Pole piece, battery cell and battery

Abstract

The utility model relates to the technical field of batteries, and provides a pole piece, a battery cell and a battery, and the pole piece comprises a current collector and a tab. The current collector is provided with a first surface and a second surface along a first direction, the first surface and the second surface are covered with an active material layer and an insulating layer, the insulating layer of the first surface is provided with a tab groove, the tab is arranged in the tab groove, and the projection of the insulating layer of the second surface covers the tab groove. Therefore, the surface of the pole piece is covered with the insulating layer, the exposed area of the pole piece is reduced, the effective insulating area of the pole piece is increased, the insulativity and safety are improved, and meanwhile, the structural strength of the pole piece can be improved and the needling safety of the battery can be improved due to the arrangement of the insulating layer. The insulating layer on the second surface covers the joint of the tab and the tab groove, so that a welding bulge generated by the tab is prevented from puncturing the diaphragm, short circuit caused by contact of positive and negative pole pieces is reduced, and the safety of the battery is improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a pole piece, a battery cell and a battery. Background Art

[0002] Batteries have been widely used in various fields. At the same time, people's safety requirements for batteries are becoming higher and higher.

[0003] In related technologies, a battery includes a cell, which has a positive electrode sheet, a separator, and a negative electrode sheet stacked in sequence. The positive and negative electrode sheets are connected to tabs, forming the battery's conductive structure. The tabs are welded to the empty foil area of ​​the electrode sheet, which has a portion of the electrode sheet.

[0004] However, during the battery cell forming process, the exposed empty foil areas on the positive and negative electrodes can easily contact each other and cause internal short circuits, affecting safety. The tab welding points on the electrodes can easily pierce the diaphragm, causing the positive and negative electrodes to contact each other and form electrical conduction, releasing a large amount of energy in a very short time, causing the internal temperature of the battery to rise sharply, and the battery may even catch fire and explode, seriously affecting battery safety. Utility Model Content

[0005] The present application provides a pole piece, a battery cell and a battery, which can improve safety.

[0006] In order to achieve the above objectives, this application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a pole piece, comprising: a current collector and a pole tab;

[0008] The current collector has a first surface and a second surface opposite to each other along a first direction, and the first surface and the second surface are respectively covered with an active material layer;

[0009] At least parts of the first surface and the second surface are covered with an insulating layer;

[0010] The first surface has at least one tab groove, at least one tab groove is located in the insulating layer of the first surface, the tab is disposed in the tab groove, and the tab is connected to the first surface of the current collector;

[0011] Along the first direction, a projection of the insulating layer on the second surface covers the tab groove.

[0012] As a possible implementation manner, along the first direction, on the same surface of the current collector, the active material layer overlaps with the insulating layer; or,

[0013] The active material layer and the insulating layer are adjacent to each other within the same surface.

[0014] As a possible implementation manner, the tab groove includes a first tab groove and a second tab groove, the first tab groove and the second tab groove are located on the first surface, and there is a gap between the first tab groove and the second tab groove; the first tab groove is located on the insulating layer of the first surface;

[0015] The electrode tab includes a first electrode tab and a second electrode tab. The first electrode tab is disposed in the first electrode tab slot, and the second electrode tab is disposed in the second electrode tab slot.

[0016] As a possible implementation, the pole piece further includes an empty foil area, and the empty foil area and the pole tab groove are spaced apart and distributed at two opposite ends of the current collector along a second direction; the second direction is perpendicular to the first direction.

[0017] As a possible implementation manner, the pole piece includes a notch area, and the notch area and the second pole tab groove are spaced apart and distributed at two opposite ends of the current collector along a second direction; the second direction is perpendicular to the first direction.

[0018] As a possible implementation manner, along the third direction, the ratio of the size of the active material layer to the size of the tab groove is 50-200; and / or,

[0019] Along the second direction, the ratio of the size of the current collector to the size of the tab slot is 2.5-10;

[0020] The third direction, the second direction and the first direction are perpendicular to each other.

[0021] As a possible implementation manner, along the first direction, a ratio of the thickness of the tab to the thickness of the insulating layer is 10-60.

[0022] As a possible implementation manner, the pole piece further includes an insulating member, the insulating member and the pole tab slot are provided in a one-to-one correspondence, the insulating member is located on a side of the pole tab away from the pole tab slot, and at least a portion of the insulating member covers the pole tab slot;

[0023] Along the first direction, a ratio of the thickness of the insulating layer to the thickness of the insulating member is 0.1-0.5.

[0024] As a possible implementation manner, along the first direction, the insulating member is not provided in a region of the insulating layer of the second surface opposite to an orthographic projection of the tab groove of the first surface.

[0025] As a possible implementation manner, the tab is welded in the tab slot to form a welding area;

[0026] Along the first direction, a ratio of a height of the welding area print to a thickness of the insulating layer is greater than or equal to 4.

[0027] The pole piece provided in the present application reduces the exposed area of ​​the pole piece by covering the first surface and the second surface of the current collector with an insulating layer, thereby increasing the effective insulating area of ​​the pole piece and improving the insulation and safety of the pole piece. At the same time, along the first direction, the projection of the insulating layer on the second surface covers the connection between the pole ear and the current collector on the first surface, which can prevent the connection between the pole ear and the current collector from piercing the diaphragm, reduce the short circuit formed by the contact between pole pieces with opposite polarities, and further improve safety.

