Current collector, pole piece, battery cell and battery

Abstract

The current collector comprises a foil and a conductive layer, the conductive layer and the foil are stacked, the conductive layer comprises a first area and a second area, the first area is closer to the edge of the foil than the second area, the conductivity of the first area in the first direction is A, the conductivity of the second area in the first direction is B, and A is smaller than B. By arranging the foil and the conductive layer, the conductivity A of the first region and the conductivity B of the second region meet the condition that A is less than B, the conductivity of the edge of the current collector can be inhibited, and the current of the current collector can be reduced, so that the temperature rise of the edge region is reduced, the temperature difference between the edge of the current collector and the middle of the current collector can be reduced, lithium precipitation is reduced, and the service life of the battery cell is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and in particular to a current collector, a pole piece, a battery core and a battery. Background Art

[0002] At present, the current collector in the battery cell usually uses metal foil as the substrate, and the conductivity is improved by coating the surface with conductive materials such as carbon black. However, when charging and discharging the battery cell, the current density near the pole ear is large, the local temperature is high, and the temperature difference with the middle of the pole core is large, which is easy to precipitate lithium, resulting in a shortened battery life. Utility Model Content

[0003] The utility model aims to provide a current collector, a pole piece, a battery cell and a battery, which solve the problem that the temperature difference between the edge and the middle of the current collector is large, lithium is easily precipitated, and the battery cell life is shortened.

[0004] In order to achieve the purpose of the utility model, the utility model provides the following technical solutions:

[0005] In the first aspect, the utility model provides a current collector, comprising a foil and a conductive layer, the edge of the foil being suitable for setting a pole ear; the conductive layer and the foil are stacked, the conductive layer comprising a first region and a second region, the first region being closer to the pole ear than the second region, the conductivity of the first region along a first direction is A, the conductivity of the second region along the first direction is B, satisfying: A<B, the first direction is the direction in which the foil and the conductive layer are stacked.

[0006] In one implementation, 1 / 3≤A / B≤1 / 2 is satisfied.

[0007] In one embodiment, the foil includes a first edge, the first edge is suitable for connecting to the pole ear, the first area includes a second edge opposite to the first edge in the second direction, in the second direction, the distance from the first edge to the second edge is C, satisfying: 0mm≤C≤5mm, and the second direction is the arrangement direction of the first area and the second area and intersects with the first direction.

[0008] In one embodiment, the foil material includes a first edge, the first edge is suitable for connecting to the pole ear, the first area includes a second edge and a third edge opposite to each other in the second direction, the third edge is connected to the second area, and in the second direction, the distance from the second edge to the third edge is D, satisfying: 1mm≤D≤5mm, and the second direction is the arrangement direction of the first area and the second area and intersects with the first direction.

[0009] In one embodiment, the conductive layer also includes a third region, which is located on the side of the second region facing away from the first region in the second direction, and the conductivity of the third region in the first direction is E, satisfying: E<B, and the second direction is the arrangement direction of the first region and the second region and intersects with the first direction.

[0010] In one implementation, 1 / 3≤E / B≤1 / 2 is satisfied.

[0011] In one embodiment, the foil further includes a fourth edge opposite to the first edge in the second direction, the third region includes a fifth edge opposite to the fourth edge in the second direction, and in the second direction, a distance from the fourth edge to the fifth edge is C1, satisfying: 0mm≤C1≤5mm.

[0012] In one embodiment, the foil also includes a fourth edge opposite to the first edge in the second direction, the third area includes a fifth edge and a sixth edge opposite to each other in the second direction, the sixth edge is connected to the second area, and in the second direction, the distance from any position of the fifth edge to the corresponding position of the sixth edge is D1, satisfying: 1mm≤D1≤5mm.

[0013] In one embodiment, the current collector is a negative electrode current collector, and the foil is a copper foil; or, the current collector is a positive electrode current collector, and the foil is an aluminum foil.

[0014] In a second aspect, the utility model further provides a pole piece, comprising an active material layer and a current collector according to any one of the various embodiments of the first aspect, wherein the active material layer is stacked on the current collector.

