Title of invention: Cylindrical secondary battery
Technical field
[One]
Cross-reference with related application(s)
[2]
This application claims the benefit of priority based on Korean Patent Application No. 10-2018-0148564 filed on November 27, 2018, and all contents disclosed in the documents of the Korean patent application are incorporated as part of this specification.
[3]
The present invention relates to a cylindrical secondary battery, and more specifically, to a cylindrical secondary battery with enhanced heat dissipation function.
Background
[4]
In recent years, as the demand for portable electronic products such as laptops, video cameras, portable telephones, etc. is rapidly increasing, and development of electric vehicles, energy storage batteries, robots, satellites, etc., There is a lot of research on it.
[5]
Examples of such secondary batteries include nickel cadmium batteries, nickel hydride batteries, nickel zinc batteries, and lithium secondary batteries. Among these, lithium secondary batteries are widely used in the field of advanced electronic devices because of the advantages of free charging and discharging, a very low self-discharge rate, a high operating voltage, and a high energy density per unit weight, as a memory effect rarely occurs compared to nickel-based secondary batteries. have.
[6]
In general, a lithium secondary battery has a structure in which a unit cell composed of a positive electrode, a negative electrode, and a separator interposed therebetween is stacked or wound, and is embedded in a case of a metal can or laminate sheet, and an electrolyte is injected or impregnated therein Is composed.
[7]
Electrode assemblies having a positive electrode/separator/cathode structure constituting a secondary battery are largely classified into a jelly roll type (winding type) and a stack type (stack type) according to their structure. The jelly-roll type is a structure in which a separator is wound between a long sheet-shaped positive electrode and a negative electrode coated with an active material, and the stack type is a structure in which a plurality of positive and negative electrodes of a predetermined size are sequentially stacked with the separator interposed therebetween.
[8]
In recent years, in order to implement a high-power and high-capacity model, components used are becoming thinner, and as a result, secondary batteries with low resistance and high capacity are increasing. However, as the resistance decreases and the capacity increases, a higher current is applied for a longer period of time, so that the problem of heat generation of the secondary battery due to high rate discharge or an external short circuit has emerged as a more important task.
[9]
In order to overcome this problem, research on a secondary battery capable of effectively controlling heat generation of an electrode tab is required.
Detailed description of the invention
Technical challenge
[10]
An object to be solved by the present invention is to provide a cylindrical secondary battery for reducing resistance and increasing the stability of a battery cell.
[11]
However, the problems to be solved by the embodiments of the present invention are not limited to the above-described problems and may be variously extended within the scope of the technical idea included in the present invention.
Means of solving the task
[12]
A cylindrical secondary battery according to an embodiment of the present invention includes an electrode assembly including a negative electrode sheet, a positive electrode sheet, and a separator, wherein the separator is located at the outermost side of the electrode assembly, and an electrode tab located inside the separator is A metal layer attached to one of the negative electrode sheet and the positive electrode sheet and positioned between the electrode tab and the separator includes an adhesive material.
[13]
The electrode tab may include a tab body attached to one of the negative electrode sheet and the positive electrode sheet, and a protrusion extending from one end of the electrode assembly, and the protrusion may be welded to the metal layer.
[14]
The tab body and the metal layer may be bonded to each other by the adhesive material.
[15]
The electrode tab may be a negative electrode tab.
[16]
The metal layer may be a rod-shaped copper foil.
[17]
The electrode tab and the metal layer may overlap at an end of the separator.
[18]
The metal layer may be connected to the electrode tab and the separator by an adhesive layer formed of the adhesive material.
[19]
The cylindrical secondary battery may further include an insulating tape fixing the boundary of the separator at the end of the separator.
[20]
The insulating tape and the metal layer may not overlap.
[21]
A device according to another embodiment of the present invention includes the cylindrical secondary battery described above as a power source.
Effects of the Invention
[22]
According to embodiments, by additionally forming a metal layer containing an adhesive component on the negative electrode tab located outside the jelly roll, the jelly roll is fixed and the negative electrode tab thickness is increased to reduce resistance and apply a high current or a short circuit occurs from the outside. It is possible to implement a cylindrical secondary battery capable of increasing the stability and life of the battery cell by diffusing the heat generated.