[0028] In a second aspect, the present application provides a battery cell, comprising a first pole piece, a diaphragm, and a second pole piece stacked in sequence;

[0029] The first pole piece is the pole piece described in the first aspect;

[0030] The first pole piece, the diaphragm and the second pole piece are stacked and wound to form a winding core.

[0031] As a possible implementation manner, the first pole piece includes a winding head portion located at an inner circle of the winding core and a winding tail portion located at an outer circle of the winding core;

[0032] The insulating layer is located at the winding head and / or the winding tail.

[0033] The battery cell provided in the present application can improve safety because it includes the electrode provided in the first aspect.

[0034] In a third aspect, the present application provides a battery, comprising a shell and the battery cell described in the second aspect, wherein the shell has a receiving cavity, and the battery cell is located in the receiving cavity.

[0035] The present application provides a battery, which can improve safety due to the inclusion of the electrode provided in the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0037] Figure 1 A schematic cross-sectional view of a pole piece provided in an embodiment of the present application Figure 1 ;

[0038] Figure 2 for Figure 1 A partial enlarged view of part A;

[0039] Figure 3 A top view of the pole piece provided in the embodiment of the present application Figure 1 ;

[0040] Figure 4 A top view of the pole piece provided in the embodiment of the present application Figure 2 ;

[0041] Figure 5 for Figure 4 Dimensioning diagram of

[0042] Figure 6 A schematic cross-sectional view of a pole piece provided in an embodiment of the present application Figure 2 ;

[0043] Figure 7 This is a schematic diagram of the cross-section of the pole piece of the experimental control group provided in this application.

[0044] Description of reference numerals:

[0045] 100-pole piece;

[0046] 110-Current collector;

[0047] 111-first surface; 112-second surface;

[0048] 113-tab slot; 113a-first tab slot; 113b-second tab slot;

[0049] 114-winding head;

[0050] 115-coiled tail;

[0051] 116-empty foil area;

[0052] 117-Gap area;

[0053] 120-pole tab; 120a-first pole tab; 120b-second pole tab;

[0054] 130-insulation layer;

[0055] 140-active material layer;

[0056] 150-insulation parts;

[0057] 160-Welding mark. DETAILED DESCRIPTION

[0058] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. The following embodiments and features in the embodiments can be combined with each other unless there is a conflict.

[0059] Batteries have been widely used in various fields. At the same time, people's safety requirements for batteries are becoming higher and higher.

[0060] In related technologies, a battery includes a cell, which has a positive electrode sheet, a separator, and a negative electrode sheet stacked in sequence. The positive and negative electrode sheets are connected to tabs, forming the battery's conductive structure. The tabs are welded to the empty foil area of ​​the electrode sheet, which has a portion of the electrode sheet.

[0061] However, during the battery cell forming process, the exposed empty foil areas on the positive and negative electrodes can easily contact each other and cause internal short circuits, affecting safety. The tab welding points on the electrodes can easily pierce the diaphragm, causing the positive and negative electrodes to contact each other and form electrical conduction, releasing a large amount of energy in a very short time, causing the internal temperature of the battery to rise sharply, and the battery may even catch fire and explode, seriously affecting battery safety.

[0062] In order to overcome the defects in the prior art, the present application provides a pole piece, a battery cell and a battery, wherein the pole piece includes a current collector and a pole tab. The current collector has a first surface and a second surface along a first direction, the first surface and the second surface are covered with an active material layer and an insulating layer, the insulating layer on the first surface is provided with a pole tab groove, the pole tab is provided in the pole tab groove, and the projection of the insulating layer on the second surface covers the pole tab groove. In this way, the surface of the pole piece is covered with an insulating layer, which reduces the exposed area of ​​the pole piece, increases the effective insulating area of ​​the pole piece, reduces the short circuit between pole pieces of opposite polarity, improves insulation and safety, and at the same time, the insulating layer on the second surface covers the connection between the pole tab and the pole tab groove, preventing the welding protrusion generated by the pole tab from piercing the diaphragm, reducing the short circuit caused by the contact between the positive and negative pole pieces, and improving the safety of the battery.

[0063] The content of the utility model will be described in detail below with reference to the accompanying drawings so that those skilled in the art can understand the content of the utility model more clearly and in detail.

[0064] Figure 1 A schematic cross-sectional view of a pole piece provided in an embodiment of the present application Figure 1 . Figure 2 for Figure 1 A partial enlarged view of part A. Figure 3A top view of the pole piece provided in the embodiment of the present application Figure 1 . Figure 4 A top view of the pole piece provided in the embodiment of the present application Figure 2 . Figure 5 for Figure 4 Dimensioning diagram. Figure 6 A schematic cross-sectional view of a pole piece provided in an embodiment of the present application Figure 2 .like Figures 1-6 As shown, this embodiment provides a pole piece 100 including a current collector 110 and a pole tab 120 .

[0065] The current collector 110 has a first surface 111 and a second surface 112 along a first direction (Z direction), and the first surface 111 and the second surface 112 are respectively covered with an active material layer 140 .

[0066] At least a portion of the first surface 111 and the second surface 112 is covered with an insulating layer 130 .

[0067] The first surface 111 has at least one tab groove 113 . The at least one tab groove 113 is located in the insulating layer 130 of the first surface 111 . The tab 120 is disposed in the tab groove 113 . The tab 120 is connected to the first surface 111 of the current collector 110 .

[0068] Along the first direction (Z direction), the projection of the insulating layer 130 on the second surface 112 covers the tab groove 113 .

