Electrode sheet, battery, and electrical device

Abstract

A battery, comprising a battery cell, wherein the battery cell is provided with electrode sheets; a current collector of each electrode sheet 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 a first direction is A, the conductivity of the second area in the first direction is B, and the following relational expression is satisfied: A<B.

Description

Electrode plates, batteries and electrical equipment

[0001] This application claims priority to Chinese Patent Application No. 202420868680.8, filed on April 24, 2024, entitled "Current Collector, Electrode, Cell and Battery", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, specifically to a current collector, electrode, cell, and battery. Background Technology

[0003] Currently, the current collector in battery cells typically uses metal foil as the substrate, and its conductivity is improved by coating the surface with conductive materials such as carbon black. However, during charging and discharging of the battery cell, the current density is high and the local temperature is high in the area near the tabs, resulting in a large temperature difference with the center of the core. This makes lithium plating more likely, leading to a shortened battery cell life. Summary of the Invention

[0004] The purpose of this application is to provide a current collector, electrode, cell, and battery to solve the problem of large temperature differences between the edge and center of the current collector, which easily leads to lithium deposition and shortens the cell life.

[0005] To achieve the objectives of this application, the following technical solution is provided:

[0006] In a first aspect, this application provides a current collector, comprising a foil and a conductive layer, wherein the edge of the foil is adapted to be provided with a tab; the conductive layer is stacked with the foil, the conductive layer comprising a first region and a second region, the first region being closer to the tab than the second region, the conductivity of the first region along a first direction being A, and the conductivity of the second region along the first direction being B, satisfying: A < B, where the first direction is the direction in which the foil and the conductive layer are stacked.

[0007] In one implementation, the following condition is satisfied: 1 / 3 ≤ A / B ≤ 1 / 2.

[0008] In one embodiment, the foil includes a first edge adapted to be connected to the tab, the first region includes a second edge opposite to the first edge in a second direction, the distance from the first edge to the second edge in the second direction is C, satisfying: 0mm≤C≤5mm, the second direction is the arrangement direction of the first region and the second region and intersects with the first direction.

[0009] In one embodiment, the foil includes a first edge adapted to be connected to the tab, the first region includes a second edge and a third edge opposite to each other in a second direction, the third edge being connected to the second region, and in the second direction, the distance from the second edge to the third edge is D, satisfying: 1mm≤D≤5mm, the second direction being the arrangement direction of the first region and the second region and intersecting with the first direction.

[0010] In one embodiment, the conductive layer further includes a third region located on the side of the second region away from the first region in the second direction. The conductivity of the third region in the first direction is E, which satisfies E < B. The second direction is the arrangement direction of the first region and the second region and intersects with the first direction.

[0011] In one implementation, the following condition is met: 1 / 3 ≤ E / B ≤ 1 / 2.

[0012] In one embodiment, the foil further includes a fourth edge opposite to the first edge in the second direction, and the third region includes a fifth edge opposite to the fourth edge in the second direction. In the second direction, the distance from the fourth edge to the fifth edge is C1, satisfying: 0mm≤C1≤5mm.

[0013] In one embodiment, the foil further includes a fourth edge opposite to the first edge in the second direction, and the third region includes a fifth edge and a sixth edge opposite to each other in the second direction. The sixth edge is connected to the second region. In the second direction, the distance from any position of the fifth edge to the corresponding position of the sixth edge is D1, which satisfies: 1mm≤D1≤5mm.

[0014] In one embodiment, the current collector is a negative current collector and the foil is a copper foil; or, the current collector is a positive current collector and the foil is an aluminum foil.

[0015] Secondly, this application also provides an electrode sheet comprising an active material layer and a current collector as described in any one of the various embodiments of the first aspect, wherein the active material layer is stacked on the current collector.

