Negative pole piece and lithium ion battery

Abstract

According to the negative pole piece and the lithium ion battery, in the negative pole piece, an active material layer is attached to the inner surface of a negative current collecting layer, and a heat conduction structure extending from the surface to the interior is built in the active material layer. The heat conduction structure comprises a heat conduction layer and heat conduction columns, the heat conduction layer is attached between the active material layer and the lithium supplementing layer, heat conduction holes are dug in the active material layer through laser, and the multiple heat conduction columns attached to the inner surface of the heat conduction layer are embedded into the corresponding heat conduction holes. Heat generated in the lithium supplementing process of the lithium supplementing layer is absorbed by the heat conduction layer and is conducted to the negative electrode current collection layer through the heat conduction column, so that a heat dissipation path extending from the surface of the pole piece to the interior is realized, and the problems of increase of by-products on the surface of the active material layer, demolding and powder falling of the pole piece and the like caused by heat generated in the lithium supplementing process of the negative electrode piece are solved; and the performance of the lithium ion battery is prevented from being influenced.

Description

Negative electrode sheet and lithium-ion battery

[0001] This application claims priority to the Chinese patent application filed on January 3, 2023, with application number 202310004330.7 and invention name “A negative electrode plate and lithium-ion battery”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of lithium-ion batteries, and in particular to a negative electrode sheet and a lithium-ion battery. Background Art

[0003] People's demand for thinner and lighter consumer products such as mobile phones and laptops, as well as longer battery life, is constantly increasing. The volumetric energy density (ED) of lithium-ion batteries is getting higher and higher. Improving the gram capacity of positive and negative electrode materials is an important measure to improve battery ED. Si materials are used as active materials for the negative electrode of batteries due to their high gram capacity, which can effectively improve the ED of battery cells. However, compared with graphite materials, Si materials not only consume more active lithium ions to form the surface SEI film, but the inactive substances in the Si materials also consume some lithium ions, which leads to a decrease in the first coulombic efficiency of the battery, which is lower than that of the graphite material system. Therefore, in order to improve the first coulombic efficiency of Si negative electrode batteries and give full play to the advantages of the high gram capacity of Si materials, it is usually necessary to carry out the process of replenishing lithium in the Si negative electrode.

[0004] Existing lithium replenishment methods include rolling replenishment and evaporation replenishment. However, the metallic lithium used in these methods for pre-replenishment is relatively active. When it comes into contact with the Si material, electrons spontaneously migrate to the Si negative electrode, resulting in high reactivity. As lithium ions embed into the Si negative electrode, a large amount of heat is released during this process. In addition, when the humidity in the lithium replenishment workshop is not adequately controlled, the metallic lithium is prone to side reactions with oxygen, nitrogen, and carbon dioxide in the air. These chemical reactions will lead to the release of a large amount of heat, resulting in excessive temperature rise on the electrode surface, causing the electrode to become too hot, resulting in the electrode peeling off, or even block delamination, etc., destroying the active material, leading to reduced lithium-ion battery performance and even low electrode quality rate.

[0005] Summary of the Invention

[0006] The present application provides a negative electrode plate and a lithium-ion battery to solve the problem that heat generated during the existing lithium replenishment process affects the performance of the lithium-ion battery.

[0007] In a first aspect, the present application provides a negative electrode plate, comprising: a negative current collecting layer; an active material layer, attached to the inner surface of the negative current collecting layer, a heat conduction hole being opened at the end of the active material layer away from the negative current collecting layer, and the length direction of the heat conduction hole extending toward the end close to the negative collecting layer; a heat conduction structure, comprising a heat conduction layer and a heat conduction column, the inner surface of the heat conduction layer is attached to the end of the active material layer away from the negative collecting layer, one end of the heat conduction column is attached to the inner surface of the heat conduction layer, and the other end of the heat conduction column is embedded in the heat conduction hole; a lithium replenishment layer, the lithium replenishment layer is attached to the outer surface of the heat conduction layer, and the lithium replenishment layer is obtained by performing a lithium replenishment process on a combination of the negative current collecting layer, the active material layer and the heat conduction structure; wherein the heat conduction layer is used to absorb heat generated in the lithium replenishment process and conduct the heat to the negative collecting layer through the heat conduction column, thereby achieving the effect of heat dissipation in the lithium replenishment process.