[0069] According to the pole piece 100 provided in this embodiment, by covering the first surface 111 and the second surface 112 with an insulating layer 130, the exposed area of ​​the pole piece 100 is reduced, the effective insulating area of ​​the pole piece 100 is increased, and the insulation and safety of the pole piece 100 are improved. At the same time, along the first direction (Z direction), the projection of the insulating layer 130 on the second surface 112 covers the connection between the pole ear 120 and the current collector 110 on the first surface 111, which can prevent the connection between the pole ear 120 and the current collector 110 from piercing the diaphragm, reduce the short circuit formed by the contact between the pole pieces 100 with opposite polarities, and further improve safety.

[0070] It should be noted that, in this embodiment, the first direction (Z direction) may be the thickness direction of the pole piece 100, the second direction (Y direction) may be the width direction of the pole piece 100, and the third direction (X direction) may be the length direction of the pole piece 100, wherein the first direction, the second direction and the third direction are perpendicular to each other.

[0071] Exemplarily, the current collector 110 in this embodiment is a metal member, such as aluminum foil, copper foil, etc. The current collector 110 has a first surface 111 and a second surface 112 facing each other along a first direction (Z direction). Both the first surface 111 and the second surface 112 are covered with an active material layer 140.

[0072] The electrode 100 provided in this embodiment can be a positive electrode. When the electrode 100 is a positive electrode, the current collector 110 is aluminum foil, and the active material layer 140 covered by the first surface 111 and the second surface 112 of the current collector 110 is a positive electrode active material, such as lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide, nickel cobalt manganese ternary material and lithium nickel cobalt aluminum oxide.

[0073] The electrode 100 provided in this embodiment can also be a negative electrode. When the electrode 100 is a negative electrode, the current collector 110 is copper foil, and the active material layer 140 covered by the current collector 110 is a negative electrode active material such as natural graphite, artificial graphite, soft carbon, hard carbon, lithium titanate, silicon-carbon composite material, etc.

[0074] The active material layer 140 and the insulating layer 130 can be connected to the corresponding first surface 111 and second surface 112 of the current collector 110 by coating. During the production process of the electrode 100, the metal foil is coated at predetermined positions on the first surface 111 and second surface 112 that are opposite to each other along the first direction (Z direction). After rolling and slitting, the current collector 110 coated with the active material layer 140 and the insulating layer 130 can be obtained.

[0075] And at least part of the first surface 111 and the second surface 112 is covered by the insulating layer 130. The insulating layer 130 can be located in the end area of ​​the first surface 111, or completely cover the first surface 111. Accordingly, the insulating layer 130 can cover a part of the second surface 112 on the second surface 112, or completely cover the second surface 112. In this way, the exposed area of ​​the current collector 110 is relatively reduced, the effective insulation area is increased, the short circuit phenomenon of the positive and negative poles is reduced, and the insulation and safety of the pole piece 100 are improved. In addition, the insulating layer 130 covers the current collector 110, which can further improve the cell puncture pass rate during the cell puncture test.

[0076] Among them, at least one pole lug groove 113 is provided on the first surface 111, and at least one pole lug groove 113 is located on the insulating layer 130 of the first surface 111. The pole lug groove 113 penetrates the insulating layer 130 of the first surface 111 along the first direction (Z direction) so that the current collector 110 is exposed along the first direction (Z direction) through the pole lug groove 113. The pole lug 120 is located in the pole lug groove 113 and is connected to the first surface 111 of the current collector 110 to form a conductive structure to supply power to external electrical equipment.

[0077] It should be noted that the number of the tab groove 113 in this embodiment may be one or more, and at least one of the multiple tab grooves 113 is located on the insulating layer 130 on the first surface 111 .

[0078] The tab groove 113 in this embodiment is covered with an insulating layer 130 on the first surface 111 and the second surface 112 corresponding to the first direction (Z direction), and the insulating layer 130 of the second surface 112 covers the insulating layer 130 of the first surface 111 in the orthographic projection of the plane where the tab groove 113 is located. In this way, the insulating layer 130 of the second surface 112 can form a protective effect on the connection between the tab 120 and the current collector 110, prevent the connection between the tab 120 and the current collector 110 from piercing the diaphragm, reduce the short circuit between the pole pieces 100 with opposite polarities, and improve insulation and safety.

[0079] The insulating layer 130 in this embodiment is a composition comprising an inorganic filler, a conductive agent, and a binder. The inorganic filler can be selected from one or more of lithium cobalt oxide, nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, nickel-cobalt-manganese-aluminum quaternary materials, lithium iron phosphate, carbon-coated lithium iron phosphate, lithium manganese phosphate, lithium manganate, and lithium-rich manganese-based materials. Alternatively, the inorganic filler can be selected from a ceramic material, specifically one or more of aluminum oxide, boehmite, magnesium oxide, and magnesium hydroxide. Alternatively, the inorganic filler can be selected from a mixture of at least one lithium-containing transition metal oxide and at least one ceramic material. The conductive agent can be selected from one or more of conductive carbon black, acetylene black, conductive graphite, Ketjen black, carbon nanotubes, and graphene. The binder can be selected from one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl pyrrolidone, polyacrylic acid, polyacrylonitrile, lithium polyacrylate, polyamide, methacrylate, and sodium carboxymethyl cellulose. The insulating layer 130 in this embodiment is produced by selecting the various components and the proportions of the components in the composition.

