Pole piece, manufacturing method of active material layer, battery and electric equipment

Abstract

The invention discloses a pole piece, a manufacturing method of an active substance layer, a battery and electric equipment. The first active substance layer is arranged between the current collector and the second active substance layer, the first active substance layer comprises a silicon-based material, the second active substance layer comprises a lithium supplement agent, and the first active substance layer and the second active substance layer both comprise active substances. Therefore, the silicon-based material is doped in the first active material layer, and the first active material layer is arranged between the current collector and the second active material layer, so that expansion of the first active material layer can be restrained and limited through the current collector and the second active material layer, and improvement of the first efficiency of the battery is facilitated; the first active material layer and the second active material layer both comprise active materials, the fast charging performance and the energy density of the battery can be improved, in addition, the second active material layer comprises the lithium supplementing agent, the first efficiency of the battery can be remarkably improved, vacancies are generated after the lithium supplementing agent reacts, electrolyte infiltration is facilitated, and the fast charging performance of the battery can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a method for manufacturing a pole piece and an active material layer, a battery and an electrical device. Background Art

[0002] In related technologies, it is difficult to further improve the energy density, fast charging and other performance of traditional liquid battery cells through iterative systems and optimized process solutions. The theoretical specific capacity of silicon material is as high as 4200mAh / g, which has obvious advantages in improving the energy density, fast charging and other performance of battery cells. However, the silicon-doped negative electrode material will expand in volume during the process of lithium insertion and extraction, causing the SEI film to continuously break and re-form, resulting in low initial efficiency. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide a pole piece having the advantages of high first efficiency, high capacity density, excellent fast charging performance, etc.

[0004] The invention also provides a method for manufacturing an active material layer.

[0005] The present invention also provides a battery having the pole piece.

[0006] The present invention also provides an electrical device having the battery.

[0007] According to an embodiment of the present invention, the pole piece includes: a current collector, a first active material layer and a second active material layer, along the thickness direction of the pole piece, the first active material layer is arranged between the current collector and the second active material layer; the first active material layer includes a silicon-based material, the second active material layer includes a lithium supplement, and the first active material layer and the second active material layer both include active materials.

[0008] According to the pole piece of the embodiment of the present invention, in the above embodiment, by doping the first active material layer with silicon-based materials and providing the first active material layer between the current collector and the second active material layer, the expansion of the first active material layer can be constrained and limited by the current collector and the second active material layer, which is beneficial to improving the first efficiency of the battery. In addition, by making the second active material layer include a lithium supplement, the first efficiency of the battery can be significantly improved. After the lithium supplement reacts, vacancies are generated, which are beneficial to the infiltration of the electrolyte, and the fast charging performance of the battery can be improved.

[0009] In an embodiment of the present invention, based on the total mass of the first active material layer being 100 wt %, the content of the silicon-based material is A, satisfying the relationship: 0.1 wt % ≤ A ≤ 10 wt %.

[0010] In an embodiment of the present invention, based on the total mass of the second active material layer being 100 wt %, the content of the lithium supplement is B, satisfying the relationship: 0.1 wt % ≤ B ≤ 0.9 wt %.

[0011] In an embodiment of the present invention, the silicon-based material includes at least one of silicon alloy, silicon carbon, silicon oxygen, and silicon particles.

[0012] In an embodiment of the present invention, the lithium supplement comprises at least one of metal lithium powder, stable metal lithium balls, lithium alloys, and lithium sulfide.

[0013] In an embodiment of the present invention, the first active material layer and / or the second active material layer further includes: a binder, and the binder is a high molecular polymer.

[0014] In an embodiment of the present invention, the active material includes: at least one of graphite, silicon, hard carbon, soft carbon, silicon carbon, tin, and lithium titanate, and the graphite includes artificial graphite and / or natural graphite; the binder includes: at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyethyleneimine, polyaniline, polyacrylic acid, sodium alginate, styrene-butadiene rubber, sodium carboxymethyl cellulose, phenolic resin, and epoxy resin.

[0015] In an embodiment of the present invention, the first active material layer and / or the second active material layer further comprises: a conductive agent, wherein the conductive agent comprises: at least one of conductive carbon black, KS-6, acetylene black, Ketjen black, conductive fiber, graphene, conductive graphite, graphene oxide, and carbon nanotubes.

