A dry electrode binder, a negative electrode dry powder mixture and its application

Abstract

This invention provides a dry electrode binder, a negative electrode dry powder mixture, and their applications. The dry electrode binder is a polymer binder, and the polymeric monomers of the polymer binder include isocyanate monomers, polypolyol monomers, other hydroxyl-containing monomers, and crosslinking agent monomers. The other hydroxyl-containing monomers are at least one of hydroxyl acrylate resin or hydroxyl liquid nitrile rubber. The negative electrode dry powder mixture includes an active material, a conductive agent, and the dry electrode binder. The dry electrode binder provided by this invention has good adhesion and good ionic conductivity. It forms a negative electrode dry powder mixture with the active material through in-situ polymerization. The dry mixing process in the dry electrode preparation process is dry, and the mixing conditions are mild, overcoming the disadvantage of the PTFE-based dry electrode preparation process, which requires mixing in a high-pressure, high-shear mixing tank. Therefore, it is possible to apply dry electrode technology to the field of lithium-ion batteries.

Description

Technical Field

[0001] This invention belongs to the field of electrode material technology, and relates to a dry electrode binder, a negative electrode dry powder mixture, and their applications. Background Technology

[0002] Currently, the commercially available products using dry electrode technology are supercapacitors, while there are no commercially available lithium-ion batteries using this technology. One reason for this is that the binder system for dry electrodes is not yet fully suitable for lithium-ion battery systems. The binder currently used in dry electrode technology is primarily PTFE, which utilizes its ability to fibrousize under high pressure and high shear to achieve adhesion of the active materials.

[0003] CN111919315A discloses a dry electrode film, comprising: a dry active material and a dry binder. The dry binder includes a fibrillable binder and a non-fibrillable microparticle binder with a D50 particle size of approximately 0.5-40 μm. The dry electrode film is self-supporting, and the fibrillable binder includes polytetrafluoroethylene (PTFE). However, current PTFE-based dry electrode preparation processes require mixing in a high-pressure, high-shear mixing tank, using high-speed shearing to fibrillate the PTFE, uniformly mixing it with the active material, and then high-pressure extrusion coating onto a current collector. This makes it difficult to apply dry electrode technology using such binders to the lithium-ion battery field.

[0004] In this field, it is desirable to develop a non-PTFE dry electrode binder system that overcomes the disadvantage of needing to mix materials in a high-pressure, high-shear mixing tank during the preparation of PTFE dry electrodes, and enables the battery to have good performance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a dry electrode binder, a negative electrode dry powder mixture, and their applications. The dry electrode binder of the present invention exhibits good adhesion and good ionic conductivity, and the mixing conditions during dry electrode preparation are mild, overcoming the disadvantage of requiring mixing in a high-pressure, high-shear mixing tank during the preparation of PTFE-based dry electrodes.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] On one hand, the present invention provides a dry electrode adhesive, wherein the dry electrode adhesive is a polymer adhesive, and the polymeric monomers of the polymer adhesive include isocyanate monomers, polypolyol monomers, other hydroxyl-containing monomers and crosslinking agent monomers, wherein the other hydroxyl-containing monomers are at least one of hydroxyl acrylate resin or hydroxyl liquid nitrile rubber.

[0008] In this invention, the dry electrode binder can also be called a "modified polyurethane dry electrode binder". It is a modified polyurethane dry electrode binder obtained by selecting isocyanate monomers and polypolyol monomers, with at least one of hydroxy acrylate or hydroxy liquid nitrile rubber and crosslinking agent monomers. It has good adhesion and good ionic conductivity and can replace the PTFE system. The dry electrode binder of this invention has mild mixing conditions in the dry electrode preparation process, which overcomes the disadvantage of needing to mix in a high-pressure and high-shear mixing tank in the dry electrode preparation process using PTFE.

[0009] In this invention, polyurethane (PU) is short for polyurethane, which is formed by the addition polymerization of polyisocyanate and polyhydroxy polymer. It is a polymer compound containing many repeating urethane segments (-NHCOO-) in the main polymer chain. The materials selected in this invention are polyisocyanate and polyhydroxy polymer (which are low molecular weight polymers).

[0010] In this invention, the polymer monomer is liquid, but the binder obtained after the reaction is in a solid state, which perfectly meets the requirements for dry electrode binders used in the preparation of dry electrodes. This dry electrode binder acts as a binder for active materials (e.g., graphite) or for binding active materials (e.g., graphite) to current collectors when preparing negative electrode dry powder mixtures or dry electrode negative electrodes. Furthermore, this invention requires the binder to have good flexibility and cohesiveness, which the modified polyurethane dry electrode binder perfectly meets. Moreover, this invention can also prepare solvent-free modified polyurethane dry electrode binders that can be uniformly mixed with active materials (e.g., graphite).

[0011] In this invention, the polymeric monomers of the polymeric binder, after being mixed with the active material (e.g., graphite) and the conductive agent, can ensure uniform mixing with the active material. Furthermore, the polymeric monomers undergo a polymerization reaction on the surfaces of the active material and the conductive agent to obtain the polymeric binder, which enables the binder to be uniformly distributed in the active material (e.g., graphite) and the conductive agent. At the same time, some isocyanates can also react with active groups such as hydroxyl groups on the surface of the active material (e.g., graphite), increasing the adhesion between the binder and the active material (e.g., graphite).

[0012] Generally, materials with large molecular weights cannot be uniformly mixed with active materials (such as graphite) with a size of tens of micrometers. This invention directly synthesizes a solvent-free modified polyurethane dry electrode binder on the surface of the active material. The reactants of isocyanate and polyol small molecules in the modified polyurethane dry electrode binder are directly mixed with a mixture of hydroxy acrylate or hydroxy liquid nitrile rubber and the active material, achieving uniform mixing of the binder and the active material. At the same time, the hydroxy acrylate or hydroxy liquid nitrile rubber also reacts with the isocyanate in the modified polyurethane dry electrode binder reactants, and the hydroxyl groups in the acrylate also participate in the reaction of the modified polyurethane dry electrode binder, realizing the cross-linking of the two binders. The appropriate degree of cross-linking between the two forms a cross-linked network, which better binds the active material. After being rolled into a graphite film, it has higher cohesive strength.

[0013] In this invention, the isocyanate groups in the isocyanate monomer react with the polyol to generate polyurethane. The isocyanate groups can also react with the hydroxyl groups in hydroxyl acrylate or hydroxyl liquid nitrile rubber to generate modified polyurethane (e.g., polyurethane-acrylate, polyurethane-nitrile rubber), which is uniformly distributed in the active material (e.g., graphite). This achieves crosslinking of various binders, and the appropriate degree of crosslinking forms a crosslinking network, which can better bond the active material. At the same time, the isocyanate groups in the isocyanate react with the active groups such as hydroxyl groups on the surface of the active material (e.g., graphite) to increase the adhesion between the binder and the active material (e.g., graphite).

