. In order to simulate the internal short (S D ), the positive-side metal terminal 210 and the negative-side metal terminal 220 are respectively shown in a state provided in each unit cell.
[83]
In FIGS. 7A and 7B, one end of the positive electrode-side metal terminal 210 is positioned on the positive electrode current collector 112, and the positive-side metal terminal 210 at this position is specifically referred to herein as the positive-side first metal terminal 211. ). In FIGS. 7C and 7D, one end of the positive electrode-side metal terminal 210 is located on the positive electrode active material layer 114, and the positive-side metal terminal 210 at this position is specifically referred to herein as the positive-side second metal terminal 212. ). In FIGS. 7A and 7C, one end of the negative electrode-side metal terminal 220 is located on the negative electrode current collector 122, and the negative electrode-side metal terminal 220 at this position is specifically referred to herein as the negative-side first metal terminal 221. ). In FIGS. 7B and 7D, one end of the negative electrode-side metal terminal 220 is located on the negative electrode active material layer 124, and the negative-side metal terminal 220 at this position is specifically referred to herein as the negative-side second metal terminal 222. ).
[84]
As such, the anode-side metal terminal 210 may be at least one of the anode-side first metal terminal 211 and the anode-side second metal terminal 212, and the cathode-side metal terminal 220 is a cathode-side first metal terminal. It may be at least one of 221 and the second metal terminal 222 on the cathode side. A unit cell to include any one of the anode-side first metal terminal 211 and the anode-side second metal terminal 212 and one of the cathode-side first metal terminal 221 and the cathode-side second metal terminal 222 If configured, the desired type of internal short can be caused through a combination of these metal terminals.
[85]
As described above, the secondary battery for an internal short test according to the present invention is, depending on the type and combination of the positive-side metal terminal 210 and the negative-side metal terminal 220, the positive electrode current collector 112-the negative electrode current collector 122, the positive electrode. It is possible to distinguish the internal short-circuit resistance between the current collector 112-the negative electrode active material layer 124, the positive electrode active material layer 114-the negative electrode current collector 122, the positive electrode active material layer 114-the negative electrode active material layer 124 have.
[86]
7A to 7C, a positive electrode current collector 112-a negative electrode current collector 122, a positive electrode current collector 112-a negative electrode active material layer 124, a positive electrode active material layer 114-a negative electrode current collector 122 In the case of an internal short circuit between the liver, the positive active material layer 114 or the negative electrode active material layer 124 is coated on each of the current collectors 112 and 122 so that the positive electrode current collector 112 or the negative current collector 122 is exposed. After removing the desired short-circuit occurrence area, the anode-side metal terminal 210 and the cathode-side metal terminal 220 may be provided.
[87]
As described above, after manufacturing the secondary battery 200 for internal short-circuit test provided with the positive-side metal terminal 210 and the negative-side metal terminal 220, the other end of each of the metal terminals 210 and 220 during the internal short test. If they are in contact with each other, simply touching them can cause an internal short circuit.
[88]
8 is a circuit diagram of the secondary battery for an internal short test of FIG. 5 during an internal short test.
[89]
5 and 8 together, the voltage of the secondary battery 200 for the internal short test in a stable state before causing the internal short will correspond to the open circuit voltage E OCV , the internal resistance is R 0 , the current is I 0 It can be said. When an internal short is caused by contacting the positive metal terminal 210 and the negative metal terminal 220 of the secondary battery 200 for internal short circuit test, the voltage of E short is applied between the two metal terminals 210 and 220. The current flowing through will be I. The short-circuit resistance in the secondary battery 200 for the internal short-circuit test in which the internal short occurs is R isc and the short-circuit current is I isc . When a resistance is connected to the other end of the anode-side metal terminal 210 and the cathode-side metal terminal 220 to measure the current flowing through both ends, I isc and R isc according to each type of internal short can be measured.