[0016] Thirdly, this application also provides an electrode sheet, the electrode sheet comprising a current collector and an active material layer, the current collector comprising a foil and a conductive layer, the edge of the foil being adapted to be provided with tabs, the foil comprising a first coating area and a second coating area, the first coating area being closer to the edge of the foil than the second coating area, the conductive layer being stacked on the second coating area; the active material layer being stacked on the first coating area and the conductive layer; the conductivity of the electrode sheet in the first coating area along a first direction is F, the conductivity of the electrode sheet in the second coating area along the first direction is G, satisfying: F < G, the first direction being the stacking direction of the foil and the conductive layer.

[0017] In one implementation, the following condition is satisfied: 1 / 3 ≤ F / G ≤ 1 / 2.

[0018] Fourthly, this application also provides a battery cell, including a tab, a separator, and an electrode sheet as described in any one of the embodiments of the second aspect or the third aspect, wherein the separator is stacked with the electrode sheet, and the tab is disposed at the edge of the foil.

[0019] Fifthly, this application also provides a battery, including a casing and a cell as described in the fourth aspect, the cell being housed within the casing.

[0020] By setting a foil and a conductive layer, the conductive layer includes a first region and a second region. The first region is closer to the edge of the foil where the tab is set compared to the second region. The conductivity A of the first region in the first direction and the conductivity B of the second region in the first direction satisfy: A < B. This can suppress the conductivity of the current collector edge, reduce its current, thereby reducing the temperature rise of the edge region, reducing the temperature difference between the current collector edge and the middle, reducing lithium plating, and extending the service life of the cell. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 is a cross-sectional view of a battery cell according to an embodiment;

[0023] Figure 2 is a cross-sectional view of an electrode sheet according to an embodiment;

[0024] Figure 3 is a top view of a current collector according to an embodiment;

[0025] Figure 4 is a cross-sectional view of the electrode sheet in another embodiment.

[0026] Explanation of reference numerals in the attached drawings: 1000-cell; 100-electrode, 101-positive electrode, 102-negative electrode; 10-current collector, 11-foil, 111-first edge, 112-fourth edge, 113-first coating area, 114-second coating area, 12-conductive layer, 121-first region, 122-second region, 123-second edge, 124-third edge, 125-third region, 126-fifth edge, 127-sixth edge, 13-negative current collector, 131-copper foil, 14-positive current collector, 141-aluminum foil; 20-active material layer, 21-positive active material layer, 22-negative active material layer; 200-separator. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] 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 it can be in a middle component. When a component is said to be "connected" to another component, it can be directly connected to the other component or it may be in a middle component.

[0029] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items.

[0030] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0031] This application provides a battery, including the battery cell described in this application embodiment. The battery can be a prismatic laminated battery, etc. Using the battery cell described in this application embodiment can solve the problem of large temperature differences within the battery cell due to high local current density, which affects the battery cell's lifespan.

[0032] The battery also includes a casing, which comprises a base plate and multiple side plates connected to the base plate and enclosing a receiving cavity. The receiving cavity is open at one end opposite to the base plate, and the battery cell is housed within the receiving cavity.

[0033] The outer shell is made of a material with high structural strength, specifically metal, high-strength plastic, ceramic, etc. Metal materials include aluminum, aluminum alloys, magnesium alloys, iron, and iron alloys. The outer shell can be a one-piece structure, meaning the base plate and side plates are manufactured using a single molding process, such as stamping or casting, with no restrictions. Alternatively, the outer shell can be a split structure, with the side plates and base plate connected and fixed by welding, bonding, snap-fitting, screwing, etc. The wall thickness of the outer shell can be approximately uniform throughout; that is, the side plates can have a roughly uniform thickness, and the base plate and side plates can also have roughly the same thickness.

[0034] The battery also includes a cover plate, which is attached to the opening in the outer casing to seal the cavity. The cover plate can be connected to the outer casing by welding, bonding, snap-fitting, screwing, etc., without limitation. The shape of the cover plate can be approximately the same as the base plate.

[0035] Please refer to Figure 1. This application embodiment provides a battery cell 1000, including a separator 200 and an electrode 100 as described in this application embodiment. The separator 200 and the electrode 100 are stacked. The electrode 100 includes an active material layer 20 and a current collector 10 as described in this application embodiment. The active material layer 20 is stacked on the current collector 10.