[0014] The performance of modified polyurethane materials largely depends on the phase structure of the hard and soft segments and the degree of microphase separation. In this invention, the main function of the isocyanate monomer is to provide the hard segment, thereby enhancing the cohesive strength of the modified polyurethane dry electrode adhesive. Isocyanates are highly polar compounds with -NCO groups at the ends of their molecular chains. These highly polar -NCO groups can react with active hydrogen atoms such as water, hydroxyl groups, and amine groups to form cross-linked structures. The polar groups can also interact to form strong hydrogen bonds, thereby increasing the overall cohesive strength and rigidity of the polymer and improving adhesive strength. In this invention, the main function of the polyol monomer is to provide the soft segment in the polyurethane structure, directly affecting the flexibility, temperature resistance, and other properties of the modified polyurethane dry electrode adhesive.

[0015] In this invention, hydroxyacrylate has excellent thermal stability and good electrochemical stability. It remains stable in the redox environment of lithium-ion batteries without side reactions, has good storage stability, is easy to transport and store, and is stable in electrolytes, which enables the battery to have good rate performance and excellent low-temperature performance.

[0016] In this invention, liquid nitrile rubber has excellent mechanical properties, which can improve the cohesive force of the adhesive, have good electrolyte resistance, good heat resistance, and improve the bonding strength of the adhesive.

[0017] Preferably, the isocyanate monomer comprises any one or a combination of at least two of the following: toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate (NDI), dimethylbiphenyl diisocyanate (TODI), hexamethylene diisocyanate (HDI), hexamethylene diisocyanate biuret, hexamethylene diisocyanate trimer, 2,2,4-trimethylhexane diisocyanate (TMDI), phenyl dimethyl diisocyanate (XDI), tetramethylphenyl dimethyl diisocyanate (TMXDI), hydrogenated phenyl dimethyl diisocyanate (HXDI), isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (HMDI), methylcyclohexane diisocyanate (HTDI), 1,4-phenyl diisocyanate (PPDI), or norbornene diisocyanate (NBDI).

[0018] Preferably, the polypolyol monomer comprises any one or a combination of at least two of polyester polyols or polyether polyols. Polyester polyols contain a large number of ester groups (-COO-), exhibiting strong polarity, resulting in modified polyurethane dry electrode adhesives with excellent performance, heat resistance, and oil resistance. Polyether polyols contain a large number of ether groups (-COC-), are not easily hydrolyzed, resulting in modified polyurethane dry electrode adhesives with excellent hydrolysis resistance, good low-temperature resistance, and high molecular chain flexibility.

[0019] Preferably, the polyester polyol comprises a polycarbonate polyol.

[0020] Preferably, the number average molecular weight of the hydroxy acrylate resin is 500-3000, such as 500, 1000, 1500, 1800, 2000, 2300, 2500, 2800 or 3000.

[0021] Preferably, the hydroxyacrylate resin comprises any one or a combination of at least two of styrene (St), acrylic acid (AA), butyl acrylate (BA), butyl methacrylate (BMA), hydroxyethyl methacrylate (HEMA), hydroxyethyl acrylate (HEA), hydroxypropyl methacrylate (HPMA), or hydroxypropyl acrylate (HPA).

[0022] In this invention, the crosslinking agent acts as a grafting agent with the monomers (isocyanate monomers and polypolyol monomers) that form polyurethane, thereby extending the molecular chains of polyurethane and increasing the molecular weight of polyurethane. The addition of the crosslinking agent improves the mechanical properties and other properties of the material.

[0023] Preferably, the crosslinking agent monomer includes any one or a combination of at least two of the following: diol crosslinking agents, triol crosslinking agents, diamine crosslinking agents, alkanolamine crosslinking agents, alicyclic alcohol crosslinking agents, aromatic alcohol crosslinking agents, glycerol allyl ether, glycidyl allyl ether, or dicumyl peroxide.

[0024] Preferably, the diol crosslinking agent includes any one or a combination of at least two of 1,4-butanediol, ethylene glycol, propylene glycol, diethylene glycol, or neopentyl glycol.

[0025] Preferably, the triol crosslinking agent includes glycerol and / or trimethylolpropane.

[0026] Preferably, the diamine crosslinking agent includes any one or a combination of at least two of 3,3-dichloro-4,4-diaminodiphenylmethane, 3,5-dimethylthiotoluenediamine, 3,5-diethyltoluenediamine, 2,4-diamino-3,5-dimethylthiochlorobenzene, or isophoronediamine.

[0027] Preferably, the alkanolamine crosslinking agent includes any one or a combination of at least two of ethanolamine, diethanolamine, triethanolamine or N,N-bis(2-hydroxypropyl)aniline.

[0028] Preferably, the alicyclic alcohol crosslinking agent includes 1,4-cyclohexanediol and / or hydrogenated bisphenol A.

[0029] Preferably, the aromatic alcohol crosslinking agent includes any one or a combination of at least two of dimethylene phenyl glycol, hydroquinone bis-β-hydroxyethyl ether, or resorcinol hydroxy ether.

[0030] Preferably, the number average molecular weight of the dry electrode adhesive is 30,000-80,000, for example, 30,000, 40,000, 50,000, 60,000, 70,000 or 80,000.

[0031] On the other hand, the present invention provides a negative electrode dry powder mixture, the negative electrode dry powder mixture comprising an active material, a conductive agent and a dry electrode binder as described above, the dry electrode binder being coated on the surfaces of the active material and the conductive agent.

[0032] Preferably, the dry electrode binder is obtained by in-situ polymerization on the surface of the active material and the conductive agent.

[0033] In-situ polymerization involves directly mixing the binder reactive monomers with the active material, and then reacting and polymerizing them on the surface of the active material to form a binder, thereby achieving a uniform mixture of the binder and the active material.

[0034] In-situ polymerization differs from conventional polymerization. Conventional polymerization synthesizes high-molecular-weight binders separately, which are then mixed with or coated onto the substrate. Conventional polymerization methods cannot uniformly mix binders with active materials (such as graphite) that are only tens of micrometers in size. In in-situ polymerization, low-molecular-weight monomers can be uniformly mixed with the active material, and then the monomers polymerize on the surface of the active material to form a high-molecular-weight binder, which is then uniformly mixed between the active materials.

