Negative plate, battery and electric equipment

Abstract

The invention discloses a negative plate, a battery and electric equipment, the negative plate comprises a negative current collector and a negative active material layer, and the negative current collector comprises a first edge; the negative electrode active material layer is stacked on the negative electrode current collector, the negative electrode active material layer comprises a first region and a second region which are sequentially arranged in a first direction X, the first region is closer to a first edge relative to the second region, the first edge extends in a second direction, and the first direction intersects with the second direction; the component of the first area comprises a first conductive agent, the first conductive agent is graphene, the component of the second area comprises a second conductive agent, and the lithium ion de-intercalation capability of the first conductive agent is smaller than that of the second conductive agent. According to the negative plate, the edge lithium precipitation effect caused by lithium ion migration and cyclic accumulation can be reduced.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a negative electrode sheet, a battery and an electrical device. Background Art

[0002] Lithium-ion batteries have been widely used in recent years due to their advantages of high energy density, high operating voltage, long service life and low self-discharge.

[0003] The edge area of ​​the lithium-ion battery's electrode will experience lithium deposition due to poor charging and discharging capabilities after multiple fast-charging cycles. The continuous accumulation of deposited lithium will cause the diaphragm to be punctured, posing a serious safety hazard to the lithium-ion battery. Summary of the invention

[0004] The purpose of the present application is to provide a negative electrode sheet, a battery and an electrical device to solve the problem of easy lithium deposition at the edge of the negative electrode sheet.

[0005] To achieve the purpose of this application, this application provides the following technical solutions:

[0006] In a first aspect, the present application provides a negative electrode sheet, comprising a negative electrode current collector and a negative electrode active material layer, wherein the negative electrode current collector comprises a first edge; the negative electrode active material layer is stacked on the negative electrode current collector, and the negative electrode active material layer comprises a first region and a second region arranged in sequence in a first direction, the first region is closer to the first edge than the second region, the first edge extends along a second direction, and the first direction intersects with the second direction; the composition of the first region comprises a first conductive agent, the first conductive agent is graphene, the composition of the second region comprises a second conductive agent, and the ability of the first conductive agent to deintercalate lithium ions is less than the ability of the second conductive agent to deintercalate lithium ions.

[0007] In one embodiment, the sheet diameter of the graphene of the first conductive agent is D1, which satisfies: 7 μm≤D1≤15 μm.

[0008] In one embodiment, the second conductive agent is any one or a combination of single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon black and graphene. When the second conductive agent includes graphene, the sheet diameter of the graphene of the second conductive agent is smaller than the sheet diameter of the graphene of the first conductive agent.

[0009] In one embodiment, the second conductive agent includes graphene, and the flake diameter of the graphene in the second conductive agent is D2, satisfying: 0.5 μm≤D2≤3 μm.

[0010] In one implementation, in the first direction, a size of the first region is smaller than a size of the second region.

[0011] In one implementation, the first region includes a second edge close to the first edge in the first direction, and in the first direction, a distance from the first edge to the second edge is A1, satisfying: 0mm≤A1≤2mm.

[0012] In one embodiment, the negative electrode current collector includes a first edge, the first region includes a second edge and a third edge opposite to each other in a first direction, the second edge is close to the first edge, the third edge is connected to the second region, and in the first direction, the distance from the second edge to the third edge is B1, satisfying: 1mm≤B1≤10mm.

[0013] In one embodiment, the negative electrode active material layer also includes a third region, and the third region is located on the side of the second region facing away from the first region in the first direction. The components of the third region include a third conductive agent, and the third conductive agent is graphene. The ability of the third conductive agent to deintercalate lithium ions is less than the ability of the second conductive agent to deintercalate lithium ions.

[0014] In one embodiment, the sheet diameter of the graphene of the third conductive agent is D3, which satisfies: 7 μm≤D3≤15 μm.

[0015] In one embodiment, the negative electrode current collector also includes a fourth edge opposite to the first edge in the first direction, the third region includes a fifth edge and a sixth edge opposite to each other in the first direction, the fifth edge is close to the fourth edge, and the sixth edge is connected to the second region, and in the first direction, the distance from the fifth edge to the sixth edge is B2, satisfying: 1mm≤B1≤10mm.

[0016] In one embodiment, the negative electrode current collector also includes a seventh edge adjacent to the first edge, the negative electrode active material layer also includes a fourth region, the fourth region and the second region are arranged sequentially in the second direction, and the fourth region is closer to the seventh edge relative to the second region, the second direction intersects with the first direction, the fourth region includes a fourth conductive agent, the fourth conductive agent is graphene, and the ability of the fourth conductive agent to deintercalate lithium ions is less than the ability of the second conductive agent to deintercalate lithium ions.

[0017] In one embodiment, the negative electrode sheet includes an overlap region and an overhang region, the overlap region is suitable for overlapping with the positive electrode active material layer of the positive electrode sheet, and the overhang region includes at least a portion of the first region.

[0018] In one implementation, a size of the overhang area in the first direction is P, satisfying: 1 mm ≤ P ≤ 3 mm.

[0019] In a second aspect, the present application further provides a battery, comprising a positive electrode sheet and a negative electrode sheet as described in any one of the various embodiments of the first aspect, wherein in the orthographic projection of the negative electrode sheet, the edge of the positive electrode active material layer of the positive electrode sheet falls within the first region.

[0020] In a third aspect, the present application further provides an electrical device, comprising an electrical device and the battery as described in the second aspect, wherein the battery supplies power to the electrical device.

[0021] By arranging a stacked negative electrode current collector and a negative electrode active material layer, the components of the first region of the negative electrode active material layer closer to the first edge of the negative electrode current collector include a first conductive agent, the first conductive agent is graphene, and the ability of the second conductive agent in the second region to deintercalate lithium ions is controlled to be greater than the ability of the first conductive agent to deintercalate lithium ions, so that the ability of the conductive agent in the edge region of the negative electrode to deintercalate lithium ions is smaller, and the lithium ion transmission in the edge region of the negative electrode is hindered, which can reduce the lithium intercalation and deintercalation activity of the negative electrode edge and reduce the edge lithium precipitation effect caused by lithium ion migration and cycle accumulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the implementation methods of the present application 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 present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 is a schematic cross-sectional view of a battery of an embodiment;

[0024] Figure 2 is a schematic top view of a negative electrode sheet of an embodiment;

[0025] Figure 3 yes Figure 2 EE section diagram in FIG.

