Slurry for electrode preparation, silicon negative electrode, and solid-state battery

Abstract

This invention provides an electrode preparation slurry, a silicon anode, and a solid-state battery. The electrode preparation slurry comprises: a carbon material, a silicon material, a gel polymer electrolyte material, a binder, and a solvent. By introducing a gel polymer electrolyte material with high ion conductivity, this electrode preparation slurry can induce uniform deposition of lithium ions in the three-dimensional pores formed by the various substances in the slurry during battery charging and discharging. This solves the dendrite growth problem caused by uneven lithium deposition. Simultaneously, the storage of lithium metal in the three-dimensional pores provides more expansion space for the silicon material, effectively mitigating the volume expansion effect of the silicon anode. Furthermore, by solving the problems of lithium dendrite growth and silicon expansion in the silicon anode, the cycle performance of the solid-state battery can be effectively improved.

Description

Technical Field

[0001] This application relates to the field of batteries, and more particularly to an electrode preparation slurry, a silicon anode, and a solid-state battery. Background Technology

[0002] All-solid-state lithium-ion batteries use inorganic solid-state electrolytes instead of flammable organic electrolytes, significantly improving the safety of lithium-ion batteries and attracting widespread attention from the research and industry sectors. Because inorganic solid-state electrolytes have a higher density than electrolytes, all-solid-state lithium-ion batteries using the same positive and negative electrode systems have lower energy densities than liquid lithium-ion batteries. Therefore, using a higher-capacity negative electrode is the core key to achieving high-energy-density all-solid-state batteries.

[0003] Currently, silicon anodes (theoretical specific capacity of approximately 4200 mAh / g) are the preferred anode material for all-solid-state batteries due to their high specific capacity. However, silicon anodes not only experience significant volume expansion after lithium intercalation, leading to substantial interface problems when applied to all-solid-state batteries, but also face the issue of lithium dendrite formation caused by excessive lithium-ion deposition.

[0004] In view of this, there is an urgent need for a technology to alleviate the expansion effect of silicon anodes and the lithium dendrite problem, thereby improving the cycle characteristics of all-solid-state batteries. Summary of the Invention

[0005] The present invention provides an electrode preparation slurry, a silicon anode, and a solid-state battery to alleviate the volume expansion and lithium dendrite growth problems of the silicon anode, thereby improving the cycle performance of the solid-state battery.

[0006] In a first aspect, the present invention provides a slurry for electrode preparation, comprising: a carbon material, a silicon material, a gel polymer electrolyte material, a binder, and a solvent;

[0007] The gel polymer electrolyte material is composed of a gel-state polymer matrix and an ionic liquid contained within the polymer matrix.

[0008] According to one embodiment of the present invention, the gel polymer electrolyte material is obtained by mixing and heating a precursor solution containing methyl methacrylate, N-isopropylacrylamide and neopentyl glycol diglycidyl ether, and then adding an ionic liquid to the polymer obtained after heating.

[0009] According to one embodiment of the present invention, the gel polymer accounts for 1 to 5% of the mass of the electrode preparation slurry, and / or the silicon material accounts for 60 to 80% of the mass of the electrode preparation slurry, and / or the carbon material accounts for 15 to 30% of the mass of the electrode preparation slurry.

[0010] According to one embodiment of the present invention, the carbon material is a carbon material after alloy vapor deposition; and / or, the silicon material is a silicon material after alloy vapor deposition;

[0011] The alloy materials used in alloy evaporation include at least one of nano-gold, nano-silver, nano-zinc, nano-magnesium, nano-aluminum, nano-platinum, nano-silicon, nano-tin, or nano-antimony.

[0012] According to one embodiment of the present invention, in the carbon material after alloy evaporation, the alloy material accounts for 0.2-5% of the mass of the carbon material after alloy evaporation; and / or, in the silicon material after alloy evaporation, the alloy material accounts for 0.2-5% of the mass of the silicon material after alloy evaporation.

[0013] According to one embodiment of the present invention, the carbon material is at least one of carbon black, acetylene black, Ketjen black, graphene, carbon nanotubes or carbon fibers; and / or, the particle size of the carbon material is 0.5~2μm.

[0014] According to one embodiment of the present invention, the silicon material is selected from at least one of silicon-carbon materials, pure silicon materials, or silicon alloy materials; and / or, the particle size of the silicon material is 30~5000 nm.