[0015] In the third aspect, the utility model also provides a pole piece, which includes a current collector and an active material layer, the current collector includes a foil and a conductive layer, the edge of the foil is suitable for setting a pole ear, the foil includes a first coating area and a second coating area, the first coating area is closer to the edge of the foil than the second coating area, and the conductive layer is stacked on the second coating area; the active material layer is stacked on the first coating area and the conductive layer; the conductivity of the pole piece in the first coating area along the first direction is F, and the conductivity of the pole piece in the second coating area along the first direction is G, satisfying: F<G, and the first direction is the stacking direction of the foil and the conductive layer.

[0016] In one implementation, 1 / 3≤F / G≤1 / 2 is satisfied.

[0017] In a fourth aspect, the utility model further provides a battery cell, comprising a pole ear, a diaphragm and a pole piece as described in the second aspect or any one of the various embodiments of the third aspect, wherein the diaphragm and the pole piece are stacked, and the pole ear is arranged at the edge of the foil.

[0018] In a fifth aspect, the utility model further provides a battery, comprising a housing and the battery cell described in the fourth aspect, wherein the battery cell is accommodated in the housing.

[0019] By setting a foil and a conductive layer, the conductive layer includes a first area and a second area, the first area is closer to the edge of the foil where the pole ear is set than the second area, the conductivity A of the first area in the first direction and the conductivity B of the second area in the first direction satisfy: A<B, the conductivity of the edge of the current collector can be suppressed, and its current can be reduced, thereby reducing the temperature rise of the edge area, and the temperature difference between the edge and the middle of the current collector can be reduced, reducing lithium plating and extending the service life of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 is a cross-sectional view of a battery cell of an embodiment;

[0022] Figure 2 is a cross-sectional view of a pole piece of an embodiment;

[0023] Figure 3 is a top view of a current collector of an embodiment;

[0024] Figure 4 is a cross-sectional view of a pole piece of another embodiment.

[0025] Description of reference numerals:

[0026] 1000-battery cells;

[0027] 100-electrode sheet, 101-positive electrode sheet, 102-negative electrode sheet;

[0028] 10-current collector, 11-foil, 111-first edge, 112-fourth edge, 113-first coating area, 114-second coating area, 12-conductive layer, 121-first area, 122-second area, 123-second edge, 124-third edge, 125-third area, 126-fifth edge, 127-sixth edge, 13-negative current collector, 131-copper foil, 14-positive current collector, 141-aluminum foil;

[0029] 20-active material layer, 21-positive electrode active material layer, 22-negative electrode active material layer;

[0030] 200-Diaphragm. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0032] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there can be a central component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there can be a central component at the same time.

[0033] Unless otherwise defined, all technical and scientific terms used in this utility model have the same meaning as those commonly understood by technicians in the technical field of this utility model. The terms used in the specification of this utility model are only for the purpose of describing specific embodiments and are not intended to limit this utility model. The term "and / or" used in this utility model includes any and all combinations of one or more related listed items.

[0034] In conjunction with the accompanying drawings, some embodiments of the present invention are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0035] The present utility model embodiment provides a battery, including the battery cell in the present utility model embodiment. The battery can be a square laminated battery, etc. The battery adopts the battery cell in the present utility model embodiment, which can solve the problem that the local current density is large, resulting in a large temperature difference in the battery cell, which affects the service life of the battery cell.

[0036] The battery also includes a shell, which includes a bottom plate and a plurality of side plates, the side plates are connected to the bottom plate and enclosed to form a receiving cavity. The receiving cavity is open at one end opposite to the bottom plate, and the battery cell is received in the receiving cavity.

[0037] The shell is a material with high structural strength, specifically metal materials, high-strength plastics, ceramics, etc. Metal materials such as aluminum, aluminum alloys, magnesium alloys, iron and iron alloys, etc. The shell can be an integrated structure, that is, the bottom plate and the side plates are an integrated structure made by an integrated molding process, and the integrated molding process can be specifically stamping, casting, etc., without limitation. The shell can also be a split structure, and the side plates and the bottom plate can be connected and fixed by welding, bonding, clamping, screwing, etc. The wall thickness of the shell can be roughly uniform everywhere, that is, the thickness of the side plates can be roughly uniform, and the thickness of the bottom plate and the side plates can also be roughly the same.

