Method for preparing dry electrode, and dry electrode obtained therefrom and use thereof

Abstract

Provided in the present application are a method for preparing a dry electrode, and a dry electrode obtained therefrom and the use thereof. A new binder formula is used in the method. The binder formula comprises a main binder and a glue solution containing a dispersive binder and an aqueous binder. The main binder and raw materials are first subjected to dry mixing to form a first dry material; the glue solution is then added thereto for dispersion; the resulting second dry material is crushed to obtain a powder in which the main binder is fiberized; and the powder is calendered, so as to prepare a dry electrode.

Description

A method for preparing a dry electrode and the obtained dry electrode and its use

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on July 19, 2023, with application number 202310886118.8. The entire contents of the above application are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the field of batteries, and for example relates to a method for preparing a dry electrode and the obtained dry electrode and its use. Background Art

[0003] Thanks to economic globalization and the increasing demands of countries around the world for carbon neutrality and environmental protection, the replacement of traditional energy with new energy has become a strong development trend. Lithium-ion batteries have gradually become indispensable in fields such as power and energy storage, and have become the main force in the new energy field.

[0004] With the rapid development of lithium-ion battery technology and the substantial increase in its market share, the development of lithium-ion power batteries is increasingly moving towards low cost, high energy density, and fast charging technology. In battery manufacturing, greater attention is paid to resource costs, energy consumption, and the recovery of volatile solvents. To improve product energy density performance, greater attention is paid to thick electrode manufacturing and initial efficiency. To enhance product fast charging and power, greater attention is paid to the battery's rate characteristics.

[0005] In the manufacturing process of lithium-ion battery cells, the key performance of the cell is mainly determined by the manufacturing process of the electrode. In the relevant technologies, the manufacturing of electrode sheets is mainly divided into two types: wet and dry processes, with the wet process being the mainstream. The wet process generally first prepares a conductive slurry with a binder, solvent, and conductive agent, then gradually adds the active material and stirs it, and finally adds a solvent to adjust the slurry viscosity. However, the traditional wet process has poor dispersion of the conductive agent. At the same solid content, the slurry viscosity is higher than that of the dry process, and the internal resistance of the battery electrode produced is also larger.

[0006] Dry electrode technology is a new preparation process different from the wet method. It basically does not use or uses a small amount of harmless solvents, which can improve compaction and manufacture thick electrodes. The dry battery can increase the energy density by more than 20%, and has better kinetic characteristics. In thick electrodes, the cycle performance and impedance are better, which can greatly reduce battery manufacturing costs, energy consumption and improve battery performance.

[0007] In the related art, a more feasible dry manufacturing process uses a fibrillable PTFE binder, for example, by mixing and stirring PTFE, SP, and graphite to obtain a premix; fiberizing the premix, fiberizing the premix to obtain a fiberized mixture; baking the mixture, baking the fiberized mixture to obtain a marshmallow-like mixture; forming the mixture into a film, repeatedly folding the marshmallow-like mixture and rolling it multiple times to obtain a thicker film; thinning the film, thinning the thicker film to obtain a negative electrode film of a suitable thickness; this negative electrode dry film preparation process and negative electrode dry film have the advantages of simple process, less material waste, and low labor and material costs, which can improve production efficiency and production benefits.

[0008] Another example is the preparation of a dry-process electrode membrane by uniformly mixing active materials, conductive agents, and PTFE polymer membranes to obtain a mixture, then subjecting the mixture to a fiberization treatment, and then subjecting the mixture to a heat-calendering treatment. This method significantly reduces the difficulty of dry-process electrode sheet preparation by using polymer membranes, reduces the requirements for fiberization equipment, and achieves more complete fiberization and better dispersion uniformity between components.

[0009] However, PTFE binders have intolerance issues in the negative electrode. During charging, the C-F bond can react with lithium, thereby consuming some lithium ions, reducing the initial efficiency of the battery, and causing capacity loss. Research in related technologies has mainly focused on PTFE modification or the use of other binders to improve this problem. However, PTFE modification mainly involves adding fluorinated monomers and copolymerizing with tetrafluoroethylene, and there is still a side reaction between the C-F bond and lithium. Other commonly used binders are PP and PE polymers with low melting points. The active materials are melt-bonded at near melting points, which is a relatively complex process. The produced pole pieces are thick and have poor flexibility.

[0010] Since the dry process of PTFE fibrillation in the production of negative electrode sheets is easier to achieve mass production and large-scale industrialization, therefore, in dry electrode technology, research on electrode formulations and corresponding new processes, to achieve modification of PTFE in the electrode or improvement of the surrounding environment, reduce side reactions and improve the actual effect, while also improving the shedding of active particles during the charge and discharge process under the pure PTFE process, etc., is of great significance for improving the electrical performance of dry battery. Technical issues

[0011] The present application provides a method for preparing a dry electrode and the obtained dry electrode and its use. The method uses a new binder formula, which includes a main binder and a glue containing a dispersible binder and an aqueous binder. The main binder is first dry-mixed with the raw material to form a first dry material, and then the glue is added for dispersion. The obtained second dry material is crushed to obtain a fiberized powder of the main binder. The powder can be calendered to prepare a dry electrode. The present application uses a dispersible binder and an aqueous binder to match the main binder to coat the fiberized main binder. On the one hand, it effectively protects the main binder and solves its intolerance problem in the electrode reaction. On the other hand, it effectively improves the bonding effect, avoids the powdering and falling off of the obtained film layer and electrode sheet, and effectively improves the first effect and cycle performance. Technical Solutions

[0012] In a first aspect, an embodiment of the present application provides a method for preparing an electrode, the method comprising the following steps:

[0013] The dispersible binder and the water-based binder are prepared into a glue solution;

[0014] dry-mixing the active material, the conductive agent and the main binder to obtain a first dry material;

[0015] adding the glue solution to the first dry material for dispersion, and drying to obtain a second dry material;

[0016] Grinding the second dry material to form a binder-fiberized powder;

[0017] pressing the powder to obtain a dry electrode;

[0018] The dispersible binder and the aqueous binder are prepared into a glue solution and the active material, the conductive agent and the main binder are dry-mixed to obtain the first dry material in no particular order.

