Negative electrode slurry and preparation method thereof, negative electrode pole piece and lithium battery

Abstract

The embodiment of the invention discloses a negative electrode slurry and a preparation method thereof, a negative electrode pole piece and a lithium battery, an auxiliary agent is added into the negative electrode slurry, the auxiliary agent at least contains an alkane group and a first group, the alkane group and an anchoring group capable of performing physical / chemical adsorption on the surface of an active material, and the first group is a second group capable of performing physical / chemical adsorption on the surface of the active material. The first group can form a hydrogen bond with carboxyl in the polyacrylic acid binder, so that the interface bonding force between the polyacrylic acid binder and the active material is remarkably enhanced, the hydrogen bond condensation between molecular chains of the polyacrylic acid binder can be effectively blocked by the steric hindrance effect of the polyacrylic acid binder, and the tendency of agglomeration in a material system is inhibited; therefore, a uniform and stable coating layer is formed on the surface of the active material.

Description

Technical Field

[0001] This application relates to the technical field of batteries, specifically to a negative electrode slurry and its preparation method, a negative electrode sheet, and a lithium battery. Background Technology

[0002] In the field of negative electrode binders, polyacrylic acid (PAA) binders are considered key materials for constructing long-life negative electrode systems because of their strong adhesion and cross-linking properties brought by abundant carboxyl functional groups, which can effectively buffer the volume expansion of active materials during charging and discharging.

[0003] In related technologies, when PAA binder is used as the negative electrode binder, the carboxyl groups on its molecular chain are too polar, and they are prone to entanglement and aggregation between molecular chains through hydrogen bonds in aqueous slurry, which makes it impossible for PAA binder to form a uniform and complete coating layer on the surface of the active material. Summary of the Invention This application provides a negative electrode slurry and its preparation method, a negative electrode sheet, and a lithium battery, aiming to solve the problem that PAA binder cannot form a uniform and complete coating layer on the surface of active materials.

[0004] In a first aspect, a negative electrode slurry is provided, the negative electrode slurry comprising an active material, a conductive agent, a polyacrylic binder, an adhesion promoter, and an aqueous solvent; The adsorption agent contains at least an alkane group and a first group, wherein the first group is capable of forming a hydrogen bond with a carboxyl group.

[0005] Optionally, in some embodiments of this application, the adhesion promoter includes a titanate coupling agent; and / or The adhesion promoter contains at least isopropoxy and acyloxy groups.

[0006] Optionally, in some embodiments of this application, the adjuvant includes at least one of isopropyl triisostearate titanate, isopropyl dioleoyloxy (dioctylphosphoyloxy) titanate, and isopropyl trioleoyloxy titanate.

[0007] Optionally, in some embodiments of this application, the active material includes at least one of graphite and silicon-based materials; and / or The conductive agent includes at least one of conductive carbon black, carbon nanotubes, graphene, acetylene black, and Ketjen black.

[0008] Optionally, in some embodiments of this application, the negative electrode slurry comprises 90.5 to 98 parts of the active material, 0.5 to 1.5 parts of the conductive agent, 0.5 to 3 parts of the polyacrylic acid binder, 0.1 to 0.5 parts of the adhesion promoter, and an aqueous solvent, and the solid content of the negative electrode slurry is 45% to 60%.

[0009] Optionally, in some embodiments of this application, additional adhesives are also included, said additional adhesives including at least one of carboxymethyl cellulose adhesive and styrene-butadiene rubber latex; Preferably, the solid content of the carboxymethyl cellulose adhesive is 1% to 5%, and the mass fraction of the carboxymethyl cellulose adhesive is 0.5 to 3 parts. Preferably, the solid content of the styrene-butadiene rubber latex is 30% to 50%, and the mass fraction of the styrene-butadiene rubber latex is 0.5 to 3 parts.

[0010] Secondly, a method for preparing a negative electrode slurry is provided, which includes the following steps: The active material and the conductive agent are mixed to obtain the first mixture; Add the first part of the polyacrylic acid adhesive and the adhesion promoter to the first mixture and stir to obtain the second mixture; Add the remaining polyacrylic acid adhesive to the second mixture and stir to obtain the negative electrode slurry; Preferably, the first portion is 30wt% to 70wt%.