[0038] The battery also includes a cover plate, which is connected to the opening of the shell to close the accommodating cavity. The connection between the cover plate and the shell can be welding, bonding, clamping, screwing, etc., without limitation. The shape of the cover plate can be roughly the same as that of the bottom plate.

[0039] Please refer to Figure 1 The embodiment of the utility model provides a battery cell 1000, including a separator 200 and a pole piece 100 in the embodiment of the utility model, wherein the separator 200 and the pole piece 100 are stacked. The pole piece 100 includes an active material layer 20 and a current collector 10 in the embodiment of the utility model, wherein the active material layer 20 is stacked on the current collector 10.

[0040] Please refer to Figure 1 and Figure 2 The utility model provides a current collector 10, comprising a foil 11 and a conductive layer 12. The edge of the foil 11 is suitable for setting a tab, and the conductive layer 12 is stacked with the foil 11. The conductive layer 12 comprises a first region 121 and a second region 122, wherein the first region 121 is closer to the tab than the second region 122, the conductivity of the first region 121 along the first direction is A, and the conductivity of the second region 122 along the first direction is B, satisfying: A<B.

[0041] Define the direction first. Please refer to Figure 1 , Y is the first direction, and X is the second direction.

[0042] Optionally, the first direction Y is the stacking direction of the foil and the conductive layer, or the stacking direction of the current collector and the active material layer. Generally, the first direction Y is the thickness direction of the current collector or the electrode sheet. The second direction X is perpendicular to the coating direction of the current collector 10, and the first direction Y is perpendicular to the second direction X.

[0043] Optionally, the first region 121 is closer to the edge of the foil 11 connected to the pole lug than at least part of the second region 122. For example, the first region 121 and the second region 122 are both rectangular, and the length of the first region 121 in the perpendicular second direction X is the same as the length of the second region 122 in the perpendicular second direction X, then the first region 121 is closer to the edge of the foil 11 connected to the pole lug as a whole than the second region 122; or, when the minimum distance from a part of the edge of the second region 122 to the edge of the foil 11 connected to the pole lug is the same as the minimum distance from the first region 121 to the edge of the foil 11 connected to the pole lug, the first region 121 is arranged opposite to the pole lug in the second direction X, the second region 122 is in a "concave" shape, and the second region 122 surrounds the outer periphery of the first region 121.

[0044] Optionally, directions of the conductivity of the first region 121 and the second region 122 along the first direction Y are both in the first direction Y, ie, the direction in which the foil 11 and the conductive layer 12 are stacked.

[0045] For the large-size battery cell 1000, the area of ​​the battery cell 1000 is relatively large, and different areas of the battery cell 1000 are prone to uneven performance due to being in different environments. Among them, the uneven temperature of different areas of the battery cell 1000 is particularly obvious. For example, when charging and discharging the battery cell 1000, the current density in the area where the pole ear is located is large, and the local temperature is high, causing the active material in this area to decay too quickly, especially when continuous high-current fast charging is performed, the current can reach 200-400A, and the temperature difference effect caused by the current density difference is more significant.

[0046] The existing current collector 10 usually uses aluminum foil (positive electrode) and copper foil (negative electrode) as the substrate, and the surface is coated with conductive materials such as carbon black to improve the conductivity. Since all currents need to be collected at the pole ear during charging and discharging, the current density at the pole ear is relatively high, the current lines are dense, and the temperature is also high. The temperature difference between the pole ear and the middle of the pole core is about 10°C. This degree of temperature difference will not only lead to a decrease in the charging capacity of the local low temperature area (low temperature, high impedance, easy lithium precipitation), but also lead to the problem of accelerated attenuation in the high temperature area.