[0019] In a second aspect, an embodiment of the present application provides a dry electrode obtained using the method described in the first aspect.

[0020] In a third aspect, an embodiment of the present application provides a battery comprising the dry electrode described in the second aspect. Beneficial effects

[0021] The beneficial effects of the present application are as follows: The present application adopts a dispersible binder and an aqueous binder in combination with the main binder for use in the manufacture of dry electrodes, which can form a coating on the fibrous main binder, significantly improve the surrounding environment of the main binder, and further protect the main binder from being reduced during the charging process, thereby solving the problem of low initial efficiency caused by its side reactions and significantly improving the initial efficiency of the dry system; at the same time, the compounded binder formula can enhance the bonding effect of active particles and active particles with conductive agents, and supplement the problem of insufficient bonding of the main binder with a mesh structure to powder particles, thereby improving the quality of the diaphragm, improving the powder loss phenomenon of the diaphragm, and improving the battery cell cycle and other electrical properties.

[0022] The binder formula used in this application is simple, and the electrode manufacturing method is time-saving and energy-efficient, which helps reduce costs and improve production efficiency. Compared with the dry process using only the main binder, at the same compaction density, the film layer and electrode sheet obtained in this application show no signs of powder loss, the membrane strength is significantly improved, and the initial efficiency and cycle stability of the battery cell after the electrode sheet is assembled are effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 is a comparison of the tensile strength of the dry-process negative electrode sheets obtained in Example 1 and Comparative Examples 1-3;

[0024] FIG2 is a charge and discharge test curve diagram of dry-process negative electrode sheets obtained in Example 1 and Comparative Examples 1-3 after being assembled into batteries. Modes for Carrying Out the Invention

[0025] The present application provides a method for preparing an electrode, the method comprising the following steps:

[0026] (1) preparing a dispersible binder and a water-based binder into a glue solution;

[0027] (2) dry-mixing the active material, the conductive agent, and the main binder to obtain a first dry material;

[0028] (3) adding the glue solution to the first dry material to disperse the mixture, and drying the mixture to obtain a second dry material;

[0029] (4) crushing the second dry material to form a binder-fiberized powder;

[0030] (5) pressing the powder to obtain a dry electrode;

[0031] Among them, step (1) and step (2) are performed in no particular order.

[0032] The purpose of this application is to provide a binder formula that improves PTFE for dry electrode manufacturing and a process for electrode processing using this formula. This application study found that a dispersed binder, especially a small molecule polymer binder such as PVP, is compounded with an aqueous binder to make a mixed glue solution and added to the fiberized powder. It can form a coating on the fiber filaments of the main binder, such as PTFE fiber filaments, and can significantly improve the environment around PTFE. Furthermore, during the charging process, it can protect PTFE from being reduced, solve the problem of low first efficiency caused by PTFE side reactions, and significantly improve the first efficiency of the dry system; at the same time, the compounded binder can bond active particles, active particles and conductive agents, and supplement the problem of insufficient bonding of the PTFE network structure to the powder particles, thereby improving the quality of the diaphragm, improving the phenomenon of diaphragm powder loss, and improving the battery cell cycle and other electrical properties.

[0033] The binder formula used in this application is simple, and the electrode manufacturing method is time-saving and energy-efficient, which helps reduce costs and improve production efficiency. Compared with the dry process using only the main binder, at the same compaction density, the film layer and electrode sheet obtained in this application show no signs of powder loss, the membrane strength is significantly improved, and the initial efficiency and cycle stability of the battery cell after the electrode sheet is assembled are effectively improved.

[0034] The following are preferred technical solutions of this application, but are not intended to limit the technical solutions provided in this application. Through the following technical solutions, the technical objectives and beneficial effects of this application can be better achieved and realized.

[0035] As a preferred technical solution of the present application, the method is carried out in a production environment with a temperature of 20 to 35° C. and a humidity of -40% RH to 60% RH.

[0036] As a preferred technical solution of the present application, the dispersed binder includes a small molecule polymer binder.

[0037] Preferably, the small molecule polymer binder includes any one or a combination of at least two of PVP (polyvinyl pyrrolidone, such as K15, K30, K60 or K90), P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer) or PEG (polyethylene glycol), typical but non-limiting examples of the combination include a combination of PVP and P123, a combination of PVP and PEG, or a combination of P123 and PEG.

[0038] Preferably, the aqueous binder includes any one or a combination of at least two of polyacrylic acid (PAA) or its salt or copolymer, carboxymethyl cellulose (CMC) or its salt or copolymer, trehalose, SBR emulsion or PEG, typical but non-limiting examples of the combination include a combination of polyacrylic acid and its salt or copolymer, a combination of carboxymethyl cellulose and its salt or copolymer, a combination of polyacrylic acid and trehalose, a combination of polyacrylic acid and SBR emulsion, a combination of polyacrylic acid and PFG, a combination of carboxymethyl cellulose and trehalose, a combination of carboxymethyl cellulose and SBR emulsion, a combination of carboxymethyl cellulose and PEG, a combination of trehalose and SBR emulsion, a combination of SBR emulsion and PEG, or a combination of PEG and trehalose.

[0039] As a preferred technical solution of the present application, in the glue solution, the mass ratio of the dispersible binder to the aqueous binder is (1-3):1, for example, 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1 or 3:1, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0040] In this application, if the amount of dispersed binder added is too large, a thicker film will be formed on the surface of the main material particles, which will affect the gram capacity and reduce the battery energy density. If the amount of dispersed binder added is too low, the effect of improving the electrochemical environment of the main binder at the negative electrode will be poor.