[0015] According to one embodiment of the present invention, the electrode preparation slurry further includes a solid electrolyte;

[0016] The solid electrolyte is Li (6-x) PS (5-x) M (1+x) Or at least one of yLi2S•(1-y)P2S5, wherein 0≤x≤0.6, 0.2≤y≤0.8, and M is Cl, Br or I;

[0017] And / or, the particle size of the solid electrolyte is 0.2~1μm;

[0018] And / or, the solid electrolyte accounts for 5-20% of the mass of the slurry used to prepare the electrode.

[0019] According to one embodiment of the present invention, the electrode preparation slurry further includes a lithium supplement and / or an ionic liquid;

[0020] The lithium replenishing agent accounts for 1-3% of the mass of the electrode preparation slurry.

[0021] In a second aspect, the present invention provides a silicon anode, the silicon anode comprising a current collector and a three-dimensional composite material protective layer disposed on at least one side of the surface of the current collector;

[0022] The three-dimensional composite material protective layer is obtained by drying the electrode preparation slurry coated on at least one side of the current collector.

[0023] The electrode preparation slurry is the electrode preparation slurry as described in the first aspect above.

[0024] According to one embodiment of the present invention, the current collector is a mesh-structured current collector with a porosity of 68-96%; and / or, the pore size distribution of the mesh-structured current collector is 0.1-2 mm.

[0025] According to one embodiment of the present invention, the material of the current collector of the mesh structure is at least one of copper, copper alloy, nickel, nickel alloy, aluminum, aluminum alloy, titanium, titanium alloy or stainless steel.

[0026] A third aspect of the present invention provides a solid-state battery, the solid-state battery comprising a positive electrode layer, a solid electrolyte layer, and a negative electrode layer;

[0027] The negative electrode layer is a silicon negative electrode as described in the second aspect above.

[0028] A fourth aspect of the present invention provides an electrical device, comprising an electrical device body and the solid-state battery described in the third aspect.

[0029] The present invention has at least the following beneficial effects:

[0030] This electrode preparation slurry incorporates a gel polymer electrolyte material with high ion conductivity. During battery charging and discharging, it induces uniform lithium ion deposition within the three-dimensional pores formed by various substances in the slurry, resolving the dendrite growth problem caused by uneven lithium metal deposition. Simultaneously, the storage of lithium metal within the three-dimensional pores provides more expansion space for the silicon material, effectively mitigating the volume expansion effect of the silicon anode. Furthermore, by addressing the expansion problem caused by lithium dendrite formation in the silicon anode, the cycle performance of the solid-state battery can be effectively improved. Attached Figure Description

[0031] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0032] Figure 1 This is a schematic diagram of a silicon anode provided in Embodiment 2 of the present invention.

[0033] Figure label:

[0034] 1-Solid electrolyte; 2-Silicon material after alloy vapor deposition; 3-Carbon material after alloy vapor deposition; 4-Gel polymer electrolyte material; 5-Lithium replenisher; 6-Mixture; 7-Network current collector; 8-Alloy material.

[0035] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0036] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Based on the above background information, Embodiment 1 of the present invention provides an electrode preparation slurry, comprising: carbon material, silicon material, gel polymer electrolyte material, binder, and solvent.

[0038] Among them, gel polymer electrolyte material is a gel electrolyte formed by solidifying organic electrolyte with polymer. It consists of a gel polymer matrix and an ionic liquid contained in the polymer matrix, and has high ion conductivity.

[0039] It should be noted that the use of carbon materials in the electrode preparation slurry can construct a continuous carbon-based network to form a rigid support and flexible buffer structure, which can significantly suppress the volume expansion of silicon during cycling and improve the cycling stability of silicon anode.

[0040] According to the inventors' research, a gel polymer electrolyte material with high ion conductivity can be added to the electrode preparation slurry used to prepare silicon anodes. On one hand, this addresses the problem of lithium dendrite growth in silicon anodes: during charging and discharging, the presence of the gel polymer electrolyte material significantly increases the lithium-ion transport rate, preventing excessive local deposition of lithium ions at the anode-electrolyte interface. This induces uniform lithium ion deposition within the three-dimensional pores formed by various substances in the slurry, thereby solving the dendrite growth caused by uneven lithium metal deposition and the resulting interface problems.

[0041] On the other hand, regarding the issue of silicon expansion in silicon anodes: during the charging process of silicon anodes, the storage of metallic lithium through three-dimensional pores provides more expansion space for the silicon material; simultaneously, due to the elasticity of the gel material, it can also provide some expansion space for the silicon material. Therefore, gel polymer electrolyte materials can effectively alleviate the volume expansion effect of silicon anodes. Furthermore, during the discharge process of silicon anodes, after lithium ions leave the anode, the gel polymer electrolyte material also provides some support to ensure the contact stability of the anode-electrolyte interface.