[0035] In this invention, a dry electrode binder is obtained by in-situ polymerization on the surface of the active material and the conductive agent, achieving uniform mixing of the binder, active material, and conductive agent. Simultaneously, hydroxyl acrylate or hydroxyl liquid nitrile rubber reacts with the isocyanate in the modified polyurethane dry electrode binder reactants, forming a cross-linked network that better bonds the active material. This results in higher cohesive strength after being rolled into a graphite film. The reactants react directly on the surface of the active material (e.g., graphite) to obtain the polymer. Furthermore, the reactants can react with active groups such as hydroxyl groups on the surface of the active material (e.g., graphite), increasing the adhesion between the binder and the active material (e.g., graphite).

[0036] Preferably, the active material includes one or a combination of at least two of graphite, silicon, silicon-based oxides, silicon-carbon materials, lithium titanate, graphene, or tin-based composite oxides, with graphite being the most preferred.

[0037] Preferably, the graphite includes one or a combination of at least two of the following: natural graphite, artificial graphite, amorphous carbon, or mesophase carbon microspheres;

[0038] Preferably, the conductive agent includes one or a combination of at least two of conductive graphite, acetylene black, carbon nanotubes, or conductive carbon black;

[0039] Preferably, the weight percentage of active material in the negative electrode dry powder mixture is 93%-98.5% (93%, 94%, 95%, 96%, 97%, 98% or 98.5%), the weight percentage of dry electrode binder is 1%-5% (e.g. 1%, 2%, 3%, 4% or 5%), and the weight percentage of conductive agent is 0.5%-2% (e.g. 0.5%, 0.8%, 1%, 1.5%, 1.8% or 2%).

[0040] On the other hand, the present invention provides a method for preparing the negative electrode dry powder mixture as described above, the preparation method comprising the following steps:

[0041] The monomers are mixed and then mixed with active materials and conductive agents to carry out a polymerization reaction to obtain the negative electrode dry powder mixture. The monomers include isocyanate monomers, polypolyol monomers, other hydroxyl-containing monomers and crosslinking agent monomers. The other hydroxyl-containing monomers are at least one of hydroxyl acrylate resin or hydroxyl liquid nitrile rubber.

[0042] In this invention, the monomers are first mixed, then mixed with the active material and conductive agent. This enhances the uniform mixing of the monomers and active material, followed by in-situ polymerization. This results in a uniform distribution of the high molecular weight polymer binder among the micron-sized active material (e.g., graphite). The core reason for using this method is to achieve uniform distribution among the active material (e.g., graphite). If the binder is polymerized first and then mixed with the active material (e.g., graphite), the binder, being solvent-free and with a viscosity of tens of thousands, will result in uneven distribution. Too much or too little binder will prevent the dry electrode from being rolled into a solid electrode, or the resulting dry electrode will have poor uniformity, leading to significant differences in battery performance.

[0043] Generally, materials with large molecular weights cannot be uniformly mixed with active materials (such as graphite) with a size of tens of micrometers. This invention directly synthesizes a solvent-free modified polyurethane dry electrode binder on the surface of the active material. The reactants of the modified polyurethane dry electrode binder reactants, namely isocyanate and polyol small molecules, are directly mixed with a mixture of hydroxy acrylate or hydroxy liquid nitrile rubber and the active material, achieving uniform mixing of the binder and the active material. At the same time, the hydroxy acrylate or hydroxy liquid nitrile rubber also reacts with the isocyanate in the reactants, and the hydroxyl groups in the acrylate also participate in the reaction of the modified polyurethane dry electrode binder, realizing the cross-linking of the two binders. The appropriate degree of cross-linking of the two forms a cross-linked network, which better binds the active material. After being rolled into a graphite film, it has higher cohesive strength.

[0044] In this invention, the isocyanate groups in the isocyanate monomer react with the polyol to generate polyurethane. The isocyanate groups can also react with the hydroxyl groups in hydroxyl acrylate or hydroxyl liquid nitrile rubber to generate modified polyurethane (e.g., polyurethane-acrylate, polyurethane-nitrile rubber), which is uniformly distributed in the active material (e.g., graphite). This achieves crosslinking of various binders, and the appropriate degree of crosslinking forms a crosslinking network, which can better bond the active material. At the same time, the isocyanate groups in the isocyanate react with the active groups such as hydroxyl groups on the surface of the active material (e.g., graphite) to increase the adhesion between the binder and the active material (e.g., graphite).

[0045] Preferably, the isocyanate monomer comprises any one or a combination of at least two of the following: toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate (NDI), dimethylbiphenyl diisocyanate (TODI), hexamethylene diisocyanate (HDI), hexamethylene diisocyanate biuret, hexamethylene diisocyanate trimer, 2,2,4-trimethylhexane diisocyanate (TMDI), phenyl dimethyl diisocyanate (XDI), tetramethylphenyl dimethyl diisocyanate (TMXDI), hydrogenated phenyl dimethyl diisocyanate (HXDI), isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (HMDI), methylcyclohexane diisocyanate (HTDI), 1,4-phenyl diisocyanate (PPDI), or norbornene diisocyanate (NBDI).

[0046] Preferably, the polyol monomer comprises any one or a combination of at least two of polyester polyols or polyether polyols.

[0047] Preferably, the polyester polyol comprises a polycarbonate polyol.

[0048] Preferably, the number average molecular weight of the hydroxy acrylate resin is 500-3000, such as 500, 1000, 1500, 1800, 2000, 2300, 2500, 2800 or 3000.

[0049] Preferably, the hydroxyacrylate resin comprises any one or a combination of at least two of styrene (St), acrylic acid (AA), butyl acrylate (BA), butyl methacrylate (BMA), hydroxyethyl methacrylate (HEMA), hydroxyethyl acrylate (HEA), hydroxypropyl methacrylate (HPMA), or hydroxypropyl acrylate (HPA).

[0050] Preferably, the polymeric monomer is a polymeric monomer that has undergone dehydration treatment. For example, the polyol monomer and the crosslinking agent monomer are first subjected to dehydration treatment.

[0051] Preferably, the molar ratio of isocyanate groups in the isocyanate monomer to hydroxyl groups in the polyol monomer is 1.2:1-4:1, for example, 1.2:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, or 4:1. Experiments have shown that within this range, modified polyurethane dry electrode adhesives with suitable hardness, flexibility, and cohesion can be obtained. Below 1.2:1, the content of the soft segment polyol is too high, and the hardness content is low, resulting in an adhesive that is too soft and lacks cohesion. Above 4:1, the content of the hard segment is too high, resulting in an adhesive that is too hard and lacks flexibility.