[0016] According to the manufacturing method of the active material layer of an embodiment of the present invention, the active material layer includes a first active material layer and a second active material layer, and the manufacturing method includes: mixing a silicon-based material, an active material, a binder, and a solvent, and coating the mixed materials to obtain the first active material layer; mixing a lithium supplement, an active material, and a binder and then fiberizing them, and obtaining the second active material layer through a dry electrode process; and coating the second active material layer on the first active material layer.

[0017] The battery according to an embodiment of the present invention includes an electrode assembly, which includes: a positive electrode sheet, a negative electrode sheet and a separator, the negative electrode sheet is the above-mentioned electrode sheet, and the positive electrode sheet, the separator and the negative electrode sheet are assembled together to form the electrode assembly.

[0018] An electric device according to an embodiment of the present invention includes the above-mentioned battery.

[0019] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0021] Figure 1 is a schematic diagram of a pole piece according to an embodiment of the present invention;

[0022] Figure 2 is a schematic diagram of an electrode after electrolyte is injected according to an embodiment of the present invention;

[0023] Figure 3 is a schematic diagram of a pole piece surface formed after injecting electrolyte according to an embodiment of the present invention;

[0024] Figure 4 is a flow chart of a method for manufacturing an active material layer according to an embodiment of the present invention.

[0025] Reference numerals:

[0026] current collector 1;

[0027] First active material layer 2; silicon-based material 21;

[0028] Second active material layer 3; lithium supplement 31; micropores 32;

[0029] Active substance 4;

[0030] Pole piece 100. DETAILED DESCRIPTION

[0031] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0032] Reference below Figure 1-Figure 4 The pole piece 100, the method for manufacturing the active material layer, the battery and the electric device according to the embodiment of the present invention are described.

[0033] like Figure 1 and Figure 2 As shown, the pole piece 100 according to an embodiment of the present invention includes: a current collector 1, a first active material layer 2 and a second active material layer 3. Along the thickness direction of the pole piece 100, the first active material layer 2 is arranged between the current collector 1 and the second active material layer 3. The first active material layer 2 includes a silicon-based material 21, the second active material layer 3 includes a lithium supplement 31, and the first active material layer 2 and the second active material layer 3 both include an active material 4.

[0034] Among them, Figure 1As shown, the electrode 100 includes a current collector 1, a first active material layer 2 and a second active material layer 3. Figure 1 The first active material layer 2 is disposed between the current collector 1 and the second active material layer 3. That is, the second active material layer 3 is disposed on the side of the first active material layer 2 away from the current collector 1. As some embodiments of the present application, along the thickness direction of the electrode sheet 100 (such as Figure 1 In the Z direction shown in the figure, first active material layers 2 are arranged on both sides of the current collector 1, and second active material layers 3 are arranged on the sides of the two first active material layers 2 facing away from the current collector 1.

[0035] Both the first active material layer 2 and the second active material layer 3 may include active material 4, which may participate in the electrochemical reaction of the battery to generate current and form a circuit. The first active material layer 2 and the second active material layer 3 may both include active material 4, which may improve the charge and discharge performance and energy density of the battery.

[0036] like Figure 1 and Figure 2 As shown, the first active material layer 2 includes a silicon-based material 21. Doping the first active material layer 2 with the silicon-based material 21 can effectively increase the energy density and fast charging performance of the battery cell. The first active material layer 2 doped with the silicon-based material 21 is arranged between the current collector 1 and the second active material layer 3, which can effectively reduce the expansion amplitude of the first active material layer 2 during the cycle. The first active material layer 2 can be made by a wet method. The required materials for making the first active material layer 2 including the silicon-based material 21 and the active material 4 can be added to a mixing tank. After mixing, the first active material layer 2 can be obtained by coating and rolling.

[0037] like Figure 1 As shown, the second active material layer 3 includes a lithium supplement agent 31, and the second active material layer 3 can be made by a dry process. The required materials for making the second active material layer 3 including the lithium supplement agent 31 and the active material 4 can be mixed and fiberized, and a film is formed by a dry electrode manufacturing process, and then the second active material layer 3 is covered with the first active material layer 2 by a pressing transfer method to form an electrode 100 with a double active material layer. The dry process does not require the use of solvents, which can reduce the risk of danger to the lithium supplement agent 31 during the process manufacturing process.

