Solid-state battery negative electrode material, preparation method thereof, and new energy automobile solid-state battery

Abstract

The application provides a solid-state battery negative material, a preparation method thereof and a new energy automobile solid-state battery. The preparation method comprises the following steps: dispersing a silicon-based active component, a carbon-based conductive component and a doping modifier in a dispersion solvent respectively to prepare a silicon-based active component dispersion liquid, a carbon-based conductive component dispersion liquid and a doping modifier dispersion liquid; mixing the silicon-based active component dispersion liquid and the carbon-based conductive component dispersion liquid, then adding the doping modifier dispersion liquid, and then adding a binder and an interface modifier, and uniformly mixing to obtain a mixed slurry; coating the mixed slurry on a substrate, drying to obtain a solidified precursor; under the protection of an inert atmosphere, performing gradient sintering treatment on the solidified precursor, and after cooling, peeling the sintered product from the substrate, and then crushing to obtain the solid-state battery negative material. According to the solid-state battery negative material, the volume expansion rate is reduced, the initial discharge specific capacity is high, the cycle performance is long, and the interface charge transfer impedance is reduced.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery materials technology for new energy vehicles, specifically to a solid-state battery anode material, its preparation method, and a solid-state battery for new energy vehicles. Background Technology

[0002] With the rapid development of new energy vehicles, the market has placed higher demands on the energy density, cycle stability, and safety of batteries. All-solid-state batteries for new energy vehicles replace traditional liquid electrolytes with solid electrolytes, fundamentally reducing safety hazards such as leakage, combustion, and explosion associated with liquid batteries. They also possess a wider electrochemical window, allowing for the matching of high-specific-capacity positive and negative electrode materials, making them the core development direction for next-generation power batteries. Their technological iteration is a key driving force for the electrification transformation of the automotive industry.

[0003] As a core component of solid-state batteries, the anode material directly determines the battery's energy density and cycle life. Traditional graphite anodes have a theoretical specific capacity of only 372 mAh / g, which is insufficient to meet the development requirements of high-energy-density solid-state batteries. Therefore, developing high-specific-capacity anode materials has become a research hotspot in this field. Silicon, with its ultra-high theoretical specific capacity of 4200 mAh / g, is considered the most promising alternative to graphite and has broad application prospects in solid-state batteries. However, silicon exhibits a volume expansion rate as high as 300% during charge and discharge, easily leading to electrode pulverization, active material shedding, and interfacial contact failure. Furthermore, silicon's inherent poor conductivity severely restricts its commercial application.

[0004] Existing technologies have proposed various modification schemes to address the volume expansion problem of silicon anodes, but all of them have obvious defects: in some schemes, the bonding force between the coating layer and the silicon core interface in the composite structure is weak, which makes it easy to peel off during cycling, and the ionic conductivity is insufficient to meet the fast charging requirements; although some technologies can control the volume expansion rate to within 150%, they have not optimized the charge transfer impedance at the electrode-electrolyte interface, resulting in poor compatibility between silicon-based materials and solid electrolyte interfaces, high battery internal resistance, and affecting rate performance.

[0005] Besides silicon-based anodes, alloy anode materials, while buffering volume expansion through pore channels, suffer from low specific capacity, complex manufacturing processes, and high costs. Graphite anodes, while possessing advantages such as low cost and low lithium potential, are prone to side reactions when in contact with sulfide electrolytes. Furthermore, the randomness of interfacial contact and the low ionic conductivity of the electrolyte coating layer lead to poor rate performance. Existing methods for suppressing side reactions significantly reduce the ionic conductivity of the electrolyte, further limiting performance improvement.

[0006] In recent years, scientific research has explored novel modification strategies for silicon-based anodes, such as the pre-lithiation-fortress synergistic strategy and multi-element doped porous carbon coating technology. Although these strategies have improved performance to some extent, they still have problems such as complex preparation processes, high costs due to multiple steps, and some solutions have limitations such as low specific capacity and poor ion transport performance, making it difficult to apply on a large scale.

[0007] Meanwhile, existing silicon-based composite anode materials suffer from insufficient synergistic modification and unreasonable component ratios: single carbon coating or single-element doping is insufficient to simultaneously achieve volume expansion suppression, electronic conductivity, and ion transport performance; in multi-element doping schemes, some result in increased costs and impurity phases due to excessively high dopant content, while others fail to achieve effective modification due to excessively low content. Furthermore, existing preparation methods often suffer from complex processes, harsh reaction conditions, high energy consumption, and a tendency to cause material agglomeration, which are detrimental to industrialization.

[0008] In addition, the interfacial charge transfer impedance problem of solid-state batteries is another key bottleneck. Poor chemical compatibility and poor contact between the electrode and the solid electrolyte lead to high interfacial charge transfer impedance, which affects lithium-ion transport efficiency. Existing impedance reduction methods mostly target single problems and are difficult to achieve long-term stable control. Furthermore, the interfacial compatibility between the negative electrode material and various solid electrolytes is generally poor, which further exacerbates this problem.

[0009] In summary, existing solid-state battery anode materials for new energy vehicles generally suffer from technical defects such as high volume expansion rate, difficulty in achieving both electron and ion transport performance, poor interfacial compatibility, complex and costly preparation processes, and unreasonable component ratios. Developing solid-state battery anode materials that combine high specific capacity, low volume expansion, excellent interfacial compatibility, long cycle life, and good rate performance, and can be prepared on a large scale at low cost, has become a core problem that urgently needs to be solved in this field. Summary of the Invention

[0010] Based on the technical problems described above, specifically addressing the shortcomings of existing solid-state battery anode materials for new energy vehicles, such as high volume expansion rate, insufficient specific capacity, poor cycle and rate performance, poor interfacial compatibility, and complex and costly manufacturing processes, this invention aims to provide a solid-state battery anode material that achieves synergistic improvement in various performance characteristics, possesses excellent interfacial compatibility and controllable cost, and is suitable for large-scale production. Furthermore, this invention aims to provide a simple, mild, and low-energy-consumption method for preparing the anode material, and further provides a solid-state battery for new energy vehicles containing this anode material, which exhibits low expansion, high specific capacity, long cycle life, and high safety, making it suitable for multiple fields including new energy vehicles.

