Electrode assemblies and battery cells

Abstract

This invention provides an electrode assembly and a battery cell that can solve the problem of low drop resistance of battery cells. [Solution] The electrode assembly of the present invention includes a first electrode piece unit and a second electrode piece unit that are wound and installed, with opposite polarities, and at least one of them includes an electrode piece, a tab, and a separator, the separator including a first separator and a second separator installed on opposite sides of the electrode piece in the thickness direction of the electrode piece, the first separator including a first extension extending from the edge of the electrode piece along the width direction of the electrode piece, the second separator including a second extension extending from the edge of the electrode piece along the width direction of the electrode piece, the tab is installed on the electrode piece and extends from the separator through the first extension and the second extension, some of the first extension and the second extension are connected to form a sealed region, the number of sealed regions is at least two, the sealed regions avoiding the tab.

Description

Technical Field

[0001] (Cross - reference to related applications) This invention claims the priority of a Chinese patent application with an application number of 202310802063.8 and an invention title of "Electrode Assembly and Battery Cell", which was filed with the Chinese Patent Office on June 30, 2023, and all of its content is incorporated herein by reference.

[0002] This invention relates to the field of electrochemical technology, and particularly to electrode assemblies and battery cells.

Background Art

[0003] As the usage scenarios of 3C (Computer, Communication, Consumer Electronic) electronic products become more diverse and complex, people's requirements for the safety of electronic products are becoming increasingly strict, and the concern for battery safety is also increasing. When a battery repeatedly drops, the battery voltage decreases, and in the worst - case scenario, it may lead to ignition or explosion. According to research, the main reasons for voltage drop, ignition, or explosion in a battery after dropping are internal short - circuits caused by the shrinkage of the separator inside the battery. When the battery repeatedly drops, the free electrolyte repeatedly impacts the separator. When the impact force of the electrolyte exceeds the binding force of the separator, the separator inside the battery shrinks, and the positive electrode plate and the negative electrode plate come into direct contact, resulting in an internal short - circuit. As a result, the voltage drops significantly and the battery stops functioning, or it directly generates smoke or fire. Therefore, since the shrinkage of the separator has a serious impact on battery safety, an urgent solution is required.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Embodiments of the present invention provide an electrode assembly and a battery cell that can solve the problem of low drop - resistance characteristics of the battery cell.

Means for Solving the Problems

[0005] In a first aspect, the present invention provides an electrode assembly. The electrode assembly includes a first electrode piece unit and a second electrode piece unit that are wound and installed, wherein the polarities of the first electrode piece unit and the second electrode piece unit are opposite. At least one of the first electrode piece unit and the second electrode piece unit includes an electrode piece, a tab, and a separator, wherein the separator includes a first separator and a second separator, respectively, installed on opposite sides of the electrode piece in the thickness direction of the electrode piece, the first separator includes a first extension extending from the edge of the electrode piece along the width direction of the electrode piece, the second separator includes a second extension extending from the edge of the electrode piece along the width direction of the electrode piece, the tab is installed on the electrode piece and extends from the separator through the first extension and the second extension, the first extension and the second extension are connected to form a sealed region, the number of sealed regions is at least two, and the sealed regions avoid the tab.

[0006] In the electrode assembly according to an embodiment of the present invention, a sealed region is formed by the connection and solidification of a portion of the area where both the first and second separators exceed the width of the electrode piece in a certain manner, thereby preventing voltage drop failures and short circuits in the battery cell caused by contact between the positive and negative electrode pieces. By positioning the two adjacent sealed regions with a gap between them, the electrolyte can penetrate between the first and second separators through the unconnected area between the first and second separators, so that the electrode assembly still has a good electrolyte immersion effect. By avoiding the tabs, the sealed regions prevent overpressure on the tabs and the electrode pieces connected to the tabs, effectively improving the stability of the characteristics of the manufactured battery cell.

[0007] In some exemplary embodiments, at least some of the sealing regions are spaced apart along the length of the electrode piece, and in the length of the electrode piece, let L be the length of the electrode piece, let l0 be the length of the sealing region, and let a1 be the distance between two adjacent sealing regions. 1 <L / l0≦200、および / または 200 ≤ L / a1 ≤ 4000, and / or 1 ≤ l0 / a1 ≤ 4000 It satisfies the condition.

[0008] According to the above embodiment, by controlling the ratio of L, l0, and a1 to an appropriate range, it becomes easy to distribute the length and spacing of the sealing region in the longitudinal direction of the electrode piece, and it becomes possible to achieve a strong sealing of the sealing region in the longitudinal direction of the electrode piece and a good electrolyte immersion effect.

[0009] In some exemplary embodiments, some of the sealing regions are spaced apart along the length of the electrode piece, and other parts of the sealing regions are spaced apart along the width of the electrode piece, and in the width direction of the electrode piece, the width of the electrode piece is W, the width of the sealing region is w0, and the width between two adjacent sealing regions is a2, 1 ≤ W / w0 ≤ 20, and / or W / a2 ≥ 20, and / or w0 / a2≧1 It satisfies the condition.

[0010] According to the above embodiment, by controlling the ratio of W, w0, and a2 within the above range, it becomes easy to distribute the length and spacing of the sealing region in the longitudinal direction of the electrode piece, resulting in a strong sealing of the sealing region in the longitudinal direction of the electrode piece and a good electrolyte immersion effect.

[0011] In some exemplary embodiments, in the width direction of the electrode piece, the first extension includes a first portion located on one side of the electrode piece, and a portion of the first portion connects with the second extension to form at least two sealed regions.

[0012] In some exemplary embodiments, in the width direction of the electrode piece, one end of the first separator opposite to the first portion is integrally molded with the second separator.

