The present invention relates to an electrode assembly including an anti-disconnection layer and a manufacturing method thereof, and more particularly, to an electrode assembly including an anti-disconnection layer formed by horizontally bending an extended negative current collector and a method of manufacturing the same.
background art
[3]
Recently, secondary batteries capable of charging and discharging have been widely used as energy sources for wireless mobile devices. In addition, secondary batteries are attracting attention as an energy source for electric vehicles, hybrid electric vehicles, etc., which are proposed as a solution to air pollution such as existing gasoline vehicles and diesel vehicles using fossil fuels. Therefore, the types of applications using secondary batteries are diversifying due to the advantages of secondary batteries, and it is expected that secondary batteries will be applied to more fields and products than now.
[4]
These secondary batteries are sometimes classified into lithium ion batteries, lithium ion polymer batteries, lithium polymer batteries, etc. according to the composition of electrodes and electrolytes. It is increasing. In general, secondary batteries include a cylindrical battery and a prismatic battery in which an electrode assembly is embedded in a cylindrical or prismatic metal can, and a pouch-type battery in which the electrode assembly is embedded in a pouch-type case of an aluminum laminate sheet, depending on the shape of the battery case. The electrode assembly embedded in the battery case is a power generating device capable of charging and discharging, consisting of a positive electrode, a negative electrode, and a separator structure interposed between the positive electrode and the negative electrode. It is classified into a jelly-roll type wound with a separator interposed therebetween, and a stack type in which a plurality of positive and negative electrodes of a predetermined size are sequentially stacked in a state in which a separator is interposed.
[5]
1 is a cross-sectional view showing a state in which disconnection occurs in a conventional laminated structure of an electrode assembly and an anode current collector.
[6]
Referring to FIG. 1 , a conventional electrode assembly 10 has a stacked structure with a separator 3 interposed between an anode 1 and a cathode 2.
[7]
Meanwhile, when a secondary battery including such an electrode assembly is repeatedly charged and discharged, the positive and negative electrodes in the electrode assembly repeat contraction and expansion. In particular, in a general electrode assembly, the length of the anode can be made shorter than the length of the cathode. In this case, as the anode repeats contraction and expansion, the cathode facing the anode with the separator in between is subjected to repeated stress. When fatigue due to such stress accumulates, disconnection occurs due to cracks in the portion of the negative current collector that contacts the end of the positive electrode as shown in FIG. 1 . In this case, the flow of current from the current collector toward the negative electrode tab is interrupted, thereby disturbing the normal operation of the battery. In particular, in the case of a cylindrical battery, there is a case in which a non-coated portion is not formed on the edge of the positive electrode (ie, a free edge). In this case, the edge of the positive electrode is thick, increasing the probability of cracking the negative electrode.
[8]
Meanwhile, Korean Patent Registration No. 10-1629498 discloses that an edge protection tape may be attached to an end of a positive electrode active material layer in order to prevent a short circuit from occurring inside the battery due to stress caused by such a step. However, in this case, when a disconnection occurs in the anode current collector due to a change in the volume of the anode, there is still a problem that the flow of current in the anode is cut off.
[9]
Therefore, there is a need for technology development to solve these problems.
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[10]
The present invention has been made to solve the above problems, and is an electrode that can prevent battery performance degradation by maintaining electrical connection in the negative electrode even when fatigue failure occurs in the negative electrode due to volume change due to contraction and expansion of the positive electrode It is an object to provide an assembly and a manufacturing method thereof.
means of solving the problem
[11]
An electrode assembly according to an embodiment of the present invention includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, wherein the positive electrode includes a positive electrode active material layer formed on a positive electrode current collector, and the negative electrode includes a negative electrode current collector. It includes a negative active material layer formed on the entirety, a non-coated portion is formed at an edge of the anode current collector, and a disconnection prevention layer formed by horizontally bending the anode current collector extending outside the non-coated portion.
[12]
In addition, the present invention provides a secondary battery including the electrode assembly as described above.
[13]
In addition, the present invention provides a method of manufacturing an electrode assembly as described above. The method of manufacturing an electrode assembly according to the present invention includes the steps of cutting a negative electrode current collector long to have a portion extending by a predetermined length; forming an anode active material layer on a portion of the anode current collector, excluding the portion extending by the predetermined length and the uncoated portion; forming a disconnection prevention layer by horizontally bending the portion extended by the predetermined length; and welding an opposite end of the horizontally bent portion to fix the disconnection prevention layer and the current collector.