[0038] The lithium supplement 31 can participate in the formation of SEI film (Solid Electrolyte Interface membrane) in the second active material layer 3. After the electrolyte is injected, the electrolyte can contact the lithium supplement 31 and electrochemically pre-lithiate. Electrochemical pre-lithiation can improve the initial efficiency of the battery. The lithium supplement 31 participating in the reaction can generate vacancies at the location where the reaction occurs to form micropores 32, so that the second active material layer 3 has multiple micropores 32. The electrolyte can more fully infiltrate the second active material layer 3 through the multiple micropores 32 to increase the electrochemical reaction speed of the second active material layer 3, thereby improving the fast charging performance of the electrode 100. Figure 3 As shown, micropores 32 of the second active material layer 3 can be found through industrial CT characterization.

[0039] Furthermore, it should be emphasized that, in the present application, the lithium supplement agent 31 is mixed with the active material 4 and other materials to form the second active material layer 3, that is, the lithium supplement agent 31 is doped into the second active material layer 3, rather than being completely attached to the outer surface of the second active material layer 3. It is understandable that the lithium supplement agent 31 is relatively active and is prone to react with air or water molecules to cause danger. If the lithium supplement agent 31 is attached to the outer surface of the second active material layer 3, safety accidents are very likely to occur. The present application effectively reduces the probability of safety accidents by doping the lithium supplement agent 31 into the second active material layer 3.

[0040] In the above embodiment, by doping the first active material layer 2 with a silicon-based material 21 and providing the first active material layer 2 between the current collector 1 and the second active material layer 3, the expansion of the first active material layer 2 can be constrained and limited by the current collector 1 and the second active material layer 3, which is beneficial to improving the first efficiency of the battery. In addition, by making the first active material layer 2 and the second active material layer 3 both include active material 4, it is beneficial to improve the fast charging performance and energy density of the battery. In addition, by making the second active material layer 3 include a lithium supplementer 31, the first efficiency of the battery can be significantly improved. After the lithium supplementer 31 reacts, vacancies are generated, which are beneficial to the infiltration of the electrolyte, and the fast charging performance of the battery can be improved.

[0041] In the embodiment of the present invention, based on the total mass of the first active material layer 2 being 100 wt %, the content of the silicon-based material 21 is A, satisfying the relationship: 0.1 wt % ≤ A ≤ 10 wt %.

[0042] Among them, the content A of the silicon-based material 21 can satisfy the relationship: 0.1wt%≤A≤10wt%, that is, the content A of the silicon-based material 21 can be any value between 0.1wt% and 10wt%, for example, the content A of the silicon-based material 21 can be but not limited to 0.1wt%, 1wt%, 5wt%, 10wt%, etc. Such a setting can make the content A of the silicon-based material 21 reasonable, can effectively improve the energy density and fast charging performance of the battery cell, and will not cause excessive expansion of the first active material layer 2, which is conducive to reducing the influence of the expansion of the first active material layer 2 on the SEI film.

[0043] In the embodiment of the present invention, based on the total mass of the second active material layer 3 being 100 wt %, the content of the lithium supplement 31 is B, satisfying the relationship: 0.1 wt % ≤ B ≤ 0.9 wt %.

[0044] Among them, the content B of the lithium supplement agent 31 can satisfy the relationship: 0.1wt%≤A≤0.9wt%, that is, the content B of the lithium supplement agent 31 can be any value between 0.1wt% and 0.9wt%, for example, the content B of the lithium supplement agent 31 can be but not limited to 0.1wt%, 0.3wt%, 0.6wt%, 0.9wt%, etc. Such a setting can make the content B of the lithium supplement agent 31 reasonable, can effectively improve the first efficiency and fast charging performance of the battery, and will not make the content of the lithium supplement agent 31 too much, which can reduce the risk of lithium precipitation.

[0045] In the embodiment of the present invention, the silicon-based material 21 includes at least one of silicon alloy, silicon carbon, silicon oxygen, and silicon particles.