[0042] In view of this, this solution can effectively solve the problems of lithium dendrite growth and silicon expansion in silicon anodes by adding gel polymer electrolyte material to the slurry used for electrode preparation, thereby effectively improving the cycle performance of solid-state batteries.

[0043] In some implementations, the gel polymer electrolyte material is obtained by mixing and heating a precursor solution containing methyl methacrylate, N-isopropylacrylamide and neopentyl glycol diglycidyl ether, and then adding an ionic liquid to the polymer obtained after heating.

[0044] Specifically, the precursor solutions of methyl methacrylate, N-isopropylacrylamide, and neopentyl glycol diglycidyl ether are first thoroughly mixed according to a preset ratio to obtain a mixed solution; the mixed solution is then heated to obtain a polymer matrix; an ionic liquid is added to the polymer matrix to obtain a gel polymer electrolyte material.

[0045] The heating treatment of intermediates typically involves two heating processes. Specifically, the first heating process induces initial polymerization and cross-linking reactions in the substances, forming a semi-cured gel intermediate. The second heating process promotes further cross-linking of the substances in the semi-cured gel intermediate to construct a dense and stable polymer matrix.

[0046] Optionally, the temperature for both the first and second heat treatments is 30~60℃. For example, the temperature for the first or second heat treatment may be a value within the range of 30~60℃, such as 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, or 60℃. This invention does not limit the specific value of the temperature for the first or second heat treatment. It should be understood that the temperatures for the first and second heat treatments can be the same or different.

[0047] In addition, the proportion of each precursor solution in the mixed solution (i.e., the preset ratio) can be adjusted according to the performance of the target gel polymer electrolyte material (such as mechanical stability, ion transport efficiency, etc.), and this application does not make specific limitations in this regard.

[0048] It should be noted that the ionic liquid can be a commonly used ionic liquid in the art, such as 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-butyl-3-methylimidazolium hexafluorophosphate, N-methyl-N-propylpyrrolidineonium bis(trifluoromethanesulfonyl)imide salt, etc. This application does not impose specific restrictions on the selection of ionic liquids.

[0049] It should be understood that the gel polymer electrolyte material in this implementation is prepared by using a polymer matrix composed of methyl methacrylate, N-isopropylacrylamide, and neopentyl glycol diglycidyl ether, combined with a suitable ionic liquid. Methyl methacrylate, with its excellent rigidity and film-forming properties, provides stable structural support for the gel, ensuring mechanical strength. N-isopropylacrylamide combines hydrophilicity and flexibility, improving the gel's wettability to the ionic liquid and mitigating the brittleness of the crosslinked network, achieving a balance between rigidity and flexibility. Neopentyl glycol diglycidyl ether, as a multifunctional crosslinking agent, has biepoxide groups that react efficiently with the monomers, precisely controlling the crosslinking density and preventing the network from being too dense or too loose. Combined with the high ionic conductivity and chemical stability of the ionic liquid, the gel ultimately possesses both good structural stability and resistance to deformation, as well as efficient ion transport channels, significantly optimizing the overall performance of the gel polymer electrolyte. Accordingly, applying this gel polymer electrolyte to electrode preparation slurries can effectively ensure the safety, mechanical stability, and cycle performance of solid-state batteries using these slurries.

[0050] In some implementations, the gel polymer accounts for 1-5% of the mass of the electrode preparation slurry, and / or, the silicon material accounts for 60-80% of the mass of the electrode preparation slurry, and / or, the carbon material accounts for 15-30% of the mass of the electrode preparation slurry.

[0051] It should be noted that the mass ratio of a certain substance in the electrode preparation slurry involved in this application refers to the mass ratio of that substance in the effective components of the electrode preparation slurry (i.e., the components in the electrode preparation slurry other than the solvent).

[0052] For example, the mass ratio of gel polymer in the electrode preparation slurry is, for example, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc., in the range of 1 to 5%, and / or, the mass ratio of silicon material in the electrode preparation slurry is, for example, 60%, 65%, 70%, 75%, 80%, etc., in the range of 60 to 80%, and / or, the mass ratio of carbon material in the electrode preparation slurry is, for example, 15%, 18%, 20%, 23%, 25%, 28%, 30%, etc., in the range of 15 to 30%.

[0053] In practical applications, the specific mass ratio of carbon materials, silicon materials, gel polymer electrolyte materials, etc. in the electrode preparation slurry can be comprehensively adjusted according to factors such as the target performance of the target electrode preparation slurry, the specific requirements of the application scenario, and production costs.