[90]
Preferably, a short circuit including a switch and a resistor is connected to the positive metal terminal 210 and the negative metal terminal 220 in a state in which the switch is off, and then the switch is turned on. This causes an internal short circuit of the unit cell 101', and the current flowing through the short circuit is measured. This is because when the positive metal terminal 210 and the negative metal terminal 220 are directly contacted without operation of the switch, spark discharge may occur in severe cases depending on the state of charge of the secondary battery 200 for internal short circuit test.
[91]
Note that the switch-on state corresponds to causing a short circuit through physical manipulation outside the secondary battery 200 for internal short circuit test, so it may look like an external short at a glance, but it is an internal short distinct from the external short. shall. That is, the internal short circuit test method according to the present invention is different from the external short circuit even if the short circuit is caused by operation outside the secondary battery.
[92]
In a simple circuit, the external short and the internal short may have the same form, but in the secondary battery, the positive lead 118 and the negative lead 128 are connected to the positive current collector 112 and the negative current collector 122, In the case of a secondary battery composed of several unit cells, when all of the unit cells are composed of circuits, a circuit difference between an external short circuit and an internal short circuit occurs.
[93]
9 is a circuit diagram for explaining a comparison between an external short and an internal short, and referring to FIG. 9, the difference becomes clear.
[94]
(A) of FIG. 9 is an external short circuit when there are several unit cells, and (b) an internal short circuit. In the present invention, an internal short circuit as shown in (b) occurs due to external operation of the secondary battery. In Figs. 9A and 9B, the locations where the actual short circuit occurs are different from those indicated by the reference numeral P. As such, the outer paragraph and the inner paragraph in the present invention are different. In addition, it should be noted that in the case of an external short circuit, an instantaneous discharge is generated in the entire secondary battery, and it is impossible to simulate a local short circuit inside the unit cell as in the present invention.
[95]
10 shows a secondary battery internal short test apparatus that can be used to more appropriately perform the secondary battery internal short test method according to the present invention.
[96]
Referring to FIG. 10, the secondary battery internal short test apparatus 300 includes an explosion-proof chamber 310, a short circuit 320, a measuring instrument 330, and a controller 340. In addition, the secondary battery internal short test apparatus 300 may further include a photographing device (not shown) so as to confirm the state of the internal short test secondary battery 200 before and after the internal short.
[97]
The explosion-proof chamber 310 is capable of loading the secondary battery 200 for an internal short circuit test into the internal space. The explosion-proof chamber 310 can be viewed as a sample chamber equipped with a safety door. The explosion-proof chamber 310 is provided to block the outside and the inside to protect a worker and its surroundings in case of an accidental ignition or explosion of a secondary battery. If the secondary battery is exploded or toxic gas is generated according to the internal short-circuit test of the secondary battery in the explosion-proof chamber 310, the inside of the explosion-proof chamber 310 is sealed so that no toxic gas is leaked to the outside of the explosion-proof chamber 310. It is desirable if it can be made. A configuration for discharging and purifying toxic gases may be further provided. A separate observation window may be provided to facilitate internal observation, or a part or all of the explosion-proof chamber 310 may be formed as a transparent case. The size of the explosion-proof chamber 310 may be designed in consideration of the foot print of the secondary battery internal short test apparatus 300.
[98]
The short circuit 320 is connected to the positive-side metal terminal 210 and the negative-side metal terminal 220 of the secondary battery 200 for an internal short-circuit test, and includes a switch 322 and a resistor 324. The switch 322 is for opening and closing the short circuit 320 and is configured to open and close at an arbitrary timing. In particular, a switch capable of responding to the current flowing during a short-circuit test, can be turned on/off in a stepped manner when switching from off (open) to on (closed), generates less noise, and has excellent switching characteristics.
[99]
The resistor 324 is also capable of responding to the current flowing during the short-circuit test, and generally used as a shunt resistor can be used. The resistor 324 can be variably set to various values.
[100]
The measuring instrument 330 measures the current I flowing through the short circuit 320.
[101]
The controller 340 controls the on/off of the switch 322. In addition, the switch 322 is normally off, including when connecting the short circuit 320 to the secondary battery 200 for internal short circuit test, and can be switched open or closed by control by the controller 340 or manual control. .