Effects of the Invention
[14]
The electrode assembly according to the present invention horizontally bends the negative electrode current collector extending outside the uncoated portion to form a disconnection prevention layer on one surface of the uncoated portion, resulting in cracks at the portion facing the anode edge of the anode current collector due to volume expansion of the anode. Even if a disconnection occurs due to the disconnection, it is possible to prevent performance deterioration of the battery by maintaining an electrical connection in the negative electrode through the disconnection prevention layer.
Brief description of the drawing
[15]
1 is a cross-sectional view showing a state in which disconnection occurs in a conventional laminated structure of an electrode assembly and an anode current collector.
[16]
2 is a cross-sectional view showing a laminated structure of an electrode assembly according to an embodiment of the present invention.
[17]
3 is a cross-sectional view showing a state in which disconnection occurs in an electrode assembly according to an embodiment of the present invention.
[18]
4 is a cross-sectional view showing a laminated structure of an electrode assembly according to another embodiment of the present invention.
[19]
5 is a schematic diagram showing the structure of a battery including an electrode assembly according to an embodiment of the present invention.
[20]
6 is a flowchart showing the sequence of the manufacturing method of the electrode assembly according to the present invention.
[21]
7 is a schematic diagram showing a manufacturing process of an anode in the manufacturing method of an electrode assembly according to the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[22]
An electrode assembly according to an embodiment of the present invention includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, wherein the positive electrode includes a positive electrode active material layer formed on a positive electrode current collector, and the negative electrode includes a negative electrode current collector. It includes a negative active material layer formed on the entirety, a non-coated portion is formed at an edge of the anode current collector, and a disconnection prevention layer formed by horizontally bending the anode current collector extending outside the non-coated portion.
[23]
In one embodiment of the present invention, a negative electrode tab is formed on the other surface on which the disconnection prevention layer of the uncoated portion is formed.
[24]
In one embodiment of the present invention, a welding portion for connecting between the disconnection prevention layer and the uncoated portion is formed at the opposite end of the horizontally bent portion.
[25]
In one embodiment of the present invention, the negative active material layer includes a first negative active material layer facing the positive electrode with a separator therebetween and a second negative active material layer formed on the opposite surface of the surface on which the first negative active material layer is formed. include
[26]
In a specific example, the length of the first negative active material layer is greater than the length of the second negative active material layer.
[27]
In a specific example, the distance between the end of the first negative active material layer and the end of the electrode assembly is smaller than the distance between the end of the positive electrode active material layer and the end of the electrode assembly, and the end of the second negative active material layer and the end of the electrode assembly The distance between them is greater than the distance between the end of the cathode active material layer and the end of the electrode assembly.
[28]
In a specific example, the disconnection prevention layer is formed on the surface on which the second negative electrode active material layer is formed, and is spaced apart from the second negative electrode active material layer by a predetermined distance.
[29]
In a specific example, the distance between the welding portion and the end of the electrode assembly is greater than the distance between the end of the positive electrode active material layer and the end of the electrode assembly.
[30]
In a specific example, the electrode assembly according to the present invention further includes an adhesive portion formed between the uncoated portion and the disconnection prevention layer.
[31]
In a specific example, the positive electrode, the negative electrode, and the separator are laminated and wound into a jelly-roll shape.
[32]
In addition, the present invention provides a secondary battery including the electrode assembly as described above.
[33]
In addition, the present invention provides a method of manufacturing an electrode assembly as described above. The method of manufacturing an electrode assembly according to the present invention includes the steps of cutting a negative electrode current collector long to have a portion extending by a predetermined length; forming an anode active material layer on a portion of the anode current collector, excluding the portion extending by the predetermined length and the uncoated portion; forming a disconnection prevention layer by horizontally bending the portion extended by the predetermined length; and welding an opposite end of the horizontally bent portion to fix the disconnection prevention layer and the current collector.
Mode for Carrying Out the Invention
[34]
Hereinafter, the present invention will be described in detail. Prior to this, terms or words used in this specification and claims should not be construed as being limited to ordinary or dictionary meanings, and the inventor appropriately uses the concept of terms in order to describe his/her invention in the best way. It should be interpreted as a meaning and concept consistent with the technical spirit of the present invention based on the principle that it can be defined in the following way.