[0054] Furthermore, in some implementations, the carbon material is an alloy-deposited carbon material; and / or, the silicon material is an alloy-deposited silicon material;

[0055] The alloy materials used in alloy evaporation include at least one of nano-gold, nano-silver, nano-zinc, nano-magnesium, nano-aluminum, nano-platinum, nano-silicon, nano-tin, or nano-antimony.

[0056] Specifically, in the electrode preparation slurry of this scheme, the carbon material used can be an alloy-deposited carbon material, and the silicon material used can be an alloy-deposited silicon material. The alloy material used for depositing the carbon and silicon materials can be any one of nano-gold, nano-silver, nano-zinc, nano-magnesium, nano-aluminum, nano-platinum, nano-silicon, nano-tin, or nano-antimony, or can be a combination of any number of the above substances. For example, it can be a combination of two, three, or more substances. This embodiment of the invention does not specifically limit this.

[0057] It should be understood that by evaporating alloy materials onto carbon and silicon materials, the lithium affinity of silicon and carbon materials can be improved (lithium deposition overpotential is less than 20mV), which further promotes the rapid adsorption and efficient migration of lithium ions on the electrode surface, induces the formation of a dense and uniform deposition layer of lithium ions to suppress lithium dendrite growth; in addition, it can also optimize the electron transport path inside the electrode, improve the overall conductivity, and thus further improve cycle stability.

[0058] In practical applications, the decision to perform vapor deposition on silicon or carbon materials can be made by comprehensively considering the actual economic benefits and the expected target performance.

[0059] As a specific example, the following method can be used to obtain carbon materials after alloy vapor deposition (the same applies to silicon materials):

[0060] Silicon material is dispersed in a solvent to form a uniformly dispersed solvent system; the solvent system is sprayed to form carbon spheres using a spray drying device; the carbon spheres are then vapor-deposited with alloy materials in a fluidized bed apparatus to form nano-alloy materials on the surface and inside of the carbon spheres, thus obtaining the alloy-deposited carbon material.

[0061] In some implementations, the alloy material accounts for 0.2-5% of the mass of the carbon material after alloy evaporation; and / or, the alloy material accounts for 0.2-5% of the mass of the silicon material after alloy evaporation.

[0062] In other words, the mass ratio of the alloy material in the carbon material after alloy evaporation is, for example, 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc., within the range of 0.2% to 5%; and / or, the mass ratio of the alloy material in the silicon material after alloy evaporation is, for example, 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc., within the range of 0.2% to 5%, and this application does not impose specific limitations on this.

[0063] It should be understood that this range of values ​​can ensure that the alloy material can form a continuous and uniform lithium-friendly interface on the surface of silicon or carbon materials while avoiding the decrease in battery specific capacity caused by vapor deposition.

[0064] In some implementations, the carbon material is at least one of carbon black, acetylene black, Ketjen black, graphene, carbon nanotubes, or carbon fibers.

[0065] Specifically, the silicon material selected above can be any one of carbon black, acetylene black, Ketjen black, graphene, carbon nanotubes or carbon fibers, or it can be a combination of any number of the above substances. For example, it can be a combination of two, three or more substances. In this respect, the embodiments of the present invention do not make specific limitations.

[0066] Optionally, the particle size of the carbon material is 0.5~2μm.

[0067] Specifically, the particle size of the carbon material is, for example, 0.5μm, 0.8μm, 1μm, 1.3μm, 1.5μm, 1.8μm, 2μm, etc., within the range of 0.5~2μm, and this application does not impose specific limitations on this.

[0068] In some implementations, the silicon material is selected from at least one of silicon-carbon materials, pure silicon materials, or silicon alloy materials.

[0069] Specifically, the silicon material can be selected from silicon-carbon materials, such as porous silicon / carbon composite microspheres, silicon-carbon nanotube composite materials, etc., or from pure silicon materials, such as nano-silicon or micron-silicon; or from silicon alloy materials, such as silicon-aluminum alloys, silicon-tin alloys, silicon-titanium alloys, silicon-zirconium alloys, etc. It should be understood that the silicon material can be at least one selected from the above materials.

[0070] Optionally, the particle size of the silicon material is 30~5000nm.

[0071] Specifically, the particle size of silicon material is, for example, 30nm, 500nm, 1000nm, 1500nm, 2000nm, 2500nm, 3000nm, 3500nm, 4000nm, 4500nm, 5000nm, etc., which are values ​​in the range of 30~5000nm. This application does not impose specific limitations on this.