[0013] According to the above embodiment, the separator cutting process can be easily reduced, contributing to improved assembly efficiency.

[0014] In some exemplary embodiments, in the width direction of the electrode piece, the first extension includes a second portion opposite to the first portion, and a portion of the second portion connects with the second extension to form at least one sealed region.

[0015] According to the above embodiment, the connection strength of multiple sealed regions is increased, preventing short circuits between two electrode pieces with opposite polarities due to displacement of the electrode pieces. At the same time, in the width direction of the electrode pieces, the electrolyte can penetrate between the first and second separators from both opposing ends of the separator, thereby contributing to an improved electrolyte immersion effect.

[0016] In some exemplary embodiments, each of the sealed regions is a hot-pressure sealed portion or a roll-rolled sealed portion, or an adhesive layer is installed between the first extended portion and the second extended portion, and the first extended portion and the second extended portion are connected via the adhesive layer to form the sealed region.

[0017] According to the above embodiment, the hot-pressed sealed portion and the roll-rolled sealed portion can be crimped together while avoiding the tabs according to a predetermined crimping pattern, and the sealed area is formed by applying an adhesive to at least one surface of the first extended portion and the second extended portion before joining them. The processing method is simple, prevents overpressure on the tabs and the electrode pieces corresponding to the tabs, and improves the stability of the properties of the manufactured electrode assembly.

[0018] In some exemplary embodiments, the electrode assembly includes a flat portion and a curved portion, and the sealing region is located in the flat portion.

[0019] According to the above embodiment, by installing a sealing region in the flat portion, the structure of the sealing region is stabilized, the separator can better protect the electrode piece, and the connection of the sealing region becomes unstable due to the large stress in the curved portion.

[0020] In some exemplary embodiments, the sealing regions are correspondingly arranged in the thickness direction of the electrode assembly, and the first extending portion and the second extending portion in the curved portion are arranged at intervals.

[0021] According to the above embodiments, it contributes to improving the electrolyte immersion effect of the electrode assembly. Also, by arranging the sealing regions, it contributes to ensuring a space for installing other components of the battery cell and reducing the space occupied by the electrode assembly. Furthermore, it contributes to improving the energy density of the battery cell.

[0022] In some exemplary embodiments, the electrode assembly includes two of the electrode sheets, at least two of the tabs, and one of the separators. At least one of the tabs is installed on one of the electrode sheets, and the electrode sheet is installed between the first separator and the second separator in the separator to form the first electrode sheet unit. The remaining tabs are installed on the other electrode sheet to form the second electrode sheet unit. The polarities of the two electrode sheets are opposite, or the electrode assembly includes two of the electrode sheets, at least two of the tabs, and two separators. At least one of the tabs is installed on one of the electrode sheets, and the electrode sheet is installed between the first separator and the second separator in one of the separators to form the first electrode sheet unit. The remaining tabs are installed on the other electrode sheet, and the electrode sheet is installed between the first separator and the second separator in the other separator to form the second electrode sheet unit. The polarities of the two electrode sheets are opposite.

[0023] According to the above embodiments, the separator can more comprehensively protect the electrode sheets and more effectively prevent the short circuit of the two electrode sheets with opposite polarities.

[0024] In some exemplary embodiments, the tab extends from the separator along the width direction of the electrode sheet. In the width direction of the electrode sheet, the width of one of the electrode sheets is smaller than the width of the other electrode sheet, and at least the electrode sheet with a smaller width is disposed between the first separator and the second separator in the separator.

[0025] According to the above embodiments, when the separator extends from the edge of the electrode sheet with a smaller width, the first extending portion and the second extending portion of the separator can separate two adjacent portions of the electrode sheet with a larger width. Thereby, the usage amount of the separator can be saved, and the space occupied by the separator can be reduced, which contributes to the improvement of the energy density of the battery cell using the electrode assembly of the present invention.

[0026] In some exemplary embodiments, the electrode sheet with a smaller width is a positive electrode sheet, and the electrode sheet with a larger width is a negative electrode sheet.

[0027] In some exemplary embodiments, the sealing region is disposed at a distance from the electrode sheet. When the distance from the edge of the sealing region facing the electrode sheet to the edge of the electrode sheet is S, S satisfies 0.1 mm ≤ S ≤ 1 mm.

[0028] According to the above embodiments, by disposing the sealing region and the electrode sheet at a distance from each other, the impact force exerted by the electrolyte on the separator can be alleviated. When the separator is impacted by the electrolyte, it can be prevented that the sealing region moves to abut against the edge of the electrode sheet and the sealing region is broken.

[0029] In some exemplary embodiments, the tab extends from the separator along the width direction of the electrode sheet. In the length direction of the electrode sheet, one of the sealing regions is disposed on one side of the tab, and the other sealing region is disposed on the other side of the tab. When the distance from the edge of the sealing region to the edge of the tab is Q, Q satisfies 0.2 mm ≤ Q ≤ 2 mm.

[0030] According to the above embodiment, placing the sealing region near the tab contributes to improving the sealing stability of the sealing region at the tab. Furthermore, by placing the two sealing regions on opposite sides of the tab, the separator acts on the tab, contributing to improved stability in the tab's placement on the electrode piece.

[0031] In a second aspect, the present invention provides a battery cell comprising an outer casing and the electrode assembly, wherein the electrode assembly is installed in the outer casing.

[0032] The electrode assembly and battery cell according to the embodiment of the present invention have at least the following beneficial effects.