[0011] Specifically, according to one aspect of the present invention, a method for preparing a solid-state battery anode material is provided, comprising the following steps: (1) The silicon-based active component, the carbon-based conductive component, and the doping modifier are dispersed in a dispersion solvent to prepare a silicon-based active component dispersion, a carbon-based conductive component dispersion, and a doping modifier dispersion; (2) The silicon-based active component dispersion is mixed with the carbon-based conductive component dispersion, then the doping modifier dispersion is added, followed by the binder and interface modifier. The mixture is then stirred until homogeneous to obtain a mixed slurry. (3) The mixed slurry is coated onto a substrate and dried to obtain a cured precursor; (4) Under an inert atmosphere, the solidified precursor is subjected to gradient sintering. After cooling, the sintered material is peeled off from the substrate and then crushed to obtain a solid-state battery anode material, wherein: The silicon-based active component is a mixture of nano-silicon powder and silicon suboxide; The carbon-based conductive component is a mixture of graphite, graphene, and carbon nanotubes; The doping modifier is a mixture of metallic and non-metallic element modifiers, wherein the metallic element modifier accounts for 40-70% of the total weight of the doping modifier, and the non-metallic element modifier accounts for 30-60% of the total weight of the doping modifier. The metallic element modifier is a mixture of tetrabutyl titanate, zirconium oxide, tin chloride, and aluminum oxide, and the non-metallic element modifier is a mixture of ammonium dihydrogen phosphate, urea, and boric acid. The adhesive is selected from at least one of carboxymethyl cellulose, sodium alginate, polyvinylidene fluoride, polyacrylic acid, lithium-ionized polyacrylic acid, and styrene-butadiene rubber; The interface modifier is selected from at least one of lithium fluoride, sodium fluoride, trimethyl borate, and fluoroethylene carbonate; Based on the total weight of silicon-based active components, carbon-based conductive components, doping modifiers, binders, and interface modifiers as 100%, the silicon-based active components account for 40-75%, the carbon-based conductive components account for 15-40%, the doping modifiers account for 3-12%, the binders account for 2-8%, and the interface modifiers account for 0.5-3%.

[0012] According to certain preferred embodiments of the present invention, the silicon-based active component is a mixture of nano-silicon powder and silicon suboxide in a weight ratio of 2:1 to 3:1.

[0013] According to certain preferred embodiments of the present invention, the average particle size of the nano-silicon powder is 50-200 nm, and the specific surface area is 10-30 m². 2 / g.

[0014] According to certain preferred embodiments of the present invention, the silicon suboxide has an average particle size of 100-300 nm and a specific surface area of ​​5-20 m². 2 / g.

[0015] According to certain preferred embodiments of the present invention, in the carbon-based conductive component, the weight ratio of graphite, graphene and carbon nanotubes is (5-10):(1-3):(1-2).

[0016] According to certain preferred embodiments of the present invention, the graphite has an average particle size of 1-5 μm and a specific surface area of ​​1-5 m². 2 / g.

[0017] According to certain preferred embodiments of the present invention, the graphene has 1-15 layers and an average sheet diameter of 0.5-10 μm.

[0018] According to certain preferred embodiments of the present invention, the carbon nanotubes have a diameter of 10-50 nm and a length of 1-10 μm.

[0019] According to certain preferred embodiments of the present invention, in the metal element modifier, the weight ratio of tetrabutyl titanate, zirconium oxide, tin chloride and aluminum oxide is (3-5):(2-4):(1-3):(1-2).

[0020] According to certain preferred embodiments of the present invention, in the non-metallic element modifier, the weight ratio of ammonium dihydrogen phosphate, urea and boric acid is (4-6):(3-5):(1-2).

[0021] According to certain preferred embodiments of the present invention, the dispersing solvent is a mixture of deionized water and ethanol.

[0022] According to certain preferred embodiments of the present invention, the dispersing solvent is a mixture of deionized water and ethanol in a weight ratio of 2:1 to 1:2.

[0023] According to certain preferred embodiments of the present invention, in the silicon-based active component dispersion, the weight ratio of the silicon-based active component to the dispersion solvent is 1:3-1:5.

[0024] According to certain preferred embodiments of the present invention, in the carbon-based conductive component dispersion, the weight ratio of the carbon-based conductive component to the dispersion solvent is 1:4-1:6.

[0025] According to certain preferred embodiments of the present invention, in the dopant-modifier dispersion, the weight ratio of the dopant-modifier to the dispersion solvent is 1:5-1:8.

[0026] According to certain preferred embodiments of the present invention, the solid content of the mixed slurry is 30-60%.

[0027] According to certain preferred embodiments of the present invention, in step (3), the substrate is a copper foil.

[0028] According to certain preferred embodiments of the present invention, in step (3), the coating thickness is 50-150 μm, and the drying adopts a gradient drying method, first drying at 80-90°C for 4-6 h, and then drying at 100-120°C for 8-18 h.

[0029] According to certain preferred embodiments of the present invention, the gradient sintering process includes: (a) Heating stage: Heat to 200-300°C at a heating rate of 5-10°C / min, and hold for 2-4 hours; (b) Intermediate temperature stage: Heat to 400-500°C at a heating rate of 3-5°C / min, and hold for 3-5 hours; (c) High temperature stage: Heat to 600-800°C at a heating rate of 2-3°C / min, and hold for 4-8 hours; (d) Cooling stage: Cool down to room temperature at a cooling rate of 5-8°C / min.

[0030] According to certain preferred embodiments of the present invention, the inert atmosphere is nitrogen or argon.

[0031] According to certain preferred embodiments of the present invention, the particle size of the pulverized solid-state battery anode material in step (4) is 3-20 μm.

[0032] According to certain preferred embodiments of the present invention, in step (1), the preparation of the silicon-based active component dispersion includes stirring and sonicating the raw materials, wherein the stirring conditions are 25-35°C and 300-500 rpm for 30-60 min, and the ultrasonic dispersion conditions are ultrasonic power of 200-400 W and ultrasonic time of 20-40 min.