[0008] In this way, a heat-conducting structure extending from the surface to the interior is established in the negative electrode plate. The heat generated during the lithium replenishment process in the lithium replenishment layer is absorbed by the heat-conducting layer and conducted to the negative electrode current collecting layer through the heat-conducting column, thereby realizing a heat dissipation path extending from the surface of the plate to the interior. This solves the problems of increased by-products on the surface of the active material layer and pole plate delamination and powdering caused by the heat generated by the negative electrode plate during the lithium replenishment process, thereby avoiding affecting the performance of the lithium-ion battery.

[0009] In some embodiments of the present application, the end of the thermal via facing the negative electrode current collecting layer is spaced a first distance L1 from the inner surface of the negative electrode current collecting layer; and the thermally conductive pillar embedded in the thermal via is spaced a first distance L1 from the inner surface of the negative electrode current collecting layer. This creates a first heat dissipation path, whereby heat is conducted from the thermally conductive pillar and the active material layer between the thermally conductive pillar and the negative electrode current collecting layer to the negative electrode current collecting layer, thereby achieving a heat dissipation path extending from the electrode surface to the interior.

[0010] In some embodiments of the present application, thermal vias extend through the inner and outer surfaces of the active material layer; thermally conductive pillars embedded in the thermal vias connect between the thermally conductive layer and the negative electrode current collecting layer. This creates a second heat dissipation path, where heat is conducted from the thermally conductive pillars to the negative electrode current collecting layer, extending the heat dissipation path from the electrode surface to the interior.

[0011] In some embodiments of the present application, the number of thermal holes is the same as the number of thermal columns, and both are multiple; the size of the thermal holes is the same as the size of the thermal columns. In this way, ensuring a certain number of thermal holes and thermal columns can improve the heat dissipation effect.

[0012] In some embodiments of the present application, along the width direction of the negative electrode plate, the negative electrode plate has a plate width and a first number of thermal vias; along the length direction of the negative electrode plate, the negative electrode plate has a plate length and a second number of thermal vias; the plate width, the plate length, the first number, and the second number satisfy a first proportional relationship. This ensures a uniform distribution of the thermal vias, achieving an interlocking ratio and improving heat dissipation.

[0013] In some embodiments of the present application, the inner surface of the thermally conductive layer is provided with a plurality of thermally conductive pillars, each of which is perpendicular to the thermally conductive layer. This allows heat to be absorbed by the thermally conductive layer in contact with the lithium replenishment layer and then conducted perpendicularly to the negative electrode current collecting layer through the thermally conductive pillars, thereby dissipating heat.

[0014] In some embodiments of the present application, the thermally conductive layer has a first thickness, the thermally conductive pillars have a second thickness, and the active material layer has a third thickness. The first thickness and the third thickness satisfy a second proportional relationship, and the second thickness and the third thickness satisfy a third proportional relationship. This allows for a negative electrode with optimal proportions, which not only improves heat dissipation but also enhances lithium-ion battery performance.

[0015] In some embodiments of the present application, the lithium replenishment layer includes a plurality of lithium replenishment blocks arranged in a rectangular array. Adjacent lithium replenishment blocks are separated by a second distance L2, where 0 ≤ L2 ≤ 5 mm. This provides the lithium replenishment layer with a discontinuous surface, preventing the generation of byproducts during the lithium replenishment process. This improves heat dissipation while maintaining the performance of the lithium-ion battery.

[0016] In some embodiments of the present application, the active material layer includes a Si-graphite active material, and the thermally conductive structure includes a material selected from graphite, graphene, carbon nanotubes, or carbon fibers. Thus, the Si-graphite active material improves lithium-ion battery performance, while the graphite, graphene, carbon nanotubes, or carbon fibers enhance heat dissipation.