[0033] By forming multiple sealed areas in the portion of the separator that extends beyond the adhesive area, short circuits in the battery are prevented when the battery cell is dropped, preventing contact between the positive and negative electrode pieces caused by separator contraction, separator folding, or misalignment of the electrode pieces. Furthermore, the safety and cycle characteristics of the battery cell are improved. Here, a portion of the area where both the first and second separators exceed the width of the electrode pieces is connected to each other and solidified in a certain manner to form a sealed area. As a result, the electrode pieces are constrained between the first and second separators, preventing contact between the positive and negative electrode pieces due to separator contraction, and reducing the occurrence of voltage drop failures and short circuits in the battery cell. When two adjacent sealed areas are installed with a gap between them, an unconnected area exists in the portion of the area where both the first and second separators exceed the width of the electrode pieces. Therefore, the electrolyte can penetrate between the first and second separators through the unconnected area between the first and second separators, thereby the electrode assembly still retains a good electrolyte immersion effect. In the process of fabricating sealing regions in the first and second extended portions, the sealing regions are positioned to avoid the tabs, thereby preventing overpressure on the tabs and the corresponding electrode pieces connected to them, and effectively improving the stability of the characteristics of the manufactured battery cells. [Brief explanation of the drawing]

[0034] In order to more clearly explain the technical concepts according to the embodiments of the present invention, the drawings necessary for the embodiments will be briefly described below. However, the drawings described below are only a part of the embodiments of the present invention, and it will be obvious to those skilled in the art that other drawings can be obtained based on these drawings.

[0035] [Figure 1] Figure 1 is a schematic perspective view of the structure of an electrode assembly according to one embodiment of the present invention. [Figure 2] Figure 2 is a schematic perspective view of the unfolded structure of the first electrode piece unit according to one embodiment of the present invention. [Figure 3] Figure 3 is a cross-sectional view along BB in Figure 1. [Figure 4] Figure 4 is a schematic front view of the unfolded structure of the first electrode piece unit according to one embodiment of the present invention. [Figure 5] Figure 5 is a magnified view of area M in Figure 4. [Figure 6] Figure 6 is a schematic side view of the tail structure of a wound electrode assembly according to one embodiment of the present invention. [Figure 7] Figure 7 is a magnified view of area N in Figure 6. [Explanation of Symbols]

[0036] 10: Electrode assembly, 11: First electrode piece unit, 12: Second electrode piece unit, 101: Sealing area, 100: Electrode piece, 110: Positive electrode piece, 120: Negative electrode piece, 200: Separator, 210: First separator, 201: First extension, 211: First part, 212: Second part, 213: Third part, 214: Fourth part, 220: Second separator, 202: Second extension, 400: Tab, 410: Protective layer, 310: flat part, 320: curved part, X: length direction, Y: width direction, Z: thickness direction. [Modes for carrying out the invention]

[0037] The present invention will be described in more detail below with reference to examples in order to further clarify its objectives, technical proposals, and advantages. The examples described herein are for illustrative purposes only and do not limit the present invention.

[0038] The inventors have discovered that, in related technologies, neither the wrap bonding method nor the low-electrolyte design method can effectively solve the problem of separator shrinkage. The wrap bonding method involves placing U-shaped adhesive tape at the leading and trailing ends of the electrode piece in the width direction, bonding the U-shaped adhesive tape to the separator on one side of the electrode piece, then wrapping it around to the other side of the electrode piece (for example, bonding the U-shaped adhesive tape to the separator in the OH region of the electrode assembly) and bonding it to the separator on the other side, thereby fixing the position of the separator with the U-shaped adhesive tape. The low-electrolyte design method involves reducing the amount of free electrolyte in the battery cell and reducing the impact of the free electrolyte on the separator in the OH region of the electrode assembly. However, during repeated drops, there is still a possibility that the separator may deform or shrink due to the impact of the electrolyte on the separator.

[0039] The inventors have further discovered the following: By providing a sealed containment area in the separator and arranging the electrode pieces within that containment area, the shrinkage of the separator due to the impact of the electrolyte can be effectively reduced. However, because the separator forms a completely sealed structure, immersion in the electrolyte is hindered, affecting the production efficiency of the battery cell. Furthermore, when sealing the separator using a roll rolling method during the manufacture of the electrode assembly, the presence of tabs means that the thickness of the tab portion of the separator is greater than other portions. This causes the composite roller and auxiliary roller to apply excessive pressure to the connection portion of the separator with the tab, making processing difficult and affecting the quality of the manufactured electrode assembly. For this reason, embodiments of the present invention provide an electrode assembly and a battery cell.

[0040] As shown in Figure 1, Figure 1 is a schematic diagram of the structure of an electrode assembly 10 according to one embodiment of the present invention. The electrode assembly 10 includes a wound-type first electrode piece unit and a second electrode piece unit, and the polarities of the first electrode piece unit and the second electrode piece unit are opposite. As shown in Figure 2, Figure 2 is a schematic perspective view of the unfolded structure of the first electrode piece unit 11 or the second electrode piece unit 12 according to one embodiment of the present invention. Both the first electrode piece unit 11 and the second electrode piece unit 12 have a length direction X, and by stacking the first electrode piece unit 11 and the second electrode piece unit 12 and aligning their length directions X, and winding the first electrode piece unit 11 and the second electrode piece unit 12 along their respective length directions X, a wound-type electrode assembly 10 can be obtained. As shown in Figure 3, Figure 3 is a cross-sectional view of the wound-type electrode assembly 10, and as can be seen from Figure 3, the first electrode piece unit 11 and the second electrode piece unit 12 are arranged alternately.