[35]
In this application, terms such as "comprise" or "having" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof. In addition, when a part such as a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the case where it is "directly on" the other part, but also the case where there is another part in the middle. Contrary
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5,000 character limit. Use the arrows to translate more.When a part such as a layer, film, region, plate, etc. is said to be "under" another part, this includes not only the case where it is "directly under" the other part, but also the case where there is another part in the middle. In addition, in the present application, being disposed "on" may include the case of being disposed not only on the top but also on the bottom.
[36]
[37]
Hereinafter, the present invention will be described in detail.
[38]
2 is a cross-sectional view showing a laminated structure of an electrode assembly according to an embodiment of the present invention.
[39]
Referring to FIG. 2, the electrode assembly 100 according to an embodiment of the present invention includes a positive electrode 110, a negative electrode 120, and a separator 130 interposed between the positive electrode 110 and the negative electrode 120. The positive electrode 110 includes a positive electrode active material layer 112 formed on a positive electrode current collector 111, and the negative electrode 120 includes a negative electrode active material layer 122 formed on a negative electrode current collector 121 Including, the uncoated portion 125 is formed at the edge of the anode current collector 121, and the disconnection prevention layer 140 formed by horizontally bending the anode current collector 121 extending outside the uncoated portion 125 ). That is, in the present invention, the disconnection prevention layer 140 is a part of the negative electrode current collector 121 and means a metal layer formed on one surface of the non-coated portion 125 .
[40]
As described above, when a secondary battery including such an electrode assembly is repeatedly charged and discharged, as the positive electrode repeats contraction and expansion, the negative electrode facing the positive electrode with the separator therebetween receives repeated stress. When fatigue due to such stress accumulates, disconnection occurs due to cracks in the portion of the negative current collector that contacts the end of the positive electrode as shown in FIG. 1 . In this case, the flow of current from the current collector toward the negative electrode tab is interrupted, thereby disturbing the normal operation of the battery.
[41]
Accordingly, the electrode assembly according to the present invention horizontally bends the negative electrode current collector extending outside the uncoated portion to form a disconnection prevention layer on one surface of the uncoated portion, thereby causing disconnection due to cracks in the negative electrode current collector due to volume expansion of the positive electrode. However, by maintaining the electrical connection in the negative electrode through the disconnection prevention layer, it is possible to prevent performance degradation of the battery.
[42]
[43]
Hereinafter, the configuration of the electrode assembly according to the present invention will be described in detail.
[44]
Referring to FIG. 2, the electrode assembly 100 according to the present invention has a structure in which an anode 110, a cathode 120, and a separator 130 interposed between the anode 110 and the cathode 120 are stacked.
[45]
Meanwhile, FIG. 2 shows only the stacked structure near the end A of the electrode assembly among the entire electrode assembly. At this time, in the present invention, the end (A) of the electrode assembly is the outermost edge of the electrode assembly, and means the end of the outermost protruding layer among the positive electrode, the negative electrode, and the separator. Referring to FIG. 2 , since the separator or the negative electrode protrudes most outward among the separator, the positive electrode, and the negative electrode, the end of the electrode assembly is the same as the end of the separator or the end of the negative electrode.
[46]
Also, referring to FIG. 2 , the positive electrode 110 has a structure in which a positive electrode active material layer 112 is formed by applying a positive electrode slurry including a positive electrode active material on a positive electrode current collector 111 . At this time, the positive electrode active material layer 112 may be formed on both sides of the positive electrode current collector 111 . In addition, in the electrode assembly according to the present invention, the positive electrode 110 has a free-edge shape and has a structure in which a non-coated portion is not formed at the edge of the positive electrode 110. In this case, the uncoated portion (not shown) of the positive electrode is formed toward the center of the anode, and a positive electrode tab (not shown) may be attached to the uncoated portion. One end of the positive electrode tab is attached to and fixed to the uncoated portion, and the other end protrudes from the electrode assembly. Since specific details of materials constituting the positive electrode current collector and the positive electrode active material are known to those skilled in the art, a detailed description thereof will be omitted.
[47]
Meanwhile, the separator 130 separates and electrically insulates the positive electrode 110 and the negative electrode 120 and may be formed of a material having uniform micropores through which lithium ions can be conducted. As the separator, for example, a multilayer film made of polyethylene, polypropylene or a combination thereof having microporous properties, polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile or polyvinylidene fluoride hexafluoropropylene A polymer film for a solid polymer electrolyte or a gel polymer electrolyte such as a copolymer may be used, and since other details are known to those skilled in the art, a detailed description thereof will be omitted.