[0047] The current collector 10 provided by the embodiment of the utility model is provided with a foil 11 and a conductive layer 12, wherein the conductive layer 12 includes a first region 121 and a second region 122, wherein the first region 121 is closer to the edge of the foil 11 where the pole ear is provided than the second region 122, and the conductivity A of the first region 121 along the first direction Y and the conductivity B of the second region 122 along the first direction Y satisfy: A<B, which can suppress the conductivity of the edge of the current collector 10, reduce its current, thereby reducing the temperature rise of the edge region, and can reduce the temperature difference between the edge and the middle of the current collector 10, reduce lithium plating, and extend the service life of the battery cell 1000.

[0048] Optionally, the material of the foil 11 may be aluminum, copper, etc., and the shape of the foil 11 may be rectangular, circular, etc., without specific limitation.

[0049] Optionally, the area of ​​the conductive layer 12 is equal to the area of ​​the foil 11 ; or, the area of ​​the conductive layer 12 is smaller than the area of ​​the foil 11 , and there is no specific limitation.

[0050] Optionally, the area of ​​the first region 121 is smaller than the area of ​​the second region 122 .

[0051] Optionally, the material of the first region 121 may be a low-conductive adhesive material with a small amount of conductive carbon black (accounting for 0.1%-2%) added to materials such as polyurethane (PU), polyethyl acrylate (PVA), and polyethylene oxide (PEO), without limitation.

[0052] Optionally, the material of the second region 122 may be conductive carbon black or the like, without limitation.

[0053] Optionally, the conductivity A of the first region 121 along the first direction Y and the conductivity B of the second region 122 along the first direction Y satisfy: 1 / 3≤A / B≤1 / 2.

[0054] Optionally, the ratio of A / B can be 5 / 12, 3 / 8, 11 / 24, etc., without limitation.

[0055] By setting the conductivity A of the first region 121 along the first direction Y and the conductivity B of the second region 122 along the first direction Y to satisfy 1 / 3≤A / B≤1 / 2, the conductivity of the edge of the current collector 10 can be suppressed, the current thereof can be reduced, and thus the temperature rise of the edge region can be reduced.

[0056] If A / B<1 / 3, the difference between the conductivity of the first region 121 along the first direction Y and the conductivity of the second region 122 along the first direction Y is too large, which is not conducive to the flow of current.

[0057] If A / B>1 / 2, the difference between the conductivity of the first region 121 along the first direction Y and the conductivity of the second region 122 along the first direction Y is small, the improvement of the local temperature difference is not obvious, and lithium plating cannot be effectively reduced.

[0058] Optional, such as Figure 3 As shown, the foil 11 includes a first edge 111, which is suitable for connecting to the pole ear. The first area 121 includes a second edge 123 and a third edge 124 that are opposite to each other in the second direction X. The first edge 111 is located on the side of the second edge 123 that is away from the third edge 124 in the second direction X, and the third edge 124 is connected to the second area 122.

[0059] Optionally, the first edge 111 , the second edge 123 and the third edge 124 are parallel, or the first edge 111 , the second edge 123 and the third edge 124 are approximately arranged in parallel.

[0060] Optionally, the foil 11 may be in a rectangular, trapezoidal, parallelogram, etc., without limitation.

[0061] Optionally, the shape of the conductive layer 12 corresponds to that of the foil 11 , and the stacking thickness of the first region 121 and the second region 122 on the foil 11 is the same.

[0062] For example, Figure 3 As shown, the foil 11 , the first region 121 , and the second region 122 are all rectangular, and there is a gap between the second edge 123 and the first edge 111 for easy processing, and the third edge 124 is connected to the second region 122 .

[0063] Optionally, the pole piece 100 further includes a pole ear (not shown in the figure), and the pole ear may be an integrated structure with the current collector 10 , or the pole ear is connected to the first edge 111 .

[0064] By setting the first edge 111 , the second edge 123 and the third edge 124 in parallel, the first edge 111 and the second edge 123 have a certain distance, leaving a coating margin of the conductive layer 12 on the foil 11 , and also facilitating multiple coatings of the coating material to form the conductive layer 12 .

[0065] Optional, such as Figure 3 As shown, the first area 121 includes a second edge 123 opposite to the first edge 111 in the second direction X. In the second direction X, the distance between any position of the first edge 111 and the corresponding position of the second edge 123 is C, satisfying: 0mm≤C≤5mm.