[0072] In addition, the binder and solvent in this invention can be the binders and solvents commonly used in the preparation of silicon-carbon electrodes in the field of batteries. This application does not impose specific restrictions on the selection of binders and solvents.

[0073] In some implementations, the adhesive is, for example, at least one of sodium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polyacrylonitrile, and polymethyl methacrylate. Specifically, the adhesive may be any one of sodium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polyacrylonitrile, and polymethyl methacrylate, or it may be a combination of any number of the above substances. For example, it may be a combination of two, three, or more substances. The embodiments of the present invention do not specifically limit this.

[0074] Optionally, the binder accounts for 1 to 3% of the mass of the slurry used for electrode preparation. Specifically, the mass ratio of the binder to the slurry used for electrode preparation may be, for example, 1%, 1.3%, 1.5%, 1.8%, 2%, 2.3%, 2.5%, 2.8%, 3%, etc., within the range of 1 to 3%, and this application does not impose specific limitations on this.

[0075] In some implementations, the solvent is, for example, water or N-methylpyrrolidone.

[0076] In some implementations, the solid content of the electrode preparation slurry is 20-45%. Specifically, the solid content of the electrode preparation slurry is, for example, a value within the range of 20-45%, such as 20%, 25%, 30%, 35%, 40%, or 45%, and this application does not impose specific limitations on this. It should be understood that the solvent content in the electrode preparation slurry can be adjusted according to the preset solid content.

[0077] Furthermore, in some implementations, since the electrode preparation slurry provided by the present invention is compatible with solid electrolytes, no adverse side reactions occur after mixing with the solid electrolyte. Therefore, in order to further improve the ionic conductivity of the electrode preparation slurry, the electrode preparation slurry also includes a solid electrolyte.

[0078] The solid electrolyte is Li (6-x) PS (5-x) M (1+x)or at least one of yLi2S•(1-y)P2S5, wherein 0≤x≤0.6, 0.2≤y≤0.8, and M is Cl, Br, or I.

[0079] Optionally, the particle size of the solid electrolyte is 0.2~1μm.

[0080] Specifically, the particle size of the solid electrolyte is, for example, 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm, 1 μm, etc., within the range of 0.2 to 1 μm. This application does not impose specific limitations on this.

[0081] Optionally, the solid electrolyte accounts for 5-20% of the mass of the slurry used for electrode preparation. Specifically, the mass ratio of the solid electrolyte to the slurry used for electrode preparation may be, for example, 5%, 8%, 12%, 15%, 18%, 20%, etc., within the range of 5-20%, and this application does not impose specific limitations on this.

[0082] Furthermore, in some implementations, in order to further improve the energy density and cycle life of solid-state batteries, the electrode preparation slurry also includes a lithium replenishing agent.

[0083] Optionally, the lithium replenishing agent accounts for 1 to 3% of the mass of the slurry used for electrode preparation. Specifically, the mass ratio of the lithium replenishing agent to the slurry used for electrode preparation is, for example, 1%, 1.3%, 1.5%, 1.8%, 2%, 2.3%, 2.5%, 2.8%, 3%, etc., within the range of 1 to 3%, and this application does not impose specific limitations on this.

[0084] It should be understood that since lithium replenishment agents can preferentially undergo lithiation reactions to release active lithium ions during the first charge and discharge process, they can precisely replenish the large amount of lithium source consumed during the lithiation stage of silicon materials and the formation of the solid electrolyte interface film, thus avoiding excessive loss of active lithium in the positive electrode. Therefore, adding lithium replenishment agents can significantly improve the first coulombic efficiency of silicon anodes, reduce initial capacity decay, and promote the formation of a stable, dense, and low-resistance solid electrolyte interface film, thereby further enhancing the energy density and long-cycle durability of solid-state batteries.

[0085] Furthermore, in some implementations, the slurry used for electrode preparation also includes ionic liquids.

[0086] It should be understood that by adding ionic liquids to the electrode preparation slurry, the ion transport efficiency of the electrode preparation slurry can be further improved, thereby guiding lithium ions to be evenly distributed in the three-dimensional pores of the slurry and alleviating the problems of dendrite growth and silicon expansion caused by lithium deposition in silicon anodes.

[0087] In addition, this embodiment of the invention also provides a method for preparing the above-mentioned electrode preparation slurry, wherein carbon material, silicon material, gel polymer electrolyte material and binder are dispersed in a solvent according to a preset ratio to obtain the electrode preparation slurry.

[0088] Optionally, carbon materials, silicon materials, gel polymer electrolyte materials, ionic liquids (and / or solid electrolytes, and / or lithium supplements), and binders can be dispersed in a solvent according to a preset ratio to obtain a slurry for electrode preparation.

