An electrode material composition, an electrode sheet, and use thereof

Abstract

The application provides an electrode material composition, an electrode pole piece and application thereof, and the electrode material composition comprises the following components in parts by mass: active material 90-98 parts, conductive agent 0.5-5.0 parts, binder 0.5-5.0 parts, organic silicon modified acrylic ester polymer 0.01-5.00 parts and siloxane coupling agent 0.01-3.00 parts. The specific organic silicon modified acrylic ester polymer and the siloxane coupling agent are used as water blocking additives, through the design of the two and the synergistic effect of the compounding of the components, the hydrophobicity of the electrode pole piece is improved, the water absorption and water content of the electrode pole piece are reduced, and the storage time is prolonged; meanwhile, chemical crosslinking occurs between the components, the force between the components and the current collector is strengthened, thereby the adhesive force and the peeling strength of the electrode pole piece are improved, the cracking of the electrode pole piece is inhibited, and the lithium ion battery containing the same has lower internal resistance and excellent cycle performance.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, specifically relating to an electrode material composition, an electrode sheet, and its application. Background Technology

[0002] Lithium-ion rechargeable batteries, as a clean energy source, are widely used in digital products, electric vehicles, and energy storage. Lithium-ion rechargeable batteries primarily utilize Li... + The charging and discharging function is achieved by repeatedly inserting and de-intercalating between the positive and negative electrodes; during charging, Li... + The electrolyte is extracted from the positive electrode and embedded into the negative electrode through the pores of the electrolyte and separator; the discharge process is the reverse of the charging process. Therefore, the positive and negative electrode materials, electrolyte, and separator of a lithium-ion secondary battery play a crucial role in the battery's capacity, cycle life, and safety performance.

[0003] The cell structure of a lithium-ion rechargeable battery has a significant impact on battery performance, requiring extremely low water content. Excessive water absorption and increased water content in the lithium-ion secondary electrode sheets lead to a substantial decrease in adhesion and excessive electrode expansion, making assembly difficult and reducing yield. Therefore, cells typically require 10-20 hours of high-temperature backing before assembly, resulting in high manufacturing costs and low efficiency. Furthermore, prolonged high-temperature baking can cause separator shrinkage or pore formation, reducing cell safety. In addition, lithium-ion secondary electrode coatings often use materials with hydrophilic functional groups as binders or additives. For example, sodium carboxymethyl cellulose (CMC) and styrene-butadiene latex (SBR) are commonly used as binders for negative electrode slurries, leading to water absorption issues. Despite the severe negative impact of electrode water absorption on lithium-ion rechargeable battery performance, research on reducing water content in lithium-ion secondary electrode sheets is scarce; most optimization efforts focus on the lithium-ion rechargeable battery processing or post-processing drying stages.

[0004] CN112984963A discloses a method for drying lithium-ion battery cells that can improve cell consistency. It uses a freeze-drying method instead of the traditional high-temperature drying method. The steps are as follows: (1) Pre-cooling: the battery cell is cooled to 0±5℃ at a cooling rate of 0.2±0.05℃ / min and held at that temperature; then the battery cell is cooled to -30±5℃ at a cooling rate of 1±0.05℃ / min and held at that temperature; (2) Vacuuming to <200Pa; 3) Sublimation drying: First, heat the battery cell to -15±5℃ at a heating rate of 0.2±0.05℃ / min and hold; then heat the battery cell to 0±5℃ at a heating rate of 1±0.05℃ / min and hold; (4) Desorption drying: Heat the battery cell to 20±5℃ at a heating rate of 1±0.05℃ / min and hold; then heat the battery cell to 45±5℃ at a heating rate of 1±0.05℃ / min and hold. Compared with the traditional high-temperature drying method, this method shortens the drying time, but it is difficult to apply on a large scale due to limitations in drying equipment.

[0005] CN114335769A discloses a method for the formation and aging of battery cells, including the following steps: First, the battery cell, after being left to stand, is subjected to negative pressure treatment, followed by multiple constant current charging-standing treatments to obtain a battery cell with complete formation; then, it is sequentially placed at 40-50℃ and 70-80℃ to obtain a battery cell with complete formation and aging. This formation and aging method allows excess moisture in the battery cell to react and dissipate during the aging process, effectively reducing the moisture content of the battery cell, avoiding more side reactions after the battery cell is finished, and improving the high-temperature storage and cycle performance of the battery cell. However, this method is cumbersome and still has low efficiency, and the control of battery cell moisture remains very stringent.