[48]
The negative electrode 120 has a structure in which a negative electrode active material layer 122 is formed by applying a negative electrode slurry containing a negative electrode active material on a negative electrode current collector 121 . The negative electrode 120 has an uncoated portion 125, which is a portion where the negative electrode active material layer is not formed, at the edge.
[49]
A disconnection prevention layer 140 is formed on one surface of the uncoated portion 125 . As described above, the disconnection prevention layer 140 is for electrical connection of the negative electrode current collector 121 when the negative electrode current collector 121 is disconnected.
[50]
The disconnection prevention layer 140 is formed by horizontally bending the anode current collector 121 extending outside the uncoated portion 125 . At this time, to form the disconnection prevention layer 140, the length of the negative current collector 121 extending outside the uncoated portion 125 may be the same as the desired length of the disconnection prevention layer 140. In this specification, the "length" of the negative electrode current collector is based on the direction in which the negative electrode current collector is extended, which is the same as the winding direction of the electrode assembly when the electrode assembly is wound into a jelly-roll shape as will be described later. means the same direction.
[51]
That is, in the electrode assembly 100 according to the present invention, the current collector constituting the uncoated portion 125 of the negative electrode may be formed in a two-layer structure. In this case, the disconnection prevention layer 140 may be formed by horizontally bending the anode current collector 121 , thereby integrating the disconnection prevention layer 140 with the anode current collector 121 . Accordingly, it is possible to prevent the disconnection prevention layer 140 from being separated from the uncoated portion 125 of the anode current collector 121 .
[52]
In addition, the anti-disconnection layer 140 is formed by horizontally bending the negative electrode current collector 121 to align the anti-disconnection layer 140 with the uncoated portion 125 to attach the anti-disconnection layer 140 to the uncoated portion 125, A process of attaching both ends of the disconnection prevention layer 140 to the uncoated portion 125 may be omitted. Accordingly, productivity and efficiency of the process may be improved.
[53]
A negative electrode tab 126 is formed on the other surface of the uncoated portion 125 on which the disconnection prevention layer 140 is formed. The cathode tab 126 has a structure in which one end is attached and fixed to the uncoated portion 125 and the other end protrudes from the electrode assembly 100 . The negative electrode tab 126 may be attached and fixed on the non-coated portion 125 formed on the negative electrode current collector 121 by, for example, welding.
[54]
Meanwhile, referring to FIG. 2 , a welding portion 141 for connecting between the disconnection prevention layer 140 and the uncoated portion 125 is formed at the opposite end of the horizontally bent portion. Accordingly, a horizontal bending portion B is formed at one end of the disconnection prevention layer 140, and a welding part 141 is formed at the opposite end thereof, and the disconnection prevention layer 140 includes the horizontal bending part B and the welding part. It is coupled to the negative electrode current collector 121 by (141).
[55]
In addition, the disconnection prevention layer 140 may secure electrical connectivity by the horizontally bent portion B and the welding portion 141 .
[56]
3 is a cross-sectional view showing a state in which disconnection occurs in an electrode assembly according to an embodiment of the present invention.
[57]
Referring to FIG. 3 , as charging and discharging are repeated, the volume expansion and contraction of the positive electrode 110 is repeated. As a result, the portion of the negative electrode 120 in contact with the end of the positive electrode 110 is stressed due to the volume change of the positive electrode. Fatigue accumulates as a result. When this phenomenon is repeated, disconnection occurs due to cracks in the anode current collector 121 as shown in FIG. 3 . However, the electrode assembly 100 according to the present invention has a disconnection prevention layer 140 electrically connected to the negative electrode current collector 121 by a horizontally bent portion B and a welded portion 141 on one side of the uncoated portion 125 of the negative electrode 120. ) is formed. Accordingly, it is possible to secure a conductive path bypassing the disconnected portion (C) due to the crack. In this case, the current from the negative electrode tab 125 to the center of the negative electrode 120, as shown in FIG. It flows along the welded part 141-negative electrode current collector 121. That is, even if the direct flow of current through the anode current collector 121 is blocked due to a crack, bypass through the disconnection prevention layer 140 is possible.