[0026] Figure 4 The present invention is a flow chart of the preparation of the negative electrode sheet of an embodiment.

[0027] Description of reference numerals:

[0028] 100-battery;

[0029] 10-negative electrode sheet, 11-negative electrode current collector, 111-first edge, 112-fourth edge, 113-seventh edge, 12-negative electrode active material layer, 121-first region, 122-second region, 123-second edge, 124-third edge, 125-third region, 126-fifth edge, 127-sixth edge, 128-fourth region, 129-fifth region;

[0030] 20-positive electrode sheet, 21-positive electrode current collector, 22-positive electrode active material layer;

[0031] 30 - diaphragm;

[0032] A1-first distance, B1-second distance, A2-third distance, B2-fourth distance, P-first size. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0034] 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.

[0035] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in this application and in the specification are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this application includes any and all combinations of one or more of the related listed items.

[0036] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0037] An embodiment of the present application provides an electrical device, including an electrical device and a battery in the embodiment of the present application, and the battery supplies power to the electrical device.

[0038] Optionally, the power-consuming device may be an electric vehicle, a hybrid vehicle, a base station, a household power load, etc. The battery may be a power battery, an energy storage battery, etc., without specific limitation.

[0039] In one embodiment, the electrical device is an electric vehicle or a hybrid vehicle, and the battery is a power battery.

[0040] The electrical equipment adopts the battery in the application embodiment, and the battery has good cycle performance and long service life.

[0041] Please refer to Figure 1 The embodiment of the present application further provides a battery 100, comprising a positive electrode sheet 20 and a negative electrode sheet 10 in the embodiment of the present application or a negative electrode sheet 10 prepared by the preparation method of the negative electrode sheet 10 in the embodiment of the present application.

[0042] Optionally, the battery 100 may be a laminated battery 100 or a wound battery 100 , and the laminated battery 100 may be, for example, a square laminated battery 100 , a blade laminated battery 100 , etc., without limitation.

[0043] Optionally, the battery 100 further includes a housing (not shown in the figure), the housing including 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 100 is received in the receiving cavity.

[0044] Optionally, the shell is a material with high structural strength, specifically metal materials, high-strength plastics, ceramics, etc., and 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.

[0045] Optionally, the battery 100 further includes a cover plate (not shown in the figure), 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.

[0046] Optionally, the positive electrode sheet 20 includes a positive electrode collector 21, and a positive electrode active material layer 22 is provided on at least one side of the positive electrode collector 21. The positive electrode active material layer 22 includes components such as positive electrode materials, conductive agents, and binders. The present application does not specifically limit these materials, and suitable materials can be selected according to actual application requirements. The positive electrode collector 21 includes but is not limited to any one of copper foil and aluminum foil. The positive electrode active material can be a phosphate positive electrode active material and a ternary positive electrode active material. In a specific embodiment, it includes lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium oxyphosphate, lithium vanadium phosphate fluorophosphate, lithium titanate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and binary material LiNix A(1-k)O2 (where A is selected from one of Co and Mn, and 0 < k < 1), ternary material LiNi m E n M(1-i-j)O2 (where E and M are independently selected from at least one of Co, Al, and Mn, and E and M are different, 0 < i < 1, 0 < j < 1), or one or more of them. The conductive agent includes one or more of Super P, Super S, graphene, acetylene black, carbon fiber, Ketjen black, C60, and carbon nanotubes, and the content of the conductive agent in the positive electrode active material layer 22 is 3 wt% - 5 wt%. The types of the binder include one or more of polyvinylidene chloride, soluble polytetrafluoroethylene, styrene-butadiene rubber, hydroxypropyl methylcellulose, methylcellulose, carboxymethylcellulose, polyvinyl alcohol, acrylonitrile copolymer, sodium alginate, chitosan, and chitosan derivatives, and the content of the binder in the positive electrode active material layer 22 is 2 wt% - 4 wt%.

[0047] Optionally, the negative electrode sheet 10 includes a negative electrode current collector 11, and a negative electrode active material layer 12 is provided on at least one side of the negative electrode current collector 11. The negative electrode active material layer 12 includes components such as a negative electrode material, a conductive agent, and a binder. This application does not make specific limitations on these materials, and appropriate materials can be selected according to actual application requirements. The negative electrode current collector 11 includes, but is not limited to, any one of copper foil, composite copper foil, or coated carbon copper foil. The negative electrode material includes, but is not limited to, carbon-based negative electrodes and silicon-based negative electrodes. Among them, the carbon-based negative electrode may include graphite, hard carbon, soft carbon, graphene, etc.; the silicon-based negative electrode may include silicon, silicon carbide, silicon oxide, silicon metal compounds, etc. In some specific embodiments, the above negative electrode material is selected from at least one of silicon monoxide, silicon carbide, and silicon-carbon composite. The conductive agent in the negative electrode active material layer 12 can improve the conductivity of the negative electrode material. The conductive agent may include one or more of acetylene black, Ketjen carbon black, Super P, Super S, carbon nanotubes, carbon nanofibers, activated carbon, and graphene.

[0048] Optionally, the battery 100 further includes a separator 30. The separator 30 can be any one of a woven membrane, a non-woven membrane (non-woven fabric), a microporous membrane, a composite membrane, a rolled membrane, etc., and can be selected according to actual application requirements, and no specific limitation is made.

[0049] Lithium-ion battery 100 is widely used in energy storage and electric vehicle and other fields because of its advantages such as high energy density, high average output voltage, large output power, small self-discharge, excellent cycle performance, fast charge and discharge, wide operating temperature range, and long service life.

[0050] The battery 100 in the embodiment of the present application can alleviate the edge lithium plating effect caused by lithium ion migration and cycle accumulation by adopting the negative electrode sheet 10 in the embodiment of the present application or the negative electrode sheet 10 prepared by the preparation method of the negative electrode sheet 10 in the embodiment of the present application, and effectively solve the capacity drop and safety problems of the battery 100 caused by edge lithium plating. The life of the battery 100 can be extended and the safety is good.

[0051] The negative electrode sheet 10 in the embodiment of the present application is described in detail below.

[0052] First define the direction. Figure 1 and Figure 2 As shown, X is the first direction, Y is the second direction, and the first direction X intersects the second direction Y. Optionally, the first direction X is perpendicular to the second direction Y.