[0006] In general, current industry practices for controlling cell moisture content primarily focus on optimizing the manufacturing process. This approach suffers from problems such as cumbersome steps, long processing times, high costs, difficulties in mass production, and poor dehydration effectiveness. No reports have been found on improving water absorption / moisture content at the material level. Therefore, developing a solution that fundamentally reduces the moisture content of electrode sheets and cells from the material level is a key research focus in this field. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the present invention aims to provide an electrode material composition, an electrode sheet and its application. By designing and compounding organosilicon-modified acrylate polymers and siloxane coupling agents, it can be used as a water-blocking additive to significantly improve the hydrophobicity of the electrode sheet, reduce the water absorption and water content of the electrode sheet, extend the storage time, and effectively improve the adhesion and peel strength of the electrode sheet.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides an electrode material composition, the electrode material composition comprising, by weight, the following components:

[0010]

[0011] The electrode material composition provided by this invention uses specific organosilicon-modified acrylate polymers and siloxane coupling agents as water-blocking additives. Through their design and synergistic compounding, these additives can chemically react with other components in the electrode material composition, consuming excess water-absorbing groups such as -OH groups. This significantly improves the hydrophobicity of the electrode material composition and the electrode sheet containing it, reducing the water absorption and water content of the electrode sheet under ambient humidity conditions. Consequently, it greatly reduces the high-temperature baking time in the backing process and extends the storage time of the electrode sheet. Specifically, the organosilicon-modified acrylate polymer has good compatibility with the binder and can better disperse to form a uniform slurry. The siloxane coupling agent contains multiple active functional groups (siloxane groups), which form chemical bonds with components such as the organosilicon-modified acrylate polymer, further enhancing the crosslinking degree of the coating of the electrode material composition and the formed electrode sheet, and improving the peel strength of the electrode sheet. Meanwhile, the electrode material composition can impart excellent hydrophobicity to the electrode sheet. On the one hand, the organosilicon-modified acrylate polymer and the siloxane coupling agent both have active siloxane groups, which can react with the water-absorbing groups on the surface of conductive agents (e.g., conductive carbon black) and current collectors (e.g., aluminum foil, copper foil), reducing the water absorption rate of the electrode sheet. On the other hand, after the aforementioned reaction, a layer of oriented hydrophobic organosilicon molecular film is formed on the surface of conductive agents (e.g., conductive carbon black) and current collectors (e.g., aluminum foil, copper foil). When water vapor in the air comes into contact with the material surface, it is difficult to stay on the material surface and is easy to remove, thereby reducing the water absorption and water content of the electrode sheet under air humidity conditions.

[0012] Therefore, the electrode material composition provided by this invention improves the hydrophobicity of the electrode sheet from the material end, which is simple to operate, low in cost, and has obvious effects, enabling large-scale mass production. Simultaneously, the chemical cross-linking effect between the organosilicon-modified acrylate polymer, the siloxane coupling agent (based on siloxane groups), and other components strengthens the interaction forces between the components of the electrode material composition and between it and the current collector, thereby improving the adhesion and peel strength of the electrode sheet, inhibiting electrode sheet cracking, effectively reducing the internal resistance of the lithium-ion battery, and improving cycle performance.

[0013] In the electrode material composition provided by the present invention, the active material has a mass fraction of 90-98 parts, for example, 91 parts, 92 parts, 93 parts, 94 parts, 95 parts, 96 parts, or 97 parts.

[0014] The conductive agent is present in a mass fraction of 0.5-5.0 parts, for example, 0.8 parts, 1.0 parts, 1.5 parts, 2.0 parts, 2.5 parts, 3.0 parts, 3.5 parts, 4.0 parts or 4.5 parts, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0015] The adhesive is in the range of 0.5-5.0 parts by weight, for example, 0.8 parts, 1.0 parts, 1.5 parts, 2.0 parts, 2.5 parts, 3.0 parts, 3.5 parts, 4.0 parts or 4.5 parts, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0016] The organosilicon-modified acrylate polymer is present in parts by weight of 0.01-5.00, for example, 0.05, 0.10, 0.50, 0.80, 1.00, 1.50, 2.00, 2.50, 3.00, 3.50, 4.00, or 4.50, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range, but preferably 0.01-2.20 parts.

[0017] The mass fraction of the siloxane coupling agent is 0.01-3.00 parts, for example, 0.05 parts, 0.10 parts, 0.50 parts, 0.80 parts, 1.00 parts, 1.50 parts, 2.00 parts or 2.50 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, but preferably 0.01-1.50 parts.

[0018] Preferably, the organosilicon-modified acrylate polymer is obtained by polymerizing acrylate monomers with alkenyl siloxanes.

[0019] Preferably, the mass ratio of the acrylate monomer to the alkenylsiloxane is 1:(0.2-1.5), for example, it can be 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, 1:1.3 or 1:1.4, etc., and more preferably 1:(0.5-1.5).

[0020] Preferably, the acrylate monomers include any one or a combination of at least two of (meth)acrylate, (meth)acrylate hydroxyalkyl ester, and (meth)acrylate phosphate, and more preferably (meth)acrylate alkyl ester and / or (meth)acrylate hydroxyalkyl ester.

[0021] Preferably, the acrylate monomers include any one or a combination of at least two of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

[0022] Preferably, the alkenyl siloxane includes any one or a combination of at least two of methyl acyloxysiloxane, acyloxysiloxane, and vinyl siloxane.