[0089] The electrode preparation slurry provided in this invention introduces a gel polymer electrolyte material with high ion conductivity. During battery charging and discharging, this slurry induces uniform deposition of lithium ions within the three-dimensional pores formed by various substances, solving the dendrite growth problem caused by uneven lithium metal deposition. Simultaneously, the storage of lithium metal within the three-dimensional pores provides more expansion space for the silicon material, effectively mitigating the volume expansion effect of the silicon anode. Furthermore, by solving the expansion problem caused by lithium dendrite formation in the silicon anode, the cycle performance of the solid-state battery can be effectively improved.

[0090] Embodiment 2 of the present invention provides a silicon anode, comprising: a silicon current collector and a three-dimensional composite material protective layer disposed on at least one side of the current collector surface;

[0091] The three-dimensional composite protective layer is obtained by drying the electrode preparation slurry coated on at least one surface of the current collector. This electrode preparation slurry is the same as the one described in the above embodiments.

[0092] It should be understood that, depending on different application requirements, the three-dimensional composite material protective layer may be provided on only one side of the current collector surface, or it may be provided on both sides of the current collector.

[0093] In addition, Embodiment 2 of the present invention also provides a method for preparing the above-mentioned silicon anode, comprising:

[0094] The silicon anode is obtained by coating the electrode preparation slurry onto at least one side of the current collector and then drying it.

[0095] Furthermore, in some implementations, the current collector is a mesh-structured current collector.

[0096] It should be understood that the silicon anode uses a current collector with a mesh structure. The three-dimensional skeleton of the mesh structure forms multi-point and three-dimensional contact with the active material. Compared with the single-point and surface contact of the planar current collector, the electron transport path is shorter and the contact area is larger. It can build a continuous electron channel through the electrode, which can further improve the conductivity and rate performance of the solid-state battery.

[0097] Optionally, the porosity of the current collector with the mesh structure is 68-96%. Specifically, the porosity of the current collector with the mesh structure is, for example, a value in the range of 68-96%, such as 68%, 70%, 75%, 80%, 85%, 90%, 96%, etc., and this application does not impose a specific limitation on it.

[0098] Optionally, the pore size distribution of the current collector in the mesh structure is 0.1~2 mm. Specifically, the porosity of the current collector in the mesh structure is, for example, a value in the range of 0.1~2 mm, such as 0.1 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, etc., and this application does not impose specific limitations on it.

[0099] Optionally, the current collector of the mesh structure is made of at least one of copper, copper alloy, nickel, nickel alloy, aluminum, aluminum alloy, titanium, titanium alloy, or stainless steel.

[0100] Specifically, the material of the current collector in the mesh structure can be any one of copper, copper alloy, nickel, nickel alloy, aluminum, aluminum alloy, titanium, titanium alloy, or stainless steel, or it can be composed of any combination of the above materials. For example, it can be composed of two, three, or more materials. In this respect, the embodiments of the present invention do not make specific limitations.

[0101] It should be understood that the total thickness of the silicon anode is 20~100μm. Therefore, the silicon anode of this design exhibits a high energy density.

[0102] Figure 1 This is a schematic diagram of a silicon anode provided in Embodiment 2 of the present invention, as shown below. Figure 1 As shown, both sides of the current collector 7 of the silicon anode mesh structure are provided with a three-dimensional composite material protective layer. The pores of the current collector 7 mesh structure include an alloy material 8 of the same material as the current collector; the three-dimensional composite material protective layer includes a solid electrolyte 1, an alloy-deposited silicon material 2, an alloy-deposited carbon material 3, a gel polymer electrolyte material 4, a lithium supplement 5, and a mixture 6 (including a binder and an ionic liquid).

[0103] The silicon anode provided by the present invention has a three-dimensional composite material protective layer on it, which is obtained by the electrode preparation slurry including the gel polymer electrolyte material. It can utilize the high ion conductivity and elasticity of the gel polymer electrolyte material to guide the uniform distribution of lithium ions during lithium deposition, with fewer problems of lithium dendrite growth and silicon expansion. Furthermore, it has strong structural stability due to the support of the gel polymer electrolyte material during discharge.

[0104] Embodiment 3 of the present invention also provides a solid-state battery, comprising: a positive electrode layer, a solid electrolyte layer, and a negative electrode layer.

[0105] The negative electrode layer is the silicon negative electrode in the above embodiment.