[58]
Meanwhile, when the volume of the positive electrode 110 expands, the portion (C) in contact with the end of the positive electrode receives the most stress in the negative electrode current collector 121 as described above. That is, in the electrode assembly according to the present invention, the negative electrode active material layer 122 and the disconnection prevention layer 140 may be formed in a specific shape to secure an electrical connection when disconnection occurs in the portion (C).
[59]
For example, the negative active material layer 122 according to the present invention may be formed on both sides of the negative electrode current collector 121 . Specifically, the negative active material layer 122 is the opposite surface of the surface on which the first negative active material layer 123 and the first negative active material layer 123 are formed facing the positive electrode 110 with the separator 130 interposed therebetween. It includes a second negative active material layer 124 formed on.
[60]
At this time, the length of the first negative active material layer 123 is greater than the length of the second negative active material layer 122 . Accordingly, referring to FIGS. 2 and 3 , the distance d 1 between the end of the first negative active material layer 123 and the end A of the electrode assembly 100 is the second negative active material layer 124 ) is smaller than the distance d 2 between the end of the electrode assembly 100 and the end of the electrode assembly 100 .
[61]
Also, in the electrode assembly 100 , an end of the positive active material layer 112 is positioned between an end of the first negative active material layer 123 and an end of the second negative active material layer 124 . Specifically, see FIGS. 2 and 3
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5,000 character limit. Use the arrows to translate more.In other words, the distance d 1 between the end of the first negative active material layer 123 and the end A of the electrode assembly 100 is the end of the positive active material layer 112 and the end of the electrode assembly 100 (A) is smaller than the distance (d 3 ), and the distance (d 2 ) between the end of the second negative electrode active material layer 124 and the end (A) of the electrode assembly 100 is the positive electrode active material layer 112 It is greater than the distance d 3 between the end of the electrode assembly 100 and the end A of the electrode assembly 100 . Through this, as will be described later, the disconnection prevention layer 140 can be formed in the portion (C) where cracks occur. On the other hand, in the present invention, when the positive electrode has a pre-edge structure in which the uncoated portion is not formed on the edge as shown in FIGS. 2 and 3, the end of the positive electrode active material layer is at the same position as the end of the positive electrode current collector or the end of the positive electrode.
[62]
Specifically, the disconnection prevention layer 140 is formed on the surface on which the second negative active material layer 124 is formed, and is spaced apart from the second negative active material layer 124 by a predetermined distance. However, depending on the electrode, the disconnection prevention layer 140 and the second negative electrode active material layer 124 may be formed adjacent to each other. Accordingly, a shape is formed in which the disconnection prevention layer 140 covers the portion (C) where the crack occurs.
[63]
At this time, referring to FIGS. 2 and 3 , the distance d 4 between the welding portion 141 and the end A of the electrode assembly 100 is the end of the positive electrode active material layer 112 and the end of the electrode assembly. (A) greater than the distance (d 3) between them. Through this, a part with a high possibility of disconnection due to a crack (a part adjacent to the end of the cathode active material layer, corresponding to C) is located between the welded part 141 and the horizontally bent part B, thereby forming a crack in the corresponding part in practice. When a disconnection occurs due to the disconnection prevention layer 140 by the welding portion 141 and the horizontally bent portion (B) electrical connection is possible.
[64]
4 is a cross-sectional view showing a laminated structure of an electrode assembly according to another embodiment of the present invention.
[65]
Referring to FIG. 4 , the electrode assembly 200 according to the present invention may further include an adhesive portion 142 formed between the uncoated portion 125 and the disconnection prevention layer 140 .
[66]
In the electrode assembly 200 according to the present invention, since the disconnection prevention layer 140 is formed by horizontally bending the extended anode current collector 121, the disconnection prevention layer 140 and the anode current collector 121 do not completely adhere to each other. , Gaps at regular intervals may be formed between the disconnection prevention layer 140 and the anode current collector 121 . In addition, in the electrode assembly 200 according to the present invention, the disconnection prevention layer 140 and the negative electrode current collector 121 are coupled by a horizontally bent portion B and a welding portion 141, and the outer portion is external to the welding portion 141. Stress acting on may be concentrated, and if the welded portion 141 is damaged due to some reason, when a disconnection occurs, an electrical connection between the disconnection prevention layer 140 and the negative electrode current collector 121 may be blocked. In the electrode assembly 200 according to the present invention, by further forming an adhesive part 142 in the gap in addition to the welding part 141, stable fixation between the negative current collector 121 and the disconnection prevention layer 140 can be secured.