[0041] Preferably, the total mass concentration of the binder in the glue solution is 5 to 30wt%, for example, 5wt%, 7wt%, 9wt%, 11wt%, 13wt%, 15wt%, 17wt%, 19wt%, 21wt%, 23wt%, 25wt%, 27wt%, 29wt% or 30wt%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0042] Preferably, the method for preparing the glue solution includes first preparing a dispersible binder and an aqueous binder into liquid A and liquid B with a mass concentration of 5 to 30 wt%, for example, 5 wt%, 7 wt%, 9 wt%, 11 wt%, 13 wt%, 15 wt%, 17 wt%, 19 wt%, 21 wt%, 23 wt%, 25 wt%, 27 wt%, 29 wt% or 30 wt%, etc., and then mixing liquid A and liquid B, and using a solvent to adjust the mass concentration to 5 to 30 wt%, for example, 5 wt%, 7 wt%, 9 wt%, 11 wt%, 13 wt%, 15 wt%, 17 wt%, 19 wt%, 21 wt%, 23 wt%, 25 wt%, 27 wt%, 29 wt% or 30 wt%, etc., to obtain the glue solution, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0043] Preferably, the solvent comprises water.

[0044] As a preferred technical solution of the present application, the main binder includes polytetrafluoroethylene (PTFE) and / or polytetrafluoroethylene derivatives.

[0045] Preferably, the polytetrafluoroethylene derivative includes any one of tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE) or tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), or a combination of at least two thereof. Typical but non-limiting examples of the combination include a combination of tetrafluoroethylene-hexafluoropropylene copolymer and ethylene-tetrafluoroethylene copolymer, a combination of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and tetrafluoroethylene-hexafluoropropylene copolymer, or a combination of ethylene-tetrafluoroethylene copolymer and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer.

[0046] Preferably, the conductive agent includes any one or a combination of at least two of conductive carbon black (SP), nanofiber carbon (VGCF), carbon nanotubes (CNTs) or graphene, typical but non-limiting examples of the combination include a combination of conductive carbon black and nanofiber carbon, a combination of conductive carbon black and carbon nanotubes, a combination of conductive carbon black and graphene, a combination of nanofiber carbon and carbon nanotubes, a combination of nanofiber carbon and graphene, or a combination of carbon nanotubes and graphene.

[0047] Preferably, when the dry electrode is a negative electrode, the active material includes any one or a combination of at least two of graphite (natural graphite and / or artificial graphite), a silicon-carbon composite material or a silicon-oxygen composite material. Typical but non-limiting examples of the combination include a combination of graphite and a silicon-carbon composite material, a combination of graphite and a silicon-oxygen composite material, or a combination of a silicon-carbon composite material and a silicon-oxygen composite material.

[0048] As a preferred technical solution of the present application, the dry mixing method includes first performing a first mixing at a first dry mixing speed, and then performing a second mixing at a second dry mixing speed higher than the first dry mixing speed.

[0049] Preferably, the dry mixing is carried out in a high-speed mixer with a cutter and a scraper.

[0050] Preferably, the cutter speed of the first dry mixing speed is 1000-30000 rpm, for example, 1000 rpm, 3000 rpm, 5000 rpm, 7000 rpm, 9000 rpm, 12000 rpm, 15000 rpm, 18000 rpm, 21000 rpm, 25000 rpm, 27000 rpm or 30000 rpm, and the scraper speed is 50-1000 rpm, for example, 50 rpm, 100 rpm, 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm or 1000 rpm, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0051] Preferably, the cutter speed of the second dry mixing speed is 1500-30000 rpm, for example, 1500 rpm, 3000 rpm, 5000 rpm, 7000 rpm, 9000 rpm, 12000 rpm, 15000 rpm, 18000 rpm, 21000 rpm, 25000 rpm, 27000 rpm or 30000 rpm, and the scraper speed is 50-1000 rpm, for example, 50 rpm, 100 rpm, 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm or 1000 rpm, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0052] Preferably, the first mixing time is 1 to 60 min, for example, 1 min, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0053] Preferably, the second mixing time is 1 to 60 min, for example, 1 min, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0054] Preferably, after the dry mixing, the first dry material is sieved to obtain a first dry material of 8 to 50 mesh, for example, 8 mesh, 11 mesh, 14 mesh, 17 mesh, 20 mesh, 23 mesh, 26 mesh, 29 mesh, 32 mesh, 35 mesh, 38 mesh, 41 mesh, 44 mesh, 47 mesh or 50 mesh, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0055] Preferably, the dry mixing is carried out in a high-speed mixer.