[0053] Please refer to Figure 2 The present application provides a negative electrode sheet 10, comprising a negative electrode current collector 11 and a negative electrode active material layer 12, wherein the negative electrode current collector 11 comprises a first edge 111, and the first edge 111 extends along a second direction Y; the negative electrode active material layer 12 is stacked on the negative electrode current collector 11, and the negative electrode active material layer 12 comprises a first region 121 and a second region 122 arranged in sequence in a first direction X, wherein the first region 121 is closer to the first edge 111 than the second region 122, and the first region 121 comprises a first conductive agent, which is graphene, and the second region 122 comprises a second conductive agent, and the ability of the first conductive agent to deintercalate lithium ions is less than the ability of the second conductive agent to deintercalate lithium ions.

[0054] Optionally, the first region 121 and the second region 122 are connected in the first direction X, or the first region 121 and the second region 122 are spaced apart in the first direction X, which is not specifically limited.

[0055] Optionally, the area of ​​the first region 121 is smaller than the area of ​​the second region 122 .

[0056] Optionally, the battery 100 further includes a negative electrode lug, which is connected to the negative electrode sheet 10 .

[0057] Optionally, the negative electrode ear can be in the form of a full-electrode ear, a multi-electrode ear or a single-electrode ear, etc. The output electrode ear can be in the form of the same-face output electrode ear, the different-face output electrode ear, the symmetrical output electrode ear or the asymmetrical output electrode ear, etc.

[0058] Optionally, in one embodiment, the negative electrode ear is connected to the first edge 111 ; or, the negative electrode ear is connected to an edge of the negative electrode current collector 11 adjacent to / opposite to the first edge 111 , and there is no specific limitation.

[0059] Optionally, the first region 121 of the negative electrode active material layer 12 includes components of a negative electrode material, a binder, etc. in addition to the first conductive agent.

[0060] Optionally, in the orthographic projection of the positive electrode sheet 20 on the negative electrode sheet 10 , the edge of the positive electrode active material layer 22 of the positive electrode sheet 20 falls on the first region 121 of the negative electrode sheet 10 .

[0061] Lithium-ion batteries 100 are widely used in fields such as energy storage and electric vehicles because of their high energy density, high average output voltage, high output power, low self-discharge, excellent cycle performance, fast charge and discharge, wide operating temperature range, and long service life. Among them, the long charging time is the main obstacle to the further development of lithium-ion batteries 100. A key factor limiting the rapid charging of lithium-ion batteries 100 is that the negative electrode of the battery 100 is prone to lithium metal deposition on the surface during rapid charging. On the one hand, the deposited lithium metal reacts with the electrolyte, consuming the active lithium of the positive electrode, causing the capacity of the battery 100 to decay rapidly. On the other hand, the continued growth of lithium metal can easily pierce the diaphragm, causing serious safety problems.

[0062] In order to solve the problem of lithium metal precipitation, it is necessary to improve the design of the negative electrode sheet 10 of the battery 100. Current research has found that lithium precipitation behavior first occurs at the edge of the negative electrode sheet 10 close to the overhang. During the charging and discharging process, the active lithium at the edge of the negative electrode will diffuse to the overhang area, making the SOC (state of charge) of the negative electrode close to the edge during charging lower than that in the middle. The current density is too high at this position during charging, resulting in the occurrence of lithium precipitation.

[0063] In the present application example, the first conductive agent is used to reduce the lithium insertion and extraction activity at the edge of the negative electrode sheet 10 (reduce the ability and efficiency of inserting and extracting lithium ions at the edge of the negative electrode sheet 10), reduce the rate and proportion of lithium ions at the edge of the negative electrode sheet 10 migrating to the overhang, and reduce the SOC difference between the edge of the negative electrode sheet 10 and the overhang position, thereby effectively avoiding the occurrence of edge lithium deposition.

[0064] The negative electrode sheet 10 in the embodiment of the present application is provided with a stacked negative electrode current collector 11 and a negative electrode active material layer 12. The components of the first region 121 of the negative electrode active material layer 12 closer to the first edge 111 of the negative electrode current collector 11 include a first conductive agent, the first conductive agent is graphene, and the ability of the second conductive agent in the second region 122 to deintercalate lithium ions is controlled to be greater than the ability of the first conductive agent to deintercalate lithium ions, so that the ability of the conductive agent in the edge region of the negative electrode to deintercalate lithium ions is smaller, and the lithium ion transmission in the edge region of the negative electrode sheet 10 is hindered, which can reduce the lithium intercalation and deintercalation activity of the first region 121, and reduce the edge lithium precipitation effect caused by lithium ion migration and cycle accumulation.

[0065] Optionally, the sheet diameter of the graphene of the first conductive agent is D1, which satisfies: 7μm≤D1≤15μm.

[0066] Optionally, the sheet diameter D1 of the graphene of the first conductive agent satisfies: 9 μm≤D1≤13 μm.

[0067] Optionally, the value of D1 may be 7 μm, 10 μm, 12 μm, 13 μm, etc., without specific limitation.

[0068] By setting the sheet diameter D1 of the graphene of the first conductive agent to satisfy 7μm≤D1≤15μm, the first conductive agent is graphene, and the sheet diameter of the graphene is relatively large, the lithium insertion and extraction activity of the first region 121 can be reduced, and the edge lithium precipitation effect caused by lithium ion migration and cycle accumulation can be reduced.

[0069] Optionally, the second conductive agent is any one or a combination of single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon black and graphene. When the second conductive agent includes graphene, the sheet diameter of the graphene of the second conductive agent is smaller than the sheet diameter of the graphene of the first conductive agent.

[0070] Optionally, the second conductive agent is any one of single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT), carbon black and graphene; or, the second conductive agent is a combination of any multiple of single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT), carbon black and graphene, and the specific proportion is not limited.

[0071] Optionally, the components of the second region 122 include, in addition to the second conductive agent, negative electrode materials, binders, etc. The amount of the second conductive agent added may be the same as or different from the amount of the first conductive agent added, and there is no specific limitation.

[0072] By setting the components of the second region 122 to include a second conductive agent, the second conductive agent is any one or a combination of multiple of single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon black and graphene. The second conductive agent will not affect the normal insertion and extraction of lithium ions in the second region 122, and can also improve the conductivity of the second region 122.