[67]
The type of the adhesive part 142 is not particularly limited as long as it can bind the negative current collector 121 and the disconnection prevention layer 140. For example, the bonding portion 142 may be formed by applying an adhesive between the anode current collector 121 and the disconnection prevention layer 140 . Alternatively, the adhesive part 142 may be in the form of a double-sided tape coated with an adhesive on both sides. Alternatively, the adhesive portion 142 may be formed through welding between the disconnection prevention layer 140 and the anode current collector 121 . In this case, when the bonding portion 142 is formed by welding, an additional conductive path between the disconnection prevention layer 140 and the negative current collector 121 may be secured. In addition, even when the adhesive 142 is in the form of a double-sided tape or adhesive, a conductive path between the disconnection prevention layer 140 and the negative current collector 121 can be secured by using a conductive material.
[68]
There is no particular limitation on the shape in which the adhesive portion 142 is formed, and the adhesive portion 142 may be formed in all or part of the space between the horizontally bent portion B and the welded portion 141 . For example, as shown in FIG. 4, an adhesive part may be formed in all of the space between the horizontally bent part B and the welding part 141, and an adhesive part may be formed in a part of the space. In addition, when the adhesive portion 142 is formed by welding, a plurality of adhesive portions 142 may be formed by welding between the horizontally bent portion B and the weld portion 141 at regular intervals. That is, the adhesive portion 142 is formed between the disconnection prevention layer 140 and the anode current collector 121 and between the horizontally bent portion B and the welding portion 141 .
[69]
Meanwhile, the positive electrode 110, the negative electrode 120, and the separator 130 may be wound into a jelly-roll shape after being laminated. At this time, as will be described later, the disconnection prevention layer 140 of the negative electrode 120 is positioned at the outermost portion of the jelly-roll.
[70]
[71]
In addition, the present invention provides a secondary battery including the electrode assembly as described above.
[72]
5 is a schematic diagram showing the structure of a secondary battery including an electrode assembly according to an embodiment of the present invention.
[73]
Referring to FIG. 5 , in the secondary battery 300, the battery case 310 in which the electrode assembly 100 is accommodated is composed of a cylindrical can 311 and a cap assembly 312 covering the top of the cylindrical can 311. It can be. The cylindrical can 311 may be made of metal, preferably made of stainless steel. In addition, the cylindrical can 311 may include a storage portion in which the electrode assembly 100 can be accommodated, and may have an open upper end.
[74]
After the electrode assembly 100 is rolled and formed into a jelly-roll shape, it is stored in the storage part of the cylindrical can 311, and an electrolyte is injected into the storage part so that the electrode assembly 100 is completely immersed in the cylindrical can 311, A cap assembly 312 is mounted and coupled to the open upper end of the cylindrical can 311 .
[75]
The electrode assembly 100 has a structure in which an anode 110, a separator 130, and a cathode 120 are sequentially stacked and wound in a round shape, and a cylindrical center pin (not shown) is inserted into the center of the electrode assembly 100. can The center pin is generally made of a metal material to impart a predetermined strength, and has a hollow cylindrical structure obtained by bending a plate material round.
[76]
An insulating plate 320 is mounted on the upper surface of the electrode assembly 100 to prevent contact with the electrode tab, thereby preventing a short circuit caused by contact between the electrode assembly 100 and the electrode tab.
[77]
Meanwhile, in the electrode assembly 100, the cathode 110 has a structure in which a cathode active material layer is formed on both sides of a cathode current collector. Also, in the electrode assembly, the positive electrode has a free-edge shape, and has a structure in which a non-coated portion is not formed at the edge of the positive electrode. In this case, the uncoated portion (not shown) of the positive electrode is formed toward the center of the anode, and a positive electrode tab (not shown) may be attached to the uncoated portion. The positive electrode tab protrudes in one direction based on a direction parallel to the winding central axis around which the electrode assembly is wound, and may be connected to the cap assembly by protruding upward from the electrode assembly, for example.
[78]
On the other hand, in the case of the negative electrode 120, the uncoated portion 125 is formed on the edge, and the negative electrode tab 126 is formed on the uncoated portion 125. The negative electrode tab 126 may protrude in the other direction with respect to the protrusion direction of the positive electrode tab based on a direction parallel to the winding central axis, and, for example, protrudes downward from the electrode assembly 100 to form a cylindrical can 311 It can be connected to the inner bottom surface of.