Brief description of the drawing
[23]
1 is an exploded perspective view showing a state before an electrode assembly according to an embodiment of the present invention is wound.
[24]
FIG. 2 is a perspective view illustrating a state after the electrode assembly of FIG. 1 is wound.
[25]
3 is a partial plan view showing an enlarged portion A of FIG. 2.
[26]
4 is a view as viewed from the X direction of FIG. 2.
[27]
5 is a partial plan view of an electrode assembly according to another embodiment of the present invention.
[28]
6 is a partial plan view of an electrode assembly according to another embodiment of the present invention.
[29]
7 is a cross-sectional view taken along line Y-Y' of FIG. 6.
[30]
8 is a perspective view showing an electrode assembly according to another embodiment of the present invention.
Mode for carrying out the invention
[31]
Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art may easily implement the present invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein.
[32]
In order to clearly describe the present invention, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification.
[33]
In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of description, and the present invention is not necessarily limited to the illustrated bar. In the drawings, the thicknesses are enlarged in order to clearly express various layers and regions. And in the drawings, for convenience of description, the thickness of some layers and regions is exaggerated.
[34]
In addition, when a part such as a layer, film, region, plate, etc. is said to be "on" or "on" another part, this includes not only "directly above" another part, but also a case where another part is in the middle. . Conversely, when one part is "right above" another part, it means that there is no other part in the middle. In addition, to be "above" or "on" the reference part means that it is located above or below the reference part, and means that it is located "above" or "on" in the direction opposite to gravity. no.
[35]
In addition, throughout the specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated.
[36]
In addition, throughout the specification, the term "on a plane" means when the object portion is viewed from above, and when the object portion is viewed from above, it means when the object portion is viewed from the side.
[37]
1 is an exploded perspective view showing a state before an electrode assembly according to an embodiment of the present invention is wound. FIG. 2 is a perspective view illustrating a state after the electrode assembly of FIG. 1 is wound.
[38]
1 and 2, a secondary battery according to an embodiment of the present invention includes an electrode assembly 100 including a negative electrode sheet 110, a positive electrode sheet 120, and a separator 130. The electrode assembly 100 may have a jelly-roll type structure. At this time, the separator 130 is interposed between the negative electrode sheet 110 and the positive electrode sheet 120, in the order of the positive electrode sheet 120, the separator 130, and the negative electrode sheet 110 in a direction from the center to the outside. Jelly-roll structures may be formed, and at least one such structure may be present. At this time, the separator 130s is positioned on the outermost side of the electrode assembly 100.
[39]
An electrode tab may be attached to the positive electrode sheet 120 and the negative electrode sheet 110, respectively, and the electrode tabs include a negative electrode tab 140 attached to the negative electrode sheet 110 and a positive electrode tab attached to the positive electrode sheet 120 ( 160).
[40]
In this embodiment, the negative electrode sheet 110 is located adjacent to the separator 130 inside the separator 130s located at the outermost part of the electrode assembly 100, and the negative electrode tab 140 is attached to the negative electrode sheet 110. I can. According to the present embodiment, the metal layer 145 may be formed between the cathode tab 140 and the separator 130s positioned at the outermost side. The metal layer 145 includes an adhesive material. The adhesive material may include an acrylic material.
[41]
The metal layer 145 may be formed of a rod-shaped copper foil. The cathode tab 140 and the metal layer 145 may be disposed to overlap each other at an end of the separation membrane 130s positioned at the outermost side. In this case, the metal layer 145 may contact the cathode tab 140 and the separator 130s positioned at the outermost side. The metal layer 145 may include a separate adhesive layer formed of an adhesive material and may contact the negative electrode tab 140 and the separator 130s through the adhesive layer.
[42]
Although not shown, one or more positive electrode tabs and negative electrode tabs may be additionally attached for high-power models. In a secondary battery of a high-power and high-capacity model, when a large current flows within a short time due to high rate discharge, overcharge, external short circuit, etc., a lot of heat is generated in the electrode tab, particularly the negative electrode tab 140 due to current concentration. In the secondary battery, charging or discharging occurs continuously and repeatedly due to an internal electrochemical reaction, and thus, when the secondary battery becomes high in capacity, heat generation due to charging and discharging increases dramatically. Due to such heat generation, the separator 130 or the like may be damaged, leading to an internal short circuit, and a temperature deviation inside the secondary battery may be caused, leading to deterioration of the performance of the secondary battery.