[0056] As a preferred technical solution of the present application, the glue is added to the first dry material for dispersion so that the solid content of the system is 70-90wt%, for example, 70wt%, 72wt%, 74wt%, 76wt%, 78wt%, 80wt%, 82wt%, 84wt%, 86wt%, 88wt% or 90wt%, etc., and the ratio of the mass of the main binder in the first dry material to the total mass of the dispersible binder and the aqueous binder in the glue is controlled to be (0.5-3):1, for example, 0.5:1, 0.7:1, 0.9:1, 1.1:1, 1.3:1, 1.5:1, 1.7:1, 1.9:1, 2.1:1, 2.3:1, 2.5:1, 2.7:1 or 3:1, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0057] Preferably, the drying temperature is 0 to 120°C, for example, 0°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C or 120°C, and the drying time is 2 to 24h, for example, 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h or 24h, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0058] Preferably, the particle size of the second dry material is 8 to 40 mesh, for example, 8 mesh, 11 mesh, 14 mesh, 17 mesh, 20 mesh, 23 mesh, 26 mesh, 29 mesh, 32 mesh, 35 mesh, 38 mesh, 41 mesh, 44 mesh, 47 mesh or 50 mesh, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0059] Preferably, based on the mass of the second dry material as 100wt%, the mass of the active substance is 92-96wt%, for example, 92wt%, 92.2wt%, 92.4wt%, 92.6wt%, 92.8wt%, 93wt%, 93.2wt%, 93.4wt%, 93.6wt%, 93.8wt%, 94wt%, 94.2wt%, 94.4wt%, 94.6wt%, 94.8wt%, 95wt%, 95.2wt%, 95.4wt%, 95.6wt%, 95.8wt% or 96wt%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0060] Preferably, based on the mass of the second dry material being 100wt%, the mass of the conductive agent is 0.5-1.5wt%, for example, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt% or 1.5wt%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0061] Preferably, the total mass of the binder is 2.5-8.5wt%, calculated based on the mass of the second dry material as 100wt%, for example, 2.5wt%, 2.7wt%, 2.9wt%, 3.1wt%, 3.3wt%, 3.5wt%, 3.7wt%, 3.9wt%, 4.1wt%, 4.3wt%, 4.5wt%, 4.7wt%, 4.9wt%, 5.1wt%, 5.3wt%, 5.5wt%, 5.7wt%, 5.9wt%, 6.1wt%, 6.3wt%, 6.5wt%, 6.7wt%, 6.9wt%, 7.1wt%, 7.3wt%, 7.5wt%, 7.7wt%, 7.9wt%, 8.1wt%, 8.3wt% or 8.5wt%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0062] Preferably, in the second dry material, the mass ratio of the main binder, the dispersible binder and the aqueous binder is (1-12):(1-3):1, for example, 1:1:1, 1:2:1, 1:3:1, 2:1:1, 2:2:1, 2:3:1, 3:1:1, 3:2:1, 3:3:1, 4:1:1, 4:2:1, 4:3:1, 5:1:1, 5:2:1, 5:3:1, 6:1:1, 6:2: 1, 6:3:1, 7:1:1, 7:2:1, 7:3:1, 8:1:1, 8:2:1, 8:3:1, 9:1:1, 9:2:1, 9:3:1, 10:1:1, 10:2:1, 10:3:1, 11:1:1, 11:2:1, 11:3:1, 12:1:1, 12:2:1 or 12:3:1, etc., but are not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0063] Preferably, based on the mass of the second dry material as 100wt%, the mass of the main binder is 1 to 5wt%, for example, 1wt%, 1.2wt%, 1.4wt%, 1.6wt%, 1.8wt%, 2wt%, 2.2wt%, 2.4wt%, 2.6wt%, 2.8wt%, 3wt%, 3.2wt%, 3.4wt%, 3.6wt%, 3.8wt%, 4wt%, 4.2wt%, 4.4wt%, 4.6wt%, 4.8wt% or 5wt%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0064] Preferably, based on the mass of the second dry material being 100wt%, the mass of the dispersible binder is 1 to 1.5wt%, for example, 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt% or 1.5wt%, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0065] Preferably, based on the mass of the second dry material being 100wt%, the mass of the aqueous binder is 0.5-1wt%, for example, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt% or 1wt%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0066] As a preferred technical solution of the present application, the pulverization is carried out in a grinding mill and / or a high-speed pulverizer.

[0067] Preferably, the pulverization is performed at a rotation speed of 1500 to 30000 rpm, such as 1500 rpm, 3000 rpm, 5000 rpm, 7500 rpm, 10000 rpm, 12500 rpm, 15000 rpm, 17500 rpm, 20000 rpm, 22500 rpm, 25000 rpm, 27500 rpm or 30000 rpm, but the speed is not limited to the above values, and other values ​​not listed in the above range are also applicable.

[0068] Preferably, the particle size of the powder is 35 to 200 mesh, for example, 35 mesh, 50 mesh, 75 mesh, 100 mesh, 125 mesh, 150 mesh, 175 mesh or 200 mesh, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0069] In the method of the invention, the particle sizes of the first dry material, the second dry material and the powder of the binder after fiberization need to be controlled to prevent the formation of particles with a high glue content due to large particle sizes, which are not conducive to dispersion.

[0070] Preferably, the pressing method comprises roller pressing.

[0071] As a preferred technical solution of this application, the method includes the following steps:

[0072] (1) firstly, using solvent water to prepare a dispersible binder and an aqueous binder into liquid A and liquid B respectively with a mass concentration of 5 to 30 wt%, then mixing liquid A and liquid B, controlling the mass ratio of the dispersible binder to the aqueous binder to be (1 to 3):1, and adjusting the mass concentration to 5 to 30 wt% using solvent water to obtain a glue solution; the dispersible binder is a small molecule polymer binder;

[0073] (2) dry-mixing the negative electrode active material, the conductive agent, and the main binder in a high-speed mixer, first performing a first mixing at a first dry mixing speed, then performing a second mixing at a second dry mixing speed higher than the first dry mixing speed, and sieving to obtain a first dry material of 8 to 50 mesh; the main binder includes polytetrafluoroethylene and / or a polytetrafluoroethylene derivative;

[0074] (3) adding the glue to the first dry material for dispersion so that the solid content of the system is 70-90 wt%, and controlling the mass ratio of the main binder in the first dry material to the total mass of the dispersible binder and the aqueous binder in the glue to be (0.5-3):1, and obtaining a second dry material with a particle size of 8-40 mesh after drying; taking the mass of the second dry material as 100 wt%, the mass of the active material is 92-96 wt%, the mass of the conductive agent is 0.5-1.5 wt%, the mass of the main binder is 1-5 wt%, the mass of the dispersible binder is 1-1.5 wt%, and the mass of the aqueous binder is 0.5-1 wt%; in the second dry material, the mass ratio of the main binder, the dispersible binder and the aqueous binder is (1-12):(1-3):1;

[0075] (4) placing the second dry material in a grinding mill and / or a high-speed pulverizer and pulverizing it at 1500 to 30000 rpm to form a binder-fiberized powder with a particle size of 35 to 200 mesh;

[0076] (5) using a roller press to press the powder to obtain a dry negative electrode;

[0077] Among them, step (1) and step (2) are performed in no particular order.

[0078] The present application provides a dry electrode obtained using the method described in the first aspect.

[0079] The present application provides a battery comprising the dry electrode described in the second aspect.