[0080] In some embodiments, along the first direction (Z direction), on the same surface of the current collector 110 , at least a portion of the active material layer 140 overlaps with at least a portion of the insulating layer 130 ; or, the active material layer 140 and the insulating layer 130 are adjacent to each other on the same surface.

[0081] On the first surface 111, the active material layer 140 and the insulating layer 130 at least partially overlap, and along the first direction (Z direction), the active material layer 140 is located on the side of the insulating layer 130 facing away from the current collector 110. That is, along the first direction (Z direction), the orthographic projection of the active material layer 140 on the plane where the insulating layer 130 is located can completely cover the insulating layer 130. In this case, the active material layer 140 and the insulating layer 130 on the first surface 111, as well as the current collector 110, are stacked sequentially along the first direction (Z direction).

[0082] Alternatively, along the first direction (Z direction), the orthographic projection of the active material layer 140 on the plane where the insulating layer 130 is located covers a portion of the insulating layer 130, that is, along the first direction (Z direction), within the first surface 111, the active material layer 140 and the insulating layer 130 have an overlapping portion.

[0083] Optionally, the active material layer 140 and the insulating layer 130 are adjacent to each other within the same surface within the first surface 111. That is, the active material layer 140 and the insulating layer 130 may be arranged sequentially along the third direction (X direction), and the active material layer 140 and the insulating layer 130 are located in the same plane, with opposite ends of the active material layer 140 and the insulating layer 130 adjacent to and in contact with each other along the third direction (X direction).

[0084] It should be noted that the first direction (Z direction) is perpendicular to the third direction (X direction). In this embodiment, the third direction (X direction) may be the length direction of the electrode 100. In addition, the active material layer 140 and the insulating layer 130 on the second surface 112 may have the same structure as the active material layer 140 and the insulating layer 130 on the first surface 111, and will not be further described in this section.

[0085] In some embodiments, the tab slots 113 include a first tab slot 113a and a second tab slot 113b. The second tab slot 113b and the first tab slot 113a are located on the first surface 111, with a gap between the first tab slot 113a and the second tab slot 113b. The first tab slot 113a is located on the insulating layer 130 of the first surface 111. The tabs 120 include a first tab 120a and a second tab 120b. The first tab 120a is located within the first tab slot 113a, and the second tab 120b is located within the second tab slot 113b. Increasing the number of tabs 120 can reduce internal resistance, increase output current, and improve energy density. Furthermore, current distribution on the electrode sheet 100 is more uniform, reducing localized heating of the electrode sheet 100, further facilitating thermal management of the battery, preventing overheating, and improving battery safety.

[0086] Combine Figure 3 and Figure 4 The first surface 111 of the two surfaces of the current collector 110 that are opposite to each other along the first direction (Z direction) has a first electrode tab groove 113 a , and the first electrode tab groove 113 a is used to connect with the first electrode tab 120 a .

[0087] In this embodiment, the first electrode tab groove 113a is located at the end of the current collector 110 along the second direction (Y direction) to facilitate the connection between the first electrode tab 120a and the first electrode tab groove 113a. After the first electrode tab 120a and the first electrode tab groove 113a are connected, the first electrode tab 120a protrudes from the end of the current collector 110 along the second direction (Y direction).

[0088] As can be understood, the portion of the second surface 112 of the current collector 110 that faces the first tab groove 113a is covered with the insulating layer 130, which reduces the exposed area of ​​the current collector 110, increases the effective insulating area of ​​the electrode sheet 100, reduces short circuits between the positive and negative electrodes, and improves the insulation of the electrode sheet 100. When the electrode sheet 100 is wound to form a battery cell, the internal insulation and safety of the battery cell are also improved, and accordingly, the internal insulation and safety of the battery are improved.

[0089] like Figure 4 As shown, the second tab groove 113b and the first tab groove 113a are both within the first surface 111 of the current collector 110. The second tab groove 113b and the first tab groove 113a are located on the same side of the current collector 110 along the second direction (Y direction). The second tab groove 113b and the first tab groove 113a are separated along the third direction (X direction). In this way, the current on the electrode 100 is distributed in different areas to avoid current concentration and reduce local heating of the electrode 100. Furthermore, the first tab groove 113a and the second tab groove 113b are located at the same end of the current collector 110 along the second direction (Y direction), which facilitates the coating of the active material layer 140 and the insulating layer 130 on the current collector 110 and improves the processing efficiency of the electrode 100.

[0090] Of course, the second electrode tab groove 113 b and the first electrode tab groove 113 a are located on different sides of the current collector 110 along the second direction (Y direction).

[0091] In combination with the aforementioned embodiment, when the active material layer 140 and the insulating layer 130 on the same surface are adjacent along the third direction (X direction), the first electrode tab groove 113a is located in the insulating layer 130 on the first surface 111, and the second electrode tab groove 113b is located in the active material layer 140 on the first surface 111. Of course, the first electrode tab groove 113a and the second electrode tab groove 113b can also be located on the insulating layer 130 at different positions on the first surface 111.

[0092] Possibly, the electrode sheet 100 in this embodiment includes an empty foil area 116 , and the empty foil area 116 and the electrode tab grooves 113 are spaced apart and distributed at two opposite ends of the current collector 110 along the second direction (Y direction).

[0093] Specifically, such as Figure 3 and Figure 4 As shown, the empty foil area 116 and the first tab groove 113 a are opposite to each other along the second direction (Y direction) and are located on both sides of the current collector 110 .