[0046] Among them, the silicon-based material 21 can include at least one of silicon alloy, silicon carbon, silicon oxygen, and silicon particles. For example, the silicon-based material 21 can include silicon alloy and silicon carbon, the silicon-based material 21 can also include silicon carbon and silicon oxygen, and the silicon-based material 21 can also include silicon alloy, silicon oxygen and silicon particles. In this way, the materials included in the silicon-based material 21 can be selected according to product requirements, which is beneficial to improving the selectivity of the silicon-based material 21, and by making the silicon-based material 21 include multiple materials at the same time, the charging and discharging performance of the battery can be improved.

[0047] In the embodiment of the present invention, the lithium supplement 31 includes at least one of metal lithium powder, stable metal lithium balls, lithium alloy, and lithium sulfide.

[0048] Among them, the lithium supplement agent 31 can include at least one of silicon metal lithium powder, stable metal lithium balls, lithium alloys, and lithium sulfide. For example, the lithium supplement agent 31 can include silicon metal lithium powder and stable metal lithium balls. The lithium supplement agent 31 can also include stable metal lithium balls and lithium alloys. The lithium supplement agent 31 can also include metal lithium powder, lithium alloys, and lithium sulfide. In this way, the materials included in the lithium supplement agent 31 can be selected according to product requirements, which is beneficial to improving the selectivity of the lithium supplement agent 31. In addition, by making the lithium supplement agent 31 include multiple materials at the same time, the battery initial efficiency can be significantly improved. The vacancies generated after the lithium supplement agent 31 reacts are conducive to the infiltration of the electrolyte, which can improve the fast charging performance of the battery.

[0049] In the embodiment of the present invention, the first active material layer 2 and / or the second active material layer 3 further includes: a binder, and the binder is a high molecular polymer.

[0050] Among them, the first active material layer 2 may include a binder, or the second active material layer 3 may include a binder, or both the first active material layer 2 and the second active material layer 3 may include a binder. The binder can be used to bond the first active material layer 2 and the second active material layer 3, the first active material layer 2 and the current collector 1, which can improve the bonding stability between the first active material layer 2 and the second active material layer 3, the first active material layer 2 and the current collector 1, and can reduce the risk of separation between the first active material layer 2 and the second active material layer 3, and the first active material layer 2 and the current collector 1, which can improve the yield rate and the reliability of the electrode 100. In addition, better bonding force can reduce the resistance of the electrode 100, which is beneficial to improving the fast charging and power performance of the battery.

[0051] In an embodiment of the present invention, the active material 4 includes: at least one of graphite, silicon, hard carbon, soft carbon, silicon carbon, tin, and lithium titanate, the graphite includes artificial graphite and / or natural graphite, and the binder includes: at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyethyleneimine, polyaniline, polyacrylic acid, sodium alginate, styrene-butadiene rubber, sodium carboxymethyl cellulose, phenolic resin, and epoxy resin.

[0052] Among them, the active material 4 may include: at least one of graphite, silicon, hard carbon, soft carbon, silicon carbon, tin, and lithium titanate, that is, the pole piece 100 is constructed as a negative pole piece, for example: the active material 4 may include graphite, silicon, hard carbon, or the active material 4 may also include soft carbon, silicon carbon, tin, lithium titanate, or the active material 4 may also include graphite, tin, and lithium titanate. The materials included in the active material 4 can be selected according to the needs of the product to improve the selectivity of the active material 4, and by making the active material 4 include a variety of materials, it is beneficial to improve the charge and discharge performance of the battery. In addition, by constructing the pole piece 100 proposed in the present application as a negative pole piece, the problem of active lithium loss caused by the SEI film formed during the charge and discharge process can be effectively solved, so that the high capacity advantage of the pole piece 100 with the addition of silicon-based material 21 can be fully utilized.

[0053] Graphite may include artificial graphite and / or natural graphite. Natural graphite can make the active material 4 have good high temperature resistance, electrical conductivity, chemical stability, and environmental protection. Artificial graphite can make the active material 4 have good electrical conductivity, long cycle life, safety, and wide applicability.