[0033] According to certain preferred embodiments of the present invention, in step (1), the preparation of the carbon-based conductive component dispersion includes stirring and sonicating the raw materials, wherein the stirring conditions are 25-35°C and 400-600 rpm for 40-80 min, and the ultrasonic dispersion conditions are ultrasonic power of 300-500 W and ultrasonic time of 30-50 min.

[0034] According to certain preferred embodiments of the present invention, in step (1), the preparation of the dopant modifier dispersion includes stirring the raw materials, wherein the stirring conditions are 50-70°C and 200-300 rpm for 20-40 min.

[0035] According to certain preferred embodiments of the present invention, in step (2), the mixing conditions of the silicon-based active component dispersion and the carbon-based conductive component dispersion are 25-35°C and 500-700 rpm for 60-90 min; the addition rate of the dopant modifier dispersion is 1-3 mL / min; and the stirring conditions after adding the binder and interface modifier are 25-35°C and 600-800 rpm for 80-120 min.

[0036] According to another aspect of the present invention, a solid-state battery anode material is provided, the solid-state battery anode material being prepared according to the method described above.

[0037] According to certain preferred embodiments of the present invention, the volume expansion rate of the solid-state battery anode material is less than or equal to 65%.

[0038] According to certain preferred embodiments of the present invention, the initial discharge specific capacity of the solid-state battery anode material is 1900-2200 mAh / g, and the initial coulombic efficiency is greater than or equal to 91%.

[0039] According to certain preferred embodiments of the present invention, the solid-state battery anode material retains a capacity of greater than or equal to 85% after 1000 cycles.

[0040] According to certain preferred embodiments of the present invention, the interfacial charge transfer impedance of the solid-state battery anode material is less than or equal to 35 Ω•cm. 2 .

[0041] According to another aspect of the present invention, a solid-state battery for new energy vehicles is provided, the solid-state battery for new energy vehicles comprising a positive electrode, a solid electrolyte layer and a negative electrode, wherein the negative electrode comprises a solid-state battery negative electrode material as described above.

[0042] According to certain preferred embodiments of the present invention, the content of the solid-state battery negative electrode material in the negative electrode sheet is 85-95% by weight.

[0043] According to certain preferred embodiments of the present invention, the negative electrode further includes a binder and a conductive agent, wherein the binder is selected from one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyimide and sodium carboxymethyl cellulose, and the conductive agent is one or more of acetylene black, Ketjen black or carbon nanotubes.

[0044] According to certain preferred embodiments of the present invention, the solid electrolyte layer is one of a sulfide solid electrolyte, an oxide solid electrolyte, or a polymer solid electrolyte.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) By screening and optimizing the proportions of components, the synergistic effect of each component is achieved, which solves the various performance defects caused by single components or unreasonable proportions in the existing technology. This allows the anode material to form a comprehensive advantage in suppressing volume expansion, improving specific capacity, and optimizing cycle and rate performance, thus breaking through the limitations of single performance improvement.

[0046] (2) The combination of multiple types of silicon-based and carbon-based components, combined with mixed doping of metal and non-metal compounds, and a combination of specific binders and interface modification components is an innovative solution not disclosed in the prior art.

[0047] (3) In response to the core technical bottleneck of silicon-based anodes, a new solution was formed through multi-dimensional component design, which achieved a synergistic improvement of low volume expansion and high specific capacity, long cycle life and high rate, and solved the technical problem that has existed in this field for a long time.

[0048] (4) Through the synergistic effect of interface modification components and doping modification components, the interface charge transfer impedance is effectively reduced, the interface side reaction is suppressed, the problem of poor contact between the negative electrode and the solid electrolyte and serious side reaction is solved, and the battery performance stability is improved.

[0049] (5) The preparation method is simple and cost-controllable. No special / expensive complex equipment or harsh reaction conditions are required. Gradient dispersion, gradient sintering and other processes are adopted. The operation is convenient and energy consumption is low. The raw materials are conventional chemical products, which significantly reduces the preparation cost and is suitable for large-scale production and industrial promotion. Attached Figure Description

[0050] The accompanying drawings are provided in this specification to more clearly explain the technical solutions of the present invention; however, the present invention is not limited thereto.

[0051] Figure 1 A flowchart illustrating the preparation process of a solid-state battery anode material according to the present invention is shown. Figure 2 A scanning electron microscope (SEM) image of the solid-state battery anode material prepared in Example 1 is shown. Detailed Implementation

[0052] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. It will be understood that other embodiments may be implemented without departing from the scope or spirit of the invention. Therefore, the following detailed description is non-limiting.

[0053] Unless otherwise specified, all figures used in this specification to represent characteristic dimensions, quantities, and physical properties should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise stated, the numerical parameters listed in the foregoing specification are approximations, and those skilled in the art can appropriately modify these approximations to obtain the desired properties using the teachings disclosed herein.

[0054] As mentioned above, existing solid-state battery anode materials for new energy vehicles suffer from the following technical problems: high volume expansion rates of silicon-based and other high-capacity materials lead to structural damage during cycling; it is difficult to simultaneously achieve good electronic conductivity and ion transport performance, resulting in insufficient rate and fast-charging capabilities; poor interfacial compatibility and high impedance between solid-state battery anode materials and solid electrolytes affect lithium-ion transport; and the complex and costly preparation processes of some high-performance materials hinder industrialization. Furthermore, existing methods for reducing interfacial charge transfer impedance primarily address single issues and are difficult to control stably over the long term. These problems collectively restrict the performance improvement and large-scale application of solid-state batteries, becoming a critical technical bottleneck that urgently needs to be overcome in this field. This invention aims to solve these problems.

[0055] Specifically, according to one aspect of the present invention, a method for preparing a solid-state battery anode material is provided. Figure 1 The flowchart illustrating the preparation process of a solid-state battery anode material according to the present invention is shown, specifically including the following steps: (1) The silicon-based active component, the carbon-based conductive component, and the doping modifier are dispersed in a dispersion solvent to prepare a silicon-based active component dispersion, a carbon-based conductive component dispersion, and a doping modifier dispersion; (2) Mix the silicon-based active component dispersion with the carbon-based conductive component dispersion, then add the doping modifier dispersion, then add the binder and interface modifier, mix evenly to obtain a mixed slurry; (3) The mixed slurry is coated onto the substrate and dried to obtain the cured precursor; (4) Under the protection of an inert atmosphere, the solidified precursor is subjected to gradient sintering treatment. After cooling, the sintered material is peeled off from the substrate and then crushed to obtain the solid battery anode material.