[43]
In particular, in the case of the negative electrode tab 140, which has a particularly high resistance among internal components of the secondary battery, the heat generation is greatest. In the case of a high-power battery cell, a high current is applied to the battery cell, and since the heat of the jelly-roll generated at this time can be radiated to the battery case formed of a metal material through the electrode tab, it is necessary to lower the heat and temperature of the electrode tab area. It is important.
[44]
The metal layer 145 according to the present exemplary embodiment described above may effectively dissipate heat generated from the negative electrode tab 140 so as to solve the heat generation problem. In addition, since the metal layer 145 contains an adhesive material, the end of the separator 130s positioned at the outermost side is fixed, thereby maintaining the shape of the electrode assembly 100 of the jelly-roll type ) Can be prevented from loosening due to internal stress. In addition, since the metal layer 145 including copper has an effect of increasing the thickness of the negative electrode tab 140, it is possible to reduce concentration of heat on the negative electrode tab 140 by reducing resistance.
[45]
In the above, it has been described that the negative electrode sheet 110 is adjacent to the separator 130s positioned at the outermost side, but the positive electrode sheet 120 may be located at the position where the negative electrode sheet 110 is formed. In this case, the positive electrode sheet 120 ), the negative electrode sheet 110 is disposed, and a jelly-roll structure may be formed in the order of the negative electrode sheet 110, the separator 130, and the positive electrode sheet 120 along a direction from the center toward the outside. In other words, the anode sheet 120 may be positioned adjacent to the separator 130 inside the separator 130s located at the outermost side. Although it is preferable to apply the metal layer 145 according to the present embodiment described above as heat is concentrated in the negative electrode tab 140, heat may also be generated in the positive electrode tab 160, so that the separator 130s located at the outermost side It is possible to form a metal layer 145 between the anode tab 160 attached thereto and the outermost separator 130s while the anode sheet 120 is positioned adjacent to the separator 130 inside. In this case, the metal layer 145 may be an aluminum foil and may include an adhesive material.
[46]
3 is a partial plan view showing an enlarged portion A of FIG. 2. 4 is a view as viewed from the X direction of FIG. 2.
[47]
3 and 4, the negative electrode tab 140 according to the present embodiment is attached on the negative electrode sheet 110 located directly inside the outermost separator 130s. The negative electrode tab 140 may have a bar shape and includes a protrusion 140p extending from one end of the electrode assembly 100. A metal layer 145 is formed directly on the negative electrode tab 140, and the metal layer 145 may be formed to cover the left and right surfaces of the negative electrode tab 140. Here, the metal layer 145 may extend not only on the tab body of the cathode tab 140 but also on the protrusion 140P.
[48]
In this embodiment, the metal layer 145 may be bonded to the cathode tab 140 and the outermost separator 130s respectively positioned on the upper and lower surfaces of the metal layer 145 by an adhesive material included in the metal layer 145. In this way, the end of the outermost separator 130s is fixed by the metal layer 145 including the adhesive material to maintain the shape of the electrode assembly 100 of the jelly-roll type structure, so that the electrode assembly 100 is caused by internal stress. It can prevent loosening.
[49]
The electrode assembly 100 according to the exemplary embodiment described above may be accommodated in a battery case (not shown) such as a metal can to form a cylindrical secondary battery.
[50]
5 is a partial plan view of an electrode assembly according to another embodiment of the present invention.
[51]
The embodiment of FIG. 5 is substantially the same as the embodiment described with reference to FIGS. 3 and 4, except that the metal layer 145 is not formed on the protrusion 140p of the cathode tab 140 and may be formed only on the tab body.
[52]
6 is a partial plan view of an electrode assembly according to another embodiment of the present invention. 7 is a cross-sectional view taken along line Y-Y' of FIG. 6.