[0017] In the second aspect, the present application provides a lithium-ion battery comprising a battery cell, an electrolyte and a packaging film, wherein the battery cell and the electrolyte are both arranged in the packaging film; the battery cell comprises a positive electrode sheet, a diaphragm and the negative electrode sheet described in the first aspect, wherein the positive electrode sheet and the negative electrode sheet are separated by the diaphragm and arranged in a stacked state. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0019] FIG1 is a schematic structural diagram of a lithium-ion battery provided in an embodiment of the present application;

[0020] FIG2 is a cross-sectional view of a lithium-ion battery provided in an embodiment of the present application;

[0021] FIG3 is a schematic structural diagram of a first negative electrode sheet 30 provided in an embodiment of the present application;

[0022] FIG4 is a schematic structural diagram of a first negative electrode plate 30 provided in an embodiment of the present application in which a heat conducting hole 103 is provided;

[0023] FIG5 is a top view of a heat conducting hole 103 provided in an active material layer 102 according to an embodiment of the present application;

[0024] FIG6 is a schematic structural diagram of a second negative electrode plate 30 provided in an embodiment of the present application in which a heat conducting hole 103 is provided;

[0025] FIG7 is a schematic structural diagram of a second negative electrode plate 30 provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] The following will clearly describe the technical solutions in the embodiments of the present application in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, other embodiments obtained by ordinary technicians in this field without making any creative work are all within the scope of protection of this application.

[0027] Hereinafter, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified with "first," "second," etc., may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0028] In addition, in this application, directional terms such as "upper", "lower", "inner" and "outer" are defined relative to the orientation of the components in the drawings. It should be understood that these directional terms are relative concepts. They are used for relative description and clarification, and they can change accordingly according to changes in the orientation of the components in the drawings.

[0029] The electronic devices described in the embodiments of the present application include but are not limited to mobile phones, notebook computers, tablet computers, laptop computers, personal digital assistants, or wearable devices, etc. The following description will be made using a mobile phone as the electronic device.

[0030] As demand for thinner, lighter, and longer-lasting electronic devices like mobile phones and laptops continues to rise, the volumetric energy density (ED) of lithium-ion batteries is increasing. Improving the gram capacity of positive and negative electrode materials is a key measure to improve battery ED. Currently, the gram capacity of graphite materials is approaching its theoretical limit (372mAh / g), while the gram capacity of Si materials is much higher than that of graphite materials (theoretical limit is 4200mAh / g). Si materials also offer many advantages, including moderate lithium insertion and deintercalation potentials, abundant reserves, low price, environmental friendliness, and mature preparation processes. Therefore, replacing graphite with high-gram-capacity Si materials as the active material for the negative electrode of batteries can effectively improve the ED of battery cells.

[0031] However, Si materials have a huge volume effect during the lithium insertion and extraction process, and the volume change rate caused by expansion / contraction is as high as 400%. Compared with graphite materials, Si materials not only consume more active lithium ions to form the surface SEI film, but the inactive substances in the Si materials also consume some lithium ions, which in turn causes the battery's first coulombic efficiency to decrease, lower than that of the graphite material system. Therefore, in order to improve the first coulombic efficiency of Si negative electrode batteries and give full play to the advantages of Si materials' high gram capacity, it is usually necessary to add a Si negative electrode lithium replenishment process.

[0032] Existing lithium replenishment methods include rolling and evaporation, which form a lithium replenishment interface on the surface of the negative electrode and complete the lithium replenishment process at the lithium replenishment interface. However, the metallic lithium used in pre-lithium replenishment is extremely active and can react with oxygen, nitrogen, and carbon dioxide in the air, as well as rapidly with silicon materials. These chemical reactions result in the release of large amounts of heat, causing excessive temperature rise in the electrode. This can easily lead to electrode delamination after lithium replenishment, intensified active lithium side reactions, and even low electrode quality. In serious cases, this can cause safety accidents such as smoke and fire.