[0056] Specifically, the core of the preparation method of the present invention lies in achieving the synergistic effect of each functional component by controlling the component ratio, solving the technical pain points of silicon-based anode such as volume expansion, poor conductivity, and poor interface compatibility, while taking into account the simplicity of the preparation process and the feasibility of industrialization.

[0057] In the preparation method of this invention, the silicon-based active component is a mixture of nano-silicon powder and silicon suboxide. This combination is fundamental to achieving a synergistic effect of high specific capacity and low volume expansion. Nano-silicon powder possesses an extremely high theoretical specific capacity and is the core active material for improving the energy density of anode materials. Silicon suboxide, on the other hand, has a relatively stable crystal structure, and its volume change during charging and discharging is far less than that of pure silicon. Furthermore, its surface oxide layer can act as a natural buffer layer, effectively suppressing the agglomeration and excessive expansion of the nano-silicon powder. Preferably, the silicon-based active component is a mixture of nano-silicon powder and silicon suboxide in a weight ratio of 2:1 to 3:1.

[0058] According to certain preferred embodiments of the present invention, the average particle size of the nano-silicon powder is 50-200 nm, and the specific surface area is 10-30 m². 2 / g. This particle size and specific surface area range ensures that the nano-silicon powder has sufficient reactive sites, improving the lithium ion insertion / extraction efficiency, while avoiding agglomeration problems caused by excessively high surface energy due to excessively small particle size.

[0059] The carbon-based conductive component is a mixture of graphite, graphene, and carbon nanotubes. These three components form a three-dimensional network conductive structure, fundamentally solving the problem of poor intrinsic conductivity of silicon-based materials, while also providing a buffer space for the volume expansion of the silicon-based active component. Graphite, as the main component of the carbon-based conductive component, has the characteristics of low cost, high conductivity, and stable layered structure, and can serve as the conductive framework of the negative electrode material. Graphene, a two-dimensional nanomaterial, has ultra-high electronic conductivity and mechanical strength, and can coat the surface of the silicon-based active component to form a conductive coating layer, while suppressing the volume expansion of the silicon-based component. Carbon nanotubes, a one-dimensional nanomaterial, can be interspersed between graphite and graphene to construct a continuous three-dimensional conductive network, improving the transmission efficiency of electrons and lithium ions. Preferably, in the carbon-based conductive component, the weight ratio of graphite, graphene, and carbon nanotubes is (5-10):(1-3):(1-2). This ratio ensures the integrity and stability of the three-dimensional conductive network. The dominant proportion of graphite can control the preparation cost while providing sufficient structural support. When the proportions of graphene and carbon nanotubes are within the above range, the conductive network can be densified, and the carbon-based component will not accumulate due to excessive proportion, thus affecting the transport of lithium ions.

[0060] Preferably, the graphite has an average particle size of 1-5 μm and a specific surface area of ​​1-5 m². 2Graphite particles within this size range (g) can form a uniform skeletal structure, avoiding agglomeration due to excessively small particle size or discontinuity in the conductive network due to excessively large particle size. Preferably, the graphene has 1-15 layers and an average sheet diameter of 0.5-10 μm. Graphene with fewer layers has higher conductivity and specific surface area, enabling effective coating of silicon-based active components. When the average sheet diameter is within the above range, effective overlap between graphene sheets can be ensured, forming a continuous conductive film. Preferably, the carbon nanotubes have a diameter of 10-50 nm and a length of 1-10 μm. Carbon nanotubes of this size have an excellent aspect ratio, allowing them to effectively intersect between components, constructing three-dimensional conductive pathways and improving electron transport efficiency.

[0061] The doping modifier is a mixture of metallic and non-metallic modifiers, wherein the metallic modifier accounts for 40-70% of the total weight of the doping modifier, and the non-metallic modifier accounts for 30-60%. The synergistic doping of these two modifiers can achieve lattice and interface modification of the silicon-based anode, further reducing the volume expansion rate and improving ion transport efficiency and cycle stability. In this invention, the metallic modifier is a mixture of tetrabutyl titanate, zirconium oxide, tin chloride, and aluminum oxide. The metal ions in this type of metal compound can partially replace silicon ions in the silicon-based lattice, doping and modifying the silicon crystal structure, inhibiting silicon grain growth during charge and discharge, and simultaneously forming an inorganic buffer layer to further alleviate volume expansion. Non-metallic element modifiers are mixtures of ammonium dihydrogen phosphate, urea, and boric acid. These non-metallic compounds decompose during sintering to produce non-metallic elements such as phosphorus, nitrogen, and boron. These elements can be doped into the lattice of carbon-based conductive components to improve the conductivity and lithium-ion adsorption capacity of the carbon-based components. At the same time, their decomposition products can form a stable solid electrolyte interfacial film (SEI film) on the electrode surface, suppressing interfacial side reactions and reducing interfacial charge transfer resistance.

[0062] Preferably, in the metal element modifier, the weight ratio of tetrabutyl titanate, zirconium oxide, tin chloride, and aluminum oxide is (3-5):(2-4):(1-3):(1-2). Tetrabutyl titanate, as a metal-doped precursor, can hydrolyze during sintering to generate titanium dioxide, forming a solid solution with the silicon-based components, effectively suppressing volume expansion. Zirconium oxide and aluminum oxide possess excellent mechanical strength and chemical stability, serving as structural buffer layers to enhance the mechanical properties of the anode material. Tin ions in tin chloride can form alloys with silicon, further improving the specific capacity and conductivity of the anode material. This ratio of metal element modifier achieves a synergistic effect of lattice modification, structural buffering, and conductivity enhancement. Preferably, in the non-metal element modifier, the weight ratio of ammonium dihydrogen phosphate, urea, and boric acid is (4-6):(3-5):(1-2). Phosphorus produced by the decomposition of ammonium dihydrogen phosphate can improve the stability of SEI film; nitrogen produced by the decomposition of urea can be doped into carbon-based components to improve their conductivity; and boron produced by the decomposition of boric acid can enhance the interfacial bonding between carbon-based and silicon-based components. The combination of these three can achieve the dual effect of interface modification and conductivity improvement.