[0036] Please refer to Figures 1 and 2. This embodiment of the application provides a current collector 10, including a foil 11 and a conductive layer 12. The edge of the foil 11 is adapted to have tabs, and the conductive layer 12 is stacked on top of the foil 11. The conductive layer 12 includes a first region 121 and a second region 122. The first region 121 is closer to the tabs than the second region 122. The conductivity of the first region 121 along a first direction is A, and the conductivity of the second region 122 along the first direction is B, satisfying: A < B.

[0037] First, define the directions. Please refer to Figure 1, where Y is the first direction and X is the second direction.

[0038] 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, and the second direction X is perpendicular to the coating direction of the current collector 10. The first direction Y is perpendicular to the second direction X.

[0039] Optionally, the first region 121 is at least partially closer to the edge of the foil 11 where the tab is connected compared to the second region 122. For example, if both the first region 121 and the second region 122 are rectangular, and the length of the first region 121 in the vertical second direction X is the same as the length of the second region 122 in the vertical second direction X, then the first region 121 is generally closer to the edge of the foil 11 where the tab is connected compared to the second region 122; or, when the minimum distance from a portion of the edge of the second region 122 to the edge of the foil 11 where the tab is connected is the same as the minimum distance from the first region 121 to the edge of the foil 11 where the tab is connected, the first region 121 is positioned directly opposite the tab in the second direction X, and the second region 122 is U-shaped, surrounding the outer periphery of the first region 121.

[0040] Optionally, the conductivity of the first region 121 and the second region 122 along the first direction Y is the same as that of the first direction Y, which is the direction in which the foil 11 and the conductive layer 12 are stacked.

[0041] For the large-size 1000 battery cell, the large area of ​​the cell makes it prone to performance inhomogeneity due to different environments in different regions. Temperature inhomogeneity is particularly noticeable in these areas. For instance, during charging and discharging, the area with the tabs experiences higher current density and localized higher temperatures, leading to faster degradation of the active material in that region. This is especially pronounced during continuous high-current fast charging (200-400A), where the temperature difference caused by the current density variation is even more significant.

[0042] Current collectors typically use aluminum foil (positive electrode) and copper foil (negative electrode) as substrates, coated with conductive materials such as carbon black to improve conductivity. Since all current needs to converge at the tab during charging and discharging, the current density at the tab is high, resulting in dense current lines and a high temperature. The temperature difference between the tab and the center of the electrode core is around 10°C. This temperature difference not only leads to a decrease in charging capacity in the local low-temperature region (low temperature, high impedance, easy lithium plating) but also causes accelerated degradation in the high-temperature region.

[0043] The current collector 10 provided in this application embodiment, by setting a foil 11 and a conductive layer 12, the conductive layer 12 includes a first region 121 and a second region 122. The first region 121 is closer to the edge of the foil 11 where the electrode tab is set compared to the second region 122. 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. This can suppress the conductivity of the edge of the current collector 10, reduce its current, thereby reducing the temperature rise of the edge region, reducing the temperature difference between the edge and the middle of the current collector 10, reducing lithium plating, and extending the service life of the cell 1000.

[0044] Optionally, the foil 11 can be made of aluminum, copper, etc., and the shape of the foil 11 can be rectangular, circular, etc., without any specific restrictions.

[0045] 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.

[0046] Optionally, the area of ​​the first region 121 is smaller than the area of ​​the second region 122.

[0047] Optionally, the material in the first region 121 may be a low-conductivity adhesive material with trace amounts of conductive carbon black (0.1%-2%) added to materials such as polyurethane (PU), polyethyl acrylate (PVA), and polyethylene oxide (PEO), without any restrictions.

[0048] Optionally, the material of the second region 122 can be conductive carbon black, etc., without limitation.

[0049] 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.