[0080] Example 1

[0081] This embodiment provides a method for preparing a dry negative electrode, the method comprising the following steps:

[0082] (1) preparing a dispersible binder and a water-based binder into a glue solution;

[0083] (2) dry-mixing the active material, the conductive agent, and the main binder to obtain a first dry material;

[0084] (3) adding the glue solution to the first dry material to disperse the mixture, and drying the mixture to obtain a second dry material;

[0085] (4) crushing the second dry material to form a binder-fiberized powder;

[0086] (5) pressing the powder to obtain a dry electrode;

[0087] Among them, step (1) and step (2) are performed in no particular order.

[0088] Specifically, step (1) comprises: first using solvent water to prepare a dispersible binder PEG and an aqueous binder CMC into liquid A and liquid B with a mass concentration of 17 wt%, respectively, then mixing liquid A and liquid B, controlling the mass ratio of the dispersible binder to the aqueous binder to be 1.5:1, and using solvent water to adjust the mass concentration to 17 wt% to obtain a glue solution; the dispersible binder is a small molecule polymer binder;

[0089] Step (2) comprises: dry-mixing the negative electrode active material graphite (G), the conductive agent conductive carbon black (SP) and the main binder polytetrafluoroethylene (PTFE) in a high-speed mixer, firstly performing a first mixing at a first dry mixing speed, then performing a second mixing at a second dry mixing speed higher than the first dry mixing, and sieving to obtain a first dry material of 20 mesh;

[0090] Step (3) comprises: adding the glue to the first dry material for dispersion so that the solid content of the system is 80wt%, and controlling the mass ratio of the main binder in the first dry material to the total mass of the dispersible binder and the aqueous binder in the glue to be 2:1, and obtaining a second dry material with a particle size of 30 mesh after drying; based on the mass of the second dry material being 100wt%, the mass of the active material is 96wt%, the mass of the conductive agent is 1wt%, the mass of the main binder is 2wt%, the mass of the dispersible binder is 0.6wt%, and the mass of the aqueous binder is 0.4wt%; in the second dry material, the mass ratio of the main binder, the dispersible binder and the aqueous binder is 5:1.5:1;

[0091] Step (4) comprises: placing the second dry material in a grinding mill and / or a high-speed pulverizer, and pulverizing the powder at 20,000 rpm to form a binder-fiberized powder, wherein the powder has a particle size of 60 mesh;

[0092] Step (5) comprises: using a roller press to press the powder to obtain a dry negative electrode.

[0093] Example 2

[0094] This embodiment provides a method for preparing a dry negative electrode, the method comprising the following steps:

[0095] (1) firstly, using solvent water to prepare a dispersible binder PVP and an aqueous binder PAA into liquid A and liquid B with a mass concentration of 5 wt%, respectively, then mixing liquid A and liquid B, controlling the mass ratio of the dispersible binder to the aqueous binder to be 3:1, and using solvent water to adjust the mass concentration to 5 wt%, to obtain a glue solution; the dispersible binder is a small molecule polymer binder;

[0096] (2) dry-mixing the negative electrode active material carbon-coated silicon particles, the conductive agent carbon nanotubes, and the main binder tetrafluoroethylene-hexafluoropropylene copolymer (FEP) in a high-speed mixer, first performing a first mixing at a first dry mixing speed, then performing a second mixing at a second dry mixing speed higher than the first dry mixing speed, and sieving to obtain a first dry material of 8 mesh;

[0097] (3) adding the glue to the first dry material for dispersion so that the solid content of the system is 70wt%, and controlling the mass ratio of the main binder in the first dry material to the total mass of the dispersible binder and the aqueous binder in the glue to be 2.75:1, and obtaining a second dry material with a particle size of 8 mesh after drying; taking the mass of the second dry material as 100wt%, the mass of the active material is 92wt%, the mass of the conductive agent is 0.5wt%, the mass of the main binder is 5.5wt%, the mass of the dispersible binder is 1.5wt%, and the mass of the aqueous binder is 0.5wt%; in the second dry material, the mass ratio of the main binder, the dispersible binder and the aqueous binder is 11:3:1;

[0098] (4) placing the second dry material in a grinder and / or a high-speed pulverizer and pulverizing it at 1500 rpm to form a binder-fiberized powder with a particle size of 200 mesh;

[0099] (5) The powder is pressed using a roller press to obtain a dry negative electrode.

[0100] Example 3

[0101] This embodiment provides a method for preparing a dry negative electrode, the method comprising the following steps:

[0102] (1) First, a dispersible binder P123 and an aqueous binder SBR are prepared into liquid A and liquid B with a mass concentration of 30 wt% respectively using solvent water, and then liquid A and liquid B are mixed to control the mass ratio of the dispersible binder to the aqueous binder to be 3:1, and the mass concentration is adjusted to 30 wt% using solvent water to obtain a glue solution; the dispersible binder is a small molecule polymer binder;

[0103] (2) dry-mixing the negative electrode active material carbon-coated silicon particles, the conductive agent carbon nanotubes, and the main binder ethylene-tetrafluoroethylene copolymer (ETFE) in a high-speed mixer, first performing a first mixing at a first dry mixing speed, then performing a second mixing at a second dry mixing speed higher than the first dry mixing speed, and sieving to obtain a first dry material of 50 mesh;

[0104] (3) adding the glue to the first dry material for dispersion so that the solid content of the system is 90 wt%, and controlling the mass ratio of the main binder in the first dry material to the total mass of the dispersible binder and the aqueous binder in the glue to be 0.5:1, and obtaining a second dry material with a particle size of 40 mesh after drying; taking the mass of the second dry material as 100 wt%, the mass of the active material is 95.5 wt%, the mass of the conductive agent is 1.5 wt%, the mass of the main binder is 1 wt%, the mass of the dispersible binder is 1.5 wt%, and the mass of the aqueous binder is 0.5 wt%; in the second dry material, the mass ratio of the main binder, the dispersible binder and the aqueous binder is 2:3:1;

[0105] (4) placing the second dry material in a grinder and / or a high-speed pulverizer and pulverizing at 30,000 rpm to form a binder-fiberized powder having a particle size of 35 mesh;

[0106] (5) The powder is pressed using a roller press to obtain a dry negative electrode.