[0023] Preferably, the alkenylsiloxane comprises any one or a combination of at least two of the following: 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropylmethyldiethoxysilane, 3-acryloxytrimethoxysilane, 3-acryloxytriethoxysilane, 3-acryloxymethyldimethoxysilane, 3-acryloxymethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltriisopropoxysilane.

[0024] Preferably, the organosilicon-modified acrylate polymer is prepared by the following method, which includes: polymerizing acrylate monomers with alkenyl siloxanes in the presence of an initiator and an organic solvent to obtain the organosilicon-modified acrylate polymer.

[0025] Preferably, based on a total mass of 100 parts of acrylate monomers, alkenyl siloxanes, initiators, and organic solvents, the mass of each component is as follows:

[0026]

[0027] The acrylate monomer is 20-50 parts, for example, 22 parts, 25 parts, 28 parts, 30 parts, 32 parts, 35 parts, 38 parts, 40 parts, 42 parts, 45 parts or 48 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0028] The alkenylsiloxane is 10-30 parts, for example, 11 parts, 13 parts, 15 parts, 17 parts, 19 parts, 20 parts, 21 parts, 23 parts, 25 parts, 27 parts or 29 parts, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0029] The organic solvent is 40-50 parts, for example, 41 parts, 42 parts, 43 parts, 44 parts, 45 parts, 46 parts, 47 parts, 48 ​​parts or 49 parts, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0030] The initiator is 0.01-2.00 parts, for example, it can be 0.03 parts, 0.05 parts, 0.08 parts, 0.10 parts, 0.30 parts, 0.50 parts, 0.80 parts, 1.00 parts, 1.20 parts, 1.50 parts or 1.80 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0031] Preferably, the initiator is a free radical initiator, including azo initiators and / or peroxide initiators.

[0032] Preferably, the azo initiator includes azobisisobutyronitrile and / or azobisisoheptanenitrile.

[0033] Preferably, the peroxide initiator includes any one or a combination of at least two of benzoyl peroxide, dodecyl peroxide, dicumyl peroxide, and tert-butyl hydroperoxide.

[0034] Preferably, the organic solvent includes any one or a combination of at least two of N-methylpyrrolidone, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, methanol, and ethanol.

[0035] Preferably, the polymerization reaction method specifically includes: mixing an acrylate monomer with an organic solvent to obtain solution A; mixing an alkenyl siloxane with an organic solvent to obtain solution B; mixing an initiator solution with solution A, and then adding solution B to it under stirring at 40-80°C, and continuing to stir the reaction after the addition is complete to obtain the organosilicon-modified acrylate polymer.

[0036] Preferably, the solution B is added dropwise.

[0037] Preferably, the addition (dropping) time of solution B is 1.0-3.0h, for example, it can be 1.5h, 2.0h or 2.5h, and specific point values ​​between the above point values ​​are not exhaustively listed in this invention due to space limitations and for the sake of brevity.

[0038] Preferably, the reaction time after the addition is completed is 3-10 hours, for example, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours or 9 hours, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0039] Preferably, the polymerization reaction temperature is 40-80℃, for example, it can be 45℃, 50℃, 55℃, 60℃, 65℃, 70℃ or 75℃, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0040] Preferably, the polymerization reaction time is 2-14 hours, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours or 13 hours, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0041] Preferably, the number average molecular weight of the organosilicon-modified acrylate polymer is ≥1000, for example, it can be 3000, 5000, 8000, 10000, 20000, 30000, 40000, 50000, 60000, 70000, 80000, 90000, 100000, 110000, 120000 or 150000, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, and it is further preferred to be 1000-100000.

[0042] Preferably, the siloxane coupling agent comprises any one or a combination of at least two of hexadecyltrimethoxysilane, hexadecyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, phenyltriethoxysilane, and diphenyldiethoxysilane.

[0043] Preferably, the active material is a negative electrode active material, more preferably a carbon-based negative electrode active material and / or a silicon-based negative electrode active material, and even more preferably a carbon-based negative electrode active material.

[0044] Preferably, the carbon-based anode active material includes any one or a combination of at least two of the following: natural graphite, artificial graphite, mesophase carbon microspheres, soft carbon, hard carbon, and silicon oxide.

[0045] Preferably, the silicon-based anode active material comprises silicon oxide.

[0046] Preferably, the negative electrode active material includes any one or a combination of at least two of the following: natural graphite, artificial graphite, mesophase carbon microspheres, soft carbon, hard carbon, and silicon oxide.

[0047] Preferably, the conductive agent includes any one or a combination of at least two of conductive carbon black, conductive graphite, modified conductive graphite, metal particles, Ketjen black, acetylene black, carbon nanotubes, carbon fibers, graphene, and conductive polymers, with conductive carbon black being more preferred.