[0063] If the doping modifier is only a metal element modifier or a non-metal element modifier, the above synergistic effect cannot be achieved. This is because the lack of non-metal element doping means that the conductivity of the carbon-based component is not effectively improved, and a stable SEI film cannot be formed on the electrode surface. This leads to increased interfacial side reactions and high interfacial charge transfer impedance.

[0064] The binder is selected from at least one of carboxymethyl cellulose, sodium alginate, polyvinylidene fluoride, polyacrylic acid, lithium-ionized polyacrylic acid, and styrene-butadiene rubber. All of the above binders have excellent bonding performance and chemical stability, which can firmly bond the silicon-based active components, carbon-based conductive components, doping modifiers, and other components together to ensure the integrity of the electrode structure. At the same time, it can be partially carbonized during the sintering process to participate in the construction of the carbon-based conductive network and further improve the conductivity of the negative electrode material.

[0065] The interface modifier is selected from at least one of lithium fluoride, sodium fluoride, trimethyl borate, and fluoroethylene carbonate. The interface modifier is a core component for reducing the charge transfer impedance at the interface between the anode material and the solid electrolyte. It can form a thin and stable interface modification layer at the electrode-electrolyte interface, suppressing chemical side reactions between the anode material and the solid electrolyte, and improving lithium-ion transport efficiency and interfacial compatibility. Simultaneously, the interface modifier can synergistically work with doping modifiers to further optimize the composition and structure of the SEI film, improving its stability and ionic conductivity.

[0066] According to the technical solution of the present invention, based on the total weight of silicon-based active components, carbon-based conductive components, doping modifiers, binders, and interface modifiers as 100%, the silicon-based active components account for 40-75%, the carbon-based conductive components account for 15-40%, the doping modifiers account for 3-12%, the binders account for 2-8%, and the interface modifiers account for 0.5-3%. This total ratio is key to achieving synergistic function among the components. As the core active material, the silicon-based active component, with a proportion of 40-75%, can ensure the high specific capacity of the anode material. If the proportion is less than 40%, the specific capacity cannot meet the requirements; if the proportion is higher than 75%, the proportion of other functional components such as carbon-based conductive components is insufficient, and it cannot effectively suppress volume expansion and improve conductivity. The carbon-based conductive component, accounting for 15-40%, can ensure the formation of a complete three-dimensional conductive network and provide sufficient buffer space for volume expansion. If the proportion is too low, the conductivity will be poor and the buffering effect will be insufficient; if the proportion is too high, it will reduce the overall specific capacity of the anode material. The doping modifier, at a concentration of 3-12%, achieves effective doping while avoiding the formation of impurity phases or a decrease in specific capacity due to excessive dopant. Too low a concentration results in insignificant modification, while too high a concentration affects the compatibility of the components. The binder, at a concentration of 2-8%, ensures strong adhesion between the components. Too low a concentration results in insufficient adhesion, while too high a concentration blocks lithium-ion transport channels, reducing ion transport efficiency. The interface modifier, at a concentration of 0.5-3%, achieves effective interface modification. Too low a concentration results in insignificant reduction in interface charge transfer impedance, while too high a concentration forms an excessively thick interface layer, increasing lithium-ion transport resistance.

[0067] In the preparation method of the present invention, the dispersing solvent is a mixture of deionized water and ethanol, preferably a mixture of deionized water and ethanol in a weight ratio of 2:1 to 1:2. The mixed solvent of deionized water and ethanol has both hydrophilic and lipophilic properties, which can achieve uniform dispersion of different polar components such as silicon-based active components, carbon-based conductive components, and doping modifiers, avoiding problems such as uneven dispersion and agglomeration caused by a single solvent.

[0068] Preferably, in the silicon-based active component dispersion, the weight ratio of the silicon-based active component to the dispersion solvent is 1:3-1:5. In the carbon-based conductive component dispersion, the weight ratio of the carbon-based conductive component to the dispersion solvent is 1:4-1:6. In the dopant-modifier dispersion, the weight ratio of the dopant-modifier to the dispersion solvent is 1:5-1:8.

[0069] Preferably, in step (1), the preparation of the silicon-based active component dispersion includes stirring and sonicating the raw materials, wherein the stirring conditions are 25-35°C and 300-500 rpm for 30-60 min, and the ultrasonic dispersion conditions are 200-400 W ultrasonic power and 20-40 min ultrasonic time. The preparation of the carbon-based conductive component dispersion includes stirring and sonicating the raw materials, wherein the stirring conditions are 25-35°C and 400-600 rpm for 40-80 min, and the ultrasonic dispersion conditions are 300-500 W ultrasonic power and 30-50 min ultrasonic time.

[0070] According to the technical solution of the present invention, step (2) is the preparation of the mixed slurry. The present invention first mixes the silicon-based active component dispersion with the carbon-based conductive component dispersion. Preferably, the mixing conditions are 25-35°C and 500-700 rpm for 60-90 min. These mixing parameters ensure thorough mixing of the silicon-based and carbon-based components, allowing the carbon-based component to uniformly coat the surface of the silicon-based component, forming a silicon-carbon composite precursor. Subsequently, the dopant modifier dispersion is slowly added at a rate of 1-3 mL / min. Slow addition ensures that the dopant modifier is uniformly dispersed in the silicon-carbon composite precursor, avoiding excessively high local dopant concentrations. After the addition is complete, a binder and an interface modifier are added, and the mixing conditions are 25-35°C and 600-800 rpm for 80-120 min. Preferably, the solid content of the mixed slurry is 30-60%. This solid content range ensures that the mixed slurry has a suitable viscosity, which is convenient for subsequent coating operations and avoids the coating film being too thin and the production efficiency being low due to too low solid content, or the coating being uneven and the film cracking due to too high solid content.

[0071] According to the technical solution of the present invention, step (3) is the preparation of a curing precursor. The substrate is preferably a copper foil. Preferably, the coating thickness is 50-150 μm.