[79]
In addition, a disconnection prevention layer 140 is formed on one surface of the uncoated portion 125 , and the disconnection prevention layer 140 may be formed by horizontally bending a negative electrode current collector extending outward of the uncoated portion 125 . Details of the disconnection prevention layer are as described above. In the secondary battery 300 according to the present invention, the anti-disconnection layer 140 is formed so that even if a disconnection occurs in the anode current collector due to a crack due to volume expansion of the positive electrode 110, the anode current collector passes through the anti-disconnection layer 140. By maintaining electrical connection within the whole, degradation of battery performance can be prevented.
[80]
[81]
In addition, the present invention provides a manufacturing method of the electrode assembly as described above.
[82]
Figure 6 is a flow chart showing the sequence of the manufacturing method of the electrode assembly according to the present invention, Figure 7 is a schematic diagram showing the negative electrode manufacturing process in the manufacturing method of the electrode assembly according to the present invention.
[83]
6 and 7 together with FIG. 2 , in the manufacturing method of the electrode assembly according to the present invention, the positive electrode 110, the negative electrode 120, and the separator 130 to be manufactured as the electrode assembly 100 are first prepared. . At this time, the anode 110 and the separator 130 are as described above.
[84]
Meanwhile, in the case of the negative current collector 121, a process for forming the disconnection prevention layer 140 is performed. First, the negative electrode current collector 121 is cut long to have a portion (D) extending by a predetermined length (S10). That is, the negative electrode current collector 121 includes a portion (E) where the negative active material layer 122 is formed, a portion (F) where the uncoated portion 125 is formed, and a portion extending outside the uncoated portion 125 by a predetermined length. It is tailored to include (D).
[85]
When the anode current collector 121 is prepared, an anode active material layer 122 is formed by applying an anode slurry containing an anode active material to the anode current collector 121 . At this time, a negative active material layer is formed on a portion of the negative current collector 121 excluding the portion (D) extending by the predetermined length and the portion (F) where the uncoated portion 125 is to be formed (S20). However, as will be described later, the lengths of the second negative active material layer and the first negative active material layer may be different. In addition, a negative electrode tab 126 may be formed on one surface of the uncoated portion.
[86]
Specifically, as shown in FIGS. 2 and 7 , the negative electrode slurry is applied to both sides of the negative electrode current collector 121 to form the first negative active material layer 123 and the negative electrode active material layer 123 , respectively.
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5,000 character limit. Use the arrows to translate more.A second negative electrode active material layer 124 is formed. At this time, as shown in FIG. 2 , the distance d 1 between the end of the first negative active material layer 123 and the end A of the electrode assembly 100 is It is smaller than the distance (d 3) between the ends (A) of the electrode (100), and the distance (d 2) between the end (A) of the electrode assembly 100 and the end of the second negative electrode active material layer 124 is the positive electrode The negative electrode slurry may be applied so as to be larger than the distance d 3 between the end of the active material layer 112 and the end A of the electrode assembly 100 .
[87]
When the negative electrode active material layer is formed, the disconnection prevention layer 140 is formed by horizontally bending the portion D extending by the predetermined length (S30). In addition, the opposite end of the horizontally bent portion (B) is welded to fix the disconnection prevention layer and the current collector (S40).
[88]
At this time, as shown in FIGS. 2 and 7 , the disconnection prevention layer 140 may be spaced apart from the second negative electrode active material layer 124 by a predetermined distance, and between the welding portion 141 and the end portion A of the electrode assembly 100. The distance d 4 of may be adjusted to be larger than the distance d 3 between the end of the positive electrode active material layer 112 and the end A of the electrode assembly.
[89]
An adhesive portion 142 may be further formed between the uncoated portion 125 and the disconnection prevention layer 140 . A method of forming the adhesive portion 142 is the same as described above.
[90]
When the manufacturing of the negative electrode is completed, the negative electrode and the positive electrode are stacked with a separator interposed between the negative electrode and the positive electrode, and wound to manufacture a jelly-roll type electrode assembly (S50). The jelly-roll type electrode assembly is accommodated in a cylindrical can-shaped battery case and manufactured as a secondary battery.