[0048] Preferably, the adhesive comprises any one or a combination of at least two of the following: styrene-butadiene rubber, polyacrylic acid, polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone, polyethylene oxide, polyurethane, modified paraffin resin, carbomer resin, polyurethane acrylate, acrylate copolymer emulsion, epoxy resin, urethane epoxy resin, acrylic epoxy resin, polyisoborneol acrylate, and modified polyurea, with styrene-butadiene rubber being more preferred.

[0049] As a preferred embodiment of the present invention, the styrene-butadiene rubber is water-based styrene-butadiene rubber, namely styrene-butadiene latex (SBR).

[0050] Preferably, the electrode material composition further includes 0.5-5.0 parts by weight of a thickener, for example, the thickener may be 0.8 parts, 1.0 parts, 1.5 parts, 2.0 parts, 2.5 parts, 3.0 parts, 3.5 parts, 4.0 parts or 4.5 parts, as well as specific values ​​between the above-mentioned values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0051] Preferably, the thickener comprises any one or a combination of at least two of sodium carboxymethyl cellulose, polyethylene oxide, polyethylene oxide, methylcellulose, hydroxypropyl methylcellulose, hydroxyethyl cellulose, gelatin, and sodium alginate, and more preferably sodium carboxymethyl cellulose (CMC).

[0052] Preferably, the electrode material composition further includes other additives.

[0053] Preferably, the other additives include any one or a combination of at least two of flame retardants, dispersants, and temperature stabilizers.

[0054] In a second aspect, the present invention provides an electrode slurry comprising a combination of an electrode material composition as described in the first aspect and a solvent.

[0055] Preferably, the solvent includes water and / or an organic solvent.

[0056] Preferably, based on 100 parts by weight of the electrode material composition, the solvent has a mass of 100-200 parts, for example, 110 parts, 120 parts, 130 parts, 140 parts, 150 parts, 160 parts, 170 parts, 180 parts or 190 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0057] Thirdly, the present invention provides an electrode sheet comprising a current collector and a coating disposed on the current collector, wherein the material of the coating comprises the electrode material composition as described in the first aspect.

[0058] Preferably, the electrode sheet is a negative electrode sheet, that is, the active material in the electrode material composition is a negative active material.

[0059] Preferably, the electrode sheet is a negative electrode sheet, and the current collector is a copper foil or a composite copper foil.

[0060] Preferably, the thickness of the coating is 25-300 μm, for example, it can be 30 μm, 50 μm, 70 μm, 90 μm, 100 μm, 120 μm, 150 μm, 180 μm, 200 μm, 220 μm, 250 μm or 280 μm, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0061] As a preferred embodiment of the present invention, the electrode coating material provided by the present invention is the electrode material composition, which has excellent hydrophobicity, thereby reducing the water absorption and water content of the electrode, and significantly shortening the high-temperature baking time in the backing process, effectively extending the storage time of the electrode. Simultaneously, the organosilicon-modified acrylate polymer, siloxane coupling agent, and other components in the electrode material composition undergo chemical cross-linking, enhancing the interaction forces between the coating components and between the coating and the current collector, giving the electrode higher adhesion and peel strength, suppressing cracking of the electrode, and thus enabling the lithium-ion battery containing the electrode to have lower internal resistance and significantly improved cycle performance.

[0062] Preferably, the electrode sheet is a negative electrode sheet with a coating thickness of 30 μm and a peel strength >19 N / m, which can reach 19.3-33.3 N / m; the water content of the negative electrode sheet after being placed in an environment with 50% RH humidity for 1 day is <100 ppm, after 2 days is <180 ppm, after 3 days is <240 ppm, after 3 days is <280 ppm, and after 5 days in an environment with 50% RH humidity is <300 ppm.

[0063] Preferably, the internal resistance of the lithium-ion battery containing the negative electrode sheet is <24mΩ, and can be 18.0-23.9mΩ; the capacity retention rate after 100 cycles is >90%, and can be 90.3-95.3%.

[0064] For example, the method for preparing the electrode sheet includes: mixing the electrode material composition with a solvent to obtain an electrode slurry; coating the electrode slurry onto a current collector and drying it to obtain the electrode sheet.

[0065] Preferably, the preparation method of the electrode slurry includes: mixing an active material, a conductive agent, a binder, an organosilicon-modified acrylate polymer, a solvent, and optionally a thickener evenly to obtain a slurry; and mixing a siloxane coupling agent evenly with the slurry to obtain the electrode slurry.

[0066] Fourthly, the present invention provides an electrochemical energy storage device, the electrochemical energy storage device comprising at least one of the electrode material composition as described in the first aspect and the electrode sheet as described in the third aspect.

[0067] Preferably, the electrochemical energy storage device includes any one of a lithium-ion battery, a sodium-ion battery, a supercapacitor, a fuel cell, or a solar cell, with a lithium-ion battery being more preferred.