[0052] Preferably, the molar ratio of isocyanate groups in the isocyanate monomer to hydroxyl groups in other hydroxyl-containing monomers is 1.2:1-12:1, for example, 1.2:1, 1.5:1, 2:1, 3:1, 5:1, 7:1, 9:1, 10:1, or 12:1. Experiments show that within this range, a modified polyurethane dry electrode binder with suitable hardness, flexibility, and cohesion can be obtained. Excessive content of soft-segment hydroxyl monomers will result in a soft binder with low cohesion. Excessive content of hard isocyanate will result in a hard binder with poor flexibility. The hydroxyl-butadiene-acrylic resin and hydroxyl-acrylic resin used simultaneously have high viscosity; using high amounts will result in a high viscosity solution after mixing, affecting the uniformity of mixing with graphite. A certain ratio range should be selected based on experiments.

[0053] Preferably, the crosslinking agent monomer includes any one or a combination of at least two of the following: diol crosslinking agents, triol crosslinking agents, diamine crosslinking agents, alkanolamine crosslinking agents, alicyclic alcohol crosslinking agents, aromatic alcohol crosslinking agents, glycerol allyl ether, glycidyl allyl ether, or dicumyl peroxide.

[0054] Preferably, the diol crosslinking agent includes any one or a combination of at least two of 1,4-butanediol, ethylene glycol, propylene glycol, diethylene glycol, or neopentyl glycol.

[0055] Preferably, the triol crosslinking agent includes glycerol and / or trimethylolpropane.

[0056] Preferably, the diamine crosslinking agent includes any one or a combination of at least two of 3,3-dichloro-4,4-diaminodiphenylmethane, 3,5-dimethylthiotoluenediamine, 3,5-diethyltoluenediamine, 2,4-diamino-3,5-dimethylthiochlorobenzene, or isophoronediamine.

[0057] Preferably, the alkanolamine crosslinking agent includes any one or a combination of at least two of ethanolamine, diethanolamine, triethanolamine or N,N-bis(2-hydroxypropyl)aniline.

[0058] Preferably, the alicyclic alcohol crosslinking agent includes 1,4-cyclohexanediol and / or hydrogenated bisphenol A.

[0059] Preferably, the aromatic alcohol crosslinking agent includes any one or a combination of at least two of dimethylene phenyl glycol, hydroquinone bis-β-hydroxyethyl ether, or resorcinol hydroxy ether.

[0060] Preferably, the molar ratio of isocyanate groups in the isocyanate monomer to reactive groups in the crosslinking agent is 1.3:1-12:1, for example, 1.3:1, 1.5:1, 2:1, 3:1, 5:1, 7:1, 8:1, 10:1, 11:1, or 12:1. The crosslinking agent also acts as a hard segment in the modified polyurethane dry cell battery adhesive, while simultaneously extending the chain to increase molecular weight and improve cohesion. Maintaining the crosslinking agent content within a suitable range is essential for obtaining a modified polyurethane dry cell battery adhesive with good flexibility and cohesion. Too low a crosslinking agent content leads to insufficient chain extension, resulting in a smaller molecular weight and weaker cohesion in the modified polyurethane dry cell battery adhesive. Conversely, too high a crosslinking agent content results in a smaller molecular weight and a harder adhesive with poor cohesion.

[0061] The active material includes one or a combination of at least two of the following: graphite, silicon, silicon-based oxides, silicon-carbon materials, lithium titanate, graphene, or tin-based composite oxides, with graphite being preferred.

[0062] Preferably, the graphite includes one or a combination of at least two of the following: natural graphite, artificial graphite, amorphous carbon, or mesophase carbon microspheres.

[0063] Preferably, the conductive agent includes one or a combination of at least two of conductive graphite, acetylene black, carbon nanotubes, or conductive carbon black.

[0064] In this invention, the mixing is performed using a high-speed mixer. Because in-situ polymerization is employed, the low-viscosity liquid monomers and active materials are uniformly dispersed under high-speed shear, resulting in a moist active material. After polymerization, a dry, solvent-free binder-based active material composite material is formed.

[0065] Preferably, the polymerization reaction is carried out at a temperature of 25-80°C, for example, 25°C, 30°C, 40°C, 50°C, 60°C, 70°C or 80°C.

[0066] Preferably, the polymerization reaction takes 1-7 days, for example, 1 day, 2 days, 3 days, 4 days, 5 days, 6 days or 7 days.

[0067] Compared with traditional wet slurry, the negative electrode dry powder mixture of the present invention for dry electrodes has significant advantages in terms of storage stability and transportation convenience.

[0068] On the other hand, the present invention provides a dry electrode negative electrode comprising a negative electrode dry powder mixture as described above.

[0069] On the other hand, the present invention provides a method for preparing the dry electrode negative electrode as described above, wherein the preparation method is: hot-rolling a mixture of negative electrode dry powder into a self-supporting film or directly hot-rolling it onto a current collector to form a dry electrode negative electrode.

[0070] Preferably, the negative electrode dry powder mixture is ground and pulverized before hot rolling.

[0071] Preferably, the temperature range of the hot roller pressing is 25-120℃, for example 25℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃ or 120℃.

[0072] The hot rolling process can be performed more than once to achieve a specific electrode thickness and good adhesion to the current collector.

[0073] The negative electrode dry powder mixture of this invention is suitable for the dry electrode negative electrode process route of pure dry method (dry mixing and dry coating), which can ensure good dispersion of active material. At the same time, the negative electrode dry powder mixture undergoes a certain degree of deformation during the hot rolling process of dry mixing and dry coating, changing from a spherical structure to a non-spherical structure, thereby providing a larger bonding area with the active material and achieving higher adhesion. The above process is different from the fibrillation process of PTFE. Instead, it produces a certain degree of deformation during dry processing, which is beneficial to the improvement of adhesion.

[0074] On the other hand, the present invention provides an electrochemical energy storage device, the electrochemical energy storage device comprising the dry electrode negative electrode as described above;

[0075] Preferably, the electrochemical energy storage device is selected from one of lithium-ion batteries, sodium-ion batteries, supercapacitors, fuel cells, or solar cells.

[0076] The dry electrode anode preparation process of the present invention realizes a solvent-free dry electrode manufacturing process throughout the entire process, which can overcome the disadvantage of the dry electrode preparation process using PTFE, which requires mixing in a high-pressure, high-shear mixing tank. Thus, it is possible to apply dry electrode technology to the field of lithium-ion batteries or energy storage devices such as supercapacitors.