[0072] The drying process employs a gradient drying method, first drying at 80-90°C for 4-6 hours, and then drying at 100-120°C for 8-18 hours.

[0073] According to the technical solution of this invention, step (4) is gradient sintering and post-treatment. Gradient sintering can achieve sufficient reaction, doping and composite of each component, while avoiding excessive internal stress caused by rapid heating / cooling, which can lead to structural cracking, component separation and other problems. The gradient sintering process described in this invention includes four stages: heating stage, medium temperature stage, high temperature stage and cooling stage. Among them, the heating stage is to heat to 200-300°C at a heating rate of 5-10°C / min and hold for 2-4 h. The medium temperature stage is to heat to 400-500°C at a heating rate of 3-5°C / min and hold for 3-5 h. The high temperature stage is to heat to 600-800°C at a heating rate of 2-3°C / min and hold for 4-8 h. The cooling stage involves cooling to room temperature at a rate of 5-8°C / min. This slow cooling rate helps prevent uneven thermal expansion and contraction of the material due to sudden temperature drops, which could lead to structural cracks, microcracks, and other defects, thus ensuring the structural integrity of the negative electrode material.

[0074] Preferably, the inert atmosphere described in this invention is nitrogen or argon.

[0075] The post-sintering processing includes stripping and pulverization. After the sintered material is stripped from the substrate, it is pulverized using conventional pulverizing equipment such as a planetary ball mill. The particle size of the solid-state battery anode material of this invention is 3-20 μm. This particle size range ensures that the anode material has good processing performance when preparing electrode sheets, while also ensuring that the porosity of the electrode sheets is suitable, which facilitates electrolyte wetting and ensures efficient electron and lithium-ion transport.

[0076] According to another aspect of the present invention, a solid-state battery anode material is provided, said solid-state battery anode material being prepared according to the method described in any of the preceding claims. The solid-state battery anode material of the present invention achieves a synergistic effect of low volume expansion, high specific capacity, high initial coulombic efficiency, long cycle life, and low interfacial charge transfer impedance through the synergistic action of its components.

[0077] Preferably, the volume expansion rate of the solid-state battery anode material is less than or equal to 65%, which is much lower than the volume expansion rate of existing silicon-based anode materials. This effectively solves the problems of electrode pulverization and active material shedding caused by excessive volume expansion during the charging and discharging process of silicon-based anodes, and ensures the long-term stability of the electrode structure.

[0078] Preferably, the initial discharge specific capacity of the solid-state battery anode material is 1900-2200 mAh / g, and the initial coulombic efficiency is greater than or equal to 91%. High specific capacity ensures high energy density in the solid-state battery, meeting the long-range requirements of new energy vehicles, portable electronic devices, and other fields; while high initial coulombic efficiency effectively improves the actual usable capacity of the battery, reduces waste of active materials, and enhances the battery's economic efficiency.

[0079] Preferably, the solid-state battery anode material retains a capacity of 85% or more after 1000 cycles. This long cycle life effectively extends the service life of the solid-state battery, reduces operating costs, and meets the stringent requirements for cycle performance in fields such as power batteries.

[0080] Preferably, the interfacial charge transfer impedance of the solid-state battery negative electrode material is less than or equal to 35 Ω•cm. 2 The low interfacial charge transfer impedance effectively improves the lithium-ion transfer efficiency between the negative electrode and the solid electrolyte, improves the rate performance and fast charging performance of the battery, and solves the core technical bottlenecks of poor interfacial compatibility and high internal resistance of existing solid batteries.

[0081] According to another aspect of the present invention, a solid-state battery for new energy vehicles is provided, the solid-state battery for new energy vehicles comprising a positive electrode, a solid electrolyte layer, and a negative electrode, wherein the negative electrode comprises a solid-state battery negative electrode material according to any one of the preceding claims. The solid-state battery for new energy vehicles of the present invention, by employing the aforementioned high-performance negative electrode material, inherits the advantages of negative electrode materials such as low volume expansion, high specific capacity, long cycle life, and low interfacial charge transfer impedance. Simultaneously, combined with the high safety of the solid electrolyte, it achieves a comprehensive improvement in high energy density, high safety, long cycle life, and high rate performance, solving the problems of low energy density, poor cycle performance, and poor rate performance of existing solid-state batteries, making it an ideal choice for next-generation power batteries.

[0082] According to certain preferred embodiments of the present invention, the content of the solid-state battery negative electrode material in the negative electrode sheet is 85-95% by weight. Preferably, the negative electrode sheet further includes a binder and a conductive agent, wherein the binder is selected from one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyimide, and sodium carboxymethyl cellulose. Preferably, the conductive agent is one or more of acetylene black, Ketjen black, or carbon nanotubes.

[0083] According to certain preferred embodiments of the present invention, the solid electrolyte layer is one of a sulfide solid electrolyte, an oxide solid electrolyte, or a polymer solid electrolyte. The anode material of the present invention exhibits excellent interfacial compatibility with various solid electrolytes. The stable interfacial layer formed by the interfacial modifier and dopant can effectively suppress side reactions between the anode material and various solid electrolytes, and reduce interfacial charge transfer impedance. Therefore, the anode material of the present invention is compatible with various mainstream solid electrolytes and has wide applicability.

[0084] The solid-state battery of the present invention can be prepared using conventional preparation methods in the art, such as the stacking method and the coating method. The positive electrode, the solid electrolyte layer and the negative electrode are assembled in a conventional manner and then packaged to obtain the finished solid-state battery. The present invention does not have any special limitation on the specific preparation method of the solid-state battery. As long as it contains the negative electrode material of the present invention, it is within the protection scope of the present invention.

[0085] The present invention will now be described in more detail with reference to embodiments. It should be noted that these descriptions and embodiments are intended to facilitate understanding of the present invention and are not intended to limit the invention.

[0086] Example In this invention, unless otherwise specified, all reagents used are commercially available products and are used directly without further purification. Furthermore, "%" refers to "weight %" and "parts" refers to "parts by weight".

[0087] Table 1 below lists specific information about the raw materials used in the embodiments and comparative examples of the present invention.

[0088] Table 1 List of Experimental Materials Table 2 below lists specific information about the experimental equipment used in the embodiments and comparative examples of the present invention.