[0106] In practical applications, solid-state batteries include a positive electrode layer, a solid electrolyte layer, and a negative electrode layer. Specifically, the positive electrode layer includes a positive current collector and a positive active layer formed of a positive active material disposed on the surface of the current collector. The solid electrolyte can be a conventional solid electrolyte in the art, such as a sulfide electrolyte or an oxide electrolyte. This invention does not impose specific limitations on the selection and preparation of the positive electrode layer and the solid electrolyte in solid-state batteries.

[0107] The solid-state battery provided by this invention, due to the silicon anode included, can effectively suppress lithium dendrite growth and silicon expansion effect. During the charging and discharging process of the battery, lithium ions are uniformly deposited in the three-dimensional pores, the loss of active lithium is greatly reduced, and the electrode structure remains intact throughout the charge and discharge cycle, and the electrode-electrolyte interface remains stable. Therefore, it has better cycle performance.

[0108] Embodiment 4 of the present invention also provides an electrical device, including a main body of the electrical device and a solid-state battery provided by the present invention.

[0109] It should be noted that the present invention does not particularly limit the type of electrical device, which can be any electrical device including the battery, including but not limited to electric vehicles, mobile phones, portable devices, laptops, electric bicycles, electric toys, energy storage devices, etc.

[0110] The present invention will be further described below through specific embodiments.

[0111] Example 1

[0112] 1) Preparation of silicon anode:

[0113] S1: Multi-walled carbon nanotubes and graphene in a mass ratio of 9:1 are dispersed in an aqueous solution and spray-dried to form carbon spheres of 1-3 μm.

[0114] S2: Carbon spheres and pure silicon materials are vapor-deposited with 5% by mass of nano-silver and nano-iron in a fluidized bed, wherein the particle size distribution of nano-silver and nano-iron is 5-10nm, to obtain silicon material and carbon material after alloy vapor deposition.

[0115] S3: A slurry for electrode preparation with a solid content of 45% is formed by dispersing 75% by mass of alloy-deposited silicon material, 15% by mass of alloy-deposited carbon material, 3% by mass of gel polymer electrolyte material, 2% by mass of ionic liquid, 5% by mass of solid electrolyte, and 2% by mass of polyacrylic acid in an aqueous solution; wherein the solid electrolyte is Li. 0.5 PS4.4 M 1.1 .

[0116] S4: The electrode preparation slurry is coated onto a 25μm thick mesh current collector with a porosity of 70%, and then dried to obtain a silicon anode with a thickness of 40μm.

[0117] 2) All-solid-state battery assembly:

[0118] Electrolyte layer: prepared according to the ratio of Li3PS4:polytetrafluoroethylene (PTFE) = 99:1, with a thickness of 20μm;

[0119] Positive electrode layer: 811 type nickel cobalt manganese oxide lithium (NCM811): superconducting carbon black (SP): carbon nanotubes (CNT): Li3YCl6:PTFE = 88.5:1:0.5:8:2, thickness 100μm;

[0120] The silicon anode, cathode, and electrolyte layers are die-cut to the design size, stacked in the order of anode-electrolyte-cathode, and then hot-pressed at 120℃ and 0.5MPa for 60s. The bare cell is then encapsulated in a soft pack and isostatically pressed at 400MPa for 3min to form a solid-state battery.

[0121] Example 2

[0122] It is basically the same as Example 1, except that no ionic liquid is added to the slurry used for electrode preparation.

[0123] Comparative Example 1

[0124] It is basically the same as Example 1, except that no gel polymer electrolyte material is added to the slurry used for electrode preparation.

[0125] Comparative Example 2

[0126] It is basically the same as Example 1, except that a 20μm thick lithium metal is used as the negative electrode.

[0127] The electrochemical performance of the solid-state batteries prepared in the above embodiments and comparative examples was tested, and the test results are shown in Table 1. The specific test contents are as follows:

[0128] (1) First-efficiency test: The battery was discharged at a constant current of 0.1C to obtain the first discharge capacity, and the solid-state battery was charged at a constant current of 0.1C to obtain the first charging capacity; the first discharge capacity was divided by the first charging capacity to obtain the first efficiency.

[0129] (2) Cyclic performance test: Starting from the second time, the number of cycles of charging and discharging at 0.5C until the capacity retention rate reaches 80% is recorded.

[0130] Table 1: Solid-state battery test results

[0131]

[0132] As can be seen from the data in Table 1, compared to Comparative Example 1 without the addition of gel polymer electrolyte material, Examples 1 and 2 provided by the present invention exhibit superior cycle performance. Examples 1 and 2 demonstrate that, compared to the silicon anode without solid electrolyte, the introduction of a solid electrolyte in Example 1 further improves the initial coulombic efficiency of the battery. Furthermore, the cycle performance and initial efficiency of the gel polymer electrolyte material provided by the present invention are significantly higher than those of the lithium metal anode in Comparative Example 2. This shows that the solid-state battery provided by the present invention maintains both high energy density and high cycle performance and initial efficiency.