[0011] Thirdly, a negative electrode sheet is provided, the negative electrode sheet comprising a current collector and an electrode layer, the electrode layer being made of a negative electrode slurry as described above or a negative electrode slurry prepared by the aforementioned method.

[0012] Optionally, in some embodiments of this application, the thickness of the electrode layer is 50 μm to 180 μm; and / or The areal density of the electrode layer is 50 g / m³. 2 Up to 180g / m 2 ; and / or The compaction density of the electrode layer is 1.3 g / m³. 3 Up to 1.8g / m 3 ; The negative electrode sheet has a rebound rate of less than or equal to 15%.

[0013] Fourthly, a lithium battery is provided, the lithium battery including the negative electrode sheet as described above.

[0014] Optionally, in some embodiments of this application, the lithium battery is at 35 o C. The capacity retention rate is greater than 90% after 1000 cycles at a 1C charge / discharge rate.

[0015] In this embodiment, an adsorption aid is added to the negative electrode slurry. The adsorption aid contains at least an alkane group and a first group. The alkane group can act as an anchoring group that undergoes physical / chemical adsorption with the surface of the active material. The first group can form hydrogen bonds with the carboxyl groups in the polyacrylic binder, which significantly enhances the interfacial bonding force between the polyacrylic binder and the active material. Its steric hindrance effect can effectively block the hydrogen bond condensation between the molecular chains of the polyacrylic binder, suppressing the tendency to agglomerate within the material system, thereby ensuring the formation of a uniform and stable coating layer on the surface of the active material. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of the adsorption agent provided in an exemplary embodiment of this disclosure; Figure 2 This is a schematic diagram of the structure of the coupling agent provided in an exemplary embodiment of this disclosure; Figure 3 This is a process flow diagram of the negative electrode slurry provided in an exemplary embodiment of this disclosure; Figure 4 This is a graph showing the capacity retention rates of exemplary embodiments 1-2 and comparative examples 1-2 of this disclosure; Figure 5 This is a graph showing the electrode rebound rate of exemplary embodiments 1-2 and comparative examples 1-2 of this disclosure. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] In related technologies, when PAA binder is used as the negative electrode binder, the carboxyl groups on its molecular chain are too polar, and they are prone to entanglement and aggregation between molecular chains through hydrogen bonds in aqueous slurry, which makes it impossible for PAA binder to form a uniform and complete coating layer on the surface of the active material.

[0020] Furthermore, the uneven bonding network prevents the negative electrode from being effectively constrained during long-term cycling, leading to localized stress concentration, particle breakage, and failure of conductive pathways. Simultaneously, poorly coated graphite or silicon materials are directly exposed to the electrolyte, triggering continuous interfacial side reactions and accelerating the irreversible consumption of active lithium. This manifests macroscopically as a rapid decline in battery cycle performance, severely hindering the commercialization of high-capacity batteries using PAA binders in long-life applications.

[0021] The negative electrode slurry technology based on PAA binder suffers from inherent dispersion problems that lead to a decline in battery cycle performance, thus restricting the stable operation of the battery in long-life application scenarios. To solve this problem, this application provides a negative electrode slurry and its preparation method, a negative electrode sheet, and a lithium battery to address the issue that the poor dispersion of PAA binder prevents it from uniformly coating graphite, resulting in insufficient cycle life of lithium-ion batteries.

[0022] According to a first aspect of this application, a negative electrode slurry is provided, the negative electrode slurry comprising an active material, a conductive agent, a polyacrylic acid binder, an adhesion promoter, and an aqueous solvent; see also Figure 1 The adhesion aid contains at least an alkane group and a first group, the first group being able to form a hydrogen bond with a carboxyl group.

[0023] By adopting the above scheme, the embodiments of this application add an adsorption aid to the negative electrode slurry. The adsorption aid contains at least an alkane group and a first group. The alkane group can be an anchoring group that can be physically / chemically adsorbed onto the surface of the active material. The first group can form hydrogen bonds with the carboxyl groups in the polyacrylic binder, which significantly enhances the interfacial bonding force between the polyacrylic binder and the active material. Its steric hindrance effect can effectively block the hydrogen bond condensation between the molecular chains of the polyacrylic binder, suppress the tendency to agglomerate in the material system, thereby ensuring the formation of a uniform and stable coating layer on the surface of the active material.