[0094] It is understandable that the preparation process of the pole piece 100 is to first machine the tab groove 113 on the entire pole piece 100 motherboard substrate, and then cut the pole piece 100 substrate into multiple pole pieces 100 along the edge of the tab groove 113. However, in the traditional process flow, due to problems such as cutting fluctuations or the accuracy of the cutting equipment, a coating area may exist between the edge of the pole piece 100 and the edge of the tab groove 113 after cutting, which affects the flatness of the pole piece 100. Therefore, a punching process is required to punch out the coating area. The present application adjusts the cutting position of the electrode 100 to form an empty foil area 116 corresponding to the electrode tab groove 113 along the second direction (Y direction), thereby avoiding the residual coating area at the electrode tab groove 113 position in the traditional electrode 100 preparation process. In this way, there is no need to punch the electrode 100 at this position, thereby reducing the number of punching times for forming the electrode 100. This not only avoids the generation of punching burrs and reduces the risk of short circuit, but also improves the structural strength of the electrode 100, especially the electrode tab groove 113 area on the electrode 100, thereby improving the reliability of the battery.

[0095] In one embodiment, the current collector 110 has a notch region 117. The notch region 117 and the second tab groove 113b are spaced apart and distributed at two opposite ends of the current collector 110 along the second direction (Y direction). It can be understood that the second tab groove 113b is located in the middle region of the current collector 110. The provision of the notch region 117 ensures that there is no exposed current collector 110 in the middle region of the electrode sheet 100. Further, it prevents two electrode sheets 100 of opposite polarity from short-circuiting at this location, thereby improving the insulation and safety of the battery.

[0096] In some embodiments, along the third direction (X direction), the size of the notch area 117 ( Figure 5 W1) is greater than or equal to the size of the second tab groove 113b ( Figure 5 In this way, it is possible to ensure that there is no exposed current collector 110 in the middle area of ​​the electrode piece 100, thereby avoiding short circuit between two electrode pieces 100 with different polarities and improving the safety of the battery.

[0097] Further, combined Figures 1-4The pole piece 100 also includes an insulating member 150. The insulating member 150 and the pole tab groove 113 are arranged in a one-to-one correspondence. The insulating member 150 is located on the side of the pole tab 120 away from the pole tab groove 113, and at least part of the insulating member 150 covers the pole tab groove 113 along the first direction (Z direction); the ratio of the thickness of the insulating layer 130 to the thickness of the insulating member 150 is 0.1-0.5. The insulating member 150 covers the pole tab groove 113 to form an insulating isolation in the pole tab groove 113, thereby improving the insulation of the pole piece 100 and then improving safety. On the basis of ensuring the insulation performance of the insulating layer 130, reducing the thickness of the insulating layer 130 as much as possible can facilitate the thickness accumulation of the connection between the pole tab 120 and the current collector 110 during the cell forming and battery forming process, thereby improving energy density.

[0098] Furthermore, an insulating member 150 is provided corresponding to the first pole tab groove 113a. The insulating member 150 is located along the first direction (Z direction) on the side of the first pole tab 120a away from the current collector 110. The insulating member 150 at least ensures that the first pole tab groove 113a is completely covered to prevent burrs in the welding area from piercing the diaphragm, causing two pole pieces 100 with opposite polarities to contact at the first pole tab groove 113a and cause an internal short circuit, thereby improving the insulation and safety of the pole piece 100.

[0099] Of course, the empty foil area 116 may or may not be provided with an insulating member 150. In some embodiments, when the empty foil area 116 is provided with an insulating member 150, the first tab groove 113a and the empty foil area 116 may also be insulated and isolated using the same insulating member 150. It is readily understood that the insulating member 150 extends along the second direction (Y direction) and simultaneously covers the first tab groove 113a and the empty foil area 116 along the first direction (Z direction). That is, the gap between the first tab groove 113a and the empty foil area 116 is still covered by the insulating member 150. This eliminates the need to cover the first tab groove 113a and the empty foil area 116 multiple times, thereby improving the production efficiency of the electrode sheet 100.

[0100] Furthermore, an insulating member 150 is provided corresponding to the second pole tab groove 113b. The insulating member 150 is located on the side of the second pole tab 120b away from the current collector 110 along the first direction (Z direction). The insulating member 150 at least completely covers the second pole tab groove 113b along the first direction (Z direction) to prevent adjacent pole pieces 100 from contacting at the second pole tab groove 113b to cause internal short circuit, thereby improving the insulation and safety of the pole piece 100.

[0101] It should be noted that the insulating member 150 in this embodiment is insulating paper or insulating tape.

[0102] In some embodiments, the portion of the insulating layer 130 on the second surface 112 that covers the tab groove 113 on the first surface 111 may be provided with an insulating member 150, or may not be provided with the insulating member 150. Preferably, along the first direction (Z direction), the insulating layer 130 on the second surface 112 and the area opposite the orthographic projection of the tab groove 113 on the first surface 111 are not provided with the insulating member 150. In this way, while ensuring safety, there is no need to apply additional glue to increase the thickness of the battery cell, thereby ensuring that the thickness of the electrode sheet 100 is reduced, improving the flatness of the battery cell, and increasing the energy density of the battery.

[0103] In this embodiment, along the first direction (Z direction), the ratio of the thickness of the insulating layer 130 to the thickness of the insulating member 150 is 0.1-0.5. While ensuring the required insulation performance, minimizing the thickness of the insulating layer 130 can facilitate the accumulation of thickness at the connection between the tab 120 and the current collector 110 during the cell and battery forming processes, thereby improving energy density.