[0050] Optionally, the ratio of A / B can be 5 / 12, 3 / 8, 11 / 24, etc., without restriction.

[0051] 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 current collector 10 at its edge can be suppressed, its current reduced, and thus the temperature rise of the edge region reduced.

[0052] If A / B < 1 / 3, the conductivity of the first region 121 along the first direction Y is too different from that of the second region 122 along the first direction Y, which is not conducive to current flow.

[0053] 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 the lithium plating cannot be effectively reduced.

[0054] Optionally, as shown in FIG3, the foil 11 includes a first edge 111 adapted to be connected to the tab, and a first region 121 includes a second edge 123 and a third edge 124 opposite to each other in the second direction X. The first edge 111 is located on the side of the second edge 123 away from the third edge 124 in the second direction X, and the third edge 124 is connected to the second region 122.

[0055] 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 parallel.

[0056] Optionally, the foil 11 can be rectangular, trapezoidal, parallelogram, etc., and there are no specific restrictions.

[0057] Optionally, the shape of the conductive layer 12 corresponds to that of the foil 11, and the first region 121 and the second region 122 have the same stacking thickness on the foil 11.

[0058] For example, as shown in Figure 3, the foil 11, the first region 121, and the second region 122 are all rectangular. There is a gap between the second edge 123 and the first edge 111 for easy processing. The third edge 124 is connected to the second region 122.

[0059] Optionally, the electrode 100 may also include a tab (not shown in the figure), which may be an integral structure with the current collector 10, or the tab may be connected to the first edge 111.

[0060] By setting parallel first edge 111, second edge 123 and third edge 124, with a certain distance between the first edge 111 and the second edge 123, a coating allowance for the conductive layer 12 is left on the foil 11, which also facilitates multiple coatings of the coating material to form the conductive layer 12.

[0061] Optionally, as shown in Figure 3, the first region 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, which satisfies: 0mm≤C≤5mm.

[0062] Optionally, the value of C can be 2mm-4mm, specifically 2.5mm, 3mm, 3.5mm, etc., without restriction.

[0063] By setting the distance between the first edge 111 and the second edge 123, a processing allowance for the conductive layer 12 is left on the foil 11, which facilitates multiple coatings. If C > 5mm, the blank space at the edge of the foil 11 will be too large, resulting in material waste.

[0064] In the above example, C is 0, meaning 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 extends beyond the conductive layer in the second direction X.

[0065] Optionally, as shown in Figure 3, the first region 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 region 122. 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, which satisfies: 1mm≤D≤5mm.

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

[0067] 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 > 5 mm, the range of the first region 121 is too large, affecting the conductivity of the current collector 10. If D < 1 mm, 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, which cannot effectively reduce the local temperature difference.

[0068] Optionally, as shown in Figure 3, the foil 11 further includes a fourth edge 112 opposite to the first edge 111, and the conductive layer 12 further 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 away from the sixth edge 127. The sixth edge 127 is connected to the second region 122. The conductivity of the third region 125 is E, which satisfies: E < B.

[0069] 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. This can be used as a reference and will not be described again.

[0070] Optionally, the fourth edge 112 is also connected to a tab. Similarly, if both the third region 125 and the second region 122 are rectangular, and the length of the third region 125 in the vertical second direction X is the same as the length of the second region 122 in the vertical second direction X, then the third region 125 is closer to the fourth edge 112 than the second region 122; or, when the minimum distance from a portion of the edge of the second region 122 to the edge of the foil 11 connected to the tab is the same as the minimum distance from the third region 125 to the edge of the foil 11 connected to the tab, the third region 125 is positioned directly opposite the tab in the second direction X, and the second region 122 is U-shaped, surrounding the outer periphery of the third region 125.

[0071] Similarly, the distance between the fourth edge 112 and the fifth edge 126 is C1, satisfying: 0mm≤C1≤5mm, which can avoid excessive blank space at the edge of the foil 11, resulting in material waste. The distance between the fifth edge 126 and the sixth edge 127 is D1, satisfying: 1mm≤D1≤5mm, which can limit the stacking range of the first region 121 and effectively reduce the local temperature difference without affecting the conductivity of the current collector 10.