[53]
The embodiments of FIGS. 6 and 7 are substantially the same as those of FIGS. 3 and 4 described above. However, in the following, only the parts with differences will be described. Excluding the differences, the contents described in the embodiments of FIGS. 3 and 4 are applicable to this embodiment.
[54]
6 and 7, the tab body of the negative electrode tab 140 and the metal layer 145 may be adhered to the tab body of the negative electrode tab 140 by an adhesive material included in the metal layer 145. However, in the protrusion 140p of the negative electrode tab 140, the metal layer 145 and the protrusion 140p of the negative electrode tab 140 may be welded to each other to be combined. By such a welding process, the cathode tab 140 and the metal layer 145 are combined, thereby improving capacity. The temperature cut-off may be reached by heat generation, resulting in insufficient capacity being used and the voltage cut-off early. However, according to the present embodiment, when the negative electrode tab 140 and the metal layer 145 are combined through the welding process to increase the heat dissipation effect, the voltage cut-off is prevented early, resulting in improved capacity I can.
[55]
8 is a perspective view showing an electrode assembly according to another embodiment of the present invention.
[56]
Referring to FIG. 8, the insulating tape 300 attached to the outer peripheral surface of the electrode assembly 100 included in the secondary battery according to the embodiment described with reference to FIGS. 3 and 4 is further included. The insulating tape 300 may serve as a finishing tape at the end of the outermost separator 130s. That is, the boundary portion 150 with the separation membrane 130 may be fixed at the end of the outermost separation membrane 130s. The insulating tape 300 may be positioned at an end of the outermost separation layer 130s so as not to overlap with the metal layer 145.
[57]
The insulating tape 300 may include a thermosetting resin selected from the group consisting of polyvinyl chloride, a mixture of nitrile rubber and phenol resin, epoxy resin, polyurethane, and combinations thereof.
[58]
In a state where the insulating tape 300 is attached to the outer circumferential surface of the electrode assembly 100, since the outermost separator 130s is once again fixed by the metal layer 145, the electrode assembly 100 having a jelly-roll type structure is more stable. ) Can be maintained.
[59]
The secondary battery described above can be applied to various devices. Such a device may be applied to a vehicle such as an electric bicycle, an electric vehicle, or a hybrid, but is not limited thereto and may be applied to various devices capable of using a secondary battery.
[60]
Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention defined in the following claims are also present. It belongs to the scope of rights of
[61]
[Explanation of code]
[62]
130, 130s: separator
[63]
140: negative electrode tab
[64]
140p: protrusion
[65]
145: metal layer
Claims
[Claim 1]
An electrode assembly including a negative electrode sheet, a positive electrode sheet, and a separator, wherein the separator is located at the outermost side of the electrode assembly, and an electrode tab located inside the separator is attached to one of the negative electrode sheet and the positive electrode sheet. And a metal layer positioned between the electrode tab and the separator includes an adhesive material.
[Claim 2]
The cylindrical secondary battery of claim 1, wherein the electrode tab includes a tab body attached to one of the negative electrode sheet and the positive electrode sheet, and a protrusion extending from one end of the electrode assembly, and the protrusion is welded to the metal layer.
[Claim 3]
The cylindrical secondary battery of claim 2, wherein the tab body and the metal layer are bonded to each other by the adhesive material.
[Claim 4]
The cylindrical secondary battery of claim 1, wherein the electrode tab is a negative electrode tab.
[Claim 5]
The cylindrical secondary battery of claim 4, wherein the metal layer is a rod-shaped copper foil.
[Claim 6]
The cylindrical secondary battery of claim 1, wherein the electrode tab and the metal layer overlap at an end of the separator.
[Claim 7]
The cylindrical secondary battery of claim 6, wherein the metal layer is connected to the electrode tab and the separator by an adhesive layer formed of the adhesive material.
[Claim 8]
The cylindrical secondary battery of claim 1, further comprising an insulating tape fixing the boundary of the separator at the end of the separator.
[Claim 9]
The cylindrical secondary battery of claim 8, wherein the insulating tape and the metal layer do not overlap.
[Claim 10]
A device comprising the cylindrical secondary battery according to any one of claims 1 to 9 as a power source.