[0066] Optionally, the value of C can be 2mm-4mm, specifically 2.5mm, 3mm, 3.5mm, etc., without limitation.

[0067] By setting the distance between the first edge 111 and the second edge 123, a processing margin of the conductive layer 12 is left on the foil 11, which is convenient for multiple coatings. If C>5mm, the edge of the foil 11 will be too blank, resulting in material waste.

[0068] In the above example, C is 0, that is, the edge of the conductive layer is flush with the edge of the foil in the second direction X. When C is greater than 0, the foil exceeds the conductive layer in the second direction X.

[0069] Optional, such as Figure 3As shown, the first area 121 includes a second edge 123 and a third edge 124 opposite to each other in the second direction X, the third edge 124 is connected to the second area 122, and in the second direction X, the distance from any position of the second edge 123 to the corresponding position of the third edge 124 is D, satisfying: 1mm≤D≤5mm.

[0070] Optionally, the value of D can be 2mm-4mm, specifically 2.5mm, 3mm, 3.5mm, etc., without limitation.

[0071] By setting the distance between the second edge 123 and the third edge 124, the stacking range of the first region 121 is limited. If D>5mm, the range of the first region 121 is too large, affecting the conductive performance of the current collector 10; if D<1mm, the range of the first region 121 is too small, and the conductivity difference between the edge and the middle of the current collector 10 is not obvious, and the local temperature difference cannot be effectively reduced.

[0072] Optional, such as Figure 3 As shown, the foil 11 also includes a fourth edge 112 opposite to the first edge 111, the conductive layer 12 also includes a third region 125, the third region 125 includes a fifth edge 126 and a sixth edge 127 opposite to each other, the fourth edge 112 is located on the side of the fifth edge 126 facing away from the sixth edge 127, the sixth edge 127 is connected to the second region 122, and the conductivity of the third region 125 is E, satisfying: E<B.

[0073] Optionally, the area of ​​the third region 125 is the same as that of the first region 121 , and the material of the third region 125 is similar to that of the first region 121 , which can be referred to without further explanation.

[0074] Optionally, the fourth edge 112 is also connected to a pole lug. Similarly, the third region 125 and the second region 122 are both rectangular, and the length of the third region 125 in the perpendicular second direction X is the same as the length of the second region 122 in the perpendicular second direction X, then the third region 125 is closer to the fourth edge 112 as a whole than the second region 122; or, when the minimum distance from a part of the edge of the second region 122 to the edge of the foil 11 connected to the pole lug is the same as the minimum distance from the third region 125 to the edge of the foil 11 connected to the pole lug, the third region 125 is arranged opposite to the pole lug in the second direction X, the second region 122 is in a "concave" shape, and the second region 122 surrounds the periphery of the third region 125.

[0075] Similarly, the distance between the fourth edge 112 and the fifth edge 126 is C1, which satisfies: 0mm≤C1≤5mm, which can avoid leaving too much blank space at the edge of the foil 11 and causing material waste. The distance between the fifth edge 126 and the sixth edge 127 is D1, which satisfies: 1mm≤D1≤5mm, which can limit the stacking range of the first region 121 and effectively reduce the local temperature difference without affecting the conductive performance of the current collector 10.

[0076] Optionally, the value of C1 can be 2mm-4mm, specifically 2.5mm, 3mm, 3.5mm, etc., without limitation; the value of D1 can be 2mm-4mm, specifically 2.5mm, 3mm, 3.5mm, etc., without limitation.

[0077] Optional, satisfying: 1 / 3≤E / B≤1 / 2.

[0078] Optionally, the ratio of E / B can be 5 / 12, 3 / 8, 11 / 24, etc., without limitation.

[0079] Optionally, the conductivity E of the third region 125 and the conductivity A of the first region 121 along the first direction Y may be the same or different, and there is no specific limitation thereto.

[0080] By setting 1 / 3≤E / B≤1 / 2, the conductivity of the edge of the current collector 10 can be suppressed, the current thereof can be reduced, and thus the temperature rise of the edge region can be reduced.