[102]
Preferably, the secondary battery internal short test apparatus 300 further includes a power supply 350 and a load 360. The power supply 350 or the load 360 may be connected between the positive lead 118 and the negative lead 128 of the secondary battery 200 for internal short circuit test. The secondary battery internal short test apparatus 300 may further include a measuring instrument 370 that measures a voltage V between the positive lead 118 and the negative lead 128.
[103]
On the other hand, an appropriate control unit (not shown) for convenient and effective driving of the power supply 350, the load 360, the measuring instruments 330, 370, etc. may be further included separately or integrated with each component. For example, the controller 340 may be responsible for all of these functions. The controller 340 is a general computer, and includes software for driving and controlling them, and may be for setting and storing various data values. Various interface devices, such as display means such as a monitor and user input means such as a keyboard, may be further included in the secondary battery internal short test apparatus 300. These can be implemented with a conventional commercial product, for example, through a monitor, it is possible to look at information such as the current test situation, test quantity, etc., and the measuring instruments 330 and 370 are the controller 340 ) To print to the monitor. The controller 340 may also be provided in the form of a control instrument incorporating the functions of the measuring instruments 330 and 370. At this time, since it is preferable that the control instrument evaluates the state of the secondary battery 200 for the internal short test during the internal short test, the above-described physical quantities such as current and voltage are measured and the switch 322 is switched. It can be configured to control. The control instrument does not need to be configured as a single device as hardware, but may be a combination of a plurality of devices. For example, the control instrument may be a general multi-channel current/voltage measuring device used for charging and discharging a secondary battery. In this case, the measurement method of the measuring instrument 330 may indicate measurement through one channel, and the measurement method of the instrument 370 may indicate measurement through another channel.
[104]
The method for evaluating an internal short circuit using the secondary battery internal short evaluation apparatus 300 may be performed in various ways, but the present invention is not limited thereto.
[105]
First method
[106]
The secondary battery 200 for internal short circuit test is loaded into the explosion-proof chamber 310.
[107]
Then, by simply contacting the other end of the anode-side metal terminal 210 and the other end of the cathode-side metal terminal 220 to cause an internal short circuit, a method of observing the state of the secondary battery 200 for a short circuit test at that time It can be by.
[108]
Method 2
[109]
As another example, after loading the secondary battery 200 for an internal short circuit test into the explosion-proof chamber 310, a short circuit 320 is applied to the other end of the anode-side metal terminal 210 and the cathode-side metal terminal 220. Connect. At this time, the switch 322 of the short circuit 320 is connected to the positive metal terminal 210 and the negative metal terminal 220 in the off state. Then, the switch 322 is turned on to cause an internal short circuit in the secondary battery 200 for the internal short circuit test, and the current flowing through the short circuit 320 is measured with a measuring instrument 330.
[110]
3rd way
[111]
As another example, after loading the secondary battery 200 for the internal short circuit test into the explosion-proof chamber 310, the short circuit 320 is connected as described above. A measuring instrument 370 that measures the voltage between the positive lead 118 and the negative lead 128 is also connected.
[112]
While the switch 322 of the short circuit 320 is turned on to cause an internal short, the voltage between the positive lead 118 and the negative lead 128 is measured with the measuring instrument 370 (corresponds to the commonly measured full cell voltage. ). The current flowing through the short circuit 320 is measured with a measuring instrument 330.
[113]
Method 4
[114]
As another example, after loading the secondary battery 200 for the internal short circuit test into the explosion-proof chamber 310, the short circuit 320 is connected as described above. A measuring instrument 370 that measures the voltage between the positive lead 118 and the negative lead 128 is also connected. A power supply 350 or a load 360 is also connected between the positive lead 118 and the negative lead 128.
[115]
When the power supply 350 is connected, the internal short test may be performed by turning on the switch 322 of the short circuit 320 while charging the secondary battery 200 for the internal short test. The current flowing through the short circuit 320 is measured with a measuring instrument 330, and a voltage between the positive lead 118 and the negative lead 128 is measured with a measuring instrument 370.