[0107] Example 4

[0108] This embodiment provides a method for preparing a dry negative electrode, wherein in step (1), the mass ratio of the dispersed binder to the aqueous binder is adjusted from 1.5:1 to 4:1, so that in step (3), the mass of the dispersed binder is adjusted from 0.6wt% to 0.8wt%, the mass of the aqueous binder is adjusted from 0.4wt% to 0.2wt%, and the mass ratio of the main binder, the dispersed binder and the aqueous binder is changed from 5:1.5:1 to 10:4:1. Apart from this, the other conditions are exactly the same as those in Example 1.

[0109] Example 5

[0110] This embodiment provides a method for preparing a dry negative electrode, wherein in step (1), the mass ratio of the dispersed binder to the aqueous binder is adjusted from 1.5:1 to 3:1, so that in step (3), the mass of the dispersed binder is adjusted from 0.6wt% to 0.75wt%, the mass of the aqueous binder is adjusted from 0.4wt% to 0.25wt%, and the mass ratio of the main binder, the dispersed binder and the aqueous binder is changed from 5:1.5:1 to 8:3:1. Apart from this, the other conditions are exactly the same as those in Example 1.

[0111] Example 6

[0112] This embodiment provides a method for preparing a dry negative electrode, wherein in step (1), the mass ratio of the dispersed binder to the aqueous binder is adjusted from 1.5:1 to 0.5:1, so that in step (3), the mass of the dispersed binder is adjusted from 0.6wt% to 0.33wt%, the mass of the aqueous binder is adjusted from 0.4wt% to 0.66wt%, and the mass ratio of the main binder, the dispersed binder and the aqueous binder is changed from 5:1.5:1 to 3:0.5:1. Apart from this, the other conditions are exactly the same as those in Example 1.

[0113] Example 7

[0114] This embodiment provides a method for preparing a dry negative electrode, wherein in step (1), the mass ratio of the dispersed binder to the aqueous binder is adjusted from 1.5:1 to 0.33:1, so that in step (3), the mass of the dispersed binder is adjusted from 0.6wt% to 0.25wt%, the mass of the aqueous binder is adjusted from 0.4wt% to 0.66wt%, and the mass ratio of the main binder, the dispersed binder and the aqueous binder is changed from 5:1.5:1 to 2.67:0.33:1. Apart from this, the other conditions are exactly the same as those in Example 1.

[0115] Example 8

[0116] This embodiment provides a method for preparing a dry negative electrode, wherein the method adjusts the amount of the main binder in step (2) so that the ratio of the mass of the main binder to the total mass of the dispersed binder and the aqueous binder in the glue in step (3) is adjusted from 2:1 to 0.5:1, and in step (3), the mass of the active material is adjusted from 96wt% to 97.5wt% and the mass of the main binder is adjusted from 2wt% to 0.5wt%, so that the mass ratio of the main binder, the dispersed binder and the aqueous binder is changed from 5:1.5:1 to 1.25:1.5:1. Apart from this, the other conditions are exactly the same as those in Example 1.

[0117] Example 9

[0118] This embodiment provides a method for preparing a dry negative electrode, wherein the method adjusts the amount of the main binder in step (2) so that the ratio of the mass of the main binder to the total mass of the dispersed binder and the aqueous binder in the glue in step (3) is adjusted from 2:1 to 1:1, and in step (3), the mass of the active material is adjusted from 96wt% to 97wt% and the mass of the main binder is adjusted from 2wt% to 1wt%, so that the mass ratio of the main binder, the dispersed binder and the aqueous binder is changed from 5:1.5:1 to 2.5:1.5:1. Apart from this, the other conditions are exactly the same as those in Example 1.

[0119] Example 10

[0120] This embodiment provides a method for preparing a dry negative electrode, wherein the method adjusts the amount of the main binder in step (2) so that the ratio of the mass of the main binder to the total mass of the dispersed binder and the aqueous binder in the glue in step (3) is adjusted from 2:1 to 3:1, and in step (3), the mass of the active material is adjusted from 96wt% to 95wt% and the mass of the main binder is adjusted from 2wt% to 3wt%, so that the mass ratio of the main binder, the dispersed binder and the aqueous binder is changed from 5:1.5:1 to 7.5:1.5:1. Apart from this, the other conditions are exactly the same as those in Example 1.

[0121] Example 11

[0122] This embodiment provides a method for preparing a dry negative electrode, wherein the method adjusts the amount of the main binder in step (2) so that the ratio of the mass of the main binder to the total mass of the dispersed binder and the aqueous binder in the glue in step (3) is adjusted from 2:1 to 4:1, and in step (3), the mass of the active material is adjusted from 96wt% to 94wt% and the mass of the main binder is adjusted from 2wt% to 4wt%, so that the mass ratio of the main binder, the dispersed binder and the aqueous binder is changed from 5:1.5:1 to 10:1.5:1. Apart from this, the other conditions are exactly the same as those in Example 1.

[0123] Example 12

[0124] This embodiment provides a method for preparing a dry negative electrode. In the method, in step (2), the particle size of the second dry material is adjusted from 30 mesh to 5 mesh. Other than that, the other conditions are exactly the same as those in Example 1.

[0125] Example 13

[0126] This embodiment provides a method for preparing a dry negative electrode. In the method, in step (2), the particle size of the second dry material is adjusted from 30 mesh to 8 mesh. Other conditions are exactly the same as those in Example 1.

[0127] Example 14

[0128] This embodiment provides a method for preparing a dry negative electrode. In the method, in step (2), the particle size of the second dry material is adjusted from 30 mesh to 40 mesh. Other than that, the other conditions are exactly the same as those in Example 1.