[0068] Compared with the prior art, the present invention has the following beneficial effects:

[0069] (1) In the electrode material composition provided by the present invention, a specific organosilicon-modified acrylate polymer and a siloxane coupling agent are used as water-blocking additives. Through the design of the two and the synergistic effect of the compounding between the components, the hydrophobicity of the electrode sheet can be significantly improved, the water absorption and water content of the electrode sheet can be reduced, and the storage time can be extended. At the same time, the organosilicon-modified acrylate polymer and the siloxane coupling agent undergo chemical cross-linking with other components, which strengthens the interaction between the components and between the components and the current collector, thereby improving the adhesion and peel strength of the electrode sheet, inhibiting the cracking of the electrode sheet, and making the lithium-ion battery containing it have lower internal resistance and better cycle performance.

[0070] (2) The electrode material composition provided by the present invention improves the hydrophobicity of the electrode sheet from the material end through the design and mutual compounding of materials. The operation is simple, the preparation cost is low, the time is short, and the effect is obvious. It can be mass-produced and has broad application prospects. Attached Figure Description

[0071] Figure 1 The graph shows the water content test results of the negative electrode sheets provided in Example 1, Comparative Example 1, and Comparative Example 5 in an ambient humidity of 50% RH.

[0072] Figure 2 The graph shows the water content test results of the negative electrode sheets provided in Example 1, Comparative Example 1, and Comparative Example 5 after absorbing water and baking. Detailed Implementation

[0073] 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.

[0074] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used herein, are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not limited to those elements and may also include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0075] "Optional" or "any one" means that the matter or event described thereafter may or may not occur, and the description includes both the possibility that the event may occur and the possibility that the event may not occur.

[0076] The indefinite articles “a” and “an” preceding an element or component of this invention do not impose any limitation on the quantity (i.e., number of times) of the element or component. Therefore, “an” or “a” should be interpreted as including one or at least one, and the singular form of an element or component also includes the plural form, unless the quantity clearly refers only to the singular form.

[0077] The terms "one embodiment," "some embodiments," "exemplary," "specific example," or "some examples," etc., used in this invention refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this document, the illustrative expressions of the above terms are not necessarily directed at the same embodiment or example.

[0078] Furthermore, the technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0079] In the following specific embodiments of the present invention, all materials used are commercially available products.

[0080] Preparation Example 1

[0081] Organosilicon-modified acrylate polymer A1 is obtained by polymerizing methyl methacrylate with 3-methacryloyloxypropyltrimethoxysilane; the specific preparation method is as follows:

[0082] (1) Dissolve 28.95 parts of methyl methacrylate in 25 parts of N-methylpyrrolidone (NMP) to prepare solution A;

[0083] (2) Dissolve 21.88 parts of 3-methacryloyloxypropyltrimethoxysilane in 20 parts of NMP to prepare solution B;

[0084] (3) Dissolve 0.17 parts of azobisisobutyronitrile (AIBN) in 4 parts of NMP solvent and add it to solution A, and stir at 50°C;

[0085] (4) Add solution B dropwise to the reaction solution obtained in step (3) at 50°C for 1 hour. After the addition is completed, stir the reaction at 50°C for 8 hours to obtain the organosilicon modified acrylate polymer A1.

[0086] Preparation Example 2-15

[0087] Organosilicon-modified acrylate polymers A2-A15 are obtained by polymerizing acrylate monomers with alkenyl siloxanes. The raw materials and amounts used in the preparation are shown in Table 1. The amounts of each component in Table 1 are in parts. The preparation method is the same as that in Preparation Example 1.

[0088] Table 1

[0089]

[0090]

[0091]

[0092] Example 1

[0093] An electrode material composition comprising, by weight, the following components:

[0094]

[0095] A negative electrode sheet includes a current collector (copper foil) and a coating disposed on the current collector, wherein the coating material is the electrode material composition provided in this embodiment; the specific preparation method of the negative electrode sheet is as follows:

[0096] (1) At room temperature, the organosilicon-modified acrylate polymer A1, natural graphite, conductive carbon black Super P, SBR, CMC and 114.85 parts of water were added to a homogenizer according to the above formula. The mixture was mixed at 600 r / min for 5 min at 25 °C, and then at 1000 r / min for 20 min to obtain a slurry. Then, hexadecyltrimethoxysilane was added to the slurry and mixed at 600 r / min for 10 min at 25 °C in a homogenizer, and then at 1000 r / min for 30 min to obtain a negative electrode slurry.

[0097] (2) Coating is performed using a scraper at a speed of 20 m / min. The negative electrode slurry obtained in step (1) is uniformly coated on the surface of a copper foil with a thickness of 10 μm. The foil is baked at 105°C for 1 hour. After removing the solvent, a smooth negative electrode sheet is obtained with a coating thickness of 198 μm.