[0072] Optionally, the value of C1 can be 2mm-4mm, specifically 2.5mm, 3mm, 3.5mm, etc., without restriction; the value of D1 can be 2mm-4mm, specifically 2.5mm, 3mm, 3.5mm, etc., without restriction.

[0073] Optionally, the following condition must be met: 1 / 3 ≤ E / B ≤ 1 / 2.

[0074] Optionally, the E / B ratio can be 5 / 12, 3 / 8, 11 / 24, etc., without restriction.

[0075] Optionally, the conductivity E of the third region 125 and the conductivity A of the first region 121 along the first direction Y can be the same or different, and there is no specific restriction.

[0076] By setting 1 / 3≤E / B≤1 / 2, the conductivity of the current collector 10 at its edge can be suppressed, reducing its current and thus reducing the temperature rise in the edge region.

[0077] Optionally, the third region 125 and the first region 121 are symmetrically arranged on the foil 11, that is: C=C1, D=D1.

[0078] Optionally, the electrode 100 includes two tabs, which are connected to the first region 121 and the third region 125 respectively. The tabs can be half tabs or full tabs, without limitation.

[0079] Optionally, the first region 121, the second region 122, and the third region 125 are sequentially coated on the foil 11 along the coating direction; or, the first region 121, the second region 122, and the third region 125 are coated on the foil 11 simultaneously, without any specific limitation. The first region 121, the second region 122, and the third region 125 can be coated once or multiple times, without any specific limitation.

[0080] By setting a 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 cell 1000.

[0081] Optionally, as shown in Figure 1, the current collector 10 is a negative current collector 13 and the foil 11 is a copper foil 131, or the current collector 10 is a positive current collector 14 and the foil 11 is an aluminum foil 141.

[0082] Optionally, the size of the negative current collector 13 is the same as the size of the positive current collector 14; or, the size of the negative current collector 13 is smaller than the size of the positive current collector 14; or, the size of the negative current collector 13 is larger than the size of the positive current collector 14, and there is no specific limitation.

[0083] For example, as shown in FIG1, 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.

[0084] Optionally, the conductive layer 12 on the negative current collector 13 has the same size and shape as the conductive layer 12 on the positive current collector 14.

[0085] By setting a positive current collector 14 and a negative current collector 13, both of which are provided with a conductive layer 12, the temperature difference between the edge and the middle of the positive current collector 14 and the negative current collector 13 is reduced, thus reducing lithium plating and extending the service life of the cell 1000.

[0086] Please refer to Figures 1 and 2. This application embodiment also provides an electrode 100, including an active material layer 20 and a current collector 10 as described in this application embodiment, wherein the active material layer 20 is stacked on the current collector 10.

[0087] Optionally, as shown in Figure 1, electrode 100 is positive electrode 101, current collector 10 is positive current collector 14, active material layer 20 is positive active material layer 21, positive active material layer 21 is stacked on the conductive layer 12 of positive current collector 14, and the material of positive active material layer 21 can be lithium cobalt oxide, lithium iron phosphate, etc., without any specific limitation.

[0088] Optionally, electrode 100 is negative electrode 102, current collector 10 is negative electrode current collector 13, active material layer 20 is negative electrode active material layer 22, negative electrode active material layer 22 is stacked on the conductive layer 12 of negative electrode current collector 13, and the material of negative electrode active material layer 22 can be graphite, etc., and there is no specific limitation.

[0089] 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.

[0090] Optionally, the size of the positive electrode 101 is the same as the size of the negative electrode 102; or, the size of the positive electrode 101 is smaller than the size of the negative electrode 102; or, the size of the positive electrode 101 is larger than the size of the negative electrode 102, and there is no specific limitation.

[0091] Optionally, the size of the positive electrode 101 is smaller than that of the negative electrode 102. The specific positional relationship is as described above for the positional relationship between the positive current collector 14 and the negative current collector 13. This can be used as a reference and will not be repeated here.