[0054] The binder may include at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyethylene imine, polyaniline, polyacrylic acid, sodium alginate, styrene-butadiene rubber, sodium carboxymethyl cellulose, phenolic resin, and epoxy resin. For example, the binder may include polyvinylidene fluoride, polytetrafluoroethylene, and polyethylene imine. The binder may also include polyaniline, polyacrylic acid, and sodium alginate. In this way, the materials included in the binder can be selected according to the requirements of the product, which is beneficial to improving the selectivity of the binder. In addition, by making the binder include multiple materials at the same time, the bonding stability can be improved.

[0055] In an embodiment of the present invention, the first active material layer 2 and / or the second active material layer 3 further include: a conductive agent, the conductive agent including: at least one of conductive carbon black, KS-6, acetylene black, Ketjen black, conductive fiber, graphene, conductive graphite, graphene oxide, and carbon nanotubes.

[0056] Among them, the first active material layer 2 may include a conductive agent, or the second active material layer 3 may include a conductive agent, or both the first active material layer 2 and the second active material layer 3 may include a conductive agent, and the conductive agent may include at least one of conductive carbon black, KS-6, acetylene black, Ketjen black, conductive fiber, graphene, conductive graphite, graphene oxide, and carbon nanotubes. For example, the conductive agent may include conductive carbon black, KS-6 and acetylene black, and the conductive agent may also include conductive carbon black, Ketjen black, conductive fiber and graphene. The conductive agent may also include acetylene black, conductive graphite, graphene oxide and carbon nanotubes. In this way, the materials included in the conductive agent can be selected according to the needs of the product, which is conducive to improving the selectivity of the conductive agent. In addition, by making the conductive agent include multiple materials at the same time, the charge and discharge performance of the battery can be improved.

[0057] Reference below Figure 4 A method for manufacturing an active material layer according to an embodiment of the present invention is described in detail. The active material layer includes a first active material layer and a second active material layer.

[0058] Among them, along the thickness direction of the electrode (such as Figure 1 In some embodiments of the present application, along the thickness direction of the pole piece (the Z direction as shown in the figure), the first active material layer is disposed between the current collector and the second active material layer, that is, the second active material layer is disposed on the side of the first active material layer away from the current collector. In some embodiments of the present application, along the thickness direction of the pole piece (the Z direction as shown in the figure), the first active material layer is disposed on both sides of the current collector, and the second active material layer is disposed on the side of the two first active material layers away from the current collector.

[0059] Both the first active material layer and the second active material layer may include active materials, which may participate in the electrochemical reaction of the battery to generate current and form a circuit. The first active material layer and the second active material layer may both include active materials, which may improve the charge and discharge performance and energy density of the battery.

[0060] The first active material layer includes a silicon-based material, and doping the silicon-based material in the first active material layer can effectively increase the energy density and fast charging performance of the battery cell. The second active material layer includes a lithium supplement, and doping the lithium supplement in the second active material layer can improve the initial efficiency of the battery.

[0061] The method for manufacturing the active material layer comprises the following steps:

[0062] S1, mixing silicon-based materials, active substances, binders, and solvents, and coating them after mixing to obtain a first active substance layer. The first active substance layer is made by a wet method, and the materials for making the first active substance layer include silicon-based materials, active substances, binders, and solvents. The above materials can be added into a mixing tank for mixing, and then coated and rolled to obtain the first active substance layer.

[0063] S2, mixing the lithium supplement, the active material, and the binder and then fiberizing them, and obtaining the second active material layer by a dry electrode process. The second active material layer is made by a dry method, and the materials for making the second active material layer include the lithium supplement, the active material, and the binder. The above materials can be mixed, fiberized after mixing, and formed into a film by a dry electrode manufacturing process.

[0064] S3, laminating the second active material layer on the first active material layer. The second active material layer can be laminated on the first active material layer by a compression transfer method to obtain a pole piece having a double active material layer.

[0065] The dry process does not require the use of solvents, which can reduce the risk of danger during the production process of lithium supplements.

[0066] This application prepared three embodiments of the pole piece 100 (embodiment 1 to embodiment 3), and the data are shown in the following table:

[0067]

[0068]

[0069] In the above table: Gr1 and Gr2 are graphite, SP is conductive carbon black, SLMP is stable metal lithium powder, PAA is polyacrylic acid, CMC is carboxymethyl cellulose, and SBR is styrene-butadiene rubber.