[0073] Optionally, the second conductive agent includes graphene, and the sheet diameter of the graphene in the second conductive agent is D2, satisfying: 0.5 μm≤D2≤3 μm.

[0074] Optionally, the sheet diameter D2 of the graphene of the second conductive agent satisfies: 1 μm≤D2≤2.5 μm.

[0075] Optionally, the value of D2 may be 1 μm, 1.2 μm, 1.5 μm, 2 μm, etc., without specific limitation.

[0076] Optionally, the second conductive agent may include only graphene; or, in addition to graphene, the second conductive agent may include any one or a combination of multiple single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs) and carbon black, without specific limitation.

[0077] By setting the second conductive agent to include graphene, the flake diameter D2 of the graphene in the second conductive agent satisfies 0.5μm≤D2≤3μm. The flake diameter of the graphene in the second conductive agent is small, which will not affect the lithium insertion and extraction activity of the second region 122, and can also improve the conductivity of the second region 122.

[0078] Optional, such as Figure 2 As shown, the first area 121 includes a second edge 123 close to the first edge 111 in the first direction X. In the first direction X, the distance from the first edge 111 to the second edge 123 is a first distance A1, which satisfies: 0 mm ≤ A1 ≤ 2 mm.

[0079] Optionally, the negative electrode current collector 11 may be rectangular, trapezoidal, parallelogram, etc., without limitation.

[0080] Optionally, the shape of the negative electrode active material layer 12 corresponds to that of the negative electrode current collector 11 , and the stacking thickness of the first region 121 and the second region 122 on the negative electrode current collector 11 is the same.

[0081] For example, Figure 3 As shown, the negative electrode current collector 11 , the first region 121 , and the second region 122 are all rectangular.

[0082] Optionally, in the first direction X, the size of the first region 121 is smaller than the size of the second region 122. In this way, while reducing the lithium insertion and extraction activity at the edge of the negative electrode sheet 10 and reducing the edge lithium precipitation effect caused by lithium ion migration and cycle accumulation, the normal insertion and extraction of lithium ions in the second region 122 is less affected, and the battery has better cycle performance.

[0083] Optionally, when the first distance A1 from the first edge 111 to the second edge 123 is zero, the first edge 111 and the second edge 123 overlap, that is, the first region 121 is arranged from the first edge 111 of the negative electrode current collector 11 to the other side of the negative electrode current collector 11 .

[0084] Optionally, when the first distance A1 from the first edge 111 to the second edge 123 satisfies: 0 mm<A1≤2 mm, there is a gap between the second edge 123 and the first edge 111 to facilitate multiple coatings.

[0085] By setting the first area 121 to include the second edge 123 close to the first edge 111 in the first direction X, a first distance A1 from the first edge 111 to the second edge 123 in the first direction X satisfies: 0 mm ≤ A1 ≤ 2 mm, which facilitates processing.

[0086] Optional, such as Figure 2 As shown, the negative electrode current collector 11 includes a first edge 111, and the first region 121 includes a second edge 123 and a third edge 124 opposite to each other in the first direction X, the second edge 123 is close to the first edge 111, and the third edge 124 is connected to the second region 122. In the first direction X, the distance from the second edge 123 to the third edge 124 is a second distance B1, satisfying: 1mm≤B1≤10mm.

[0087] Optionally, the second distance B1 from the second edge 123 to the third edge 124 satisfies: 3 mm ≤ B1 ≤ 7 mm.

[0088] Optionally, the value of B1 can be 3mm, 5mm, 6mm, 7mm, etc., without specific limitation.

[0089] By setting the first region 121 to include a second edge 123 and a third edge 124 opposite to each other in the first direction X, a second distance B1 from the second edge 123 to the third edge 124 satisfies 1mm≤B1≤10mm, and the lithium insertion and extraction activity of the first region 121 is relatively low, which can reduce the edge lithium precipitation effect caused by lithium ion migration and cycle accumulation. The coating area of ​​the first region 121 is appropriate, and while effectively reducing the lithium insertion and extraction activity of the edge of the negative electrode sheet 10, the good conductive performance of the negative electrode sheet 10 is still maintained.

[0090] Optional, such as Figure 2 As shown, the negative electrode active material layer 12 further includes a third region 125, which is located on the side of the second region 122 facing away from the first region 121 in the first direction X. The components of the third region 125 include a third conductive agent, which is graphene. The ability of the third conductive agent to deintercalate lithium ions is less than that of the second conductive agent to deintercalate lithium ions.

[0091] Optionally, the third region 125 is rectangular, and the area of ​​the third region 125 is the same as the area of ​​the first region 121 .

[0092] Optionally, the third region 125 and the second region 122 are connected in the first direction X, or the third region 125 and the second region 122 are spaced apart in the first direction X, which is not specifically limited.

[0093] By setting the negative electrode active material layer 12 to also include a third region 125 located on the side of the second region 122 facing away from the first region 121, the components of the third region 125 include a third conductive agent, the third conductive agent is graphene, and the ability of the third conductive agent to deintercalate lithium ions is less than the ability of the second conductive agent to deintercalate lithium ions, the lithium intercalation and deintercalation activity of the negative electrode edge can be reduced, and the edge lithium precipitation effect caused by lithium ion migration and cycle accumulation can be reduced.

[0094] Optionally, the sheet diameter of the graphene of the third conductive agent is D3, satisfying: 7 μm≤D3≤15 μm.

[0095] Optionally, a sheet diameter D3 of the graphene of the third conductive agent satisfies: 9 μm≤D3≤13 μm.

[0096] Optionally, the value of D3 may be 7 μm, 10 μm, 12 μm, 13 μm, etc., without specific limitation.

[0097] Optionally, the diameter D3 of the graphene sheet of the third conductive agent may be the same as or different from the diameter D1 of the graphene sheet of the first conductive agent, and there is no specific limitation thereto.

[0098] By setting the sheet diameter D3 of the graphene of the third conductive agent to satisfy 7μm≤D3≤15μm, the third conductive agent is graphene, and the sheet diameter of the graphene is relatively large, the lithium insertion and extraction activity of the third region 125 can be reduced, and the edge lithium precipitation effect caused by lithium ion migration and cycle accumulation can be reduced.