[0098] Examples 2-15, Comparative Examples 1-5

[0099] An electrode material composition and a negative electrode sheet are disclosed, differing from Example 1 in that the components and amounts of the electrode material composition are different, as shown in Table 2. In Table 2, the amount of each component is expressed in "parts," and "thickness (μm)" refers to the thickness of the coating in the negative electrode sheet; "--" indicates that the component was not added. The preparation method of each negative electrode sheet is the same as in Example 1, and the materials and parameters not shown in Table 2 are the same as in Example 1.

[0100] For the sake of brevity, the specific types and corresponding numbers of siloxane coupling agents are as follows:

[0101] Siloxane Coupling Agent B1 hexadecyltrimethoxysilane Siloxane Coupling Agent B2 3-Aminopropyltriethoxysilane, KH550 Siloxane Coupling Agent B3 3-Aminopropyltrimethoxysilane

[0102] Table 2

[0103]

[0104]

[0105]

[0106] The performance of the negative electrode sheets provided in Examples 1-15 and Comparative Examples 1-5 was tested, and the specific methods are as follows:

[0107] I. Peel strength test of negative electrode sheet with coating thickness of 30μm

[0108] Following the proportions and process conditions in Examples 1-15 and Comparative Examples 1-5, negative electrode sheets with a coating thickness of 30 μm were prepared by adjusting only the height of the scraper. These sheets were then cut into strips measuring 10 cm × 2 cm and subjected to a 10 × 10⁻⁶ ohmmeter process. 4 After being calendered under a unit length load of N / m, the current collector side of the negative electrode sheet was fixed to a steel plate with a thickness of 1mm using double-sided tape, and transparent tape was pasted on the coating layer side. Under the condition of 25℃, the transparent tape was stretched and peeled in the 180° direction using a universal electronic testing machine at a peeling speed of 100mm / min. The peeling stress was recorded and the peeling strength was obtained. The specific results are shown in Table 3.

[0109] II. Cracks in the Electrode

[0110] The negative electrode sheets provided in Examples 1-15 and Comparative Examples 1-5 were dried at 105°C for 1 hour. The surface condition of the dried electrode sheets was observed using an optical microscope. The electrode sheets that were intact were marked as ○, those with slight cracks (number of cracks in a single electrode sheet < 10) were marked as □, and those with severe cracks (number of cracks in a single electrode sheet ≥ 10) were marked as ×. The specific results are shown in Table 3.

[0111] III. Water Content Test of Negative Electrode Sheet

[0112] (1) The negative electrode sheets provided in Examples 1-15 and Comparative Examples 1-5 were placed in an environment with 50% RH humidity, and the water content of the negative electrode sheets was tested at different time intervals (1 day, 2 days, 3 days, 4 days, and 5 days, respectively). The results are shown in Table 4. The water content test results of the negative electrode sheets provided in Example 1, Comparative Example 1, and Comparative Example 5 are shown in the figure below. Figure 1 As shown;

[0113] (2) Take the negative electrode sheet after absorbing water after the test in (1), and place it in a 60℃ forced-air drying oven to dry for different times (10min, 20min, 30min, 40min, 50min, 60min). Test the water content of the negative electrode sheet. The results are shown in Table 5. Among them, the water content test results of the negative electrode sheets provided in Example 1, Comparative Example 1 and Comparative Example 5 are shown in the figure. Figure 2 As shown;

[0114] The water content testing instrument was a Wantong 885-917 moisture analyzer.

[0115] IV. Preparation and Performance Testing of Lithium-ion Batteries

[0116] The negative electrode sheets provided in Examples 1-15 and Comparative Examples 1-5 are used to assemble lithium-ion batteries (secondary batteries). The specific method is as follows:

[0117] Preparation of the positive electrode sheet: The positive electrode active material (lithium iron phosphate), conductive agent (conductive carbon black), and binder (polyvinylidene fluoride, PVDF) are mixed in a mass ratio of 95.5:2.0:2.5. The mixture is then added to NMP at a solid content of 50 wt% and thoroughly stirred to form a uniform positive electrode slurry. After passing through a 100-mesh sieve, the slurry is coated onto the positive electrode current collector Al foil, dried, and then rolled using rollers at a speed of 10 × 10⁻⁶ mm. 4 A positive electrode sheet is obtained by rolling with a unit length load of N / m.

[0118] Negative electrode: Negative electrode provided in Examples 1-15 and Comparative Examples 1-5;

[0119] Separator: Celgard ceramic diaphragm is used as the diaphragm;

[0120] Assembly: The positive electrode, separator, and negative electrode are wound in sequence to obtain the battery cell; the battery cell is encapsulated with aluminum-plastic film, baked to remove water, and then injected with electrolyte (the volume ratio of ethylene carbonate EC: methyl ethyl carbonate EMC: diethyl carbonate DEC is 1:1:1, 1.0M lithium hexafluorophosphate). After vacuum sealing, resting, formation, secondary sealing, shaping and other processes, a lithium-ion battery is obtained, and the following performance tests are performed.