[0033] In order to reduce the impact of heat generated during the lithium replenishment process on battery performance, an embodiment of the present application provides a lithium-ion battery, which adds a heat-conducting structure to the high-gram capacity Si negative electrode plate to solve the problems of increased by-products on the surface of the active material layer and electrode delamination and powder loss caused by the high heat generated during the lithium replenishment process of the Si negative electrode plate, thereby improving battery performance.

[0034] FIG1 is a schematic structural diagram of a lithium-ion battery provided in an embodiment of the present application.

[0035] As shown in Figure 1, in some embodiments, a lithium-ion battery may include a battery cell, an electrolyte, and a packaging film 10. The packaging film 10 is a hollow shell, in which the battery cell and electrolyte are disposed. The battery cell is the energy storage component of a rechargeable battery. The electrolyte, a carrier for ion transport within the battery, is typically composed of a lithium salt and an organic solvent. The electrolyte conducts ions between the positive and negative electrodes of a lithium-ion battery and is essential for achieving the advantages of high voltage and high specific energy.

[0036] FIG2 is a cross-sectional view of a lithium-ion battery provided in an embodiment of the present application.

[0037] As shown in FIG2 , in some embodiments, a battery cell may include a positive electrode sheet 20, a separator 40, and a negative electrode sheet 30. When the battery cell adopts a laminated structure, the number of positive electrode sheets 20 and negative electrode sheets 30 can be multiple, and both the positive electrode sheets 20 and negative electrode sheets 30 can be thin and light flat structures. When the battery cell is formed by the laminated structure, multiple positive electrode sheets 20 and multiple negative electrode sheets 30 are separated by a separator 40, and the positive electrode sheets 20 and negative electrode sheets 30 are arranged alternately, that is, there is one negative electrode sheet 30 for every two adjacent positive electrode sheets 20, and there is one positive electrode sheet 20 for every two adjacent negative electrode sheets 30. The individual electrode sheets are stacked together, and the adjacent positive electrode sheets 20 and negative electrode sheets 30 are separated by a separator 40. The separator 40 separates the individual electrode sheets in a "z"-shaped structure and is housed in the packaging film 10 to obtain a battery cell in a laminated state. For example, the diaphragm 40 may be made of a porous polymer material.

[0038] The positive electrode tab 20 is connected to the positive electrode tab 50, and the negative electrode tab 30 is connected to the negative electrode tab 60. The number of positive electrode tabs 50 is the same as the number of positive electrode tabs 20, and the number of negative electrode tabs 60 is the same as the number of negative electrode tabs 30. The positive electrode tabs 50 and the negative electrode tabs 60 extend from the length direction of the packaging film 10.

[0039] In conjunction with the content shown in Figure 1, the lithium-ion battery has a width W0 and a length H0. The length direction of the chip is along the length H0 of the lithium-ion battery, and the width direction of the chip is along the width W0 of the lithium-ion battery. In other words, the length S of the negative electrode sheet 30 is h Along the length H0 of the lithium-ion battery, the width of the negative electrode sheet 30 is along the width W0 of the lithium-ion battery.

[0040] FIG3 is a schematic structural diagram of a first negative electrode plate 30 provided in an embodiment of the present application.

[0041] As shown in Figure 3, in some embodiments, the negative electrode plate 30 may include: a negative electrode current collector layer 101, an active material layer 102, a thermally conductive structure 104, and a lithium replenishment layer 105. The negative electrode current collector layer 101 serves as a carrier for the negative electrode coating layer, storing the negative electrode material to achieve conductivity. The active material layer 102 is used to improve the ED of the battery cell. The lithium replenishment layer 105 is obtained by performing a lithium replenishment process on the combination of the negative electrode current collector layer 101, the active material layer 102, and the thermally conductive structure 104. The thermally conductive structure 104 is used to dissipate heat during the lithium replenishment process.

[0042] The negative electrode current collecting layer 101 may adopt a flat plate structure. The negative electrode current collecting layer 101 is made of copper foil. It is understood that the two opposite surfaces of the copper foil are also coated with negative electrode active materials.