[0099] Optional, such as Figure 2 As shown, the negative electrode current collector 11 also includes a fourth edge 112 opposite to the first edge 111 in the first direction X, and the third region 125 includes a fifth edge 126 close to the fourth edge 112 in the first direction X. In the first direction X, a third distance from the fourth edge 112 to the fifth edge 126 is A2, satisfying: 0mm≤A2≤2mm.

[0100] Optionally, the fourth edge 112 may be connected to a negative electrode tab. In one embodiment, the negative electrode sheet 10 includes two negative electrode tabs, which are respectively connected to the first edge 111 and the third edge 124. The tabs may be half tabs or full tabs, without limitation.

[0101] Optionally, the third region 125 is also rectangular, and the stacking thickness of the third region 125, the first region 121 and the second region 122 on the negative electrode current collector 11 is the same.

[0102] Optionally, when the third distance A2 from the fifth edge 126 to the fourth edge 112 is zero, the fourth edge 112 and the fifth edge 126 overlap, that is, the third region 125 is arranged from the fourth edge 112 to the first edge 111 of the negative electrode current collector 11 .

[0103] Optionally, when the third distance A2 from the fifth edge 126 to the fourth edge 112 satisfies: 0 mm<A2≤2 mm, there is a gap between the fourth edge 112 and the fifth edge 126 to facilitate multiple coatings.

[0104] By setting the negative electrode current collector 11 to also include a fourth edge 112 opposite to the first edge 111 in the first direction X, the third region 125 includes a fifth edge 126 close to the fourth edge 112, and in the first direction X, a third distance A2 from the fourth edge 112 to the fifth edge 126 satisfies: 0mm≤A2≤2mm, which facilitates processing.

[0105] Optional, such as Figure 2 As shown, the negative electrode current collector 11 also includes a fourth edge 112 opposite to the first edge 111 in the first direction X, and the third region 125 includes a fifth edge 126 and a sixth edge 127 opposite to each other in the first direction X, the fifth edge 126 is close to the fourth edge 112, and the sixth edge 127 is connected to the second region 122. In the first direction X, a fourth distance from the fifth edge 126 to the sixth edge 127 is B2, satisfying: 1mm≤B2≤10mm.

[0106] Optionally, a fourth distance B2 from the fifth edge 126 to the sixth edge 127 satisfies: 3 mm ≤ B2 ≤ 7 mm.

[0107] Optionally, the value of B2 can be 3mm, 5mm, 6mm, 7mm, etc., without specific limitation.

[0108] Optionally, the second distance B1 from the second edge 123 to the third edge 124 and the fourth distance B2 from the fifth edge 126 to the sixth edge 127 may be the same or different, and there is no specific limitation thereto.

[0109] By setting the negative electrode current collector 11 to also include a fourth edge 112 opposite to the first edge 111 in the first direction X, the third region 125 includes a fifth edge 126 close to the fourth edge 112 in the first direction X and a sixth edge 127 connected to the second region 122, and in the first direction X, a fourth distance B2 from the fifth edge 126 to the sixth edge 127 satisfies: 1mm≤B2≤10mm, which can reduce the lithium insertion and extraction activity of the second region 122 and reduce the edge lithium precipitation effect caused by lithium ion migration and cycle accumulation. Optionally, as Figure 3As shown, the negative electrode current collector 11 also includes a seventh edge 113 adjacent to the first edge 111, and the negative electrode active material layer 12 also includes a fourth region 128. The fourth region 128 and the second region 122 are arranged in sequence in the second direction Y, and the fourth region 128 is closer to the seventh edge 113 than the second region 122. The second direction Y intersects with the first direction X. The fourth region 128 includes a fourth conductive agent, which is graphene, and the ability of the fourth conductive agent to deintercalate lithium ions is less than that of the second conductive agent to deintercalate lithium ions.

[0110] Optionally, the second direction Y is perpendicular to the first direction X.

[0111] Optionally, the fourth region 128 is a rectangle, and the area size of the fourth region 128 may be the same as or different from the area sizes of the first region 121 and the third region 125 , and there is no specific limitation thereto.

[0112] Optionally, the fourth region 128 and the second region 122 are connected in the second direction Y, or the fourth region 128 and the second region 122 are spaced apart in the second direction Y, which is not specifically limited.

[0113] Optionally, the negative electrode tab may also be connected to the seventh edge 113 .

[0114] By setting the negative electrode current collector 11 to also include a seventh edge 113 adjacent to the first edge 111, the negative electrode active material layer 12 also includes a fourth region 128 arranged in sequence with the second region 122 in the second direction Y, the components of the fourth region 128 include a fourth conductive agent, the fourth conductive agent is graphene, and the ability of the fourth conductive agent to deintercalate lithium ions is less than the ability of the second conductive agent to deintercalate lithium ions, so that the lithium intercalation and deintercalation activity of the fourth region 128 can be reduced, and the edge lithium precipitation effect caused by lithium ion migration and cycle accumulation can be reduced.

[0115] Optionally, the sheet diameter of the graphene of the fourth conductive agent is D4, which satisfies: 7 μm≤D4≤15 μm.

[0116] Optionally, the diameter D4 of the graphene sheet of the fourth conductive agent may be the same as or different from the diameter D1 of the graphene sheet of the first conductive agent, and there is no specific limitation thereto.

[0117] By setting the sheet diameter D4 of the graphene of the fourth conductive agent to satisfy 7μm≤D3≤15μm, the fourth conductive agent is graphene, and the sheet diameter of the graphene is relatively large, the lithium insertion and extraction activity of the fourth region 128 can be reduced, and the edge lithium precipitation effect caused by lithium ion migration and cycle accumulation can be reduced.

[0118] Similarly, the positional relationship between the fourth region 128 and the seventh edge 113 is similar to the positional relationship between the first region 121 and the first edge 111 described above, which can be referred to without further explanation.

[0119] Optional, such as Figure 3 As shown, the negative electrode active material layer 12 also includes a fifth region 129, which is located on the side of the second region 122 facing away from the fourth region 128 in the second direction Y. The composition of the fifth region 129 includes a fifth conductive agent, which is graphene. The fifth conductive agent is suitable for reducing the lithium insertion and extraction activity of the fifth region 129.

[0120] Optionally, the sheet diameter of the fifth conductive agent is similar to that of the aforementioned first conductive agent, and the configuration of the fifth region 129 is similar to that of the aforementioned fourth region 128, which can be referred to without further explanation.