[91]
As described above, the method of manufacturing an electrode assembly according to the present invention forms a disconnection prevention layer so that even if disconnection occurs in the negative electrode current collector due to cracks due to volume expansion of the positive electrode, the battery is electrically connected to the negative electrode through the disconnection prevention layer. performance degradation can be prevented.
[92]
In addition, since the disconnection prevention layer is formed by horizontally bending the negative electrode current collector, the process of aligning the disconnection prevention layer with the uncoated portion and attaching both ends of the disconnection prevention layer to the uncoated portion can be omitted. Accordingly, productivity and efficiency of the process may be improved.
[93]
[94]
The above description is merely an example of the technical idea of the present invention, and various modifications and variations can be made to those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the drawings disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain, and the scope of the technical idea of the present invention is not limited by these drawings. The protection scope of the present invention should be construed according to the following claims, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.
[95]
[96]
Meanwhile, terms indicating directions such as up, down, left, right, front, and back are used in this specification, but these terms are only for convenience of explanation and may vary depending on the location of the target object or the location of the observer. It is self-evident that it can
[97]
[98]
[Description of code]
[99]
10, 100, 200: electrode assembly
[100]
1, 110: anode
[101]
2, 120, cathode
[102]
3, 130 separator
[103]
111: positive current collector
[104]
112: positive electrode active material layer
[105]
121: negative electrode current collector
[106]
122: negative electrode active material layer
[107]
123: first negative active material layer
[108]
124: second negative electrode active material layer
[109]
125: no thumb
[110]
126: cathode tab
[111]
140: disconnection prevention layer
[112]
141: welding part
[113]
142: adhesive part
[114]
300: secondary battery
[115]
310: battery case
[116]
311: can
[117]
312: cap assembly
[118]
320: insulating plate

Weclaims
[Claim 1]
An electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, wherein the positive electrode includes a positive electrode active material layer formed on a positive electrode current collector, and the negative electrode includes a negative electrode active material layer formed on a negative electrode current collector A non-coated portion is formed at an edge of the anode current collector, and an electrode assembly comprising a disconnection prevention layer formed by horizontally bending the anode current collector extending outside the non-coated portion.
[Claim 2]
The electrode assembly of claim 1, wherein a negative electrode tab is formed on the other surface of the uncoated portion on which the disconnection prevention layer is formed.
[Claim 3]
The electrode assembly of claim 1, wherein a welding portion is formed at an opposite end of the horizontally bent portion to connect between the disconnection prevention layer and the uncoated portion.
[Claim 4]
The electrode of claim 1, wherein the negative active material layer includes a first negative active material layer facing the positive electrode with a separator therebetween and a second negative active material layer formed on a surface opposite to the surface on which the first negative active material layer is formed. assembly.
[Claim 5]
The electrode assembly of claim 4, wherein the length of the first negative active material layer is greater than that of the second negative active material layer.
[Claim 6]
The method of claim 5, wherein the distance between the end of the first negative active material layer and the end of the electrode assembly is smaller than the distance between the end of the positive electrode active material layer and the end of the electrode assembly, and the end of the second negative active material layer and the electrode assembly The distance between the ends of the electrode assembly is greater than the distance between the end of the positive electrode active material layer and the end of the electrode assembly.
[Claim 7]
The electrode assembly of claim 6, wherein the disconnection prevention layer is formed on the surface on which the second negative active material layer is formed, and is spaced apart from the second negative active material layer by a predetermined distance.
[Claim 8]
The electrode assembly of claim 7, wherein a distance between the welded portion and an end of the electrode assembly is greater than a distance between an end of the positive electrode active material layer and an end of the electrode assembly.
[Claim 9]
The electrode assembly of claim 1, further comprising an adhesive portion formed between the uncoated portion and the disconnection prevention layer.
[Claim 10]
The electrode assembly of claim 1, wherein the positive electrode, the negative electrode, and the separator are wound in a jelly-roll shape after being laminated.
[Claim 11]
A secondary battery comprising the electrode assembly according to claim 1.
[Claim 12]
In the manufacturing method of the electrode assembly according to claim 1, Cutting the negative electrode current collector to have a portion extending by a predetermined length; forming an anode active material layer on a portion of the anode current collector, excluding the portion extending by the predetermined length and the uncoated portion; forming a disconnection prevention layer by horizontally bending the portion extended by the predetermined length; and welding an opposite end of the horizontally bent portion to fix the disconnection prevention layer and the current collector.