[0081] Optionally, the third area 125 and the first area 121 are symmetrically arranged on the foil 11 , that is, C=C1, D=D1.

[0082] Optionally, the pole piece 100 includes two pole tabs, and the two pole tabs are respectively connected to the first region 121 and the third region 125 . The pole tabs may be half pole tabs or full pole tabs, without limitation.

[0083] Optionally, the first area 121, the second area 122 and the third area 125 are sequentially coated on the foil 11 along the coating direction; or, the first area 121, the second area 122 and the third area 125 are coated on the foil 11 at the same time, without specific limitation. The first area 121, the second area 122 and the third area 125 can be coated once or multiple times, without specific limitation.

[0084] By setting the third region 125 , the conductivity E of the third region 125 and the conductivity B of the second region 122 along the first direction Y satisfy: E<B, which can reduce the temperature difference between the edge and the middle of the current collector 10 , reduce lithium plating, and extend the service life of the battery cell 1000 .

[0085] Optional, such as Figure 1As shown, the current collector 10 is a negative electrode current collector 13 , and the foil material 11 is a copper foil 131 , or the current collector 10 is a positive electrode current collector 14 , and the foil material 11 is an aluminum foil 141 .

[0086] Optionally, the size of the negative electrode current collector 13 is the same as that of the positive electrode current collector 14; or, the size of the negative electrode current collector 13 is smaller than that of the positive electrode current collector 14; or, the size of the negative electrode current collector 13 is larger than that of the positive electrode current collector 14, and there is no specific limitation.

[0087] For example, Figure 1 As shown, the first edge 111 of the aluminum foil 141 falls between the first edge 111 of the copper foil 131 and the second edge 123 of the conductive layer 12 of the copper foil 131 . Similarly, the fourth edge 112 of the aluminum foil 141 falls between the fourth edge 112 of the copper foil 131 and the fifth edge 126 of the conductive layer 12 of the copper foil 131 .

[0088] Optionally, the conductive layer 12 on the negative electrode current collector 13 and the conductive layer 12 on the positive electrode current collector 14 are the same in size and shape.

[0089] By providing a positive electrode current collector 14 and a negative electrode current collector 13, both the positive electrode current collector 14 and the negative electrode current collector 13 are provided with a conductive layer 12, the temperature difference between the edge and the middle of the positive electrode current collector 14 and the negative electrode current collector 13 is reduced, lithium plating is reduced, and the service life of the battery cell 1000 is extended.

[0090] Please refer to Figure 1 and Figure 2 The embodiment of the utility model further provides a pole piece 100 , which includes an active material layer 20 and a current collector 10 in the embodiment of the utility model, wherein the active material layer 20 is stacked on the current collector 10 .

[0091] Optional, such as Figure 1 As shown, the electrode sheet 100 is a positive electrode sheet 101, the current collector 10 is a positive current collector 14, the active material layer 20 is a positive active material layer 21, and the positive active material layer 21 is stacked on the conductive layer 12 of the positive current collector 14. The material of the positive active material layer 21 can be lithium cobalt oxide, lithium iron phosphate, etc., and there is no specific limitation.

[0092] Optionally, the electrode sheet 100 is a negative electrode sheet 102, the current collector 10 is a negative current collector 13, the active material layer 20 is a negative active material layer 22, the negative active material layer 22 is stacked on the conductive layer 12 of the negative current collector 13, and the material of the negative active material layer 22 can be graphite, etc., without specific limitation.

[0093] Optionally, the negative electrode active material layer 22 has the same size and shape as the positive electrode active material layer 21 , and the active material layer 20 has the same size and shape as the conductive layer 12 .

[0094] Optionally, the size of the positive electrode sheet 101 is the same as that of the negative electrode sheet 102; or, the size of the positive electrode sheet 101 is smaller than that of the negative electrode sheet 102; or, the size of the positive electrode sheet 101 is larger than that of the negative electrode sheet 102, without specific limitation.

[0095] Optionally, the size of the positive electrode sheet 101 is smaller than that of the negative electrode sheet 102 . The specific positional relationship is the same as the positional relationship between the positive electrode current collector 14 and the negative electrode current collector 13 described above, which can be used for reference and will not be described in detail.