[0024] In some embodiments of this application, the adsorption aid includes titanate coupling agents.

[0025] By adopting the above scheme, titanate coupling agents contain at least inorganic-loving groups, which can combine with the surface of active materials through hydrolysis or chemical adsorption; titanate coupling agents also contain organic-loving groups, which are reactive and can chemically react or physically entangle with organic materials, thereby enhancing the compatibility between active materials and polyacrylic adhesives.

[0026] In some embodiments of this application, please refer to Figure 2 The adhesion promoter contains at least an isopropoxy group and an acyloxy group. Exemplarily, the adhesion promoter may include at least one of isopropyl triisostearate titanate, isopropyl dioleoyloxy (dioctylphosphoyloxy) titanate, and isopropyl trioleoyloxy titanate.

[0027] By employing the above-mentioned scheme, the molecules of isopropyl triisostearate titanate, isopropyl dioleoyloxy (dioctylphosphoyloxy) titanate, and isopropyl trioleoyloxy titanate all contain isopropyl groups. During material preparation, these molecules can undergo hydrolysis and condensation reactions with active materials to form stable Ti-OC covalent bonds. These titanate coupling agents also contain acyloxy groups, which can form hydrogen bonds with the carboxyl groups of polyacrylic acid binders, thereby achieving a bridging effect and significantly improving the interfacial bonding force between graphite and polyacrylic acid binders. In addition, isopropyl dioleoyloxy (dioctylphosphoyloxy) titanate also has a long dioleoyloxy aliphatic chain, which can physically isolate the hydrogen bonds between carboxyl groups in polyacrylic acid binders, effectively inhibiting the aggregation of polyacrylic acid binder molecular chains.

[0028] In some embodiments of this application, the active material may include at least one of graphite and silicon-based materials. Graphite and silicon-based materials are commonly used negative electrode active materials in commercial lithium-ion batteries.

[0029] In some embodiments of this application, the conductive agent may include at least one of conductive carbon black, carbon nanotubes, graphene, acetylene black, and Ketjen black.

[0030] In some embodiments of this application, the negative electrode slurry includes 90.5 to 98 parts of active material, 0.5 to 1.5 parts of conductive agent, 0.5 to 3 parts of polyacrylic acid binder, 0.1 to 0.5 parts of adhesion promoter and aqueous solvent, and the solid content of the negative electrode slurry is 45% to 60%.

[0031] By adopting the above scheme, the negative electrode slurry of this application embodiment is made with the formula described above. An adhesion promoter is added to the negative electrode slurry. The adhesion promoter can improve the interfacial bonding force between the active material and the polyacrylic binder, thereby forming a uniform and stable coating layer on the surface of the active material.

[0032] In some embodiments of this application, the negative electrode slurry further includes additional binders, which may include at least one of carboxymethyl cellulose adhesive and styrene-butadiene rubber latex.

[0033] By adopting the above scheme, carboxymethyl cellulose adhesive acts as a binder in the negative electrode slurry, which helps to further improve the adhesion between the active material and the polyacrylic binder. Styrene-butadiene rubber latex can also act as a binder, and can also adjust the viscosity of the slurry to meet different application requirements.

[0034] In some embodiments of this application, the solid content of the carboxymethyl cellulose adhesive is 1% to 5%, and the mass fraction of the carboxymethyl cellulose adhesive is 0.5 to 3 parts. Exemplarily, the mass fraction of the carboxymethyl cellulose adhesive can be 0.5 parts, 0.8 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, and 3 parts, as well as any value between two consecutive values ​​mentioned above.

[0035] In some embodiments of this application, the solid content of the styrene-butadiene rubber latex is 30% to 50%, and the mass fraction of the styrene-butadiene rubber latex is 0.5 to 3 parts.

[0036] By adopting the above scheme, the solid content of the styrene-butadiene rubber latex is relatively large, and the viscosity of the slurry system is adjusted, thereby achieving the adjustment of the viscosity of the negative electrode slurry.

[0037] According to a second aspect of the embodiments of this application, a method for preparing a negative electrode slurry is provided, referring to... Figure 3 The method for preparing the aforementioned negative electrode slurry includes the following steps: S100. The active material and the conductive agent are mixed to obtain the first mixture; S200: Add the first portion of polyacrylic acid adhesive and adhesion promoter to the first mixture and stir to obtain a second mixture; preferably, the first portion is 30wt% to 70wt%; S300. Add the remaining portion of the polyacrylic acid adhesive to the second mixture and stir to obtain the negative electrode slurry.