[0121] Optionally, the negative electrode active material layer 12 includes the second region 122 , and any one or more of the first region 121 , the third region 125 , the fourth region 128 , and the fifth region 129 , without limitation.

[0122] In one embodiment, Figure 2 As shown, the negative electrode active material layer 12 includes a first region 121 , a second region 122 , a third region 125 , a fourth region 128 , and a fifth region 129 .

[0123] Optionally, the negative electrode sheet 10 includes an overlapping region and an overhang region, the overlapping region is suitable for overlapping with the positive electrode active material layer 22 of the positive electrode sheet 20 , and the overhang region includes at least a portion of the first region 121 .

[0124] Optional, such as Figure 1 As shown, the overhang area may include only the first area 121, or may include the first area 121 and part of the second area 122, and there is no specific limitation. In the first direction X, the size of the overhang area is a first size P, which satisfies: 1mm≤P≤3mm.

[0125] Optionally, the first size P may be 1 mm, 2 mm, 3 mm, etc., without limitation. The first size P of the overhang area is set to satisfy 1 mm ≤ P ≤ 3 mm, which can prevent lithium deposition on the negative electrode sheet 10 while ensuring the performance of the battery.

[0126] By configuring the negative electrode sheet 10 to include an overlapping area and an overhang area, the overhang area can prevent lithium deposition on the negative electrode sheet 10 , thereby improving the safety of the battery 100 .

[0127] Optionally, the present application also provides a method for preparing the negative electrode sheet 10, such as Figure 4 As shown, including:

[0128] Step S10, providing a negative electrode current collector 11, wherein the negative electrode current collector 11 includes a first edge 111;

[0129] In step S20, a negative electrode active material layer 12 is stacked on the negative electrode current collector 11, wherein the negative electrode active material layer 12 includes a first region 121 and a second region 122 arranged in sequence in a first direction X, wherein the first region 121 is closer to the first edge 111 than the second region 122, and a component of the first region 121 includes a first conductive agent, which is graphene, and is suitable for reducing the lithium insertion and extraction activity of the first region 121.

[0130] By arranging a stacked negative electrode current collector 11 and a negative electrode active material layer 12, the components of the first region 121 of the negative electrode active material layer 12 closer to the first edge 111 of the negative electrode current collector 11 include a first conductive agent, and the first conductive agent is graphene, which can reduce the lithium insertion and extraction activity of the first region 121 and reduce the edge lithium precipitation effect caused by lithium ion migration and cycle accumulation.

[0131] Optionally, a negative electrode active material layer 12 is stacked on the negative electrode current collector 11, further comprising:

[0132] The sheet diameter of the graphene of the first conductive agent is D1, which satisfies: 7 μm≤D1≤15 μm.

[0133] By setting the sheet diameter D1 of the graphene of the first conductive agent to satisfy 7μm≤D1≤15μm, the first conductive agent is graphene, and the sheet diameter of the graphene is relatively large, the lithium insertion and extraction activity of the first region 121 can be reduced, and the edge lithium precipitation effect caused by lithium ion migration and cycle accumulation can be reduced.

[0134] Optionally, a negative electrode active material layer 12 is stacked on the negative electrode current collector 11, further comprising:

[0135] The second region 122 includes a second conductive agent, which is any one or a combination of multiple of single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon black, and graphene.

[0136] By setting the components of the second region 122 to include a second conductive agent, the second conductive agent is any one or a combination of single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon black and graphene. The second conductive agent will not affect the lithium insertion and extraction activity of the second region 122, and can also improve the conductive performance of the second region 122.

[0137] The embodiment of the present application also provides a battery 100, including a positive electrode sheet 20 and the negative electrode sheet 10 in the embodiment of the present application or a negative electrode sheet 10 prepared by the preparation method of the negative electrode sheet 10 in the embodiment of the present application, and in the orthographic projection of the negative electrode sheet 10, the edge of the positive electrode active material layer 22 of the positive electrode sheet 20 falls in the first area 121.

[0138] The technical solution of the present invention is described in detail below through specific embodiments.

[0139] Example 1

[0140] This embodiment provides a negative electrode sheet, which includes a negative electrode current collector and a negative electrode active material layer, wherein the negative electrode current collector is copper foil, the negative electrode active material layer includes a first region and a second region, and the conductive agent in the first region is graphene.

[0141] The method for preparing the negative electrode sheet comprises the following steps:

[0142] (1) Ingredients: preparing a first slurry for forming the first region and a second slurry for forming the second region; each slurry comprises an active material, a conductive agent, a binder and a solvent, wherein the active material is lithium iron phosphate particles, and the binder is selected from polytetrafluoroethylene. The first conductive agent in the first slurry is graphene, and the sheet diameter of the graphene is 10 μm. The second conductive agent in the second slurry is single-walled carbon nanotubes and carbon black.

[0143] (2) Coating and layering: coating the first slurry and the second slurry on the surface of the copper foil respectively to form a connected first area and a second area, wherein the coating width of the first area is 4 mm (i.e., the size of the first area in the first direction X is 4 mm), and the negative electrode sheet is prepared by baking and rolling.

[0144] Example 2

[0145] The negative electrode sheet of this embodiment includes a negative electrode current collector, a first region and a second region. The difference between this embodiment and the first embodiment is that the sheet diameter of the graphene of the first conductive agent is 7 μm.

[0146] Example 3

[0147] The negative electrode sheet of this embodiment includes a negative electrode current collector, a first region and a second region. The difference between this embodiment and the first embodiment is that the sheet diameter of the graphene of the first conductive agent is 15 μm.

[0148] Example 4

[0149] The negative electrode sheet of this embodiment includes a negative electrode current collector, a first region and a second region. The difference between this embodiment and the first embodiment is that the first conductive agent is graphene, and the diameter of the graphene sheet is 3 μm.

[0150] Example 5

[0151] The negative electrode sheet of this embodiment includes a negative electrode current collector, a first region and a second region. The difference between this embodiment and the first embodiment is that the first conductive agent is graphene, and the diameter of the graphene sheet is 18 μm.

[0152] Example 6

[0153] The negative electrode sheet of this embodiment includes a negative electrode current collector, a first region and a second region. The difference between this embodiment and the embodiment 1 is that the coating width of the first region is 6 mm.