[0092] By setting an active material layer 20, a positive electrode active material layer 21 is stacked on a positive electrode current collector 14 to form a positive electrode sheet 101, and a negative electrode active material layer 22 is stacked on a negative electrode current collector 13 to form a 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, which reduces lithium plating and extends the service life of the cell 1000.

[0093] In another embodiment, as shown in FIG4, the electrode 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 region 113 and a second coating region 114 arranged sequentially in the second direction X. The first coating region 113 is closer to the edge of the foil 11 than the second coating region 114. The conductive layer 12 is stacked on the second coating region 114. The active material layer 20 is stacked on the first coating region 113 and the conductive layer 12. The conductivity of the electrode 100 in the first coating region 113 along the first direction Y is F, and the conductivity of the electrode 100 in the second coating region 114 along the first direction Y is G, satisfying: F < G.

[0094] Optionally, the material of the conductive layer 12 is similar to that of the aforementioned second region 122, and can be referred to without further explanation.

[0095] 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 region 121 and the second region 122 mentioned above, and can be referred to without further explanation.

[0096] Optionally, the following condition must be met: 1 / 3 ≤ F / G ≤ 1 / 2.

[0097] Optionally, the F / G ratio can be 5 / 12, 3 / 8, 11 / 24, etc., without restriction.

[0098] By setting 1 / 3≤F / G≤1 / 2, the conductivity of the current collector 10 at its edge can be suppressed, reducing its current and thus reducing the temperature rise in the edge region.

[0099] 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. Therefore, the conductivity at the edge of the current collector 10 is less than the conductivity at the center of the current collector 10.

[0100] By setting a current collector 10 and an active material layer 20, a conductive layer 12 is stacked on the second coating area 114, and an 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. This 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.

[0101] Please refer to Figure 1. This application embodiment also provides a battery cell 1000, including a separator 200 and an electrode 100 provided in this application embodiment, wherein the separator 200 and the electrode 100 are stacked.

[0102] Optionally, as shown in Figure 1, the positive electrode 101, the separator 200 and the negative electrode 102 are stacked, and there is a separator 200 between adjacent positive electrode 101 and negative electrode 102.

[0103] The positive electrode 101, the separator 200 and the negative electrode 102 are stacked, and there is a separator 200 between adjacent positive electrode 101 and negative electrode 102.

[0104] Optionally, both the positive electrode 101 and the negative electrode 102 are the electrode 100 shown in the embodiment of FIG. 2; or, the positive electrode 101 is the electrode 100 shown in the embodiment of FIG. 2, and the negative electrode 102 is the current collector 10 shown in FIG. 4; or, the positive electrode 101 includes the current collector 10 shown in FIG. 4, and the negative electrode 102 includes the current collector 10 shown in FIG. 2, and so on. In short, the electrode 100 in the battery cell 1000 can be a combination of the electrode 100 in the above various embodiments, and there is no specific limitation.

[0105] The battery cell 1000 in this embodiment of the application can solve the problem of large local temperature difference in the battery cell 1000, which affects the service life of the battery cell 1000, by adopting the electrode 100 in this embodiment of the application.

[0106] In the description of the embodiments of this application, it should be noted that the orientation or positional relationship of the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and other indicators are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0107] The above-disclosed embodiments are merely preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art will understand that all or part of the processes for implementing the above embodiments and equivalent variations made in accordance with the claims of this application are still within the scope of this application.

Claims

1. A current collector (10), characterized in that, include: Foil (11), the edges of which are adapted to be provided with tabs; A conductive layer (12) is stacked with the foil (11). The conductive layer (12) includes a first region (121) and a second region (122). The first region (121) is closer to the tab than the second region (122). The conductivity of the first region (121) along a first direction is A, and the conductivity of the second region (122) along the first direction is B, satisfying: A < B. The first direction is the direction in which the foil (11) and the conductive layer (12) are stacked.