[0043] The active material layer 102 is attached to the inner surface of the negative electrode current collecting layer 101. The material of the active material layer 102 may include Si-graphite active material. The Si-graphite active material is made into a slurry, and the active material layer 102 is formed on the inner surface of the negative electrode current collecting layer 101 by injection molding. Exemplarily, the thickness h0 of the active material layer 102 can be 20-300μm, preferably 50-150μm. It should be noted that in order to achieve the performance of the lithium-ion battery, the active material layer 102 may also include a conductive network and a bonding network, which are not described here.

[0044] FIG4 is a schematic structural diagram of a first type of negative electrode plate 30 provided in an embodiment of the present application, in which a heat conducting hole 103 is provided.

[0045] As shown in Figure 4, in some embodiments, the outer surface of the active material layer 102 is the surface of the Si-graphite negative electrode layer, which is used to form the lithium replenishment layer 105 for the lithium replenishment process. The outer surface of the active material layer 102 is the end surface of the active material layer 102 away from the negative electrode current collecting layer 101.

[0046] To dissipate heat during the lithium replenishment process, a thermal via 103 is laser-processed between the lithium replenishment interface and the surface of the Si-graphite negative electrode layer on the end of the active material layer 102 away from the negative electrode current collecting layer 101. The length of the thermal via 103 extends toward the end closest to the negative electrode current collecting layer 101. In other words, the thermal via 103 is formed by an inward depression on the outer surface of the active material layer 102.

[0047] For example, the cross section of the heat conducting hole 103 is circular, and the diameter D of the heat conducting hole 103 is 103 It can be 5-200 μm.

[0048] FIG5 is a top view of a heat conducting hole 103 provided in the active material layer 102 according to an embodiment of the present application.

[0049] As shown in FIG5 , in some embodiments, to ensure heat dissipation, there are multiple thermal vias 103. The thermal vias 103 may be evenly distributed in the active material layer 102 to achieve an interlocking ratio.

[0050] Along the width direction of the negative electrode plate 30, the negative electrode plate 30 has a plate width S W , the number of the heat conducting holes 103 is a first value n; along the length direction of the negative electrode plate 30, the negative electrode plate 30 has a plate length S h , the number of the heat conducting holes 103 is the second value m. In order to achieve the interlocking ratio and ensure the heat dissipation effect, the width of the pole piece S W , Pole length S h , the first value n and the second value m satisfy a first proportional relationship.

[0051] Among them, the relationship formula of the first proportional relationship is: S W / (n+1)=S h / (m+1). Where n>10, m>10.

[0052] Referring again to FIG. 3 and FIG. 4 , in one implementation, the end position where the thermal via 103 extends into the active material layer 102 may be located in the middle of the thickness h0 of the active material layer 102. That is, the end of the thermal via 103 facing the negative electrode current collecting layer 101 is at a first distance L1 from the inner surface of the negative electrode current collecting layer 101. The thickness h of the thermal via 103 is 103 The sum of the distance L1 and the first distance L1 is the thickness h0 of the active material layer 102 .

[0053] To dissipate heat during the lithium replenishment process, a highly thermally conductive material is coated on the outer surfaces of the thermal holes 103 and the active material layer 102 to form a thermally conductive structure 104. Thus, the thermally conductive structure 104 includes a thermally conductive layer 1041 and thermally conductive pillars 1042. The thermally conductive layer 1041 and the thermally conductive pillars 1042 can be integrally formed to form the thermally conductive structure 104. The thermally conductive structure 104 is made of a highly thermally conductive material, exemplarily comprising graphite, graphene, carbon nanotubes, or carbon fibers.

[0054] The inner surface of the heat conductive layer 1041 is in contact with the end of the active material layer 102 away from the negative electrode current collecting layer 101 . In other words, the heat conductive layer 1041 is coated on the outer surface of the active material layer 102 .