[116]
When the load 360 is connected, the internal short test may be performed by turning on the switch 322 of the short circuit 320 while discharging the secondary battery 200 for the internal short test. The current flowing through the short circuit 320 is measured with a measuring instrument 330, and a voltage between the positive lead 118 and the negative lead 128 is measured with a measuring instrument 370.
[117]
During the internal short test, whether the secondary battery 200 for the internal short test is exploded or ignited is also checked. After the test, when the secondary battery 200 for internal short-circuit test is stabilized, it is collected from the explosion-proof chamber 310 and dismantled to analyze its internal components. If the secondary battery 200 for internal short circuit test is not exploded or ignited, a secondary battery manufactured including a positive electrode plate 110, a negative electrode plate 120, a separator 130, and an electrolyte constituting the internal short test secondary battery 200 Is determined to be suitable. If the secondary battery 200 for the internal short circuit test is provided with a current interrupting means or the like capable of suppressing the destruction of the battery even when an internal short occurs, it is determined that the current interrupting means or the like has been properly operated.
[118]
If, as a result of the opposite result, there is an explosion or ignition of the secondary battery 200 for the internal short test as a result of simulating the internal short circuit, the positive plate 110, the negative plate 120, and the separator constituting the secondary battery 200 for the internal short test (130) and the secondary battery manufactured including the electrolyte is unsuitable. In addition, if the secondary battery 200 for internal short circuit test is provided with a current interrupting means or the like capable of suppressing destruction of the battery even when an internal short occurs, it is determined that the current interrupting means or the like is not appropriate. Accordingly, it is determined that it is necessary to change the elements constituting the secondary battery or to change the design conditions such as the current blocking means, and take action.
[119]
In addition, various forms of safety evaluation that are not described herein will be possible in the verification of the safety evaluation items after the secondary battery design stage or secondary battery manufacturing. It should be viewed as becoming.
[120]
According to an embodiment, one secondary battery for internal short test is configured to test only one type of internal short. For example, the secondary battery 200 for an internal short test described with reference to FIGS. 4 to 6 corresponds to a configuration capable of simulating only the internal short (S D ) between the positive active material layer 114 and the negative active material layer 124 . . If a secondary battery including each unit cell as shown in FIGS. 7A to 7D is separately manufactured, it will be a secondary battery capable of testing only each internal short circuit.
[121]
Depending on the embodiment, it may be configured to test two or more types of internal shorts in one secondary battery for internal short test. 11 is an exploded perspective view of a secondary battery for an internal short test according to another embodiment of the present invention, and FIG. 12 is an exploded perspective view of a secondary battery for an internal short test according to another embodiment of the present invention. In FIGS. 11 and 12, only the unit cell portion is shown, and the secondary batteries for the internal short test are positive lead 118, negative lead 128, sealing tape S, and battery case 230 as described with reference to FIG. 5. ) May be further included.
[122]
For example, as shown in FIG. 11, the secondary battery 200' for internal short-circuit test includes a positive first metal terminal 211, a positive second metal terminal 212 in one unit cell 101', The cathode-side first metal terminal 221 and the cathode-side second metal terminal 222 are both included. Through an appropriate combination between these metal terminals, all of a desired type of internal short can be generated in one secondary battery 200 ′ for internal short test. For example, when the other end of the first metal terminal 211 on the positive electrode and the other end of the first metal terminal 221 on the negative electrode contact each other, an internal short circuit between the positive electrode current collector 112 and the negative electrode current collector 122 (S A ) Can be used for simulating, and when the other end of the first metal terminal 211 on the positive electrode and the other end of the second metal terminal 222 on the negative electrode contact each other, the positive electrode current collector 112-the negative electrode active material layer 124 It can be used to simulate the internal short circuit (S B ). Likewise, when the other end of the positive second metal terminal 212 and the other end of the negative first metal terminal 221 are in contact with each other, the internal short S C between the positive active material layer 114 and the negative current collector 122 is formed. It can be simulated, and when the other end of the second metal terminal 212 on the anode side and the other end of the second metal terminal 222 on the cathode side contact each other, the inner short between the anode active material layer 114 and the cathode active material layer 124 (S D ) can be copied.