[0154] Example 7

[0155] The negative electrode sheet of this embodiment includes a negative electrode current collector, a first region and a second region. The difference between this embodiment and the embodiment 1 is that the coating width of the first region is 0.5 mm.

[0156] Example 8

[0157] The negative electrode sheet of this embodiment includes a negative electrode current collector, a first region and a second region. The difference between this embodiment and the embodiment 1 is that the coating width of the first region is 12 mm.

[0158] Example 9

[0159] The negative electrode sheet of this embodiment includes a negative electrode current collector, a first region and a second region. The preparation method of the negative electrode sheet includes the following steps:

[0160] (1) Ingredients: preparing a first slurry for forming the first region and a second slurry for forming the second region; each slurry comprises an active material, a conductive agent, a binder and a solvent, wherein the active material is lithium iron phosphate particles, and the binder is selected from polytetrafluoroethylene. The first conductive agent in the first slurry is graphene, and the sheet diameter of the graphene is 10 μm; the second conductive agent in the second slurry is single-walled carbon nanotubes, carbon black and graphene, and the sheet diameter of the graphene is 2 μm.

[0161] (2) Coating and layering: coating the first slurry and the second slurry on the surface of the copper foil respectively to form a first area and a second area connected to each other. The coating width of the first area is 4 mm. After baking and rolling, a negative electrode sheet is prepared.

[0162] Example 10

[0163] The negative electrode sheet of this embodiment includes a negative electrode current collector, a first region and a second region. The difference between this embodiment and embodiment 9 is that the second conductive agent in the second slurry is single-walled carbon nanotubes, carbon black and graphene, and the sheet diameter of the graphene is 0.4 μm.

[0164] Embodiment 11

[0165] The negative electrode sheet of this embodiment includes a negative electrode current collector, a first region and a second region. The difference between this embodiment and embodiment 9 is that the second conductive agent in the second slurry is single-walled carbon nanotubes, carbon black and graphene, and the sheet diameter of the graphene is 4 μm.

[0166] Example 12

[0167] The negative electrode sheet of this embodiment includes a negative electrode current collector, a first region, a second region and a third region. The preparation method of the negative electrode sheet includes the following steps:

[0168] (1) Ingredients: a first slurry for forming the first region, a second slurry for forming the second region, and a third slurry for forming the third region are respectively prepared; each slurry contains an active material, a conductive agent, a binder, and a solvent, wherein the active material is lithium iron phosphate particles, and the binder is selected from polytetrafluoroethylene. The first conductive agent in the first slurry is graphene, and the graphene sheet diameter is 10 μm. The second conductive agent in the second slurry is single-walled carbon nanotubes and carbon black. The third conductive agent in the third slurry is graphene, and the graphene sheet diameter is 10 μm.

[0169] (2) Coating and layering: coating the first slurry, the second slurry and the third slurry on the surface of the copper foil respectively to form a first region, a second region and a third region which are connected in sequence, and the coating width of the first region and the third region (i.e., the size of the first region and the third region in the first direction X) are both 4 mm. After baking and rolling, a negative electrode sheet is prepared.

[0170] Embodiment 13

[0171] The negative electrode sheet of this embodiment includes a negative electrode current collector, a first region, a second region and a third region. The difference between this embodiment and Embodiment 12 is that the coating width of the third region is 0.5 mm.

[0172] Embodiment 14

[0173] The negative electrode sheet of this embodiment includes a negative electrode current collector, a first region, a second region and a third region. The difference between this embodiment and Embodiment 12 is that the coating width of the third region is 12 mm.

[0174] Comparative Example 1

[0175] The negative electrode sheet of this embodiment includes a negative electrode current collector, a first region and a second region. The difference between this embodiment and the embodiment 1 is that the first conductive agent in the first slurry is single-walled carbon nanotubes and carbon black.

[0176] Comparative Example 2

[0177] The negative electrode sheet of this embodiment includes a negative electrode current collector, a first region and a second region. The difference between this embodiment and the first embodiment is that the second conductive agent in the second slurry is graphene, and the diameter of the graphene sheet is 10 μm.

[0178] The negative electrode sheets provided in the above-mentioned Examples 1 to 14 and the negative electrode sheets provided in Comparative Examples 1 to 2 are respectively assembled into batteries according to the following methods:

[0179] Positive electrode sheet: The positive electrode active material is evenly mixed with conductive carbon, binder, water, etc. to make positive electrode slurry, which is then coated on the positive electrode collector and dried and rolled to obtain the positive electrode sheet.

[0180] The positive electrode sheet, negative electrode sheet and separator prepared according to the above process are assembled into a soft-pack battery, and the electrolyte is injected to complete the battery assembly.

[0181] The electrochemical performance test of the battery assembled in the above battery embodiment was carried out under the following test conditions:

[0182] Charge to 3.8V at 0.33C, let stand for 30min, then discharge to 2.0V at 0.33C. The capacity of the first discharge cycle is Q1.

[0183] Capacity retention rate after 500 cycles: The above steps are repeated until the 500th cycle, and the capacity discharged at the 500th cycle is Q 500 , the capacity retention rate of 500 cycles is Q 500 / Q1.

[0184] Capacity retention rate after 1000 cycles: Follow the above steps to cycle 1000 times, and the discharge capacity of the 1000th cycle is Q 1000 , the capacity retention rate after 1000 cycles is Q 1000 / Q1.

[0185] Capacity retention rate after 1500 cycles: Follow the above steps to cycle 1500 cycles, and the discharge capacity at the 1500th cycle is Q 1500 , the capacity retention rate of 1500 cycles is Q 1500 / Q1.

[0186] The test results obtained according to the above test conditions are shown in Table 1 below:

[0187] Table 1

[0188]

[0189]

[0190] From the test results of Example 1 and Comparative Examples 1 to 2 in Table 1, it can be seen that the first conductive agent whose ability to deintercalate lithium ions is less than that of the second conductive agent at the edge of the negative electrode sheet can improve the capacity retention rate of the battery after 500 cycles, 1000 cycles and 1500 cycles. If the negative electrode sheet uses graphene of the same size as a conductive agent, it will affect the overall deintercalation performance of the negative electrode sheet, and the cycle performance of the battery is poor. Therefore, the first conductive agent is used in the first area close to the edge of the negative electrode sheet, and the second conductive agent is used in the second area, and the ability of the first conductive agent to deintercalate lithium ions is less than that of the second conductive agent to deintercalate lithium ions, which can reduce the lithium intercalation and deintercalation activity of the negative electrode edge, reduce the edge lithium precipitation effect caused by lithium ion migration and cycle accumulation, and improve the cycle performance of the battery.