[0096] By setting the active material layer 20, the positive electrode active material layer 21 is stacked on the positive electrode collector 14 to form the positive electrode sheet 101, and the negative electrode active material layer 22 is stacked on the negative electrode collector 13 to form the negative electrode sheet 102. The temperature difference between the edge and the middle of the positive electrode sheet 101 and the negative electrode sheet 102 is reduced, thereby reducing lithium plating and extending the service life of the battery cell 1000.

[0097] In another embodiment, Figure 4 As shown, the pole piece 100 includes a current collector 10 and an active material layer 20. The current collector 10 includes a foil 11 and a conductive layer 12. The foil 11 includes a first coating area 113 and a second coating area 114 arranged in sequence in the second direction X. The first coating area 113 is closer to the edge of the foil 11 than the second coating area 114, and the conductive layer 12 is stacked on the second coating area 114. The active material layer 20 is stacked on the first coating area 113 and the conductive layer 12; the conductivity of the pole piece 100 in the first coating area 113 along the first direction Y is F, and the conductivity of the pole piece 100 in the second coating area 114 along the first direction Y is G, satisfying: F<G.

[0098] Optionally, the material of the conductive layer 12 is similar to the material of the aforementioned second region 122 , which can be referred to without further details.

[0099] Optionally, the size relationship between the first coating area 113 and the second coating area 114 is similar to the size relationship between the first area 121 and the second area 122 described above, which can be used as a reference and will not be described in detail.

[0100] Optional, satisfying: 1 / 3≤F / G≤1 / 2.

[0101] Optionally, the ratio of F / G can be 5 / 12, 3 / 8, 11 / 24, etc., without limitation.

[0102] By setting 1 / 3≤F / G≤1 / 2, the conductivity of the edge of the current collector 10 can be suppressed, and its current can be reduced, thereby reducing the temperature rise in the edge area.

[0103] In this embodiment, the second coating area 114 of the foil 11 is stacked with the conductive layer 12, the first coating area 113 is directly stacked with the active material layer 20, the second coating area 114 is stacked with the active material layer 20 above the conductive layer 12, and the first coating area 113 is closer to the edge of the foil 11 than the second coating area 114, so the conductivity of the edge of the current collector 10 is less than the conductivity of the center of the current collector 10.

[0104] By setting the current collector 10 and the active material layer 20, the conductive layer 12 is stacked on the second coating area 114, and the active material layer 20 is stacked on the first coating area 113 and the conductive layer 12. The conductivity F of the first coating area 113 and the conductivity G of the second coating area 114 satisfy: F<G, which can reduce the temperature difference between the edge and the middle of the current collector 10, reduce lithium plating, and extend the service life of the battery cell 1000.

[0105] Please refer to Figure 1 The embodiment of the utility model further provides a battery cell 1000, comprising a diaphragm 200 and a pole piece 100 provided in the embodiment of the utility model, wherein the diaphragm 200 and the pole piece 100 are stacked.

[0106] Optional, such as Figure 1 As shown, the positive electrode sheet 101 , the separator 200 and the negative electrode sheet 102 are stacked, and there is a separator 200 between adjacent positive electrode sheets 101 and negative electrode sheets 102 .

[0107] The positive electrode sheet 101 , the separator 200 and the negative electrode sheet 102 are stacked, and there is a separator 200 between adjacent positive electrode sheets 101 and negative electrode sheets 102 .

[0108] Optionally, the positive electrode sheet 101 and the negative electrode sheet 102 are Figure 2 The electrode 100 in the embodiment shown; or, the positive electrode 101 is as follows Figure 2 The embodiment shown in FIG. 100 and the negative electrode 102 are as follows. Figure 4 The current collector 10 shown; or, the positive electrode sheet 101 includes Figure 4 The current collector 10 shown, the negative electrode sheet 102 includes Figure 2 The current collector 10 shown, etc. In short, the pole piece 100 in the battery cell 1000 can be a combination of the pole pieces 100 in the above various embodiments, and there is no specific limitation.