[0129] Example 15

[0130] This embodiment provides a method for preparing a dry negative electrode. In the method, in step (2), the particle size of the second dry material is adjusted from 30 mesh to 45 mesh. Other than that, the other conditions are exactly the same as those in Example 1.

[0131] Example 16

[0132] This embodiment provides a method for preparing a dry negative electrode. In the method, in step (4), the particle size of the powder is adjusted from 60 mesh to 35 mesh. Other than that, the other conditions are exactly the same as those in Example 1.

[0133] Example 17

[0134] This embodiment provides a method for preparing a dry negative electrode. In the method, in step (4), the particle size of the powder is adjusted from 60 mesh to 100 mesh. Other conditions are exactly the same as those in Example 1.

[0135] Example 18

[0136] This embodiment provides a method for preparing a dry negative electrode. In the method, in step (4), the particle size of the powder is adjusted from 60 mesh to 200 mesh. Other conditions are exactly the same as those in Example 1.

[0137] Example 19

[0138] This embodiment provides a method for preparing a dry negative electrode. In the method, in step (4), the particle size of the powder is adjusted from 60 mesh to 210 mesh. Other than that, the other conditions are exactly the same as those in Example 1.

[0139] Example 20

[0140] This embodiment provides a method for preparing a dry negative electrode. In the method, in step (1), the aqueous binder is replaced by PEG instead of CMC, so that the dispersible binder is the same as the aqueous binder. Other than that, the other conditions are exactly the same as those in Example 1.

[0141] Comparative Example 1

[0142] This comparative example provides a method for preparing a dry negative electrode, which does not use a dispersible binder and an aqueous binder. That is, in step (1), the dispersible binder and the aqueous binder are replaced with an equal amount of a main binder and prepared into a glue solution for subsequent steps. Apart from this, the other conditions are exactly the same as those in Example 1.

[0143] Comparative Example 2

[0144] This comparative example provides a method for preparing a dry negative electrode, which does not use an aqueous binder. That is, in step (1), the aqueous binder is replaced by an equal amount of a main binder and the main binder is prepared into a glue solution with a dispersible binder for subsequent steps. Apart from this, other conditions are exactly the same as those in Example 1.

[0145] Comparative Example 3

[0146] This comparative example provides a method for preparing a dry negative electrode, which does not use a dispersible binder. That is, in step (1), the dispersible binder is replaced by an equal amount of a main binder and the main binder is prepared into a glue solution with an aqueous binder for subsequent steps. Apart from this, other conditions are exactly the same as those in Example 1.

[0147] The dry-process negative electrode sheets obtained in the examples and comparative examples were assembled into a battery CR-2025 (negative electrode half-cell), and the battery's initial charge and discharge conditions, cycle performance, etc. were tested on a Xinwei battery test cabinet;

[0148] FIG1 is a comparison of the tensile strength of the dry-process negative electrode sheets obtained in Example 1 and Comparative Examples 1-3. It can be seen from the figure that the tensile strength and elongation at break of the membranes prepared by compounding with the main binder without adding other binders and compounding with the main binder with a single binder are lower than those of the membranes prepared by combining the aqueous binder and the dispersible binder as proposed in this application;

[0149] FIG2 is a charge-discharge test curve of the dry-process negative electrode sheets obtained in Example 1 and Comparative Examples 1-3 after being assembled into batteries. It can be seen from the figure that the buckle battery prepared by compounding the membrane without adding other binders with the main binder and compounding the membrane with a single binder with the main binder has higher side reactions at low voltage during discharge than the membrane processed by combining the aqueous binder and the dispersible binder proposed in this application;

[0150] The results of other embodiments and comparative examples are listed in Table 1.

[0151] Table 1

[0152] As can be seen from Table 1:

[0153] From the comparison of Example 1 and Comparative Examples 1-3, it can be seen that the first effect and gram capacity of the battery when only a single aqueous binder or dispersed binder is added are not as good as the effect when the aqueous binder and the dispersed binder are used together; from the comparison of Example 1 and Examples 4-7, it can be seen that the ratio between the aqueous binder and the dispersed binder will affect the gram capacity and the first effect of the battery; from the comparison of Hydrophobic 1 and Examples 8-11, it can be seen that the addition amount of the main binder PTFE has an impact on the gram capacity and the first effect of the battery, and the increase in its usage occupies too much of the usage of the active material, and at this time, the same proportion of aqueous binder and dispersed binder is used. The improvement effect of the adhesive on the incremental main adhesive is weakened; from the comparison of Example 1 and Examples 12-15, it can be seen that if the particle size of the second dry material obtained by adding the glue to disperse is too large, it will affect the dispersion effect, and thus slightly affect the performance of the diaphragm, and from the comparison of Example 1 and Examples 16-19, it can be seen that the particle size of the finally obtained binder fiberized powder is crucial. When the particle size is large, the performance of the diaphragm will be reduced; from the comparison of Example 1 and Example 20, it can be seen that when the water-based binder and the dispersible binder both use the small molecule polymer PEG, it has an impact on the gram capacity and the first effect of the battery, and its effect is not as good as that of Example 1.

Claims

1. A method for preparing a dry electrode, the method comprising the following steps: The dispersible binder and the water-based binder are prepared into a glue solution; dry-mixing the active material, the conductive agent and the main binder to obtain a first dry material; Adding the glue solution to the first dry material to disperse the mixture, and drying the mixture to obtain a second dry material; The second dry material is crushed to form a powder of binder fiberization; Pressing the powder to obtain a dry electrode; The dispersible binder and the water-based binder are prepared into a glue solution and the active material, the conductive agent and the main binder are dry-mixed to obtain the first dry material in no particular order.

2. The method according to claim 1, wherein: The dispersed binder includes a small molecule polymer binder; Preferably, the small molecule polymer binder includes any one of PVP, P123 or PEG or a combination of at least two thereof; Preferably, the aqueous binder includes any one of polyacrylic acid or its salt or copolymer, carboxymethyl cellulose or its salt or copolymer, alginate, SBR emulsion or PEG, or a combination of at least two thereof.