[0077] Compared with the prior art, the present invention has the following beneficial effects:

[0078] The dry electrode binder provided by this invention has good adhesion and good ionic conductivity. The polymer monomers of the dry electrode binder are mixed with active materials and conductive agents to achieve uniform mixing. Then, in-situ polymerization is used to form a negative electrode dry powder mixture with active materials and conductive agents. The dry electrode negative electrode is obtained by using a dry preparation process. The dry mixing process in the dry electrode preparation process is mild and overcomes the disadvantage of the dry electrode preparation process using PTFE, which requires mixing in a high-pressure and high-shear mixing tank. Thus, the dry electrode technology can be applied to the field of lithium-ion batteries. Detailed Implementation

[0079] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0080] Example 1

[0081] In this embodiment, a dry electrode binder, a negative electrode dry powder mixture, and a method for preparing the same are provided. The dry electrode binder is a polymer binder obtained by polymerizing polycarbonate polyol, hexamethylene diisocyanate trimer, hydroxyl liquid nitrile rubber, and crosslinking agent 1,4-butanediol as polymerizing monomers.

[0082] The preparation method of the negative electrode dry powder mixture includes the following steps:

[0083] (1) Add 21.18g of dehydrated polycarbonate polyol (Ube Industries PH-300), 2.82g of hexamethylene diisocyanate trimer, 0.252g of crosslinking agent 1,4-butanediol and 2.27g of hydroxyl liquid nitrile rubber (Jining Tangyi Chemical Co., Ltd. TL910) to a mixing tank and mix for 10min at 2000rpm in a defoamer.

[0084] (2) Take 1.6g of the mixture obtained in step (1) and add it to the mixture of graphite and conductive carbon (18.2g graphite and 0.2g conductive carbon). Mix the mixture at 2000rpm for 10min in a defoamer. Then place it at 25℃ for 7 days until the binder is cured to obtain the negative electrode dry powder mixture.

[0085] Example 2

[0086] In this embodiment, a dry electrode binder, a negative electrode dry powder mixture, and a method for preparing the same are provided. The dry electrode binder is a polymer binder obtained by polymerizing polyether polyol, trimethylhexamethylene diisocyanate, hydroxy acrylate, and trimethylolpropane as a crosslinking agent.

[0087] The preparation method of the negative electrode dry powder mixture includes the following steps:

[0088] (1) Add 22.14g of dehydrated polyether polyol (BASF, polytetrahydrofuran ether PTMG3000), 1.86g of trimethylhexamethylene diisocyanate, 0.273g of crosslinking agent trimethylolpropane and 1.37g of hydroxy acrylate (Qingdao Linke Industry & Trade Co., Ltd. OX7000L) to the mixing tank and mix for 10min at 2000rpm in a defoamer.

[0089] (2) Take 1.6g of the mixture obtained in step (1) and add it to the mixture of graphite and conductive carbon (18.2g graphite and 0.2g conductive carbon). Mix the mixture at 2000rpm for 10min in a defoamer. Then place it at 25℃ for 7 days until the binder is cured to obtain the negative electrode dry powder mixture.

[0090] Example 3

[0091] In this embodiment, a dry electrode binder, a negative electrode dry powder mixture, and a method for preparing the same are provided. The dry electrode binder is a polymer binder obtained by polymerizing polyether polyol, hexamethylene diisocyanate, hydroxy acrylate, and crosslinking agent 1,6-hexanediol as polymer monomers.

[0092] The preparation method of the negative electrode dry powder mixture includes the following steps:

[0093] (1) Add 18.21g of dehydrated polyether polyol (Mitsubishi Chemical Corporation, PTMG2000), 5.79g of hexamethylene diisocyanate, 0.284g of crosslinking agent 1,6-hexanediol and 51.40g of hydroxy acrylate (Toa Synthetic Co., Ltd., UH-2000) to a mixing tank and mix for 10min at 2000rpm in a defoamer.

[0094] (2) Take 1.0g of the mixture obtained in step (1) and add it to the mixture of graphite and conductive carbon (18.8g of graphite and 0.2g of conductive carbon). Mix the mixture at 2000rpm for 10min in a defoamer. Then place it in a 60℃ oven to react for 3 days until the binder is cured to obtain the negative electrode dry powder mixture.

[0095] Example 4

[0096] In this embodiment, a dry electrode binder, a negative electrode dry powder mixture, and a method for preparing the same are provided. The dry electrode binder is a polymer binder obtained by polymerizing polycarbonate polyol, hexamethylene diisocyanate trimer, hydroxyl liquid nitrile rubber, and crosslinking agent 1,4-butanediol as polymerizing monomers.

[0097] The preparation method of the negative electrode dry powder mixture includes the following steps:

[0098] (1) Add 16.62g of dehydrated polycarbonate polyol (Ube Industries, Inc. PH-300), 7.38g of hexamethylene diisocyanate trimer, 0.198g of crosslinking agent 1,4-butanediol and 23.69g of hydroxyl liquid nitrile rubber (Jining Tangyi Chemical Co., Ltd. TL910) to a mixing tank and mix for 10min at 2000rpm in a defoamer.

[0099] (2) Take 1.6g of the mixture obtained in step (1) and add it to the mixture of graphite and conductive carbon (18.2g graphite and 0.2g conductive carbon). Mix the mixture at 2000rpm for 10min in a defoamer. Then place it at 40℃ for 4 days until the binder is cured to obtain the negative electrode dry powder mixture.

[0100] Example 5

[0101] In this embodiment, a dry electrode binder, a negative electrode dry powder mixture, and a method for preparing the same are provided. The dry electrode binder is a polymer binder obtained by polymerizing polycarbonate polyol, hexamethylene diisocyanate trimer, hydroxyl liquid nitrile rubber, and crosslinking agent 1,4-butanediol as polymerizing monomers.

[0102] The preparation method of the negative electrode dry powder mixture includes the following steps:

[0103] (1) Add 18.78g of dehydrated polycarbonate polyol (Ube Industries, Inc. PH-300), 5.22g of hexamethylene diisocyanate trimer, 0.223g of crosslinking agent 1,4-butanediol, and 13.42g of hydroxyl liquid nitrile rubber (Jining Tangyi Chemical Co., Ltd. TL910) to a mixing tank and mix for 10min at 2000rpm in a defoamer.

[0104] (2) Take 1.6g of the mixture obtained in step (1) and add it to the mixture of graphite and conductive carbon (18.2g graphite and 0.2g conductive carbon). Mix the mixture at 2000rpm for 10min in a defoamer. Then place it at 70℃ for 1 day until the binder is cured to obtain the negative electrode dry powder mixture.

[0105] Example 6

[0106] In this embodiment, a dry electrode binder, a negative electrode dry powder mixture, and a method for preparing the same are provided. The dry electrode binder is a polymer binder obtained by polymerizing polyether polyol, trimethylhexamethylene diisocyanate, hydroxy acrylate, and trimethylolpropane as a crosslinking agent.