[0104] Illustratively, the ratio of the thickness of the insulating layer 130 to the thickness of the insulating member 150 can be 0.1, 0.25, 0.3, 0.5, etc. This embodiment does not make any specific restrictions on this, and it is only necessary to ensure that the ratio of the thickness of the insulating layer 130 to the thickness of the insulating member 150 falls within the above range.

[0105] In some embodiments, as Figure 1 As shown, along the third direction (X direction), the size of the active material layer 140 on the first surface 111 is larger than the size of the active material layer 140 on the second surface 112. This can reduce the thickness accumulation of the electrode sheet 100 during the winding process, and the thickness of the battery cell and battery is correspondingly reduced, which helps to improve the energy density.

[0106] In fact, in this embodiment, the electrode 100 can be used as a positive electrode. The positive electrode is generally located on the outside of the winding core. It is not difficult to understand that the first surface 111 is located on the inside of the winding core, and the second surface 112 is located on the outside of the winding core. The second surface 112 does not have a corresponding negative electrode, and the active material layer 140 on the second surface 112 undergoes relatively few chemical reactions. Therefore, reducing the length of the active material layer 140 on the second surface 112 can reduce material costs on the one hand, and on the other hand, it can also reduce the thickness accumulation of the electrode 100 during the battery cell or battery forming process. The thickness of the battery cell and battery is correspondingly thinned, and the energy density is further improved.

[0107] In some embodiments, along the third direction (X direction), the size of the active material layer 140 ( Figure 5 W3) and the size of the tab slot 113 ( Figure 5 The ratio of W2) is 50-200; and / or, along the second direction (Y direction), the size of the current collector 110 ( Figure 5 H1) and the size of the tab slot 113 ( Figure 5 The ratio of H2) is 2.5-10. In this embodiment, the size of the tab slot 113 is minimized as much as possible on the basis of meeting the electrical connection requirements between the tab 120 and the current collector 110, so as to reduce the exposed area of ​​the current collector 110. Correspondingly, the effective insulation area of ​​the pole piece 100 is increased, the probability of internal short circuit between adjacent pole pieces 100 is reduced, that is, the failure probability is reduced, and the insulation, stability and safety are improved.

[0108] For example, along the third direction (X direction), the size of the active material layer 140 ( Figure 5 W3) and the size of the tab slot 113 ( Figure 5 The ratio of W2) can be 50, 67, 79, 85, 135, 156, 200, etc., and this embodiment does not make any specific restrictions on this. It is only necessary to ensure that the size of the active material layer 140 ( Figure 5 W3) and the size of the tab slot 113 ( Figure 5 Correspondingly, along the second direction (Y direction), the size of the current collector 110 ( Figure 5 H1) and the size of the tab slot 113 ( Figure 5 The ratio of H2) can be 2.5, 4, 5.8, 8.2, 10, etc., and this embodiment does not make any specific restrictions on this. It is only necessary to ensure that the size of the current collector 110 ( Figure 5 H1) and the size of the tab slot 113 ( Figure 5 The ratio of H2) indicated in the figure may fall within the above range.

[0109] In some embodiments, the ratio of the thickness of the tab 120 to the thickness of the insulating layer 130 is 10-60. While meeting the insulation requirements of the insulating layer 130 and the connection requirements between the tab 120 in the tab groove 113 and the current collector 110, the thickness of the insulating layer 130 is minimized as much as possible to reduce the thickness accumulation at the tab position, thereby improving battery safety and increasing battery energy density.

[0110] It is understandable that the active material layer 140 is relatively thick, which can improve the energy density and capacity of the formed battery cell and battery. However, if the active material layer 140 is too thick, it is easy to increase the internal resistance, reduce the conductivity, and affect the charge and discharge rate. The active material layer 140 should be selected with an appropriate thickness according to the design requirements during actual use. On the basis of meeting the insulation requirements of the electrode 100, the thickness of the insulating layer 130 can be reasonably reduced to increase the energy density. Therefore, in this embodiment, the thickness of the insulating layer 130 on the same surface is less than the thickness of the active material layer 140.

[0111] It should be noted that the ratio of the thickness of the tab 120 to the thickness of the insulating layer 130 is 10-60, that is, the thickness of the tab 120 is greater than the thickness of the insulating layer 130. While meeting the insulation requirements of the pole piece 100, the thickness of the insulating layer 130 is reduced as much as possible to avoid thickness accumulation at the connection of the tab 120, thereby improving the energy density.

[0112] Illustratively, the ratio of the thickness of the tab 120 to the thickness of the insulating layer 130 is 10, 22, 35, 40, 51, 60, etc. This embodiment does not impose any specific limitation on this, and only needs to ensure that the ratio of the thickness of the tab 120 to the thickness of the insulating layer 130 is within the above range.

[0113] Optionally, the tab 120 is welded to the tab groove 113 to form a welding zone; along the first direction (Z direction), the ratio of the height of the weld mark 160 in the welding zone to the thickness of the insulating layer 130 is greater than or equal to 4. The relatively thin insulating layer 130 is conducive to reducing the thickness of the connection between the tab 120 and improving energy density.