[0038] By adopting the above scheme, a portion of PAA adhesive is first added. Under high viscosity conditions, with the guidance of the adhesion promoter, the molecules of PAA adhesive can be forced to adhere to the surface of the active material in an oriented manner, achieving precise anchoring. Then, the remaining PAA adhesive is added to fill the gaps in the primary coating layer, constructing a complete cross-linked network that combines strength and toughness.

[0039] According to a third aspect of the embodiments of this application, a negative electrode sheet is provided, the negative electrode sheet including a current collector and an electrode layer, the electrode layer including the negative electrode slurry as described above or the negative electrode slurry prepared by the method described above.

[0040] By adopting the above solution, the negative electrode sheet of this application embodiment has a more stable structure, which can suppress the expansion of the active material during cycling and reduce the interfacial side reactions between the active material and the PAA binder.

[0041] In some embodiments of this application, the thickness of the electrode layer is from 50 μm to 180 μm. Exemplarily, the thickness of the electrode layer can be 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, or any value between two adjacent values ​​mentioned above.

[0042] In some embodiments of this application, the areal density of the electrode layer is 50 g / m². 2 Up to 180g / m 2 Furthermore, the areal density of the electrode layer can be 50 g / m². 2 Up to 130g / m 2 For example, the areal density of the negative electrode sheet can be 50 g / m². 2 75g / m 2 100g / m 2 130g / m 2 150g / m 2 180g / m 2 And any value between the two adjacent values ​​mentioned above.

[0043] By adopting the above scheme, a suitable areal density helps to ensure a high energy density, while also facilitating sufficient electrolyte wetting. If the areal density of the electrode layer is too low, the energy density will be too low; if the areal density of the electrode layer is too high, the electrolyte will not be able to wet it.

[0044] In some embodiments of this application, the compaction density of the electrode layer is 1.3 g / m³. 3 Up to 1.7g / m 3 For example, the compaction density of the negative electrode sheet is 1.3 g / m³. 3 1.4g / m 3 1.5g / m 3 1.6g / m 3 1.7g / m 3 And any value between the two adjacent values ​​mentioned above.

[0045] By adopting the above scheme, the compaction density of the electrode layer should not be too high, otherwise it will lead to particle breakage.

[0046] In some embodiments of this application, the electrode rebound rate of the negative electrode is less than or equal to 15%. Exemplarily, the electrode rebound rate of the negative electrode can be 15%, 14%, 13%, 12%, 11%, 10%, 9%, or any value between two adjacent values ​​mentioned above.

[0047] According to a fourth aspect of the embodiments of this application, a lithium battery is provided, the lithium battery including the negative electrode sheet as described above.

[0048] By adopting the above-described solution, the lithium battery of this application embodiment has all the beneficial effects of the aforementioned negative electrode sheet, which will not be repeated here.

[0049] In some embodiments of this application, the lithium battery is at 35 o The capacity retention rate is greater than 90% after 1000 cycles at a 1C charge / discharge rate.

[0050] By adopting the above solution, the lithium battery of this application embodiment is 35 o At C, after 1000 cycles of 1C charge-discharge rate, the capacity retention rate can reach over 90%, which is far superior to batteries in related technologies.

[0051] The present application will be specifically described below through specific embodiments. These embodiments are only some embodiments of the present application and are not intended to limit the present application. Unless otherwise specified, the raw materials used in the following embodiments are all commercially available products.