[0041] Both the first electrode piece unit 11 and the second electrode piece unit 12 include an electrode piece 100 and a tab 400. The tab 400 is provided on the electrode piece 100 and is used to electrically connect to an external circuit. The polarity of the first electrode piece unit 11 and the second electrode piece unit 12 is opposite; that is, one of the electrode pieces 100 of the first electrode piece unit 11 and the other of the electrode piece 100 of the second electrode piece unit 12 is the negative electrode piece 120, and the other is the positive electrode piece 110. The tab 400 provided on the positive electrode piece 110 is the positive electrode tab 400, and the tab 400 provided on the negative electrode piece 120 is the negative electrode tab 400. For example, if the electrode piece 100 of the first electrode piece unit 11 is the positive electrode piece 110, then the electrode piece 100 of the second electrode piece unit 12 is the negative electrode piece 120. If the electrode piece 100 of the first electrode piece unit 11 is the negative electrode piece 120, then the electrode piece 100 of the second electrode piece unit 12 is the positive electrode piece 110.

[0042] At least one of the first electrode piece unit 11 and the second electrode piece unit 12 further includes a separator 200. The separator 200 is insulating, and at least a portion of the separator 200 is provided between the electrode piece 100 of the first electrode piece unit 11 and the electrode piece 100 of the second electrode piece unit 12, thereby preventing a short circuit between the two electrode pieces 100 with opposite polarities. The material of the separator 200 may include at least one of polyethylene and polypropylene, but embodiments of the present invention do not limit the material of the separator 200, and all materials commonly used in the manufacture of separators 200 in the art are applicable to the present invention.

[0043] Here, the separator 200 includes a first separator 210 and a second separator 220, respectively, installed on opposite sides of the electrode piece 100 in the thickness direction Z of the electrode piece 100. The first separator 210 includes a first extension 201 extending from the edge of the electrode piece 100 along the width direction Y of the electrode piece 100, and the second separator 220 includes a second extension 202 extending from the edge of the electrode piece 100 along the width direction Y of the electrode piece 100. The tab 400 is installed on the electrode piece 100 and extends from the separator 200 through the space between the first extension 201 and the second extension 202. The first extension 201 and the second extension 202 are connected to form a sealed region 101, of which there are at least two sealed regions 101, and the sealed regions 101 avoid the tab 400.

[0044] In this embodiment of the present invention, by forming multiple sealed regions 101 in the portion of the separator 200 that extends from the adhesive region, a short circuit in the battery caused by contact between the positive electrode piece 110 and the negative electrode piece 120 due to shrinkage of the separator 200, folding of the separator 200, or misalignment of the electrode piece 100 when the battery cell is dropped is prevented, and furthermore, the safety and cycle characteristics of the battery cell are improved. Here, a sealed region 101 is formed when a portion of the area in which both the first separator 210 and the second separator 220 exceed the width of the electrode piece 100 is connected to each other and solidified in a certain manner, thereby constraining the electrode piece 100 between the first separator 210 and the second separator 220, and preventing voltage drop failure and short circuits in the battery cell due to contact between the positive electrode piece 110 and the negative electrode piece 120. When two adjacent sealed regions 101 are installed with a gap between them, there are unconnected areas in the region where both the first separator 210 and the second separator 220 exceed the width of the electrode piece 100. As a result, the electrolyte can penetrate between the first separator 210 and the second separator 220 through the unconnected areas between them, thereby allowing the electrode assembly 10 to still have a good electrolyte immersion effect. During the process of fabricating the sealed regions 101 in the first extended portion 201 and the second extended portion 202, the sealed regions 101 are positioned to avoid the tabs 400, thereby preventing overpressure on the tabs 400 and the electrode pieces 100 connected to the tabs 400, and effectively improving the stability of the characteristics of the manufactured battery cell.

[0045] Preferably, the sealing region 101 is installed with a gap between it and the electrode piece 100, thereby mitigating the impact force of the electrolyte on the separator 200. When the separator 200 is subjected to an impact from the electrolyte, the sealing region 101 moves until it contacts the edge of the electrode piece 100, preventing the sealing region 101 from tearing. Referring to Figures 4 and 5, if S is the distance from the edge of the sealing region 101 facing the electrode piece 100 to the edge of the electrode piece 100, then S satisfies 0.1 mm ≤ S ≤ 1 mm. S may be 0.1 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or any two of these, for example, 0.1 mm ≤ S ≤ 0.5 mm, 0.1 mm ≤ S ≤ 0.6 mm, 0.1 mm ≤ S ≤ 0.7 mm, 0.1 mm ≤ S ≤ 0.8 mm, 0.1 mm ≤ S ≤ 0.9 mm, etc.

[0046] At least some of the sealed regions 101 are spaced apart along the longitudinal direction X of the electrode piece 100. For example, there are at least two sealed regions 101 spaced apart along the longitudinal direction X of the electrode piece 100. The tab 400 extends a separator 200 from between the first extending portion 201 and the second extending portion 202 along the width direction Y of the electrode piece 100, and in the longitudinal direction X of the electrode piece 100, one sealed region 101 is provided on one side of the tab 400 and is located close to the tab 400, and the other sealed region 101 is provided on the other side of the tab 400 and is located close to the tab 400. Here, if Q is the distance from the edge of the sealed region 101 located close to the tab 400 to the edge of the tab 400, then Q satisfies 0.2 mm ≤ Q ≤ 2 mm. Q may be 0.3 mm, 0.6 mm, 0.9 mm, 1.1 mm, 1.5 mm, 1.8 mm, or any two of these in the range, for example, 0.2 mm ≤ Q ≤ 0.3 mm, 0.2 mm ≤ Q ≤ 0.6 mm, 0.2 mm ≤ Q ≤ 0.9 mm, 0.2 mm ≤ Q ≤ 1.1 mm, 0.2 mm ≤ Q ≤ 1.5 mm, 0.2 mm ≤ Q ≤ 1.8 mm, etc. Also, when Q satisfies 0.2 mm ≤ Q ≤ 2 mm, the separator 200 also plays a role on the surface of the tab 400, improving the stability of the tab 400 being placed on the electrode piece 100.