[0114] Specifically, the tab 120 is laser welded to the first surface 111 of the current collector 110 through the tab groove 113, and a weld mark 160 is formed at the connection between the tab 120 and the current collector 110 along the first direction (Z direction). In essence, the weld mark 160 is uneven, and the distance from the highest point of the weld mark 160 to the first surface 111 of the current collector 110 is the thickness of the weld mark 160. The ratio of the thickness of the weld mark 160 to the thickness of the insulating layer 130 is greater than or equal to 4, that is, the thickness of the insulating layer 130 is less than the thickness of the weld mark 160, which can not only meet the insulation requirements, but also reduce the thickness of the welding area of ​​the tab 120, thereby improving the energy density.

[0115] This embodiment provides a pole piece 100, comprising a current collector 110 and a tab 120. The current collector 110 has a first surface 111 and a second surface 112 along a first direction (Z direction), each of which is covered with an active material layer 140. At least portions of the first and second surfaces 111, 112 are covered with an insulating layer 130. The first surface 111 has at least one tab groove 113, located in the insulating layer 130 on the first surface 111. The tab 120 is disposed within the tab groove 113 and is connected to the first surface 111 of the current collector 110. Along the first direction (Z direction), the projection of the insulating layer 130 on the second surface 112 covers the tab groove 113. This structural arrangement improves safety.

[0116] In addition, this embodiment may also provide a battery cell comprising a first electrode sheet, a separator, and a second electrode sheet stacked in sequence; the first electrode sheet is the electrode sheet 100 in the aforementioned embodiment; the first electrode sheet, the separator, and the second electrode sheet are stacked and wound to form a core. The first electrode sheet and the second electrode sheet have opposite polarities, and the first electrode sheet is a positive electrode.

[0117] Furthermore, the first pole piece includes a winding head located at the inner circle of the winding core and a winding tail located at the outer circle of the winding core; the insulating layer is located at the winding head and / or the winding tail.

[0118] The first pole piece is the pole piece 100 mentioned in the above embodiment, and the insulating layer 130 is located at the winding head 114 and / or the winding tail 115;

[0119] Specifically, the winding head 114 and the winding tail 115 are located at two different ends of the first electrode sheet along the third direction (X direction). It can be understood that the insulating layer 130 on the first surface 111 of the current collector 110 covers the winding head 114 or the winding tail 115, or covers both the winding head 114 and the winding tail 115; and the insulating layer 130 on the second surface 112 of the current collector 110 covers the winding head 114 or the winding tail 115, or covers both the winding head 114 and the winding tail 115. The insulating layer 130 reduces the exposed area of ​​the first electrode sheet, thereby improving the insulation and needle puncture safety of the battery cell.

[0120] In this embodiment, the portion of the winding head 114 within the first surface 111 and the portion of the winding head 114 on the second surface 112 may both cover the insulating layer 130, or only one of them may cover the insulating layer 130. Figure 1As shown, the tab groove 113 is provided on the portion of the insulating layer 130 on the first surface 111 located at the winding head 114. Correspondingly, the insulating layer 130 on the second surface 112 is also provided on the winding head 114 to cover the tab groove 113 on the first surface 111 along the first direction (Z direction). In this way, the insulating layer 130 is provided on both sides of the winding head 114 that are opposite to each other along the first direction (Z direction), which can increase the effective insulation area of ​​the current collector 110 and prevent the connection between the tab 120 and the current collector 110 from piercing the separator.

[0121] Since the battery cell in this embodiment includes the electrode piece 100 in any of the aforementioned embodiments, safety can be improved.

[0122] Furthermore, this embodiment may also provide a battery, comprising a housing and the battery cell according to the above embodiment, wherein the housing has a receiving cavity, and the battery cell is located in the receiving cavity.

[0123] Thus, the battery in this embodiment can improve safety because it includes the aforementioned battery cells.

[0124] Furthermore, the researchers also proved through testing experiments that the safety performance of the battery produced using the electrode 100 provided in the aforementioned embodiment is improved.

[0125] It should be noted that in the experiment, the size of the active material layer 140 along the third direction (X direction) ( Figure 5 The size of the current collector 110 along the second direction (Y direction) is 900 mm. Figure 5 The H1 marked in the figure is 58 mm, the thickness of the tab 120 is 80 μm; the dimension of the tab groove 113 along the third direction (X direction) ( Figure 5 W2) is 10 mm, and the dimension of the tab slot 113 along the second direction (Y direction) is ( Figure 5 H2) is 30 mm; the thickness of the weld mark 160 after welding the tab 120 and the current collector 110 is 12 μm; the thickness of the insulating member 150 is 15 μm; and the thickness of the insulating layer 130 is 2.0 μm.

[0126] Figure 7 This is a schematic diagram of the cross-section of the pole piece of the experimental control group provided in this application.

[0127] On this basis, if Figure 7 As shown, the tab grooves 113 of the control group are located on the insulating layer 130 on the first surface 111 and the second surface 112 opposite to each other along the first direction (Z direction) of the current collector 110 , and the insulating member 150 is attached to the tab grooves 113 .

[0128] like Figure 1As shown, compared with the control group, the tab grooves 113 of the experimental group are only arranged on the first surface 111 of the current collector 110 and are connected to the tabs 120 of the experimental group at the same position on the current collector 110. Other structures are the same as those of the control group.

[0129] The tabs 120 of the battery cells formed in the experimental and control groups were measured respectively. The thickness of the experimental group was reduced by about 13μm compared with the control group, and the energy density was improved to a certain extent.

[0130] After further packaging, formation, and capacity grading, the cells in the experimental and control groups were subjected to safety testing, specifically needle penetration and heavy object impact testing. The needle penetration test focused on the area around tab 120. The final safety test results are shown in Table 1.