[0133] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A paste for electrode preparation, characterized in that, The electrode preparation slurry includes: carbon materials, silicon materials, gel polymer electrolyte materials, binders, and solvents; The gel polymer electrolyte material is composed of a gel-state polymer matrix and an ionic liquid contained within the polymer matrix; the gel polymer electrolyte material is obtained by mixing and heating a precursor solution containing methyl methacrylate, N-isopropylacrylamide and neopentyl glycol diglycidyl ether, and then adding the ionic liquid to the polymer obtained after heating. The heat treatment includes two heat treatments: the first heat treatment is used to induce preliminary polymerization and cross-linking reactions of the substances to form a semi-cured gel intermediate; the second heat treatment is used to promote further cross-linking of the substances in the semi-cured gel intermediate to construct a dense and stable polymer matrix; the temperature of both the first and second heat treatments is 30~60℃. The electrode preparation slurry forms three-dimensional pores after the electrode is made, which is used to induce lithium ions to be uniformly deposited in the three-dimensional pores to suppress dendrite growth, and to provide expansion space for silicon material through the three-dimensional pores. The gel polymer accounts for 1-5% of the mass of the electrode preparation slurry, and / or the silicon material accounts for 60-80% of the mass of the electrode preparation slurry, and / or the carbon material accounts for 15-30% of the mass of the electrode preparation slurry.

2. The electrode preparation slurry according to claim 1, characterized in that, The carbon material is a carbon material after alloy vapor deposition; and / or, the silicon material is a silicon material after alloy vapor deposition; The alloy materials used in alloy evaporation include at least one of nano-gold, nano-silver, nano-zinc, nano-magnesium, nano-aluminum, nano-platinum, nano-silicon, nano-tin, or nano-antimony.

3. The electrode preparation slurry according to claim 2, characterized in that, In the carbon material after alloy vapor deposition, the alloy material accounts for 0.2-5% of the mass of the carbon material after alloy vapor deposition; and / or, in the silicon material after alloy vapor deposition, the alloy material accounts for 0.2-5% of the mass of the silicon material after alloy vapor deposition.

4. The electrode preparation slurry according to any one of claims 1 to 3, characterized in that, The carbon material is at least one of carbon black, graphene, carbon nanotubes or carbon fibers; and / or the particle size of the carbon material is 0.5~2μm.

5. The electrode preparation slurry according to any one of claims 1 to 3, characterized in that, The silicon material is selected from at least one of silicon-carbon materials, pure silicon materials, or silicon alloy materials; and / or, the particle size of the silicon material is 30~5000nm.

6. The electrode preparation slurry according to any one of claims 1 to 3, characterized in that, The electrode preparation slurry also includes a solid electrolyte; The solid electrolyte is At least one of the following, 0≤x≤0.6, 0.2≤y≤0.8, and M is Cl, Br or I; And / or, the particle size of the solid electrolyte is 0.2~1μm; And / or, the solid electrolyte accounts for 5-20% of the mass of the slurry used to prepare the electrode.

7. The electrode preparation slurry according to any one of claims 1 to 3, characterized in that, The electrode preparation slurry also includes a lithium supplement and / or an ionic liquid; The lithium replenishing agent accounts for 1-3% of the mass of the electrode preparation slurry.

8. A silicon anode, characterized in that, The silicon anode includes a current collector and a three-dimensional composite material protective layer disposed on at least one side of the surface of the current collector; The three-dimensional composite material protective layer is obtained by drying the electrode preparation slurry coated on at least one side of the current collector. Wherein, the electrode preparation slurry is the electrode preparation slurry as described in any one of claims 1 to 7.

9. The silicon anode according to claim 8, characterized in that, The current collector is a mesh-structured current collector with a porosity of 68-96%; and / or, the pore size distribution of the mesh-structured current collector is 0.1-2 mm.

10. The silicon anode according to claim 9, characterized in that, The current collector of the mesh structure is made of at least one of copper, copper alloy, nickel, nickel alloy, aluminum, aluminum alloy, titanium, titanium alloy, or stainless steel.

11. A solid-state battery, characterized in that, The solid-state battery includes a positive electrode layer, a solid electrolyte layer, and a negative electrode layer; The negative electrode layer is a silicon negative electrode as described in any one of claims 8 to 10.

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