[0047] In the length direction X of the electrode sheet 100, when the length of the electrode sheet 100 is L and the length of the sealing region 101 is l0, L and l0 satisfy 1 < L / l0 ≤ 200. L / l0 may be 1, 20, 30, 50, 60, 100, 130, 150, 200, or a range consisting of any two of these, for example, 1 < L / l0 ≤ 20, 1 < L / l0 ≤ 30, 1 < L / l0 ≤ 50, 1 < L / l0 ≤ 60, 1 < L / l0 ≤ 100, 1 < L / l0 ≤ 130, 1 < L / l0 ≤ 150, etc. Within the above range, since the length of the sealing region 101 is appropriate and the structure of the sealing region 101 is strong, it can effectively withstand the impact from the electrolytic solution.

[0048] In the length direction X of the electrode sheet 100, when the width between two adjacent sealing regions 101 is a1, L / a1 satisfies 200 ≤ L / a1 ≤ 40,000. L / a1 may be 200, 300, 500, 800, 1000, 2000, 4000, or a range consisting of any two of these, for example, 200 ≤ L / a1 ≤ 300, 200 ≤ L / a1 ≤ 500, 200 ≤ L / a1 ≤ 800, 200 ≤ L / a1 ≤ 1000, 300 ≤ L / a1 ≤ 500, etc. Within the above interval range, the interval between two adjacent sealing regions 101 in the length direction X of the electrode sheet 100 is appropriate and contributes to the immersion of the electrolytic solution.

[0049] Here, 1 ≤ l0 / a1 ≤ 4000, and l0 / a1 may be 10, 100, 500, 800, 1000, 2000, 4000, or a range consisting of any two of these, for example, 1 ≤ l0 / a1 ≤ 10, 1 ≤ l0 / a1 ≤ 100, 1 ≤ l0 / a1 ≤ 500, 1 ≤ l0 / a1 ≤ 800, 1 ≤ l0 / a1 ≤ 1000, 1 ≤ l0 / a1 ≤ 2000, 10 ≤ l0 / a1 ≤ 4000, etc. By controlling the ratio of l0 to a1 within an appropriate range, it becomes easy to distribute the length and interval of the sealing region 101 in the length direction X of the electrode sheet 100. In the length direction X of the electrode sheet 100, the sealing of the sealing region 101 is strong and it is possible to have a good electrolytic solution immersion effect.

[0050] Furthermore, in the longitudinal direction X of the electrode piece 100, the lengths l0 of the multiple sealed regions 101 (first sealed region 1011) may be the same or different, and the width a1 between any two adjacent sealed regions 101 (first sealed region 1011) may be the same or different.

[0051] The lengthwise dimension X of the electrode piece 100 is greater than the widthwise dimension Y of the electrode piece 100, and correspondingly, the dimension of the separator 200 in the lengthwise direction X of the electrode piece 100 is greater than the dimension of the separator 200 in the widthwise direction Y of the electrode piece 100. Furthermore, in the wound electrode assembly 10, the electrode piece 100 and the separator 200 can interact, and the electrode piece 100 can be supported by the separator 200 in the lengthwise direction (winding direction) of the electrode piece 100, thus contributing to reducing the shrinkage width of the separator 200. Therefore, when subjected to impact, the shrinkage or folding of the separator 200 in the widthwise direction Y of the electrode piece 100 is more likely to cause a short circuit between two electrode pieces 100 with opposite polarities. In this embodiment of the present invention, by forming a sealed region 101 in the portion of the electrode piece 100 of the separator 200 that extends from the electrode piece 100 in the width direction Y, it is possible to prevent short circuits between two electrode pieces 100 with opposite polarities due to contraction in the width direction Y of the electrode piece 100.

[0052] When the first extension portion 201 and the second extension portion 202 are installed at a distance from each other at both ends of the electrode piece 100 in the longitudinal direction X, preferably, as shown in Figure 4, the width to which the first extension portion 201 and the second extension portion 202 extend in the longitudinal direction X of the electrode piece 100 is set to be larger than the width to which the first extension portion 201 and the second extension portion 202 extend in the width direction Y of the electrode piece 100. By increasing the width to which the first extension portion 201 and the second extension portion 202 extend in the longitudinal direction X of the electrode piece 100, a short circuit between two electrode pieces 100 with opposite polarities due to the contraction of the separator 200 in the longitudinal direction X of the electrode piece 100 is prevented.

[0053] Naturally, if both ends of the separator 200 are not fixed in the longitudinal direction X of the electrode piece 100, there is still a risk of short-circuiting two electrode pieces 100 with opposite polarities due to contraction of both ends of the separator 200 in the longitudinal direction X of the electrode piece 100. Preferably, some sealing regions 101 (first sealing regions) are installed at intervals along the longitudinal direction X of the electrode piece 100, and other sealing regions 101 (second sealing regions) are installed at intervals along the width direction Y of the electrode piece 100. In other words, by forming sealing regions 101 in the width direction Y and the longitudinal direction X of the electrode piece 100, the portions of the separator 200 that extend from the electrode piece 100 are respectively prevented from short-circuiting two electrode pieces 100 with opposite polarities due to contraction of the separator 200 in the longitudinal direction X and the width direction Y of the electrode piece 100.