[0131] Table 1 Test results

[0132] Group Acupuncture safety Heavy object impact safety Whether it meets the standards control group 6 10 Not meeting standards Experimental group 45 47 meet the standards

[0133] It should be noted that the values ​​in Table 1 are the number of safety tests that passed, and the number of test samples is 50.

[0134] The analysis shows that the experimental group can effectively improve safety, that is, the battery formed by using the electrode piece 100 provided by the present application can improve safety.

[0135] It should be noted that references in this specification to "one embodiment," "an embodiment," "an exemplary embodiment," "some embodiments," and the like indicate that the described embodiment may include a particular feature, structure, or characteristic, but not necessarily every embodiment includes that particular feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, it is within the knowledge of those skilled in the art to implement such feature, structure, or characteristic in conjunction with other embodiments, whether explicitly described or not.

[0136] Generally speaking, terms should be understood, at least in part, based on the context in which they are used. For example, as used herein, the term "one or more" can be used to describe any feature, structure, or characteristic in the singular sense, or can be used to describe a combination of features, structures, or characteristics in the plural sense, depending at least in part on the context. Similarly, terms such as "a," "an," or "the" can also be understood to convey either singular or plural usage, depending at least in part on the context.

[0137] It should be readily understood that “on,” “above,” and “over” in this application should be interpreted in the broadest manner, such that “on” means not only “directly on something,” but also includes “on something” with intervening features or layers therebetween, and “above” or “over” includes not only the meaning of “above” or “over,” but also includes the meaning of “above” or “over” with no intervening features or layers therebetween (i.e., directly on something).

[0138] Additionally, spatially relative terms, such as "below," "beneath," "beneath," "above," and the like, may be used herein for ease of description to describe the relationship of one element or feature relative to other elements or features as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be in other orientations (rotated 90° or at other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pole piece, characterized in that: include: Current collector and tab; The current collector has a first surface and a second surface opposite to each other along a first direction, and the first surface and the second surface are respectively covered with an active material layer; At least a portion of the first surface and the second surface is covered with an insulating layer; The first surface has at least one pole lug groove, at least one of the pole lug grooves is located in the insulating layer of the first surface, the pole lug is arranged in the pole lug groove, and the pole lug is connected to the first surface of the current collector; Along the first direction, a projection of the insulating layer on the second surface covers the tab groove.

2. The pole piece according to claim 1, characterized in that: Along the first direction, within the same surface of the current collector, the active material layer overlaps with the insulating layer; or, The active material layer and the insulating layer are adjacent to each other in the same surface.

3. The pole piece according to claim 1, characterized in that: The pole tab groove comprises a first pole tab groove and a second pole tab groove, the first pole tab groove and the second pole tab groove are located on the first surface, and there is a gap between the first pole tab groove and the second pole tab groove; the first pole tab groove is located on the insulating layer of the first surface; The pole tab includes a first pole tab and a second pole tab. The first pole tab is disposed in the first pole tab slot, and the second pole tab is disposed in the second pole tab slot.

4. The pole piece according to claim 1, characterized in that: It also includes an empty foil area, wherein the empty foil area and the tab grooves are spaced apart and distributed at two opposite ends of the current collector along a second direction; the second direction is perpendicular to the first direction.

5. The pole piece according to claim 3, characterized in that: The pole piece includes a notch area, and the notch area and the second pole lug groove are spaced apart and distributed at two opposite ends of the current collector along a second direction; the second direction is perpendicular to the first direction.

6. The pole piece according to any one of claims 1 to 5, characterized in that: Along the third direction, the ratio of the size of the active material layer to the size of the tab groove is 50-200; and / or, Along the second direction, the ratio of the size of the current collector to the size of the tab groove is 2.5-10; The third direction, the second direction and the first direction are perpendicular to each other.

7. The pole piece according to any one of claims 1 to 5, characterized in that: Along the first direction, a ratio of the thickness of the tab to the thickness of the insulating layer is 10-60.

8. The pole piece according to any one of claims 1 to 5, characterized in that: It also includes an insulating member, the insulating member and the pole lug slot are arranged in a one-to-one correspondence, the insulating member is located on a side of the pole lug away from the pole lug slot, and at least a portion of the insulating member covers the pole lug slot; Along the first direction, a ratio of a thickness of the insulating layer to a thickness of the insulating member is 0.1-0.

5.

9. The pole piece according to claim 8, characterized in that: Along the first direction, the insulating member is not disposed in a region of the insulating layer of the second surface that is opposite to the orthographic projection of the electrode tab groove of the first surface.

10. The pole piece according to any one of claims 1 to 5, characterized in that: The tab is welded in the tab slot to form a welding area; Along the first direction, a ratio of a height of the welding area weld print to a thickness of the insulating layer is greater than or equal to 4.

11. A battery cell, characterized in that: It includes a first pole piece, a diaphragm and a second pole piece which are stacked in sequence; The first pole piece is the pole piece according to any one of claims 1 to 10; The first pole piece, the diaphragm and the second pole piece are stacked and wound to form a winding core.

12. The battery cell according to claim 11, characterized in that: The first pole piece includes a winding head located at the inner circle of the winding core and a winding tail located at the outer circle of the winding core; The insulating layer is located at the winding head and / or the winding tail.

13. A battery, characterized in that: It comprises a shell and the battery cell according to claim 11 or 12, wherein the shell has a containing cavity, and the battery cell is located in the containing cavity.

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