[0055] One end of the thermally conductive pillar 1042 is attached to the inner surface of the thermally conductive layer 1041, and the other end of the thermally conductive pillar 1042 is embedded in the thermally conductive hole 103. The inner surface of the thermally conductive layer 1041 can be provided with multiple thermally conductive pillars 1042, each of which is perpendicular to the thermally conductive layer 1041. The number of thermally conductive holes 103 is the same as the number of thermally conductive pillars 1042, and both are multiple. The dimensions of the thermally conductive holes 103 and the dimensions of the thermally conductive pillars 1042 are the same. Then, the thermally conductive pillars 1042 embedded in the thermally conductive holes 103 are at a first distance L1 from the inner surface of the negative electrode current collecting layer 101.

[0056] The thickness h2 of the heat conducting column 1042 and the thickness h 103 The same, the diameter D of the heat conducting column 1042 1042 The diameter D of the heat conduction hole 103 103 The distance between two adjacent heat-conducting pillars 1042 is equal to the distance between two adjacent heat-conducting holes 103 , and the distance between two adjacent heat-conducting holes 103 can be defined by the surface area of ​​the active material layer 102 , the first value n, and the second value m.

[0057] To achieve optimal heat dissipation and battery performance, the thermal conductive layer 1041 has a first thickness h1, the thermal conductive column 1042 has a second thickness h2, and the active material layer 102 has a third thickness h0; the first thickness h1 and the third thickness h0 satisfy a second proportional relationship, and the second thickness h2 and the third thickness h0 satisfy a third proportional relationship.

[0058] Among them, the relationship formula of the second proportional relationship is:

[0059] For example, the first thickness h1 may be 0-50 μm, preferably 0-20 μm, the second thickness h2 may be 10-150 μm, preferably 20-70 μm, and the third thickness h0 may be 20-300 μm, preferably 50-150 μm.

[0060] During the lithium replenishment process on the first type of negative electrode plate 30, the lithium replenishment layer 105 is attached to the outer surface of the thermally conductive layer 1041. The lithium replenishment layer 105 is used for the lithium replenishment process. Heat generated during the lithium replenishment process is absorbed by the thermally conductive layer 1041 and conducted to the negative electrode current collecting layer 101 via the thermally conductive pillars 1042 and the active material layer 102 between the thermally conductive pillars 1042 and the negative electrode current collecting layer 101. This creates a heat dissipation path extending from the surface of the plate to the interior, resolving issues such as an increase in byproducts on the surface of the active material layer and plate delamination caused by heat generated during the lithium replenishment process.

[0061] In some embodiments, the lithium replenishment layer 105 can have a discontinuous surface. Thus, the lithium replenishment layer 105 includes a plurality of lithium replenishment blocks 1051 arranged in a rectangular array. A second distance L2 is defined between adjacent lithium replenishment blocks 1051, where 0 ≤ L2 ≤ 5 mm. This discontinuous surface prevents the generation of byproducts during the lithium replenishment process, improving heat dissipation while maintaining the performance of the lithium-ion battery.

[0062] In some embodiments, the second distance L2 may be set to 0, so that the lithium replenishing blocks 1051 are connected to each other, so that the lithium replenishing layer 105 can be a continuous surface.

[0063] ​The first negative electrode plate 30 provided in the embodiment of the present application has a heat-conducting structure 104 extending from the surface to the interior established in the negative electrode plate 30, and the heat-conducting layer 1041 is attached between the active material layer 102 and the lithium replenishing layer 105. Heat-conducting holes 103 are dug in the active material layer 102 by laser, and multiple heat-conducting columns 1042 attached to the inner surface of the heat-conducting layer 1041 are embedded in the corresponding heat-conducting holes 103. The heat-conducting columns 1042 have a first distance from the suspended end of the heat-conducting layer 1041 to the negative electrode current collecting layer 101. The heat generated during the lithium replenishment process in the lithium replenishment layer 105 is absorbed by the heat conductive layer 1041 and conducted to the negative electrode current collecting layer 101 through the heat conductive column 1042 and the active material layer 102 between the heat conductive column 1042 and the negative electrode current collecting layer 101, thereby realizing a heat dissipation path extending from the electrode surface to the interior, and solving the problems of increased by-products on the surface of the active material layer, electrode delamination and powder loss caused by the heat generated by the negative electrode 30 during the lithium replenishment process.