[0054] In the width direction Y of the electrode piece 100, if the width of the electrode piece 100 is W and the width of the sealed region 101 is w0, then W and w0 satisfy 1 ≤ W / w0 ≤ 20. W / w0 is in the range of 1, 4, 8, 10, 15, 18, 20, or any two of these, for example, 1 ≤ W / w0 ≤ 4, 1 ≤ W / w0 ≤ 8, 1 ≤ W / w0 ≤ 15, 4 ≤ W / w0 ≤ 20, etc.

[0055] In the width direction Y of the electrode piece 100, if the width between two adjacent sealed regions 101 is a2, then W and a2 satisfy 20 ≤ W / a2. W / a2 is 20, 25, 50, 80, 100, 200, 400, or any numerical range thereof, for example, 25 ≤ W / a2, 50 ≤ W / a2, 80 ≤ W / a2, 100 ≤ W / a2, 200 ≤ W / a2, 400 ≤ W / a2, etc.

[0056] Here, w0 and a2 satisfy 1 ≤ w0 / a2. w0 / a2 is 20, 25, 50, 80, 100, 200, 400, or any of these ranges, for example, 20 ≤ w0 / a2, 25 ≤ w0 / a2, 50 ≤ w0 / a2, 80 ≤ w0 / a2, 100 ≤ w0 / a2, 200 ≤ w0 / a2, etc. Similarly, by controlling the ratio of W, w0, and a2 within the above range, it becomes easy to distribute the length and spacing of the sealed region 101 in the width direction Y of the electrode piece 100, resulting in a strong seal of the sealed region 101 and a good electrolyte immersion effect.

[0057] Furthermore, in the width direction Y of the electrode piece 100, the widths w0 of the multiple sealed regions 101 (second sealed regions) may be the same or different, and the width a2 between any two adjacent sealed regions 101 (second sealed regions) may be the same or different.

[0058] Preferably, the first separator 210 and the second separator 220 are installed integrally. Specifically, in the width direction Y of the electrode piece 100, the first extension 201 includes a first portion 211 located on one side of the electrode piece 100, and a portion of the first portion 211 is connected to the second extension 202 to form at least two sealed regions 101. The end of the first separator 210 opposite to the first portion 211 is integrally molded with the second separator 220, forming a complete sealing structure on one side of the electrode piece 100. For example, a single separator substrate can be wound from one side of the electrode piece 100 along one long side of the electrode piece 100 to the other side of the electrode piece 100, thereby forming the first separator 210 in the thickness direction Z of the electrode piece 100 and the second separator 220 in the portion located on the other side of the electrode piece 100. This makes it easier to reduce the cutting process for the separator 200, contributing to improved assembly efficiency.

[0059] Preferably, the first separator 210 and the second separator 220 are installed separately. Specifically, the first extension 201 includes a first portion 211, a second portion 212, a third portion 213, and a fourth portion 214. In the width direction Y of the electrode piece 100, the first portion 211 is located on one side of the electrode piece 100, and the second portion 212 is located on the other side of the electrode piece 100. In the length direction X of the electrode piece 100, the third portion 213 is located on one side of the electrode piece 100, and the fourth portion 214 is located on the other side of the electrode piece 100. Here, a portion of the first portion 211 is connected to the second extended portion 202 to form at least two sealed regions 101, a portion of the second portion 212 is connected to the second extended portion 202 to form at least one sealed region 101, a portion of the third portion 213 is connected to the second extended portion 202 to form at least one sealed region 101, and a portion of the fourth portion 214 is connected to the second extended portion 202 to form at least one sealed region 101. This contributes to improving the electrolyte immersion effect.

[0060] Preferably, the first extended portion 201 and the second extended portion 202 form a sealed region 101 by a crimping method. For example, each sealed region 101 is a hot-pressure sealed portion or a roll-rolled sealed portion. When forming the sealed region 101 by a crimping method, the sealed region 101 can be crimped while avoiding the tab 400 according to a preset crimping pattern. This prevents overpressure on the tab 400 and the portion of the electrode piece 100 connected to the tab 400, and improves the stability of the characteristics of the manufactured electrode assembly 10.

[0061] Preferably, the first extended portion 201 and the second extended portion 202 form a sealed region 101 by an adhesive method. For example, an adhesive layer is placed between the first extended portion 201 and the second extended portion 202, and the first extended portion 201 and the second extended portion 202 are connected via the adhesive layer to form a sealed region 101. The sealed region 101 can also be formed by applying an adhesive to at least one surface of the first extended portion 201 and the second extended portion 202 before bonding, with the adhesive applied while avoiding the tab 400.

[0062] As shown in Figure 6, the wound electrode assembly 10 includes a flat portion 310 and a curved portion 320, where the stress is greater in the curved portion 320. Due to the presence of stress, the connection between the first extended portion 201 and the second extended portion 202 that form the sealing region 101 in the curved portion 320 is likely to be insufficient, and when the stress is high, wrinkles are likely to occur, which may interfere with the separator 200 in other regions.

[0063] Preferably, a sealed region 101 is formed in both the curved portion 320 and the flat portion 310, and the length of the sealed region 101 in the curved portion 320 is set to be shorter than the length of the sealed region 101 in the flat portion 310, thereby reducing the influence of stress in the curved portion 320 on the structural stability of the sealed region 101.

[0064] Preferably, a sealed region 101 is formed in the flat portion 310, and the first extended portion 201 and the second extended portion 202 of the curved portion 320 are spaced apart. Here, in the embodiment of the present invention, the surface of the flat portion 310 may be flat (i.e., the flat portion 310 may be plate-like), or the flat portion 310 may be slightly curved, but the curvature of the curve of the flat portion 310 is smaller than the curvature of the curved portion 320, and the difference in curvature between the flat portion 310 and the curved portion 320 is large.