[0052] Example 1 A negative electrode sheet includes a copper foil current collector, and an electrode layer is formed on the surface of the copper foil current collector by a coating process using a negative electrode slurry; wherein the negative electrode slurry is prepared by the following method: 95 wt% graphite and 1 wt% conductive carbon black were dry-mixed for 1 hour at a stirring speed of 10 rpm to obtain the first mixture. Add 0.27 wt% carboxymethyl cellulose (CMC) solution, 0.6 wt% PAA solution, and 0.2 wt% isopropyl triisostearate titanate to the first mixture and mix. Stir for 1 hour at a stirring speed of 10 rpm to obtain the second mixture; wherein the solid content of the CMC solution is 3% and the solid content of the PAA solution is 5%. Add 0.63wt% CMC adhesive and 1.4wt% PAA adhesive to the second mixture and mix. Stir for 2 hours at a stirring speed of 25 rpm to obtain the third mixture. Add 0.9 wt% styrene-butadiene rubber latex (SBR latex) to the third mixture and adjust the viscosity to 5000 mPa·s to obtain the negative electrode slurry; wherein, the solid content of the SBR latex is 40%; The negative electrode paste was coated onto an 8μm copper foil, and the negative electrode paste was uniformly coated on the surface of the copper foil. The areal density of the negative electrode was 75g / m². 2 Then 85 o Bake in oven C for 10 minutes. After drying, coat the negative electrode paste onto the other side of the copper foil. The surface density and baking temperature are the same as in the previous steps. The dried electrode sheets are rolled using a roller press to achieve a compaction density of 1.5 g / m³. 3 This yields the negative electrode sheet.

[0053] Example 2 The difference from Example 1 lies in the formulation of the negative electrode slurry. In this example, the negative electrode slurry formulation consists of 97 wt% graphite, 0.6 wt% carbon black, 1 wt% PAA adhesive, 0.2 wt% isopropyl triisostearate titanate, 0.6 wt% carboxymethyl cellulose adhesive, and 0.6 wt% styrene-butadiene rubber latex. The areal density of the negative electrode sheet in this example is 90 g / m². 2 The compacted density is 1.6 g / cm³. 3 .

[0054] Example 3 The difference from Example 1 lies in the type of adhesion promoter. In this example, γ-aminopropyltriethoxysilane KH-550 is used as the PAA adhesion promoter, while the remaining steps are consistent with those in Example 1.

[0055] Comparative Example 1 The difference from Example 1 is the absence of an adhesion promoter; the specific steps are as follows: 95 wt% graphite and 1 wt% conductive carbon black were dry-mixed for 1 hour at a stirring speed of 10 rpm to obtain the first mixture. Add 0.27wt% CMC adhesive and 0.6wt% PAA adhesive to the first mixture and mix. Stir for 1 hour at a stirring speed of 10 rpm to obtain the second mixture. Add 0.63wt% CMC adhesive and 1.4wt% PAA adhesive to the second mixture and mix. Stir for 2 hours at a stirring speed of 25 rpm to obtain the third mixture. Add 0.9 wt% SBR emulsion to the third mixture and adjust the viscosity to 5000 mPa·s to obtain the negative electrode slurry.

[0056] Comparative Example 2 The difference from Example 2 is the absence of an adhesion promoter; the remaining steps are the same as in Example 2.

[0057] Performance testing: Using lithium iron phosphate as the positive electrode active material, lithium iron phosphate, carbon black, carbon nanotubes, and polytetrafluoroethylene were prepared in a ratio of 96:1:1.4:1.6 to obtain a positive electrode slurry. The positive electrode slurry was coated onto aluminum foil, and the areal density of the positive electrode was configured according to an NP ratio of 1.1, with a compaction density of 2.3 g / cm³. 3 ; The lithium iron phosphate positive electrode, negative electrode, separator and electrolyte are assembled into a 2Ah soft pack battery; At 35o Under C conditions, 1C / 1C charge-discharge cycles were performed, with DC charging and DC discharging. The charging and discharging current was the current corresponding to the 1C rate, and the charging and discharging voltage range was 2.5-3.7V. The discharge capacity of the example and comparative examples was recorded at different numbers of cycles. The test results are shown in Table 1. The soft-pack battery cells of the examples and comparative examples were disassembled, and the thickness of the negative electrode sheet at 100% SOC and 0% SOC was recorded. The full charge rebound rate of the electrode sheet was calculated, and the test results are shown in Table 1.

[0058] Table 1

[0059] Compared with Examples 1-3 and Comparative Examples 1-2, the adhesion aids in Examples 1-3 contain at least alkane groups and a first group, which can form hydrogen bonds with carboxyl groups. No adhesion aids were added in Comparative Examples 1-2. As can be seen from Table 1, the use of adhesion aids to generate steric hindrance effect can effectively block the hydrogen bond condensation between polyacrylic acid adhesive molecular chains, suppress the tendency to agglomerate in the material system, and thus ensure the formation of a uniform and stable coating layer on the surface of the active material.