[0121] (1) Internal resistance test

[0122] The internal resistance of lithium-ion batteries was tested using a Solartron electrochemical workstation, and the test results are shown in Table 3.

[0123] (2) Cyclic performance test

[0124] At 25℃, the lithium-ion battery under test was charged to 4.2V at a constant current of 0.33C, then charged to the cutoff current of 0.02C at a constant voltage, rested for 5 minutes, and then discharged to 2.5V at 0.33C, rested for 5 minutes. The discharge capacity after the first cycle was recorded. The battery was then charged to 4.2V at a constant current of 0.33C again, then charged to the cutoff current of 0.02C at a constant voltage, rested for 5 minutes, and then discharged to 2.5V at 0.33C, rested for 5 minutes. This cycle was repeated 100 times. The discharge capacity after the 100th cycle was recorded. The capacity retention rate of the lithium-ion battery after 100 cycles was calculated using the following formula:

[0125] Capacity retention rate (%) after 100 cycles = 100% × discharge capacity of the 100th cycle / discharge capacity of the first cycle.

[0126] The results are shown in Table 3.

[0127] Table 3

[0128]

[0129]

[0130] Table 4

[0131]

[0132]

[0133] Table 5

[0134]

[0135]

[0136] Based on the performance test data in Tables 3-5, it can be seen that, compared with the conventional electrode material composition and negative electrode sheet in Comparative Example 5, the electrode material compositions provided in Examples 1-15 of this invention, using specific organosilicon-modified acrylate polymers and siloxane coupling agents as water-blocking additives, significantly improve the hydrophobicity of the negative electrode sheet and reduce its water absorption and water content through their design and synergistic effect. At 50% RH, the water content is <100ppm after 1 day, <180ppm after 2 days, <240ppm after 3 days, and <280ppm after 3 days. The water content of the negative electrode sheet is less than 300 ppm after 5 days of storage under RH humidity, and less than 60 ppm after baking at 60℃ for 60 minutes, effectively extending the storage time of the negative electrode sheet. At the same time, the components in the electrode material composition undergo chemical cross-linking, which strengthens the interaction between components and between components and current collector, improves the adhesion of the negative electrode sheet, and has a peel strength of 19.3-33.3 N / m. It can also inhibit electrode sheet cracking, so that the internal resistance of the lithium-ion battery containing it is 18.0-23.9 mΩ, and the capacity retention rate after 100 cycles is 90.3-95.3%, which has lower internal resistance and better cycle performance.

[0137] Comparing the effect data of Example 2 with those of Comparative Examples 1-4, it can be seen that the specific organosilicon-modified acrylate polymer and siloxane coupling agent used in this invention as water-blocking additives have a significant synergistic effect, thereby giving the negative electrode sheet excellent hydrophobicity, reducing water absorption and water content, and having high adhesion, thus improving the internal resistance and cycle performance of lithium-ion batteries; however, using organosilicon-modified acrylate polymer or siloxane coupling agent alone cannot significantly improve the effect.

[0138] The applicant declares that the present invention illustrates the electrode material composition, electrode sheet, and their applications through the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. An electrode material composition, characterized in that, The electrode material composition comprises the following components in parts by weight: 90-98 parts of active material Conductive agent 0.5-5.0 parts Adhesive 0.5-5.0 parts Organosilicon-modified acrylate polymers, 0.01-5.00 parts 0.01-3.00 parts of siloxane coupling agent; The siloxane coupling agent includes any one or a combination of at least two of the following: hexadecyltrimethoxysilane, hexadecyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, phenyltriethoxysilane, and diphenyldiethoxysilane.

2. The electrode material composition according to claim 1, characterized in that, The organosilicon-modified acrylate polymers are obtained by polymerizing acrylate monomers with alkenyl siloxanes.

3. The electrode material composition according to claim 2, characterized in that, The mass ratio of the acrylate monomer to the alkenyl siloxane is 1:(0.2-1.5).

4. The electrode material composition according to claim 3, characterized in that, The mass ratio of the acrylate monomer to the alkenyl siloxane is 1:(0.5-1.5).

5. The electrode material composition according to claim 2, characterized in that, The acrylate monomers include any one or a combination of at least two of (meth)acrylate alkyl esters, (meth)acrylate hydroxyalkyl esters, and (meth)acrylate phosphate esters.

6. The electrode material composition according to claim 5, characterized in that, The acrylate monomers include (meth)acrylate alkyl esters and / or (meth)acrylate hydroxyalkyl esters.

7. The electrode material composition according to claim 5, characterized in that, The acrylate monomers include any one or a combination of at least two of the following: methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

8. The electrode material composition according to claim 2, characterized in that, The alkenyl siloxane includes any one or a combination of at least two of methyl acyloxysiloxane, acyloxysiloxane, and vinyl siloxane.