[0065] Referring to Figures 6 and 7, when a sealed region 101 is formed in the flat portion 310, the sealed region 101 of the flat portion 310 is positioned correspondingly in the thickness direction of the electrode assembly 10, and the first extended portion 201 and the second extended portion 202 of the curved portion 320 are positioned with a gap between them. This contributes to improving the electrolyte immersion efficiency. Here, the width direction of the electrode assembly 10 and the width direction Y of the electrode piece 100 coincide, and the thickness direction of the electrode assembly 10 is the thickness direction Y of the electrode piece 100 in the flat portion 310.

[0066] In other embodiments, the sealed regions 101 in the flat portion 310 are offset from each other in the thickness direction Z of the electrode assembly 10, or they partially overlap.

[0067] In the wound electrode assembly 10, two electrode pieces 100 with opposite polarities are alternately arranged in the thickness direction Z of the electrode assembly 10, and even between any two electrode pieces 100 with opposite polarities, a separator 200 is required to isolate the two electrode pieces 100 with opposite polarities to prevent short circuits. Preferably, referring to Figure 3, one electrode piece 100 is arranged so as to be constrained between a first separator 210 and a second separator 220 in the same separator 200. Specifically, the electrode assembly 10 includes two electrode pieces 100, at least two tabs 400 and one separator 200. At least one tab 400 is placed on one electrode piece 100, and the electrode piece 100 is placed between the first separator 210 and the second separator 220 in the separator 200 to form a first electrode piece unit 11. The remaining tab 400 is placed on the other electrode piece 100 to form a second electrode piece unit 12. The two electrode pieces 100 have opposite polarities. As a result, in the wound electrode assembly 10, the two portions of the electrode pieces 100 with opposite polarities are isolated in the thickness direction Z of the electrode assembly 10.

[0068] Preferably, the electrode assembly 10 is installed such that one electrode piece 100 is constrained between the first separator 210 and the second separator 220 in one separator 200, and the other electrode piece 100 is constrained between the first separator 210 and the second separator 220 in the other separator 200. Specifically, the electrode assembly 10 includes two electrode pieces 100, at least two tabs 400, and two separators 200. At least one tab 400 is installed on one electrode piece 100, and the electrode piece 100 is installed between the first separator 210 and the second separator 220 in one separator 200 to form a first electrode piece unit 11. The remaining tab 400 is installed on the other electrode piece 100, and the electrode piece 100 is installed between the first separator 210 and the second separator 220 in the other separator 200 to form a second electrode piece unit 12. The polarities of the two electrode pieces 100 are opposite. This allows the separator 200 to protect the electrode pieces 100 more comprehensively and more effectively prevent a short circuit between the two electrode pieces 100 with opposite polarities.

[0069] The tab 400 extends from the separator 200 along the width direction Y of the electrode piece 100, and in the width direction Y of the electrode piece 100, the width of one electrode piece 100 is smaller than the width of the other electrode piece 100, and at least the narrower electrode piece 100 is installed between the first separator 210 and the second separator 220 of the separator 200. As a result, when the separator 200 extends from the edge of the narrower electrode piece 100, the first extended portion 201 and the second extended portion 202 of the separator 200 can isolate two adjacent portions of the wider electrode piece 100, further saving the amount of separator 200 used and the space occupied by the separator 200, thereby contributing to an improvement in the energy density of the battery cell using the electrode assembly 10 of the present invention.

[0070] Preferably, the narrower electrode piece 100 is the positive electrode piece 110, and the wider electrode piece 100 is the negative electrode piece 120.

[0071] The electrode assembly 10 further includes a protective layer 410 placed on the surface of the tab 400, which avoids the connection between the tab 400 and the electrode piece 100. The protective layer 410 is used to prevent the tab 400 from coming into contact with other structures. For example, it prevents the tab 400 from coming into contact with sharp structures such as burrs generated during the manufacturing process of other structures. Here, the protective layer 410 is placed on the surface where the tab 400 extends from the separator 200, and further extends between the separator 200 and the tab 400, thereby contributing to buffering the stress when the tab 400 is attached to the electrode piece 100. For example, the protective layer 410 is an adhesive for the tab. The protective layer 410 is further used to connect to other structures of the battery cell to fix the position of the tab 400. For example, the protective layer 410 connects to the outer casing (packaging) of the battery cell.

[0072] An embodiment of the present invention further provides a battery cell comprising an outer casing and the electrode assembly 10 described above, the electrode assembly 10 being installed in the internal space of the outer casing. Here, a tab 400 extends from the electrode piece 100 to the outer casing and is used to electrically connect to an external circuit, and the tab 400 is fixed to the outer casing.

[0073] In embodiments of the present invention, the battery cells include soft pack batteries and hard shell batteries. The casing of the soft pack battery may be an aluminum plastic film, and tabs 400 extend from the casing and connect to the aluminum plastic film. Furthermore, a protective layer 410, which is installed on the surface of tabs 400, is connected to the aluminum plastic film and, for example, the material of the protective layer 410 may be polypropylene (PP) or polyethylene (PE). The casing of the hard shell battery may be an aluminum shell. The hard shell battery further includes electrode posts installed on the casing, and tabs 400 extend from electrode pieces 100 to connect to the electrode posts and connect to an external circuit via the electrode posts. Alternatively, tabs 400 may extend from electrode pieces 100 to connect to the casing and electrically connect to an external circuit.

[0074] The numerical values ​​and ranges in the embodiments of the present invention are approximations, and errors within a certain range may occur due to the influence of the manufacturing process. These errors can be understood by those skilled in the art as being negligible.