[0107] The preparation method of the negative electrode dry powder mixture includes the following steps:

[0108] (1) Add 18.75g of dehydrated polyether polyol (BASF, polytetrahydrofuran ether PTMG3000), 5.25g of trimethylhexamethylene diisocyanate, 0.224g of crosslinking agent trimethylolpropane and 15.54g of hydroxy acrylate (Qingdao Linke Industry & Trade Co., Ltd. OX7000L) to the mixing tank and mix for 10min at 2000rpm in a defoamer.

[0109] (2) Take 1.6g of the mixture obtained in step (1) and add it to the mixture of graphite and conductive carbon (18.2g graphite and 0.2g conductive carbon). Mix the mixture at 2000rpm for 10min in a defoamer. Then place it at 45℃ for 5 days until the binder is cured to obtain the negative electrode dry powder mixture.

[0110] Example 7

[0111] In this embodiment, a dry electrode binder, a negative electrode dry powder mixture, and a method for preparing the same are provided. The dry electrode binder is a polymer binder obtained by polymerizing polyether polyol, isoflurane diisocyanate, hydroxy acrylate, and trimethylolpropane as a crosslinking agent.

[0112] The preparation method of the negative electrode dry powder mixture includes the following steps:

[0113] (1) Add 19.68g of dehydrated polyether polyol (BASF, polytetrahydrofuran ether PTMG3000), 4.32g of isoflurane diisocyanate, 0.243g of crosslinking agent trimethylolpropane and 8.11g of hydroxy acrylate (Qingdao Linke Industry & Trade Co., Ltd. OX7000L) to the mixing tank and mix for 10min at 2000rpm in a defoamer.

[0114] (2) Take 1.6g of the mixture obtained in step (1) and add it to the mixture of graphite and conductive carbon (18.2g graphite and 0.2g conductive carbon). Mix the mixture at 2000rpm for 10min in a defoamer. Then place it at 70℃ for 1 day until the binder is cured to obtain the negative electrode dry powder mixture.

[0115] Example 8

[0116] In this embodiment, a dry electrode binder, a negative electrode dry powder mixture, and a method for preparing the same are provided. The dry electrode binder is a polymer binder obtained by polymerizing polyether polyol, trimethylhexamethylene diisocyanate, hydroxy acrylate, and trimethylolpropane as a crosslinking agent.

[0117] The preparation method of the negative electrode dry powder mixture includes the following steps:

[0118] (1) Add 20.43g of dehydrated polyether polyol (BASF, polytetrahydrofuran ether PTMG3000), 3.57g of trimethylhexamethylene diisocyanate, 0.252g of crosslinking agent trimethylolpropane, and 8.43g of hydroxy acrylate (Qingdao Linke Industry & Trade Co., Ltd. OX7000L) to a mixing tank and mix for 10min at 2000rpm in a defoamer.

[0119] (2) Take 1.6g of the mixture obtained in step (1) and add it to the mixture of graphite and conductive carbon (18.2g graphite and 0.2g conductive carbon). Mix the mixture at 2000rpm for 10min in a defoamer. Then place it at 60℃ for 4 days until the binder is cured to obtain the negative electrode dry powder mixture.

[0120] Example 9

[0121] In this embodiment, a dry electrode binder, a negative electrode dry powder mixture, and a method for preparing the same are provided. The dry electrode binder is a polymer binder obtained by polymerization of polyether polyol, trimethylhexamethylene diisocyanate, hydroxy acrylate, and crosslinking agent 1,6-hexanediol as monomers.

[0122] The preparation method of the negative electrode dry powder mixture includes the following steps:

[0123] (1) Add 19.83g of dehydrated polyether polyol (BASF, polytetrahydrofuran ether PTMG3000), 4.16g of trimethylhexamethylene diisocyanate, 0.309g of crosslinking agent 1,6-hexanediol, 4.09g of hydroxyl acrylate (Qingdao Linke Industry & Trade Co., Ltd. OX7000L) and 7.09g of hydroxyl liquid nitrile rubber (Jining Tangyi Chemical Co., Ltd. TL910) to a mixing tank and mix for 10min at 2000rpm in a defoamer.

[0124] (2) Take 1.6g of the mixture obtained in step (1) and add it to the mixture of graphite and conductive carbon (18.2g graphite and 0.2g conductive carbon). Mix the mixture at 2000rpm for 10min in a defoamer. Then place it at 60℃ for 4 days until the binder is cured to obtain the negative electrode dry powder mixture.

[0125] Example 10

[0126] In this embodiment, a dry electrode binder, a negative electrode dry powder mixture, and a method for preparing the same are provided. The dry electrode binder is a polymer binder obtained by polymerizing polyether polyol, isoflurane diisocyanate, hydroxy acrylate, and crosslinking agent 1,6-hexanediol as polymer monomers.

[0127] The preparation method of the negative electrode dry powder mixture includes the following steps:

[0128] (1) Add 19.68g of dehydrated polyether polyol (BASF, polytetrahydrofuran ether PTMG3000), 4.32g of isoflurane diisocyanate, 0.307g of crosslinking agent 1,6-hexanediol, and 8.11g of hydroxy acrylate (Qingdao Linke Industry & Trade Co., Ltd. OX7000L) to a mixing tank and mix for 10min at 2000rpm in a defoamer.

[0129] (2) Take 1.6g of the mixture obtained in step (1) and add it to the mixture of graphite and conductive carbon (18.2g graphite and 0.2g conductive carbon). Mix the mixture at 2000rpm for 10min in a defoamer. Then place it at 70℃ for 1 day until the binder is cured to obtain the negative electrode dry powder mixture.

[0130] Comparative Example 1

[0131] The only difference from Example 1 is that the hydroxy acrylate is replaced with hydroxyl-terminated polybutadiene (Tianyuan Aviation Materials (Yingkou) Technology Co., Ltd. hydroxyl-terminated polybutadiene-I type).

[0132] Comparative Example 2

[0133] The only difference from Example 2 is that the hydroxy acrylate is replaced with hydroxyl-terminated polybutadiene (Tianyuan Aviation Materials (Yingkou) Technology Co., Ltd. hydroxyl-terminated polybutadiene-I type).

[0134] Comparative Example 3

[0135] The only difference from Example 1 is that hydroxyl liquid nitrile rubber is not added in the preparation method of the negative electrode dry powder mixture; otherwise, it is the same as Example 1.