9. The electrode material composition according to claim 8, characterized in that, The alkenyl siloxane includes any one or a combination of at least two of the following: 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropylmethyldiethoxysilane, 3-acryloxytrimethoxysilane, 3-acryloxytriethoxysilane, 3-acryloxymethyldimethoxysilane, 3-acryloxymethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltriisopropoxysilane.

10. The electrode material composition according to claim 1, characterized in that, The organosilicon-modified acrylate polymer is prepared by the following method, which includes: polymerizing acrylate monomers with alkenyl siloxanes in the presence of an initiator and an organic solvent to obtain the organosilicon-modified acrylate polymer.

11. The electrode material composition according to claim 10, characterized in that, Based on a total mass of 100 parts for acrylate monomers, alkenyl siloxanes, initiators, and organic solvents, the mass of each component is as follows: 20-50 parts of acrylate monomers Contains 10-30 parts of alkenylsiloxane 40-50 parts organic solvent Initiator 0.01-2.00 parts.

12. The electrode material composition according to claim 10 or 11, characterized in that, The initiator includes azo initiators and / or peroxide initiators.

13. The electrode material composition according to claim 10 or 11, characterized in that, The organic solvent includes any one or a combination of at least two of N-methylpyrrolidone, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, methanol, and ethanol.

14. The electrode material composition according to claim 10, characterized in that, The polymerization reaction is carried out at a temperature of 40-80℃.

15. The electrode material composition according to claim 10, characterized in that, The polymerization reaction takes 2-14 hours.

16. The electrode material composition according to claim 1, characterized in that, The number average molecular weight of the organosilicon-modified acrylate polymer is ≥1000.

17. The electrode material composition according to claim 16, characterized in that, The number average molecular weight of the organosilicon-modified acrylate polymer is 1,000-100,000.

18. The electrode material composition according to claim 1, characterized in that, The active material is a negative electrode active material.

19. The electrode material composition according to claim 18, characterized in that, The active material is a carbon-based anode active material and / or a silicon-based anode active material.

20. The electrode material composition according to claim 18, characterized in that, The negative electrode active material includes any one or a combination of at least two of the following: natural graphite, artificial graphite, mesophase carbon microspheres, soft carbon, and hard carbon.

21. The electrode material composition according to claim 1, characterized in that, The conductive agent includes any one or a combination of at least two of the following: conductive carbon black, conductive graphite, modified conductive graphite, metal particles, carbon nanotubes, carbon fibers, graphene, and conductive polymers.

22. The electrode material composition according to claim 21, characterized in that, The conductive agent includes conductive carbon black.

23. The electrode material composition according to claim 1, characterized in that, The adhesive comprises any one or a combination of at least two of the following: styrene-butadiene rubber, polyacrylic acid, polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone, polyethylene oxide, polyurethane, modified paraffin resin, carbomer resin, polyurethane acrylate, acrylate copolymer emulsion, epoxy resin, urethane epoxy resin, acrylic epoxy resin, polyisoborneol acrylate, and modified polyurea.

24. The electrode material composition according to claim 23, characterized in that, The adhesive includes styrene-butadiene rubber.

25. The electrode material composition according to claim 1, characterized in that, The electrode material composition further includes 0.5-5.0 parts by weight of thickener.

26. The electrode material composition according to claim 25, characterized in that, The thickener includes any one or a combination of at least two of the following: sodium carboxymethyl cellulose, polyethylene oxide, polyethylene oxide, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, gelatin, and sodium alginate.

27. The electrode material composition according to claim 1, characterized in that, The electrode material composition also includes other additives.

28. The electrode material composition according to claim 27, characterized in that, The other additives include any one or a combination of at least two of flame retardants, dispersants, and temperature stabilizers.

29. An electrode paste, characterized in that, The electrode slurry comprises a combination of the electrode material composition as described in any one of claims 1-28 and a solvent.

30. The electrode slurry according to claim 29, characterized in that, The solvent includes water and / or organic solvents.

31. The electrode slurry according to claim 29, characterized in that, The mass of the solvent is 100-200 parts, based on 100 parts by weight of the electrode material composition.

32. An electrode sheet, characterized in that, The electrode sheet includes a current collector and a coating disposed on the current collector, wherein the material of the coating includes the electrode material composition as described in any one of claims 1-28.

33. The electrode sheet according to claim 32, characterized in that, The electrode sheet is a negative electrode sheet.

34. The electrode sheet according to claim 32, characterized in that, The coating thickness is 25-300 μm.

35. An electrochemical energy storage device, characterized in that, The electrochemical energy storage device includes at least one of the electrode material composition as described in any one of claims 1-28 and the electrode sheet as described in any one of claims 32-34.

36. The electrochemical energy storage device according to claim 35, characterized in that, The electrochemical energy storage device includes any one of lithium-ion batteries, sodium-ion batteries, supercapacitors, fuel cells, or solar cells.

37. The electrochemical energy storage device according to claim 36, characterized in that, The electrochemical energy storage device includes a lithium-ion battery.

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