[0089] Table 2 List of Experimental Equipment Performance testing methods (a) Volume expansion rate Referring to the national standard GB / T 44027.2-2024 "Determination of Carbon Materials - Part 2: Determination of Expansion Rate", the test steps are as follows: The negative electrode material samples prepared in the following examples and comparative examples, conductive carbon black, and polyvinylidene fluoride (PVDF) were mixed at a mass ratio of 90:5:5 to form a slurry, which was then coated onto a 12 μm thick copper foil current collector. After vacuum drying at 120°C, the electrode was compacted to a set density using a roller press and cut into 14 mm diameter discs. The thickness was measured at the center of the electrode and at four evenly distributed points using a high-precision digital micrometer, and the arithmetic mean was taken as the initial thickness d0. In an argon-filled glove box KMS-1200, using this electrode as the working electrode and a lithium metal sheet as the counter electrode, an electrolyte (1.0 mol / L LiPF6 EC / DMC / EMC solution, volume ratio 1:1:1) was injected to assemble a CR2032 coin cell. The battery was placed in a constant temperature environment of 25.0±1.0°C and operated at a 0.1C rate from 0.005 to 1.500 V (vs. Li). +The battery was subjected to 1000 charge-discharge cycles within the / Li voltage range. After the cycle, the battery was disassembled, the electrodes were cleaned with anhydrous ethanol and dried, and the thickness was measured again at the same five points. The average value was taken as the thickness d1 after the cycle. The volume expansion rate (η, expressed as a percentage) was calculated using the following formula: η = [(d1– d0) / d0] × 100% Each sample was tested in parallel three times, and the average value was taken as the final result.

[0090] (ii) First discharge specific capacity Referring to the national standard GB / T 44027.1-2024 Determination Methods for Carbon Materials Part 1: Determination of Initial Discharge Specific Capacity, Initial Coulombic Efficiency, and Capacity Retention Rate at Different Discharge Rates, the test steps are as follows: Using the negative electrode material samples prepared in the following examples and comparative examples as active materials, they were uniformly mixed with conductive carbon black and PVDF binder at a mass ratio of 90:5:5. N-methylpyrrolidone (NMP) was added to prepare a slurry, which was then coated onto a copper foil current collector. After vacuum drying at 120°C for 12 hours, the slurry was cut into circular electrode sheets with a diameter of 12 mm as the working electrode. In an argon-filled glove box (water and oxygen content <0.1 ppm), lithium metal sheets were used as the counter and reference electrodes. The electrolyte was a solution of ethylene carbonate / diethyl carbonate / methyl ethyl carbonate (volume ratio 1:1:1) containing 1.0 mol / L LiPF6. The separator was Celgard 2400, and a CR2032 type coin cell was assembled. The battery was placed in a constant temperature chamber at 25.0±0.5°C and tested using the Blue Electric CT3001A battery testing system from 0.005 V to 1.500 V (vs. Li). + Within the voltage range of / Li), the electrode was initially charged at a constant current of 0.1C to the upper limit voltage, followed by constant voltage charging until the current dropped to 0.01C. After resting for 5 minutes, it was discharged at the same rate of 0.1C to the lower limit voltage. The initial discharge capacity was recorded and divided by the mass of the negative electrode material sample in the electrode sheet to obtain the initial discharge specific capacity (unit: mAh / g).

[0091] Each sample was tested in parallel three times, and the average value was taken as the final result.

[0092] (III) First Coulomb Efficiency Following the national recommended standard GB / T 44027.1-2024 Determination of Carbon Materials - Part 1: Determination of Initial Discharge Specific Capacity, Initial Coulombic Efficiency, and Capacity Retention Rate at Different Discharge Rates, the test steps are as follows: The negative electrode material samples prepared in the following examples and comparative examples, conductive carbon black, and PVDF binder are uniformly mixed at a mass ratio of 90:5:5. N-methylpyrrolidone (NMP) solvent is added to prepare a slurry, which is then coated onto a copper foil current collector. The slurry is dried in a vacuum oven at 120°C for 12 hours to remove the solvent, and then rolled and punched into circular electrode sheets with a diameter of approximately 12 mm as the working electrode. In a glove box filled with high-purity argon gas (water and oxygen content both <0.1ppm), using this electrode as the working electrode and a lithium metal sheet as the counter and reference electrodes, an electrolyte (1.0 mol / L LiPF6 EC / DMC / EMC solution, volume ratio 1:1:1) was injected, and a polypropylene composite separator was used to assemble a CR2032 coin cell. The battery was placed in a constant temperature environment of 25.0±1.0°C, and a Blue Electric CT3001A battery testing system was used to test it from 0.005V to 1.500V (relative to Li). + Within the / Li) voltage range, the first charge-discharge cycle test was performed at a constant current rate of 0.1C. The initial charge capacity (Q) was recorded. 充电 ) and first discharge capacity (Q 放电 The initial Coulomb efficiency (η) is calculated using the following formula: η = (Q 放电 / Q 充电 )× 100%.

[0093] Each sample was tested in parallel three times, and the average value was taken as the final result.

[0094] (iv) Capacity retention rate after 1000 cycles Referring to the national standard GB / T 37207-2018 "Methods for Testing the Electrochemical Performance of Lithium Nickel Cobalt Manganese Oxide - Discharge Platform Capacity Ratio and Cycle Life", the test steps are as follows: Electrode sheets are prepared and coin-type half-cells are assembled according to the "First Coulombic Efficiency Determination" method. The battery is placed in a constant temperature environment of 25.0±1.0°C, and a battery testing system is used from 0.005V to 1.500V (relative to Li). + Within the / Li) voltage window, continuous constant current charge-discharge cycle tests were performed at a 1C rate. The discharge capacity of each cycle was recorded, with the discharge capacity of the 3rd cycle used as the initial capacity (C0). After 1000 consecutive charge-discharge cycles, the discharge capacity of the 1000th cycle (C0) was recorded. 1000 The capacity retention rate (R) after 1000 cycles is calculated using the following formula: R = (C 1000 / C0) × 100%.

[0095] Each sample was tested in parallel three times, and the average value was taken as the final result.