[0070] The production process of Examples 1 to 3 is explained below.

[0071] Embodiment 1:

[0072] Step 1: Preparation of the first active material layer 2. 91.0wt% Gr1, 0.5wt% SP, 5wt% silicon carbon, 0.5wt% PAA, 1.5wt% CMC, and 1.5wt% SBR were prepared into a uniform first active material layer 2 slurry, and the first active material layer 2 was prepared by conventional coating and rolling methods.

[0073] Step 2: Preparation of the second active material layer 3. 96.0 wt% Gr2, 0.5 wt% SP, 0.6 wt% SLMP, 1.5 wt% PAA, 1.0 wt% CMC, and 0.4 wt% SBR were mixed and fiberized, and the second active material layer 3 was prepared by a dry electrode method.

[0074] The third step is to manufacture the pole piece 100 with double active material layers. The second active material layer 3 is laminated on the surface of the first active material layer 2 by rolling, so as to complete the pole piece 100 with double active material layers.

[0075] Embodiment 2:

[0076] Step 1: Preparation of the first active material layer 2. 91.0wt% Gr2, 0.5wt% SP, 5wt% silicon carbon, 0.5wt% PAA, 1.5wt% CMC, and 1.5wt% SBR were prepared into a uniform first active material layer 2 slurry, and the first active material layer 2 was prepared by conventional coating and rolling methods.

[0077] Step 2: Preparation of the second active material layer 3. 96.3 wt% Gr1, 0.5 wt% SP, 0.3 wt% SLMP, 1.5 wt% PAA, 1.0 wt% CMC, and 0.4 wt% SBR were mixed and fiberized, and the second active material layer 3 was prepared by a dry electrode method.

[0078] The third step is to manufacture the pole piece 100 with double active material layers. The second active material layer 3 is laminated on the surface of the first active material layer 2 by rolling, so as to complete the pole piece 100 with double active material layers.

[0079] Embodiment 3:

[0080] Step 1: Preparation of the first active material layer 2. 93.5wt% Gr2, 0.5wt% SP, 2.5wt% silicon carbon, 0.5wt% PAA, 1.5wt% CMC, and 1.5wt% SBR were prepared into a uniform first active material layer 2 slurry, and the first active material layer 2 was prepared by conventional coating and rolling methods.

[0081] Step 2: Preparation of the second active material layer 3. 96.3 wt% Gr1, 0.5 wt% SP, 0.3 wt% SLMP, 1.5 wt% PAA, 1.0 wt% CMC, and 0.4 wt% SBR were mixed and fiberized, and the second active material layer 3 was prepared by a dry electrode method.

[0082] The third step is to manufacture the pole piece 100 with double active material layers. The second active material layer 3 is laminated on the surface of the first active material layer 2 by rolling, so as to complete the pole piece 100 with double active material layers.

[0083] The present application prepared two comparative examples of pole pieces 100 (Comparative Example 1 and Comparative Example 2), and the data are shown in the following table:

[0084]

[0085] In the above table: Gr1 and Gr2 are graphite, SP is conductive carbon black, PAA is polyacrylic acid, CMC is carboxymethyl cellulose, and SBR is styrene-butadiene rubber.

[0086] The preparation process of Comparative Example 1 and Comparative Example 2 is explained below.

[0087] Comparative Example 1:

[0088] Step 1: Preparation of the second active material layer 3. 96.6wt% Gr2, 0.5wt% SP, 1.5wt% PAA, 1.0wt% CMC, and 0.4wt% SBR were prepared into a uniform second active material layer 3 slurry, and the second active material layer 3 was prepared by a dry electrode method.

[0089] Step 2: Preparation of the first active material layer 2. 96.0wt% Gr2, 0.5wt% SP, 0.6wt% SLMP, 1.5wt% PAA, 1.0wt% CMC, and 0.4wt% SBR were mixed and fiberized to prepare the first active material layer 2 by dry electrode method.