[0191] It can be seen from the test results of Examples 1 to 5 in Table 1 that when the sheet diameter D1 of the graphene of the first conductive agent satisfies 7μm≤D1≤15μm, the effect of reducing the edge lithium precipitation effect is better, and the impact on the normal deintercalation of lithium ions is small, and the battery cycle performance is better.

[0192] It can be seen from the test results of Examples 6 to 8 in Table 1 that when the coating width of the first region, that is, the second distance B1 from the second edge to the third edge satisfies 1mm≤B1≤10mm, the coating area of ​​the first region 121 is appropriate, while effectively reducing the lithium insertion and extraction activity of the edge of the negative electrode sheet 10, the good conductive performance of the negative electrode sheet 10 is still maintained.

[0193] It can be seen from the test results of Examples 9 to 11 in Table 1 that when the component of the second conductive agent in the second region includes graphene and the sheet diameter D2 of the graphene of the second conductive agent satisfies 0.5μm≤D2≤3μm, since the sheet diameter of the graphene in the second conductive agent is small, it will not affect the normal insertion and extraction of lithium ions, and the battery has better cycle performance.

[0194] It can be seen from the test results of Examples 12 to 14 in Table 1 that the negative electrode sheet is also provided with a third region, and the graphene of the third conductive agent in the third region also adopts a larger sheet diameter to reduce the lithium insertion and extraction activity at the edge of the negative electrode, which can improve the cycle performance of the battery. When the coating width of the third region, that is, B2 satisfies 1mm≤B2≤10mm, the effect of reducing the edge lithium precipitation effect is better, and the influence on the normal extraction and insertion of lithium ions is small.

[0195] In the description of the embodiments of the present application, 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 application 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 application.

[0196] What is disclosed above is only a preferred embodiment of the present application, and it certainly cannot be used to limit the scope of rights of the present application. Ordinary technicians in this field can understand that all or part of the processes of implementing the above embodiment and equivalent changes made according to the claims of the present application are still within the scope covered by the present application.

Claims

1. A negative electrode sheet, characterized in that: include: a negative electrode current collector including a first edge; A negative electrode active material layer, stacked on the negative electrode current collector, the negative electrode active material layer comprising a first region and a second region arranged in sequence in a first direction, the first region being closer to the first edge than the second region, the first edge extending along a second direction, and the first direction intersecting the second direction; The first region includes a first conductive agent, which is graphene. The second region includes a second conductive agent, which has a lower ability to deintercalate lithium ions than the second conductive agent.

2. The negative electrode sheet according to claim 1, characterized in that: The sheet diameter of the graphene of the first conductive agent is D1, which satisfies: 7 μm≤D1≤15 μm.

3. The negative electrode sheet according to claim 1, characterized in that: The second conductive agent is any one or a combination of single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon black and graphene. When the second conductive agent includes graphene, the sheet diameter of the graphene of the second conductive agent is smaller than the sheet diameter of the graphene of the first conductive agent.

4. The negative electrode sheet according to claim 3, characterized in that: The second conductive agent includes graphene, and the sheet diameter of the graphene in the second conductive agent is D2, which satisfies: 0.5 μm≤D2≤3 μm.

5. The negative electrode sheet according to claim 1, characterized in that: In the first direction, a size of the first region is smaller than a size of the second region.

6. The negative electrode sheet according to any one of claims 1 to 5, characterized in that: The first region includes a second edge close to the first edge in the first direction. In the first direction, a distance from the first edge to the second edge is A1, satisfying: 0mm≤A1≤2mm.

7. The negative electrode sheet according to any one of claims 1 to 5, characterized in that: The first area includes a second edge and a third edge opposite to each other in a first direction, the second edge is close to the first edge, the third edge is connected to the second area, and in the first direction, a distance from the second edge to the third edge is B1, satisfying: 1mm≤B1≤10mm.

8. The negative electrode sheet according to any one of claims 1 to 5, characterized in that: The negative electrode active material layer also includes a third region, which is located on the side of the second region facing away from the first region in the first direction, and the components of the third region include a third conductive agent, which is graphene, and the ability of the third conductive agent to deintercalate lithium ions is less than that of the second conductive agent to deintercalate lithium ions.

9. The negative electrode sheet according to claim 8, characterized in that: The sheet diameter of the graphene of the third conductive agent is D3, which satisfies: 7 μm≤D3≤15 μm.

10. The negative electrode sheet according to claim 8, characterized in that: The negative electrode current collector also includes a fourth edge opposite to the first edge in the first direction, the third region includes a fifth edge and a sixth edge opposite to each other in the first direction, the fifth edge is close to the fourth edge, the sixth edge is connected to the second region, and in the first direction, the distance from the fifth edge to the sixth edge is B2, satisfying: 1mm≤B2≤10mm.

11. The negative electrode sheet according to any one of claims 1 to 5, characterized in that: The negative electrode current collector also includes a seventh edge adjacent to the first edge, the negative electrode active material layer also includes a fourth region, the fourth region and the second region are arranged sequentially in the second direction, and the fourth region is closer to the seventh edge than the second region, the fourth region includes a fourth conductive agent, the fourth conductive agent is graphene, and the ability of the fourth conductive agent to deintercalate lithium ions is less than the ability of the second conductive agent to deintercalate lithium ions.

12. The negative electrode sheet according to claim 1, characterized in that: The negative electrode sheet includes an overlap region and an overhang region, the overlap region is suitable for overlapping with the positive electrode active material layer of the positive electrode sheet, and the overhang region includes at least a portion of the first region.

13. The negative electrode sheet according to claim 12, characterized in that: The size of the overhang area in the first direction is P, satisfying: 1mm≤P≤3mm.

14. A battery, characterized in that: The invention comprises a positive electrode sheet and the negative electrode sheet as claimed in any one of claims 1 to 13, wherein in the orthographic projection of the negative electrode sheet, the edge of the positive electrode active material layer of the positive electrode sheet falls within the first region.

15. An electrical equipment, characterized in that: It comprises an electric device and the battery as claimed in claim 14, wherein the battery supplies power to the electric device.

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