[0109] The battery cell 1000 in the embodiment of the utility model can solve the problem of large local temperature difference in the battery cell 1000 and affecting the service life of the battery cell 1000 by adopting the pole piece 100 in the embodiment of the utility model.

[0110] In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationship of terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inside" and "outside" are based on the orientation or positional relationship described in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0111] The above disclosure is only a preferred embodiment of the present invention, and certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A current collector, characterized in that: include: A foil material, the edge of which is suitable for arranging a tab; A conductive layer is stacked with the foil material, the conductive layer includes a first area and a second area, the first area is closer to the pole ear than the second area, the conductivity of the first area along a first direction is A, the conductivity of the second area along the first direction is B, satisfying: A<B, the first direction is the direction in which the foil material and the conductive layer are stacked.

2. The current collector according to claim 1, characterized in that: Satisfies: 1 / 3≤A / B≤1 / 2.

3. The current collector according to claim 1, characterized in that: The foil material includes a first edge, the first edge is suitable for connecting to the pole ear, the first area includes a second edge opposite to the first edge in a second direction, in the second direction, the distance from the first edge to the second edge is C, satisfying: 0mm≤C≤5mm, and the second direction is the arrangement direction of the first area and the second area and intersects with the first direction.

4. The current collector according to claim 1, characterized in that: The foil material includes a first edge, the first edge is suitable for connecting to the pole ear, the first area includes a second edge and a third edge opposite to each other in a second direction, the third edge is connected to the second area, and in the second direction, the distance from the second edge to the third edge is D, satisfying: 1mm≤D≤5mm, and the second direction is the arrangement direction of the first area and the second area and intersects with the first direction.

5. The current collector according to claim 3 or 4, characterized in that: The conductive layer also includes a third region, which is located on the side of the second region facing away from the first region in the second direction. The conductivity of the third region in the first direction is E, satisfying: E<B, and the second direction is the arrangement direction of the first region and the second region and intersects with the first direction.

6. The current collector according to claim 5, characterized in that: Satisfies: 1 / 3≤E / B≤1 / 2.

7. The current collector according to claim 5, characterized in that: The foil also includes a fourth edge opposite to the first edge in the second direction, the third region includes a fifth edge opposite to the fourth edge in the second direction, and in the second direction, a distance from the fourth edge to the fifth edge is C1, satisfying: 0mm≤C1≤5mm.

8. The current collector according to claim 5, characterized in that: The foil also includes a fourth edge opposite to the first edge in the second direction, the third area includes a fifth edge and a sixth edge opposite to each other in the second direction, the sixth edge is connected to the second area, and in the second direction, a distance from the fifth edge to the sixth edge is D1, satisfying: 1mm≤D1≤5mm.

9. The current collector according to claim 1, characterized in that: The current collector is a negative electrode current collector, and the foil material is a copper foil; or, the current collector is a positive electrode current collector, and the foil material is an aluminum foil.

10. A pole piece, characterized in that: The invention comprises an active material layer and the current collector according to any one of claims 1 to 9, wherein the active material layer is stacked on the current collector.

11. A pole piece, characterized in that: include: A current collector, comprising a foil and a conductive layer, wherein the edge of the foil is suitable for arranging a tab, the foil comprises a first coating area and a second coating area, the first coating area is closer to the edge of the foil than the second coating area, and the conductive layer is stacked on the second coating area; an active material layer stacked on the first coating region and the conductive layer; The conductivity of the electrode piece in the first coating area along the first direction is F, and the conductivity of the electrode piece in the second coating area along the first direction is G, satisfying: F<G, and the first direction is the stacking direction of the foil and the conductive layer.

12. The pole piece according to claim 11, characterized in that: Satisfies: 1 / 3≤F / G≤1 / 2.

13. A battery cell, characterized in that: It comprises a pole ear, a diaphragm and a pole piece as claimed in any one of claims 10 to 12, wherein the diaphragm and the pole piece are stacked, and the pole ear is arranged at the edge of the foil.

14. A battery, characterized in that: It comprises a shell and the battery core as claimed in claim 13, wherein the battery core is accommodated in the shell.

Images