[123]
In addition, as shown in FIG. 12, the secondary battery 200" for internal short test includes two types of unit cells 101' and 101". An appropriate separator (not shown) may be further included between the two unit cells 101 ′ and 101 ″. One unit cell 101 ′ includes a second metal terminal 212 on the anode side as described in FIG. 6. And the second metal terminal 222 on the negative side, and the other unit cell 101" includes the first metal terminal 211 on the positive side and the first metal terminal 221 on the negative side. , From the unit cell 101 ′, the other end of the anode-side second metal terminal 212 and the other end of the cathode-side second metal terminal 222 are brought into contact with each other to form a positive electrode active material layer 114-a negative electrode active material layer 124. ) , it is possible to simulate the internal short (S D ), and from the other unit cell 101", the other end of the positive first metal terminal 211 and the other end of the negative first metal terminal 221 It can be used for the purpose of simulating the internal short (S A ) between the positive electrode current collector 112 and the negative electrode current collector 122 by making contact . You can see from
[124]
In this way, in one secondary battery for internal short test, the positive first metal terminal 211, the positive second metal terminal 212, the negative first metal terminal 221 and the negative second metal terminal 222 are all If it is configured to be included, it would be very desirable if the terminals were formed to be distinguishable with the naked eye from each other as described above, so that a desired pair of terminal combinations could be easily selected.
[125]
When comparing the conventional ISC device 1 shown in FIG. 1 with the secondary battery 200 for an internal short circuit test according to the present invention, the present invention has the following advantages.
[126]
In the present invention, the metal terminals 210 and 220 that are comparable to the copper disk 10 and the aluminum disk 40 of the ISC device 1 are located outside the secondary battery, and the wax layer 30 of the ISC device 1 It differs from the ISC element 1 in that there is no wax layer corresponding to the. In the present invention, since the other end of the metal (short-circuit switch metal) that may cause a short circuit is formed on the outside of the secondary battery, it is possible to accurately control the timing of the internal short circuit. In the case of the conventional ISC device 1, an experiment is possible only under a high temperature condition in which the wax layer 30 is melted, but the present invention has no temperature limitation.
[127]
In the case of the conventional ISC device 1, once a short circuit occurs, it is difficult to reuse the secondary battery including the ISC device 1, and it is difficult to generate an internal short after the cycle proceeds. In contrast, according to the present invention, since a short circuit is generated after the secondary battery 200 for internal short test is manufactured, there is an advantage that the internal short test can be performed after deliberately deteriorating the secondary battery 200 for internal short test. According to the present invention, each unit according to the occurrence of an internal short circuit between a secondary battery immediately after manufacture (a.k.a. a secondary battery including a fresh unit cell) and a secondary battery after a cycle (a secondary battery including a degenerated unit cell) It is effective to analyze the difference in safety of cells. For example, it is possible to analyze the difference between the internal short-circuit between the unit cell in the BOL (Birth Of Life) state and the unit cell in the EOL (End Of Life) state, meaning that it is absolutely not possible when the ISC element (1) is used. There is.
[128]
In the conventional ISC device 1, as described with reference to FIG. 2, since a hole H must be made in the separator 130 of the secondary battery to be inserted, the separator 130 is damaged. In addition, if the ISC element 1 is inserted and assembled during the secondary battery manufacturing step, the wax layer 30 melts in the process of lamination and high-temperature aging, so the manufactured secondary battery must be disassembled and inserted before use. In contrast, the secondary battery 200 for an internal short circuit test according to the present invention does not cause damage to the separator 130 and maintains the anode-side metal terminal 210 and the cathode-side metal terminal 220 as it is, while following general secondary battery manufacturing steps. Just add it. It is no different from implementing a structure that can cause an internal short circuit from the secondary battery manufacturing stage in-situ.
[129]
Hereinafter, the present invention will be described in more detail through experimental examples of the present invention. However, the experimental examples below are provided only to aid understanding of the present invention, and the present invention is not limited to the experimental examples below.