[0136] Application Example 1-10 and Comparative Application Example 1-3

[0137] The preparation process of the dry electrode negative electrode sheet is as follows:

[0138] The negative electrode dry powder mixture prepared above was ground with an agate mortar and then dry coated onto the current collector copper foil. The dry electrode negative electrode sheets of Application Examples 1-10 and Comparative Application Examples 1-3 were obtained by hot rolling at 60°C.

[0139] The preparation method of lithium-ion batteries is as follows:

[0140] The dry electrode negative plates of Application Examples 1-10 and the dry electrode negative plates of Comparative Application Examples 1-3 were assembled with lithium metal electrodes to form lithium-ion coin cells. LiPF6 was dissolved at a concentration of 1 mol / L in an electrolyte with EC / DEC / EMC = 2:3:1. After the coin cell assembly was completed, the following steps were taken to test the first charge specific capacity, first discharge specific capacity, and first efficiency: stand for 2 hours; constant current discharge: 0.1C to 0.005V; 0.08C to 0.001V; 0.05C to 0.001V; 0.02C to 0.001V; stand for 10 minutes; constant current charge: 0.1C to 1.5V.

[0141] The results of the initial charge specific capacity, initial discharge specific capacity, and initial efficiency test are shown in Table 1.

[0142] Table 1

[0143]

[0144] As shown in Table 1, the dry electrode sheet made of the negative electrode dry powder mixture of the present invention can achieve relatively high values ​​in the button cell test, including capacity (specific capacity of 370 mAh / g or more for the first charge and 395 mAh / g or more for the first discharge) and efficiency (95% or more).

[0145] In Comparative Application Example 1 and Comparative Application Example 2, the hydroxyl acrylate in the negative electrode dry powder mixture was replaced with hydroxyl-terminated polybutadiene. The modified polyurethane dry electrode binder prepared with polybutadiene had poor strength and toughness, resulting in poor toughness and strength of the prepared dry electrode sheet. After multiple charge and discharge cycles, the binder could not cope with the volume change of the negative electrode, causing some graphite to fall off, thus deteriorating the battery performance. As a result, the charging specific capacity, discharging specific capacity, and first-time efficiency of the prepared lithium-ion coin cell were significantly reduced.

[0146] In contrast, the negative electrode dry powder mixture used in Application Example 3 did not use hydroxyl acrylate resin and hydroxyl liquid nitrile rubber. Because hydroxyl acrylate resin and hydroxyl liquid nitrile rubber were not used, the binder had poor resistance to electrolyte, which caused the electrode sheet to not maintain long-term stability during charging and discharging. As a result, the battery performance was poor, and the specific capacity, discharge capacity and first efficiency of the prepared lithium-ion coin cell were significantly reduced.

[0147] The applicant declares that the present invention is illustrated through the above embodiments to demonstrate the dry electrode binder, negative electrode dry powder mixture, and their applications. However, the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the products of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A dry electrode adhesive, characterized in that, The dry electrode adhesive is a solvent-free polymer adhesive, and the polymeric monomers of the polymer adhesive include isocyanate monomers, polypolyol monomers, other hydroxyl-containing monomers and crosslinking agent monomers. The other hydroxyl-containing monomers are at least one of hydroxyl acrylate resin or hydroxyl liquid nitrile rubber. The dry electrode binder is obtained by in-situ polymerization on the surface of the active material and the conductive agent.

2. The dry electrode adhesive according to claim 1, characterized in that, The isocyanate monomers include any one or a combination of at least two of the following: toluene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, dimethylbiphenyl diisocyanate, hexamethylene diisocyanate, hexamethylene diisocyanate biuret, hexamethylene diisocyanate trimer, 2,2,4-trimethylhexane diisocyanate, phenyl diisocyanate, tetramethylphenyl diisocyanate, hydrogenated phenyl diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, 1,4-phenyl diisocyanate, or norbornene diisocyanate.

3. The dry electrode adhesive according to claim 1, characterized in that, The polyol monomer includes any one or a combination of at least two of polyester polyols or polyether polyols.

4. The dry electrode adhesive according to claim 3, characterized in that, The polyester polyols include polycarbonate polyols.

5. The dry electrode adhesive according to claim 1, characterized in that, The number average molecular weight of the hydroxyacrylate resin is 500-3000.

6. The dry electrode adhesive according to claim 1, characterized in that, The hydroxy acrylate resin includes any one or a combination of at least two of hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, or hydroxypropyl acrylate.

7. The dry electrode adhesive according to claim 1, characterized in that, The crosslinking agent monomer includes any one or a combination of at least two of the following: diol crosslinking agents, triol crosslinking agents, diamine crosslinking agents, alkanolamine crosslinking agents, alicyclic alcohol crosslinking agents, aromatic alcohol crosslinking agents, glycerol allyl ether, glycidyl allyl ether, or dicumyl peroxide.

8. The dry electrode adhesive according to claim 7, characterized in that, The diol crosslinking agent includes any one or a combination of at least two of 1,4-butanediol, ethylene glycol, propylene glycol, diethylene glycol, or neopentyl glycol.

9. The dry electrode adhesive according to claim 7, characterized in that, The triol crosslinking agent includes glycerol and / or trimethylolpropane.

10. The dry electrode binder according to claim 7, characterized in that, The diamine crosslinking agent includes any one or a combination of at least two of 3,3-dichloro-4,4-diaminodiphenylmethane, 3,5-dimethylthiotoluenediamine, 3,5-diethyltoluenediamine, 2,4-diamino-3,5-dimethylthiochlorobenzene, or isophoronediamine.

11. The dry electrode binder according to claim 7, characterized in that, The alkanolamine crosslinking agent includes any one or a combination of at least two of ethanolamine, diethanolamine, triethanolamine or N,N-bis(2-hydroxypropyl)aniline.

12. The dry electrode binder according to claim 7, characterized in that, The alicyclic alcohol crosslinking agent includes 1,4-cyclohexanediol and / or hydrogenated bisphenol A.

13. The dry electrode binder according to claim 7, characterized in that, The aromatic alcohol crosslinking agent includes any one or a combination of at least two of dimethylene phenyl glycol, hydroquinone bis-β-hydroxyethyl ether, or resorcinol hydroxy ether.

14. The dry electrode binder according to claim 1, characterized in that, The number average molecular weight of the dry electrode binder is 30,000-80,000.

15. A negative electrode dry powder mixture, characterized in that, The negative electrode dry powder mixture includes an active material, a conductive agent, and a dry electrode binder as described in any one of claims 1-14, wherein the dry electrode binder is coated on the surfaces of the active material and the conductive agent.

16. The negative electrode dry powder mixture according to claim 15, characterized in that, The active material includes one or a combination of at least two of the following: graphite, silicon, silicon-based oxides, silicon-carbon materials, lithium titanate, graphene, or tin-based composite oxides.