[0075] In the description of this invention, a list of items connected by the terms "at least one of...", "at least one of...", "at least one type of...", or other similar terms means any combination of the enumerated items. For example, if items A and B are enumerated, the phrase "at least one of A and B" means A only, B only, or A and B. As another example, if items A, B, and C are enumerated, the phrase "at least one of A, B, and C" means A only, B only, C only, A and B (excluding C), A and C (excluding B), B and C (excluding A), or A, B, and C all of the above.

[0076] The above description is merely a preferred embodiment of the present application and does not limit it. Any amendments, equivalent substitutions, modifications, etc., made within the spirit and principles of the present application shall all be included within the scope of protection of the present application.

Claims

1. An electrode assembly comprising a first electrode piece unit and a second electrode piece unit that are wound and installed, wherein the polarities of the first electrode piece unit and the second electrode piece unit are opposite. At least one of the first electrode piece unit and the second electrode piece unit includes an electrode piece, a tab, and a separator, wherein the separator includes a first separator and a second separator, respectively, installed on opposite sides of the electrode piece in the thickness direction of the electrode piece, the first separator includes a first extension extending from the edge of the electrode piece along the width direction of the electrode piece, the second separator includes a second extension extending from the edge of the electrode piece along the width direction of the electrode piece, the tab is installed on the electrode piece and extends from the separator through the first extension and the second extension, the first extension and the second extension are connected to form a sealed region, the number of sealed regions is at least two, and the sealed regions avoid the tab. An electrode assembly characterized by the following features.

2. At least a portion of the sealing area is spaced apart along the length of the electrode piece, and in the length of the electrode piece, let L be the length of the electrode piece and l be the length of the sealing area. ０ Let a1 be the distance between two adjacent sealed regions. 1 < L / l ０ ≤ 200, and / or 200 ≤ L / a1 ≤ 4000, and / or 1≦l ０ / a1≦4000 The electrode assembly according to claim 1, characterized in that it satisfies the following conditions.

3. Some of the sealing regions are spaced apart along the length of the electrode piece, and other parts of the sealing regions are spaced apart along the width of the electrode piece, where W is the width of the electrode piece and w is the width of the sealing region in the width direction of the electrode piece. ０ If the width between the two adjacent sealed regions is a2, 1 ≤ W / w ０ ≤ 20, and / or W / a² ≥ 20, and / or w ０ / a2≧1 The electrode assembly according to claim 2, characterized in that it satisfies the following conditions.

4. In the width direction of the electrode piece, the first extension includes a first portion located on one side of the electrode piece, and a portion of the first portion connects with the second extension to form at least two sealed regions. In the width direction of the electrode piece, one end of the first separator opposite to the first portion is integrally molded with the second separator, or In the width direction of the electrode piece, the first extension includes a second portion opposite to the first portion, and a portion of the second portion connects with the second extension to form at least one sealed region. The electrode assembly according to claim 1, characterized in that

5. Each of the aforementioned sealed areas is a hot-pressure sealed section or a roll-rolled sealed section, or An adhesive layer is placed between the first extended portion and the second extended portion, and the first extended portion and the second extended portion are connected via the adhesive layer to form the sealed region. The electrode assembly according to claim 1, characterized in that

6. The electrode assembly includes a flat portion and a curved portion, and the sealing region is located in the flat portion. The electrode assembly according to claim 1, characterized in that

7. The sealed regions are positioned correspondingly in the thickness direction of the electrode assembly, and the first and second extended portions in the curved portion are spaced apart. The electrode assembly according to claim 6, characterized in that

8. The electrode assembly comprises two electrode pieces, at least two tabs, and one separator, wherein at least one tab is placed on one electrode piece, and the electrode piece is placed between the first separator and the second separator in the separator to form the first electrode piece unit, and the remaining tab is placed on the other electrode piece to form the second electrode piece unit, and the polarities of the two electrode pieces are opposite, or The electrode assembly comprises two electrode pieces, at least two tabs, and two separators, wherein at least one tab is placed on one electrode piece, and the electrode piece is placed between the first separator and the second separator in one of the separators to form the first electrode piece unit, and the remaining tab is placed on the other electrode piece, and the electrode piece is placed between the first separator and the second separator in the other separator to form the second electrode piece unit, and the polarities of the two electrode pieces are opposite. The electrode assembly according to claim 1, characterized in that

9. The tab extends from the separator along the width direction of the electrode piece, and in the width direction of the electrode piece, the width of one electrode piece is smaller than the width of the other electrode piece, and at least the electrode piece with the smaller width is installed between the first separator and the second separator in the separator. The electrode assembly according to claim 8, characterized in that

10. The electrode piece with a smaller width is the positive electrode piece, and the electrode piece with a larger width is the negative electrode piece. The electrode assembly according to claim 9, characterized in that

11. The sealing region is installed with a gap between it and the electrode piece, and if S is the distance from the edge of the sealing region toward the electrode piece to the edge of the electrode piece, then S satisfies 0.1 mm ≤ S ≤ 1 mm, and / or The tab extends from the separator along the width direction of the electrode piece, and in the length direction of the electrode piece, one sealing region is located on one side of the tab, and the other sealing region is located on the other side of the tab, and when Q is the distance from the edge of the sealing region to the edge of the tab, Q satisfies 0.2 mm ≤ Q ≤ 2 mm. The electrode assembly according to claim 1, characterized in that

12. Exterior and A battery cell comprising an electrode assembly according to any one of claims 1 to 11, The electrode assembly is installed in the exterior. A battery cell characterized by the following features.

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