[130]
13 is a photograph of a secondary battery for an internal short test according to an experimental example of the present invention, and FIGS. 13A to 13D are sequentially dismantling the completed secondary battery for an internal short test in order to show the lamination process by manufacturing steps. The internal pictures taken as the sun goes down are arranged in the reverse order of disassembly, and FIG. 13E shows the final completed picture.
[131]
Referring first to FIG. 13(e) and describing the finished state first, the positive lead 118 and the negative lead 128 are exposed on one side of the secondary battery 200 for internal short circuit test, and the positive lead 118 and The anode-side metal terminal 210 and the cathode-side metal terminal 220 are formed to be exposed on the other side where the cathode lead 128 is not formed.
[132]
In (a) of FIG. 13, one end of the negative electrode-side metal terminal 220 can be seen on the negative electrode plate 120. In (b), it can be seen that one end of the anode-side metal terminal 210 is placed on the separator 130. One ends of each of the metal terminals 210 and 220 were aligned within the secondary battery 200 for internal short circuit test. (c) shows a state in which the positive plate 110 is placed thereon. (d) shows that an additional separator 130' is included. In the photo, the yellow part indicates the insulation treatment. Inside the secondary battery 200 for the internal short test, a portion of the metal terminals 210 and 220 that did not directly contact each electrode plate 110 and 120 was insulated.
[133]
14 is a photograph of an element implementing a short circuit used in an experimental example of the present invention. For a simple experiment, a short circuit (320 in FIG. 10) including a switch (322 in FIG. 10) and a resistor (324 in FIG. 10) was implemented on a breadboard 326 (breadboard). As is well known, breadboards are solderless devices that can be used and reused to build (usually temporary) prototypes of electronic circuits. A typical breadboard has a strip of interconnecting electrical terminals, known as a bus strip, and one or both sides, like part of the main unit or an isolated block, are fitted to extend the power line. The breadboard 326 used in the experimental example is composed of a plastic perforated block with a spring clip under the hole. An integrated circuit, which is a dual in-line package (DIP), can be inserted by spreading the centerline of the block. In order to complete the circuit phase, a pin-type resistor 324 (R load ), a pin-type switch 322, and an internal connection wire were inserted into the holes of the breadboard 326.
[134]
Short circuit by providing a sensing terminal 328 on the breadboard 326 so that the voltage can be measured by connecting to the positive metal terminal 210 and the negative metal terminal 220 of the secondary battery 200 for internal short circuit test. A circuit implementation device 329 was fabricated. This was connected to the secondary battery 200 for an internal short test to perform an internal short test. Resistor 324 was used by changing 90mΩ, 50mΩ, and 35mΩ, thereby adjusting the resistance value of the short circuit 320 to a desired value. The switch 322 caused a short circuit to occur due to manual operation on, and to release the short circuit by manual operation off.
[135]
15 is a schematic diagram of a state in which a secondary battery for an internal short test and a short circuit implementation element are connected according to an experimental example of the present invention.
[136]
As shown, the short circuit implementation element 329 was connected to the secondary battery 200 for an internal short circuit test in the off state of the switch 322. The voltage between the positive lead 118 and the negative lead 128 of the secondary battery 200 for internal short test is connected to a general multi-channel current/voltage measuring device used for charging and discharging tests of secondary batteries (full cell voltage). ) Was measured in channel 1 (Ch1. V Full cell ). The voltage between the positive-side metal terminal 210 and the negative-side metal terminal 220 was measured in channel 1 and other channel 2 (Ch2. V load ).
[137]
16 shows the full cell voltage drop measured by the internal short test in the experimental example of the present invention.