[0060] Figure 4 This is a graph showing the capacity retention rates of Examples 1-2 and Comparative Examples 1-2. Figure 4 It can be seen that the sample of Example 1 achieved a capacity retention rate of 91.8% after 1000 cycles, which is an improvement of 2.7%; the battery of Example 2 achieved a capacity retention rate of 90.1% after 1000 cycles, which is an improvement of 3.9%.

[0061] Figure 5 This is a graph showing the electrode rebound rate of Examples 1-2 and Comparative Examples 1-2. (From...) Figure 5 It can be seen that the electrode rebound rate of the sample in Example 1 after full charging was 12%, which was reduced by 5%; the electrode rebound rate of the sample in Example 2 after full charging was 13%, which was reduced by 6%.

[0062] The foregoing has provided a detailed description of the negative electrode slurry and its preparation method, the negative electrode sheet, and the lithium battery provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A negative electrode slurry, characterized in that, The negative electrode slurry includes active materials, conductive agents, polyacrylic acid binders, adhesion promoters, and aqueous solvents; The adsorption agent contains at least an alkane group and a first group, wherein the first group is capable of forming a hydrogen bond with a carboxyl group.

2. The negative electrode slurry according to claim 1, characterized in that, The adhesion promoter includes titanate coupling agents; and / or The adhesion promoter contains at least isopropoxy and acyloxy groups.

3. The negative electrode slurry according to claim 2, characterized in that, The adhesion promoter includes at least one of isopropyl triisostearate titanate, isopropyl dioleoyloxy (dioctylphosphoyloxy) titanate, and isopropyl trioleoyloxy titanate.

4. The negative electrode slurry according to claim 1, characterized in that... The active material includes at least one of graphite and silicon-based materials; and / or The conductive agent includes at least one of conductive carbon black, carbon nanotubes, graphene, acetylene black, and Ketjen black.

5. The negative electrode slurry according to any one of claims 1 to 4, characterized in that, The negative electrode slurry comprises 90.5 to 98 parts of the active material, 0.5 to 1.5 parts of the conductive agent, 0.5 to 3 parts of the polyacrylic acid binder, 0.1 to 0.5 parts of the adhesion promoter, and the aqueous solvent, and the solid content of the negative electrode slurry is 45% to 60%.

6. The negative electrode slurry according to any one of claims 1 to 5, characterized in that, It also includes other adhesives, which include at least one of carboxymethyl cellulose adhesive and styrene-butadiene rubber latex; Preferably, the solid content of the carboxymethyl cellulose adhesive is 1% to 5%, and the mass fraction of the carboxymethyl cellulose adhesive is 0.5 to 3 parts. Preferably, the solid content of the styrene-butadiene rubber latex is 30% to 50%, and the mass fraction of the styrene-butadiene rubber latex is 0.5 to 3 parts.

7. A method for preparing a negative electrode slurry, characterized in that, The method for preparing the negative electrode slurry as described in any one of claims 1 to 6 comprises the following steps: The active material and the conductive agent are mixed to obtain the first mixture; Add the first part of the polyacrylic acid adhesive and the adhesion promoter to the first mixture and stir to obtain the second mixture; Add the remaining polyacrylic acid adhesive to the second mixture and stir to obtain the negative electrode slurry; Preferably, the first portion is 30wt% to 70wt%.

8. A negative electrode sheet, characterized in that, The negative electrode includes a current collector and an electrode layer, wherein the electrode layer is made of a negative electrode slurry as described in any one of claims 1 to 5 or a negative electrode slurry prepared by the method described in claim 6 or 7.

9. The negative electrode sheet according to claim 8, characterized in that, The thickness of the electrode layer is 50 μm to 180 μm; and / or The areal density of the electrode layer is 50 g / m³. 2 Up to 180g / m 2 ; and / or The compaction density of the electrode layer is 1.3 g / m³. 3 Up to 1.8g / m 3 ; The negative electrode sheet has a rebound rate of less than or equal to 15%.

10. A lithium battery, characterized in that, The lithium battery includes the negative electrode sheet as described in claim 8 or 9.

11. The lithium battery according to claim 10, characterized in that, The lithium battery is at 35 o C. The capacity retention rate is greater than 90% after 1000 cycles at a 1C charge / discharge rate.

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