[0090] The third step is to manufacture the pole piece 100 with double active material layers. The second active material layer 3 is laminated on the surface of the first active material layer 2 by rolling, so as to complete the pole piece 100 with double active material layers.

[0091] Comparative Example 2:

[0092] Step 1: Preparation of the second active material layer 3. 96.0wt% Gr2, 0.5wt% SP, 0.6wt% SLMP, 1.5wt% PAA, 1.0wt% CMC, and 0.4wt% SBR were prepared into a uniform second active material layer 3 slurry, and the second active material layer 3 was prepared by conventional coating and rolling methods.

[0093] Step 2: Preparation of the first active material layer 2. 96.0 wt% Gr1, 0.5 wt% SP, 0.5 wt% PAA, 1.5 wt% CMC, and 1.5 wt% SBR were mixed and fiberized to prepare the first active material layer 2 by dry electrode method.

[0094] The third step is to manufacture the pole piece 100 with double active material layers. The second active material layer 3 is laminated on the surface of the first active material layer 2 by rolling, so as to complete the pole piece 100 with double active material layers.

[0095] The difference between Comparative Example 1 and Example 1 is that the second active material layer 3 is not doped with the lithium supplement agent 31.

[0096] The difference between Comparative Example 2 and Example 1 is that the first active material layer 2 does not include the silicon-based material 21.

[0097] The produced double-layer active material layer electrode 100 is matched with the positive electrode and the separator to form a battery cell, and its performance is tested. The test results are shown in the following table:

[0098]

[0099] From the above examples 1-3 and comparative examples 1-2, it can be seen that the silicon-doped lithium-supplemented electrode 100 with a double-layer active material structure proposed in the present invention has good performance in terms of cycle performance and rate performance after being assembled into a battery cell.

[0100] Comparing Example 1 with Example 2, in terms of formulation, the lithium supplement 31 in the second active material layer 3 of Example 2 is reduced by 50%. After 800 cycles at discharge rates of 0.5C, 1C, and 2C, the capacity retention rate of Example 1 is higher than that of Example 2, indicating that doping the lithium supplement 31 in the negative electrode is beneficial to the cycle performance and fast charging performance of the battery cell. In terms of formulation, the silicon-based material 21 doped in the first active material layer 2 of Example 3 is lower than that of Example 2. After 800 cycles at discharge rates of 0.5C, 1C, and 2C, the capacity retention rate of Example 2 is higher than that of Example 3, indicating that doping a certain amount of silicon-based material 21 in the first active material layer 2 is also beneficial to the improvement of cycle performance. The pole piece 100 produced by the present invention adopts the method of doping the second active material layer 3 with a lithium supplement 31. The lithium supplement 31 participates in the formation of the SEI film during the formation process, effectively improving the first efficiency of the battery cell. At the same time, the lithium supplement 31 of the second active material layer 3 can form a plurality of micropores 32 inside the electrode after the reaction, which is conducive to the infiltration of the electrolyte and improves the rate performance of the battery cell. The first active material layer 2 is doped with a silicon material with a theoretical specific capacity of up to 4200mAh / g, which helps to improve the cycle and rate performance.

[0101] According to an embodiment of the present invention, the battery includes an electrode assembly, and the electrode assembly includes: a positive electrode sheet, a negative electrode sheet and a separator, the negative electrode sheet is the above-mentioned electrode sheet 100, and the positive electrode sheet, the separator and the negative electrode sheet are assembled to form an electrode assembly. By doping the first active material layer 2 with a silicon-based material 21, and making the first active material layer 2 disposed between the current collector 1 and the second active material layer 3, the expansion of the first active material layer 2 can be constrained and limited by the current collector 1 and the second active material layer 3, which is beneficial to improving the first effect of the battery, and by making the first active material layer 2 and the second active material layer 3 both include active material 4, it is beneficial to improve the fast charging performance and energy density of the battery. In addition, by making the second active material layer 3 include a lithium supplement 31, the first effect of the battery can be significantly improved. After the lithium supplement 31 reacts, vacancies are generated, which are beneficial to the infiltration of the electrolyte, and the fast charging performance of the battery can be improved.