2. The current collector (10) according to claim 1, characterized in that, It satisfies: 1 / 3≤A / B≤1 / 2.

3. The current collector (10) according to claim 1 or 2, characterized in that, The foil (11) includes a first edge (111) adapted to be connected to the tab, and the first region (121) includes a second edge (123) opposite to the first edge (111) in a second direction. In the second direction, the distance from the first edge (111) to the second edge (123) is C, which satisfies: 0mm≤C≤5mm. The second direction is the arrangement direction of the first region (121) and the second region (122) and intersects with the first direction.

4. The current collector (10) according to any one of claims 1 to 3, characterized in that, The foil (11) includes a first edge (111) adapted to be connected to the tab. The first region (121) includes a second edge (123) and a third edge (124) opposite each other in the second direction. The third edge (124) is connected to the second region (122). In the second direction, the distance from the second edge (123) to the third edge (124) is D, which satisfies: 1mm≤D≤5mm. The second direction is the arrangement direction of the first region (121) and the second region (122) and intersects with the first direction.

5. The current collector (10) according to any one of claims 1 to 3, characterized in that, The conductive layer (12) further includes a third region (125), which is located on the side of the second region (122) away from the first region (121) in the second direction. The conductivity of the third region (125) in the first direction is E, which satisfies: E < B. The second direction is the arrangement direction of the first region (121) and the second region (122) and intersects with the first direction.

6. The current collector (10) according to claim 5, characterized in that, It satisfies: 1 / 3≤E / B≤1 / 2.

7. The current collector (10) according to claim 5, characterized in that, The foil (11) further includes a fourth edge (112) opposite to the first edge (111) in the second direction, and the third region (125) includes a fifth edge (126) opposite to the fourth edge (112) in the second direction. In the second direction, the distance from the fourth edge (112) to the fifth edge (126) is C1, which satisfies: 0mm≤C1≤5mm.

8. The current collector (10) according to claim 5, characterized in that, The foil (11) further includes a fourth edge (112) opposite to the first edge (111) in the second direction. The third region (125) includes a fifth edge (126) and a sixth edge (127) opposite to each other in the second direction. The sixth edge (127) is connected to the second region (122). In the second direction, the distance from the fifth edge (126) to the sixth edge (127) is D1, which satisfies: 1mm≤D1≤5mm.

9. The current collector (10) according to any one of claims 1 to 8, characterized in that, The current collector (10) is a negative current collector (13), and the foil (11) is a copper foil (131), or the current collector (10) is a positive current collector (14), and the foil (11) is an aluminum foil (141).

10. An electrode (100), characterized in that, It includes an active material layer (20) and a current collector (10) as described in any one of claims 1 to 9, wherein the active material layer (20) is stacked on the current collector (10).

11. An electrode (100), characterized in that, include: The current collector (10) includes a foil (11) and a conductive layer (12). The edge of the foil (11) is adapted to be provided with tabs. The foil (11) includes a first coating area (113) and a second coating area (114). The first coating area (113) is closer to the edge of the foil (11) than the second coating area (114). The conductive layer (12) is stacked on the second coating area (114). An active material layer (20) is stacked on the first coating area (113) and the conductive layer (12); The conductivity of the electrode (100) in the first coating area (113) along the first direction is F, and the conductivity of the electrode (100) in the second coating area (114) along the first direction is G, satisfying: F < G, where the first direction is the stacking direction of the foil (11) and the conductive layer (12).

12. The electrode (100) according to claim 11, characterized in that, It satisfies: 1 / 3≤F / G≤1 / 2.

13. A battery cell (1000), characterized in that, It includes tabs, a diaphragm (200), and an electrode sheet (100) as described in any one of claims 10 to 12, wherein the diaphragm (200) and the electrode sheet (100) are stacked together, and the tabs are disposed at the edge of the foil (11).

14. A battery, characterized in that, It includes a housing and a battery cell (1000) as described in claim 13, wherein the battery cell (1000) is housed within the housing.

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