[0064] FIG6 is a schematic structural diagram of a second type of negative electrode plate 30 provided in an embodiment of the present application, in which a heat conducting hole 103 is provided.

[0065] As shown in FIG6 , in some embodiments, the structure of the second negative electrode plate 30 differs from that of the first negative electrode plate 30 in that the thickness of the heat conducting hole 103 (heat conducting column 1042 ) is different. Other structures may refer to the structural content of the first negative electrode plate 30 and will not be elaborated here.

[0066] In the second negative electrode sheet 30 , the thermal via 103 may terminate its extension into the active material layer 102 at the inner surface of the active material layer 102 . In this way, the thermal via 103 penetrates both the inner and outer surfaces of the active material layer 102 .

[0067] For example, the thickness h of the second type of heat conducting hole 103 is 103 It is the same as the thickness h0 of the active material layer 102 .

[0068] FIG7 is a schematic structural diagram of a second negative electrode plate 30 provided in an embodiment of the present application.

[0069] As shown in FIG7 , in some embodiments, the second type of thermal conductive column 1042 has the same size as the second type of thermal conductive hole 103 , and the thickness h2 of the thermal conductive column 1042 is the same as the thickness h0 of the active material layer 102 . In this way, the thermal conductive column 1042 embedded in the thermal conductive hole 103 is connected between the thermal conductive layer 1041 and the negative electrode current collecting layer 101 .

[0070] Thus, the second thickness h2 of the thermally conductive pillar 1042 and the third thickness h0 of the active material layer 102 satisfy the third proportional relationship: h2 / h0=1.

[0071] When the second type of negative electrode plate 30 is subjected to the lithium replenishment process, the lithium replenishment process performed on the outer surface of the lithium replenishment layer 105 generates heat. The heat is absorbed by the heat conductive layer 1041 and conducted to the negative electrode current collecting layer 101 through the heat conductive column 1042, thereby realizing a heat dissipation path extending from the surface of the plate to the interior, thereby solving the problems of increased by-products on the surface of the active material layer, and plate delamination and powdering caused by the heat generated by the negative electrode plate 30 during the lithium replenishment process.

[0072] The second negative electrode plate 30 provided in the embodiment of the present application has a heat-conducting structure 104 extending from the surface to the interior of the negative electrode plate 30. The heat-conducting layer 1041 is attached between the active material layer 102 and the lithium replenishment layer 105. Heat-conducting holes 103 are laser-drilled in the active material layer 102. The heat-conducting holes 103 are through-holes. A plurality of heat-conducting pillars 1042 attached to the inner surface of the heat-conducting layer 1041 are embedded in the corresponding heat-conducting holes 103. The heat-conducting pillars 1042 are connected between the heat-conducting layer 1041 and the negative electrode current collecting layer 101. The heat generated during the lithium replenishment process in the lithium replenishment layer 105 is absorbed by the heat-conducting layer 1041 and conducted to the negative electrode current collecting layer 101 through the heat-conducting pillars 1042, thereby realizing a heat dissipation path extending from the surface of the plate to the interior, thereby solving the problems of increased byproducts on the surface of the active material layer and plate delamination caused by the heat generated by the negative electrode plate 30 during the lithium replenishment process.

[0073] It should be noted that those skilled in the art will readily conceive of other embodiments of the present application after considering the specification and practicing the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered merely as exemplary, and the true scope and spirit of the present application are indicated by the following claims.