[138]
16 is a measurement of the full cell voltage immediately after turning on the switch 322 in the connected state as in FIG. 15 (With R load ). For comparison, a value measured after subtracting the resistor 324 from the short circuit implementation element 329 is also shown (No R load ). As shown in FIG. 16, a voltage drop over time is observed from immediately after the positive-side metal terminal 210 and the negative-side metal terminal 220 are in contact with each other (time 0 sec) by the switch 322 on. The voltage drop means the discharge of the secondary battery 200 for the internal short circuit test, which proves that the internal short occurs. It can be seen that the difference between the presence of the resistor 324 and the absence of the resistor 324 can also be detected. From the observation of the full-cell voltage drop, according to the present invention, it is confirmed that an internal short circuit occurs even when the positive-side metal terminal 210 and the negative-side metal terminal 220 are simply contacted from the outside of the secondary battery 200 for internal short-circuit test. Could Since the difference in voltage drop depending on the presence or absence of the resistor 324 was confirmed, it was confirmed that measuring the current flowing across the resistor 324 also enables the measurement of short-circuit current and short-circuit resistance according to each type of internal short circuit.
[139]
17 is a graph showing changes in short-circuit current by performing an internal short-circuit test on two secondary batteries for internal short-circuit tests having different positive electrode active material layers according to the experimental example of the present invention.
[140]
In order to cause an internal short for two types of positive electrodes, one internal short test secondary battery uses active material A to make a positive active material layer, and the other internal short test secondary battery uses a different type of active material B from active material A to create a positive active material layer. It was prepared in the same manner, except that it was prepared. Thereafter, the current applied across the resistor 324 was measured while performing the internal short test by making the connection as shown in FIG. 15.
[141]
Referring to FIG. 17, which is the result, the short-circuit current is measured differently in the secondary battery for internal short-circuit test using active material A and the secondary battery for internal short-circuit test using active material B. I could get it. That is, according to the present invention, it was confirmed that the internal short-circuit pattern, which varies depending on the type of the positive electrode active material layer, can be meaningfully identified and measured. As described above, the present invention can also measure the difference in short-circuit current resulting from the difference in the internal short due to the change of the active material layer, and it can be seen that it can be used for the purpose of checking the internal short from the secondary battery design stage.
[142]
As described above, although the present invention has been described by limited embodiments and drawings, the present invention is not limited thereto, and the technical idea of ​​the present invention and the following by those of ordinary skill in the art to which the present invention pertains. It goes without saying that various modifications and variations are possible within the equivalent range of the claims to be described.
Claims
[Claim 1]
A positive electrode plate having a positive electrode active material layer formed on the positive electrode current collector; A negative electrode plate having a negative electrode active material layer formed on the negative electrode current collector; And a separator interposed between the positive electrode plate and the negative electrode plate; and in any one of the unit cells, one end is positioned between the positive electrode plate and the separator, and the other end is external to the unit cell. A positive electrode side metal terminal that comes out; And a negative metal terminal in which one end portion is positioned between the negative electrode plate and the separator and the other end extends to the outside of the unit cell in the unit cell having the positive metal terminal, and the other end of the positive metal terminal and A secondary battery for an internal short circuit test used for the purpose of causing an internal short circuit of the unit cell by contacting the other ends of the negative metal terminal with each other.
[Claim 2]
According to claim 1, A positive electrode tab formed on the positive electrode plate and an anode lead connected to one end of the positive electrode tab; A negative electrode tab formed on the negative electrode plate and a negative electrode lead having one end connected to the negative electrode tab; And a pouch-type battery case accommodating and sealing the unit cell and the electrolyte, wherein the other ends of the positive electrode lead, the negative electrode lead, the positive electrode-side metal terminal and the negative electrode-side metal terminal are exposed to the outside of the battery case. A secondary battery for internal short-circuit test characterized by.
[Claim 3]
The interior according to claim 2, wherein the anode-side metal terminal and the cathode-side metal terminal are formed to be visually distinguishable between the anode-side metal terminal, the cathode-side metal terminal, and the anode lead and the cathode lead. Secondary battery for short circuit test.
[Claim 4]
The anode-side metal terminal of claim 1, wherein the anode-side metal terminal is at least one of a cathode-side first metal terminal, the one end of which is located on the positive electrode current collector, and the anode-side second metal terminal, where the one end is on the positive electrode active material layer. Wherein the negative electrode-side metal terminal is at least one of a negative electrode-side first metal terminal at one end of the negative electrode current collector and a negative electrode-side second metal terminal at the one end of the negative electrode active material layer. Secondary battery for short circuit test.