[0102] The electrical equipment according to the embodiment of the present invention includes the above-mentioned battery. By doping the first active material layer 2 with a silicon-based material 21 and providing the first active material layer 2 between the current collector 1 and the second active material layer 3, the expansion of the first active material layer 2 can be constrained and limited by the current collector 1 and the second active material layer 3, which is beneficial to improving the first efficiency of the battery. In addition, by providing the first active material layer 2 and the second active material layer 3 with active material 4, it is beneficial to improve the fast charging performance and energy density of the battery. In addition, by providing the second active material layer 3 with a lithium supplement 31, the first efficiency of the battery can be significantly improved. After the lithium supplement 31 reacts, vacancies are generated, which are beneficial to the infiltration of the electrolyte and can improve the fast charging performance of the battery.

[0103] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0104] In the description of the present invention, "first feature" or "second feature" may include one or more of the features.

[0105] In the description of the present invention, "plurality" means two or more.

[0106] In the description of the present invention, a first feature being “on” or “under” a second feature may include that the first and second features are directly in contact with each other, or may include that the first and second features are not in direct contact with each other but are in contact with each other via another feature therebetween.

[0107] In the description of the present invention, “on”, “over” and “above” a first feature from a second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature.

[0108] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0109] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A pole piece (100), characterized in that: include: A current collector (1), a first active material layer (2) and a second active material layer (3), wherein along the thickness direction of the pole piece (100), the first active material layer (2) is arranged between the current collector (1) and the second active material layer (3); The first active material layer (2) comprises a silicon-based material (21), the second active material layer (3) comprises a lithium supplement (31), and both the first active material layer (2) and the second active material layer (3) comprise an active material (4).

2. The pole piece (100) according to claim 1, characterized in that: Taking the total mass of the first active material layer (2) as 100 wt%, the content of the silicon-based material (21) is A, satisfying the relationship: 0.1 wt%≤A≤10 wt%.

3. The pole piece (100) according to claim 1, characterized in that: Based on the total mass of the second active material layer (3) being 100 wt%, the content of the lithium supplement (31) is B, satisfying the relationship: 0.1 wt%≤B≤0.9 wt%.

4. The pole piece (100) according to claim 1, characterized in that: The silicon-based material (21) comprises at least one of silicon alloy, silicon carbon, silicon oxygen and silicon particles.

5. The pole piece (100) according to claim 1, characterized in that: The lithium supplement (31) comprises at least one of metal lithium powder, stable metal lithium balls, lithium alloys and lithium sulfide.

6. The pole piece (100) according to claim 1, characterized in that: The first active material layer (2) and / or the second active material layer (3) further comprises: a binder, wherein the binder is a high molecular polymer.

7. The pole piece (100) according to claim 6, characterized in that: The active material (4) comprises: at least one of graphite, silicon, hard carbon, soft carbon, silicon carbon, tin, and lithium titanate, and the graphite comprises artificial graphite and / or natural graphite; The binder comprises at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyethyleneimine, polyaniline, polyacrylic acid, sodium alginate, styrene-butadiene rubber, sodium carboxymethyl cellulose, phenolic resin and epoxy resin.

8. The pole piece (100) according to claim 1, characterized in that: The first active material layer (2) and / or the second active material layer (3) further comprises: a conductive agent, wherein the conductive agent comprises: at least one of conductive carbon black, KS-6, acetylene black, Ketjen black, conductive fiber, graphene, conductive graphite, graphene oxide, and carbon nanotubes.

9. A method for producing an active material layer, characterized in that: The active material layer includes a first active material layer and a second active material layer, and the manufacturing method includes: Mixing a silicon-based material, an active substance, a binder, and a solvent, and coating the mixed materials to obtain a first active substance layer; The lithium supplement agent, active material and binder are mixed and fiberized, and a second active material layer is obtained by a dry electrode process; The second active material layer is laminated on the first active material layer.

10. A battery, characterized in that: It comprises an electrode assembly, wherein the electrode assembly comprises: a positive electrode sheet, a negative electrode sheet and a separator, wherein the negative electrode sheet is a electrode sheet (100) according to any one of claims 1 to 8, and the positive electrode sheet, the separator and the negative electrode sheet are assembled together to form the electrode assembly.

11. An electrical device, characterized in that: Comprising a battery according to claim 10.

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