[0074] It should be understood that the present application is not limited to the exact structures described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A negative electrode plate, characterized in that: include: A negative electrode current collecting layer (101); An active material layer (102) is attached to the inner surface of the negative electrode current collecting layer (101), a heat conducting hole (103) is provided at an end of the active material layer (102) away from the negative electrode current collecting layer (101), and a length direction of the heat conducting hole (103) extends toward an end close to the negative electrode current collecting layer (101); A heat-conducting structure (104), comprising a heat-conducting layer (1041) and a heat-conducting column (1042), wherein the inner surface of the heat-conducting layer (1041) is bonded to an end of the active material layer (102) away from the negative electrode current collecting layer (101), one end of the heat-conducting column (1042) is bonded to the inner surface of the heat-conducting layer (1041), and the other end of the heat-conducting column (1042) is embedded in the heat-conducting hole (103); a lithium replenishing layer (105), the lithium replenishing layer (105) being attached to the outer surface of the heat-conducting layer (1041), the lithium replenishing layer (105) being obtained by subjecting the combination of the negative electrode current collecting layer (101), the active material layer (102) and the heat-conducting structure (104) to a lithium replenishing process; The heat-conducting layer (1041) is used to absorb the heat generated by the lithium replenishing process and conduct the heat to the negative electrode current collecting layer (101) through the heat-conducting column (1042), thereby achieving the effect of heat dissipation in the lithium replenishing process.

2. The negative electrode sheet according to claim 1, characterized in that: An end of the heat conducting hole (103) facing the negative electrode current collecting layer (101) is at a first distance L1 from the inner surface of the negative electrode current collecting layer (101); The heat-conducting column (1042) embedded in the heat-conducting hole (103) has the first distance L1 from the inner surface of the negative electrode current collecting layer (101).

3. The negative electrode sheet according to claim 1, characterized in that: The heat conducting hole (103) penetrates the inner and outer surfaces of the active material layer (102); The heat-conducting column (1042) embedded in the heat-conducting hole (103) is connected between the heat-conducting layer (1041) and the negative electrode current collecting layer (101).

4. The negative electrode sheet according to claim 2 or 3, characterized in that: The number of the heat-conducting holes (103) is the same as the number of the heat-conducting columns (1042), and both are multiple; The size of the heat-conducting hole (103) is the same as the size of the heat-conducting column (1042).

5. The negative electrode sheet according to claim 4, characterized in that: Along the width direction of the negative electrode plate, the negative electrode plate has a plate width, and the number of the heat conducting holes (103) is a first value; Along the length direction of the negative electrode plate, the negative electrode plate has a plate length, and the number of the heat conducting holes (103) is a second value; The pole piece width, pole piece length, first value and second value satisfy a first proportional relationship.

6. The negative electrode sheet according to claim 5, characterized in that: The inner surface of the heat-conducting layer (1041) is provided with a plurality of heat-conducting columns (1042), and the plurality of heat-conducting columns (1042) are all perpendicular to the heat-conducting layer (1041).

7. The negative electrode sheet according to claim 6, characterized in that: The heat-conducting layer (1041) has a first thickness, the heat-conducting column (1042) has a second thickness, and the active material layer (102) has a third thickness; The first thickness and the third thickness satisfy a second proportional relationship, and the second thickness and the third thickness satisfy a third proportional relationship.

8. The negative electrode sheet according to any one of claims 1 to 7, characterized in that: The lithium replenishing layer (105) includes a plurality of lithium replenishing blocks (1051) distributed in a rectangular array; There is a second distance L2 between two adjacent lithium replenishing blocks (1051), wherein 0≤L2≤5mm.

9. The negative electrode sheet according to claim 8, characterized in that: The material of the active material layer (102) includes Si-graphite active material; The material of the heat-conducting structure (104) includes one of graphite, graphene, carbon tube or carbon fiber.

10. A lithium ion battery, characterized in that: It comprises a battery core, an electrolyte and a packaging film (10), wherein the battery core and the electrolyte are both arranged in the packaging film (10); The battery cell comprises a positive electrode sheet (20), a separator (40) and a negative electrode sheet (30) according to any one of claims 1 to 9, wherein the positive electrode sheet (20) and the negative electrode sheet (30) are separated by the separator (40) and are arranged in a stacked state.

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