[Claim 5]
The secondary battery according to claim 4, wherein the number of unit cells is plural, and only one of the unit cells includes the anode-side metal terminal and the cathode-side metal terminal.
[Claim 6]
The method of claim 4, wherein the number of unit cells is plural, and one of the anode-side first metal terminal and the anode-side second metal terminal, and a cathode-side first metal terminal and a cathode-side agent in one of the unit cells. 2 Any one of the metal terminals is included, and the other one of the positive first metal terminal and the positive second metal terminal and the other one of the negative first metal terminal and the negative second metal terminal in another unit cell The secondary battery for internal short test, characterized in that included.
[Claim 7]
The unit cell of claim 1, wherein one end of the positive metal terminal and the negative metal terminal is aligned at the same position in a vertical direction inside the unit cell, and the other end of the positive metal terminal and the negative metal terminal is the unit cell. The secondary battery for internal short-circuit test, characterized in that formed to be spaced apart from each other in a horizontal direction outside of.
[Claim 8]
The secondary battery according to claim 7, wherein the positive-side metal terminal and the negative-side metal terminal are formed in a curved shape on a plane.
[Claim 9]
A positive electrode plate having a positive electrode active material layer formed on the positive electrode current collector; A negative electrode plate having a negative electrode active material layer formed on the negative electrode current collector; And a separator interposed between the positive electrode plate and the negative electrode plate, for a secondary battery including at least one unit cell including: Providing an anode-side metal terminal protruding from the outside of the unit cell; (b) in the unit cell having the anode-side metal terminal, providing a cathode-side metal terminal having one end positioned between the anode plate and the separator and the other end extending out of the unit cell; And (c) causing an internal short circuit of the unit cell by contacting the other end of the positive metal terminal and the other end of the negative metal terminal with each other.
[Claim 10]
The method of claim 9, wherein the step (c) comprises: connecting a short circuit including a switch and a resistor to the positive metal terminal and the negative metal terminal in a state in which the switch is off; And turning on the switch to cause an internal short circuit of the unit cell, and measuring a current flowing through the short circuit.
[Claim 11]
The method of claim 10, wherein the secondary battery comprises: a positive electrode tab formed on the positive electrode plate and a positive electrode lead having one end connected to the positive electrode tab; A negative electrode tab formed on the negative electrode plate and a negative electrode lead having one end connected to the negative electrode tab; And a pouch-type battery case accommodating and sealing the unit cell and the electrolyte, wherein the other ends of the positive electrode lead, the negative electrode lead, the positive electrode-side metal terminal and the negative electrode-side metal terminal are exposed to the outside of the battery case. And measuring a voltage between the positive lead and the negative lead while causing the internal short in step (c).
[Claim 12]
The method of claim 11, wherein the secondary battery is charged by connecting a power source between the positive lead and the negative lead, or the step (c) is performed while discharging the secondary battery by connecting a load between the positive lead and the negative lead. Secondary battery internal short test method, characterized in that.
[Claim 13]
10. The method of claim 9, wherein the positive electrode-side metal terminal is at least one of a positive electrode-side first metal terminal having one end of the positive electrode current collector and a positive electrode-side second metal terminal having the one end of the positive electrode active material layer. The negative electrode-side metal terminal is provided such that the one end portion is at least one of a negative electrode-side first metal terminal disposed on the negative electrode current collector and the negative electrode-side second metal terminal disposed on the negative electrode active material layer. Secondary battery internal short test method.
[Claim 14]
An explosion-proof chamber capable of loading the secondary battery for an internal short-circuit test according to any one of claims 1 to 8; A short circuit connected to a positive metal terminal and a negative metal terminal of the secondary battery for internal short test, and including a switch and a resistance; A measuring instrument measuring the current flowing through the short circuit; And a controller for controlling on-off of the switch.
[Claim 15]
The method of claim 14, further comprising: a power source or a load connected between the positive electrode lead and the negative electrode lead of the secondary battery for internal short circuit test; And a measuring device for measuring a voltage between the positive lead and the negative lead.