17. The negative electrode dry powder mixture according to claim 16, characterized in that, The active substance is graphite.

18. The negative electrode dry powder mixture according to claim 17, characterized in that, The graphite includes one or a combination of at least two of the following: natural graphite, artificial graphite, amorphous carbon, or mesophase carbon microspheres.

19. The negative electrode dry powder mixture according to claim 15, characterized in that, The conductive agent includes one or a combination of at least two of conductive graphite, carbon nanotubes, or conductive carbon black.

20. The negative electrode dry powder mixture according to claim 15, characterized in that, The negative electrode dry powder mixture contains 93%-98.5% by weight of active material, 1%-5% by weight of dry electrode binder, and 0.5%-2% by weight of conductive agent.

21. The method for preparing the negative electrode dry powder mixture according to any one of claims 15-20, characterized in that, The preparation method includes the following steps: The monomers are mixed and then mixed with active materials and conductive agents to carry out in-situ polymerization to obtain the negative electrode dry powder mixture. The monomers include isocyanate monomers, polypolyol monomers, other hydroxyl-containing monomers and crosslinking agent monomers. The other hydroxyl-containing monomers are at least one of hydroxyl acrylate resin or hydroxyl liquid nitrile rubber.

22. The preparation method according to claim 21, characterized in that, The isocyanate monomers include any one or a combination of at least two of the following: toluene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, dimethylbiphenyl diisocyanate, hexamethylene diisocyanate, hexamethylene diisocyanate biuret, hexamethylene diisocyanate trimer, 2,2,4-trimethylhexane diisocyanate, phenyl diisocyanate, tetramethylphenyl diisocyanate, hydrogenated phenyl diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, 1,4-phenyl diisocyanate, or norbornene diisocyanate.

23. The preparation method according to claim 21, characterized in that, The polyol monomer includes any one or a combination of at least two of polyester polyols or polyether polyols.

24. The preparation method according to claim 23, characterized in that, The polyester polyols include polycarbonate polyols.

25. The preparation method according to claim 21, characterized in that, The number average molecular weight of the hydroxyacrylate resin is 500-3000.

26. The preparation method according to claim 21, characterized in that, The hydroxy acrylate resin includes any one or a combination of at least two of hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, or hydroxypropyl acrylate.

27. The preparation method according to claim 21, characterized in that, The polymer monomer is a polymer monomer that has undergone dehydration treatment.

28. The preparation method according to claim 21, characterized in that, The molar ratio of isocyanate groups in the isocyanate monomer to hydroxyl groups in the polyol monomer is 1.2:1-4:

1.

29. The preparation method according to claim 21, characterized in that, The molar ratio of the isocyanate group in the isocyanate monomer to the hydroxyl group in other hydroxyl-containing monomers is 1.2:1-12:

1.

30. The preparation method according to claim 21, characterized in that, The crosslinking agent monomer includes any one or a combination of at least two of the following: diol crosslinking agents, triol crosslinking agents, diamine crosslinking agents, alkanolamine crosslinking agents, alicyclic alcohol crosslinking agents, aromatic alcohol crosslinking agents, glycerol allyl ether, glycidyl allyl ether, or dicumyl peroxide.

31. The preparation method according to claim 30, characterized in that, The diol crosslinking agent includes any one or a combination of at least two of 1,4-butanediol, ethylene glycol, propylene glycol, diethylene glycol, or neopentyl glycol.

32. The preparation method according to claim 30, characterized in that, The triol crosslinking agent includes glycerol and / or trimethylolpropane.

33. The preparation method according to claim 30, characterized in that, The diamine crosslinking agent includes any one or a combination of at least two of 3,3-dichloro-4,4-diaminodiphenylmethane, 3,5-dimethylthiotoluenediamine, 3,5-diethyltoluenediamine, 2,4-diamino-3,5-dimethylthiochlorobenzene, or isophoronediamine.

34. The preparation method according to claim 30, characterized in that, The alkanolamine crosslinking agent includes any one or a combination of at least two of ethanolamine, diethanolamine, triethanolamine or N,N-bis(2-hydroxypropyl)aniline.

35. The preparation method according to claim 30, characterized in that, The alicyclic alcohol crosslinking agent includes 1,4-cyclohexanediol and / or hydrogenated bisphenol A.

36. The preparation method according to claim 30, characterized in that, The aromatic alcohol crosslinking agent includes any one or a combination of at least two of dimethylene phenyl glycol, hydroquinone bis-β-hydroxyethyl ether, or resorcinol hydroxy ether.

37. The preparation method according to claim 21, characterized in that, The molar ratio of isocyanate groups in the isocyanate monomer to reactive groups in the crosslinking agent is 1.3:1-12:

1.

38. The preparation method according to claim 21, characterized in that, The active material includes one or a combination of at least two of the following: graphite, silicon, silicon-based oxides, silicon-carbon materials, lithium titanate, graphene, or tin-based composite oxides.

39. The preparation method according to claim 38, characterized in that, The active substance is graphite.

40. The preparation method according to claim 38, characterized in that, The graphite includes one or a combination of at least two of the following: natural graphite, artificial graphite, amorphous carbon, or mesophase carbon microspheres.

41. The preparation method according to claim 21, characterized in that, The conductive agent includes one or a combination of at least two of conductive graphite, carbon nanotubes, or conductive carbon black.

42. The preparation method according to claim 21, characterized in that, The in-situ polymerization temperature is 25-80℃.

43. The preparation method according to claim 21, characterized in that, The in-situ polymerization time is 1-7 days.

44. A dry electrode negative electrode, characterized in that, The dry electrode negative electrode comprises the negative electrode dry powder mixture as described in any one of claims 15-20.

45. The method for preparing the dry electrode negative electrode according to claim 44, characterized in that, The preparation method is as follows: the negative electrode dry powder mixture according to any one of claims 15-20 is hot-rolled into a self-supporting film or directly hot-rolled onto the current collector to form a dry electrode negative electrode.

46. ​​The method for preparing the dry electrode negative electrode according to claim 45, characterized in that, The negative electrode dry powder mixture is ground and pulverized before hot rolling.

47. The method for preparing the dry electrode negative electrode according to claim 45, characterized in that, The temperature range of the hot roller pressing is 25-120℃.

48. An electrochemical energy storage device, characterized in that, The electrochemical energy storage device includes the dry electrode negative electrode as described in claim 44.

49. The electrochemical energy storage device according to claim 48, characterized in that, The electrochemical energy storage device is selected from one of lithium-ion batteries, sodium-ion batteries, supercapacitors, fuel cells, or solar cells.

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