3. The method according to claim 1 or 2, wherein: In the glue solution, the mass ratio of the dispersible binder to the water-based binder is (1-3):1; Preferably, the total mass concentration of the binder in the glue solution is 5 to 30 wt %; Preferably, the method for preparing the glue solution comprises first preparing a dispersible binder and an aqueous binder into liquid A and liquid B with a mass concentration of 5 to 30 wt %, respectively, then mixing liquid A and liquid B, and adjusting the mass concentration to 5 to 30 wt % using a solvent to obtain the glue solution; Preferably, the solvent comprises water.

4. The method according to any one of claims 1 to 3, wherein: The main binder includes polytetrafluoroethylene and / or polytetrafluoroethylene derivatives; Preferably, the polytetrafluoroethylene derivative includes any one of tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer or tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer or a combination of at least two thereof; Preferably, the conductive agent comprises any one of conductive carbon black, nanocarbon fiber, carbon nanotube or graphene, or a combination of at least two thereof; Preferably, when the dry electrode is a negative electrode, the active material includes graphite, silicon-carbon composite material Or any one of silicon-oxygen composite materials or a combination of at least two thereof.

5. The method according to any one of claims 1 to 4, wherein: The dry mixing method comprises first performing a first mixing at a first dry mixing speed, and then performing a second mixing at a second dry mixing speed higher than the first dry mixing speed; Preferably, the dry mixing is carried out in a high-speed mixer with a cutter and a scraper; Preferably, the cutter speed of the first dry mixing speed is 1000-30000 rpm, and the scraper speed is 50-1000 rpm; Preferably, the cutter speed of the second dry mixing speed is 1500-30000 rpm, and the scraper speed is 50-1000 rpm; Preferably, the first mixing time is 1 to 60 minutes; Preferably, the second mixing time is 1 to 60 minutes; Preferably, after the dry mixing, sieving is performed to obtain a first dry material of 8 to 50 mesh.

6. The method according to any one of claims 1 to 5, wherein: Add the glue solution to the first dry material for dispersion, so that the solid content of the system is 70-90wt%, and the ratio of the mass of the main binder in the first dry material to the total mass of the dispersible binder and the water-based binder in the glue solution is controlled to be (0.5-3):1; Preferably, the drying temperature is 0 to 120° C. and the drying time is 2 to 24 hours; Preferably, the particle size of the second dry material is 8 to 40 mesh; Preferably, based on 100wt% of the mass of the second dry material, the mass of the active substance is 92-96wt%; Preferably, based on 100wt% of the mass of the second dry material, the mass of the conductive agent is 0.5-1.5wt%; Preferably, based on 100wt% of the mass of the second dry material, the total mass of the binder is 2.5-8.5wt%; Preferably, in the second dry material, the mass ratio of the main binder, the dispersible binder and the aqueous binder is (1-12):(1-3):1; Preferably, based on 100wt% of the mass of the second dry material, the mass of the main binder is 1-6wt%; Preferably, based on 100wt% of the mass of the second dry material, the mass of the dispersible binder is 1-1.5wt%; Preferably, based on 100 wt % of the mass of the second dry material, the mass of the water-based binder is 0.5-1 wt %.

7. The method according to any one of claims 1 to 6, wherein: The pulverization is carried out in a grinding mill and / or a high-speed pulverizer; Preferably, the pulverizing is carried out at a rotation speed of 1500 to 30000 rpm; Preferably, the particle size of the powder is 35 to 200 mesh; Preferably, the pressing method comprises roller pressing.

8. The method according to any one of claims 1 to 7, wherein: The method of preparing the dispersible binder and the water-based binder into a glue solution comprises: firstly using solvent water to prepare the dispersible binder and the water-based binder into liquid A and liquid B respectively with a mass concentration of 5-30wt%, then mixing liquid A and liquid B, controlling the mass ratio of the dispersible binder to the water-based binder to be (1-3):1, and using solvent water to adjust the mass concentration to 5-30wt% to obtain a glue solution; the dispersible binder is a small molecule polymer binder; The step of dry-mixing the active material, the conductive agent and the main binder to obtain the first dry material comprises: dry-mixing the negative electrode active material, the conductive agent and the main binder in a high-speed mixer, firstly performing a first mixing at a first dry mixing speed, then performing a second mixing at a second dry mixing speed higher than the first dry mixing speed, and sieving to obtain a first dry material of 8 to 50 meshes; the main binder comprises polytetrafluoroethylene and / or a polytetrafluoroethylene derivative; The method of adding the glue to the first dry material for dispersion and drying to obtain the second dry material comprises: adding the glue to the first dry material for dispersion so that the solid content of the system is 70-90wt%, and controlling the mass ratio of the main binder in the first dry material to the total mass of the dispersible binder and the water-based binder in the glue to be (0.5-3):1, and drying at 0-120°C for 2-24h to obtain the second dry material with a particle size of 8-40 mesh; taking the mass of the second dry material as 100wt%, the mass of the active material is 92-96wt%, the mass of the conductive agent is 0.5-1.5wt%, the mass of the main binder is 1-6wt%, the mass of the dispersible binder is 1-1.5wt%, and the mass of the water-based binder is 0.5-1wt%; in the second dry material, the mass ratio of the main binder, the dispersible binder and the water-based binder is (1-12):(1-3):1; The step of crushing the second dry material to form a binder fiberized powder comprises: placing the second dry material in a grinding mill and / or a high-speed powder machine, crushing the second dry material at 1500 to 30000 rpm to form a binder fiberized powder, wherein the particle size of the powder is 35 to 200 meshes; The pressing of the powder to obtain a dry electrode comprises: using a roller press to roll the powder to obtain a dry negative electrode; The dispersible binder and the water-based binder are prepared into a glue solution and the active material, the conductive agent and the main binder are dry-mixed to obtain the first dry material in no particular order.

9. A dry electrode obtained by the method according to any one of claims 1 to 8.

10. A battery comprising the dry electrode according to claim 9.

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