[0096] (v) Interfacial charge transfer impedance test Referring to the national recommended standard GB / T 40007-2021 General Rules for Contact Measurement of Resistivity of Nanomaterials in Nanotechnology and the general test rules for electrochemical impedance spectroscopy, the test steps are as follows: The negative electrode material samples prepared in the following examples and comparative examples were used to fabricate working electrodes (preparation method is the same as in "First Coulombic Efficiency Determination"). In a glove box filled with high-purity argon gas (water and oxygen content both <0.1ppm), the working electrode, lithium metal counter electrode, reference electrode, liquid electrolyte (1.0 mol / L LiPF6 EC / DMC / EMC solution), and separator were assembled into a CR2032 coin cell. The battery was left to stand at 25.0±1.0°C for 12 hours. Using a CS300M electrochemical workstation, a sinusoidal AC voltage disturbance with a frequency range of 0.01Hz to 1MHz and an amplitude of 5mV was applied under open-circuit voltage conditions to perform electrochemical impedance spectroscopy tests. The obtained Nyquist plot data was fitted using software such as ZView, employing an equivalent circuit model (R(QR)(QR) model) that represents the charge transfer process at the electrode / electrolyte interface. From the fitting results, the numerical value representing the interfacial charge transfer impedance between the electrode material and the electrolyte was extracted and denoted as the interfacial charge transfer impedance, with units of Ω•cm. 2 .

[0097] Example 1 (E1) The specific preparation steps of Example 1 are as follows: (1) Weighing the dispersing solvent and raw materials: A dispersion solvent was prepared using deionized water and anhydrous ethanol at a weight ratio of 2:1. 40g of the silicon-based active component (nano-silica powder:silicon suboxide = 1:1), 40g of the carbon-based conductive component (graphite:graphene:carbon nanotubes = 4:4:2), 12g of doping modifier (40% by weight of metallic modifier and 60% by weight of non-metallic modifier, wherein the metallic modifier was tetrabutyl titanate:zirconia:tin chloride:alumina = 2:5:2:1, and the non-metallic modifier was ammonium dihydrogen phosphate:urea:boric acid = 3:6:1), 5g of binder carboxymethyl cellulose, and 3g of interface modifier lithium fluoride were weighed out. All raw materials were commercially available analytical grade and did not undergo further purification.

[0098] (2) Preparation of dispersions of each phase: A uniform silicon-based active component dispersion was obtained by adding 120g of dispersion solvent to a 25°C constant temperature water bath, stirring at 300rpm for 30min, and then ultrasonically dispersing at 200W for 20min. A carbon-based conductive component dispersion was obtained by adding 160g of dispersion solvent, stirring at 25°C and 400rpm for 40min, and then ultrasonically dispersing at 300W for 30min. A dopant-modifier dispersion was obtained by adding 60g of dispersion solvent, heating to 50°C, and stirring at 200rpm for 20min.

[0099] (3) Preparation of mixed slurry: The dispersions of silicon-based active components and carbon-based conductive components were transferred to a high-speed dispersion vessel and stirred at 25°C and 500 rpm for 60 min to ensure thorough mixing of the two phases. Then, the dopant-modifier dispersion was slowly added at a rate of 1 mL / min, and stirring continued for 30 min after the addition was complete. Next, carboxymethyl cellulose and lithium fluoride were added to the system, the stirring speed was adjusted to 600 rpm, and stirring was continued at 25°C for 80 min, ultimately yielding a homogeneous slurry with a solid content of approximately 30% by weight, exhibiting no particle agglomeration. In the slurry, based on the total weight of the silicon-based active component, carbon-based conductive component, dopant-modifier, binder, and interface modifier as 100%, the silicon-based active component accounted for 40%, the carbon-based conductive component for 40%, the dopant-modifier for 12%, the binder for 5%, and the interface modifier for 3%.

[0100] (4) Preparation of cured precursor: A blade coating method was used to uniformly coat the mixed slurry onto a 12 μm thick electrolytic copper foil substrate, controlling the coating thickness to be 50 μm. The coated copper foil was then placed in a vacuum drying oven for gradient drying. First, it was dried at 80°C for 4 hours to remove most of the low-boiling-point solvents, and then the temperature was raised to 100°C for 8 hours to fully remove residual solvents, resulting in a smooth, crack-free cured precursor.

[0101] (5) Gradient sintering and post-treatment: The solidified precursor was placed in a tube furnace, and high-purity nitrogen was introduced into the furnace as an inert protective atmosphere for gradient sintering: In the heating stage, the temperature was increased to 200°C at a rate of 5°C / min and held for 2 hours; in the intermediate stage, the temperature was increased to 400°C at a rate of 3°C / min and held for 3 hours; in the high-temperature stage, the temperature was increased to 600°C at a rate of 2°C / min and held for 4 hours; and in the cooling stage, the temperature was allowed to naturally cool to room temperature at a rate of 5°C / min. The sintered composite film was completely peeled off from the copper foil substrate, pulverized using a planetary ball mill, and passed through a standard sieve to obtain solid-state battery anode material 1 with a particle size of 5-15 μm. This material was then sealed and stored in an argon-atmosphere glove box for later use.

[0102] Figure 2 A scanning electron microscope (SEM) image of the solid-state battery anode material 1 prepared in Example 1 is shown. Figure 2 As shown, the solid-state battery anode material 1 is in the form of particles with a particle size distribution in the range of 5-8 μm.

[0103] Examples 2-13 (E2-E13) and Comparative Examples 1-5 (CE1-CE5) Examples 2-13 (E2-E13) and Comparative Examples 1-5 (CE1-CE5) were prepared in a manner similar to that of Example 1 to prepare solid-state battery anode materials 2-13 and comparative solid-state battery anode materials 1-5, the only difference being that the component types and ratios were changed as shown in Table 3 below.

[0104] Furthermore, the solid-state battery anode materials 2-13 and the comparative solid-state battery anode materials 1-5 were tested according to the methods described above for testing volume expansion rate, initial discharge specific capacity, initial coulombic efficiency, capacity retention after 1000 cycles, and interfacial charge transfer impedance, and the results are shown in Table 4 below.

[0105] Table 3. Formulations and preparation conditions for Examples 1-13 (E1-E13) and Comparative Examples 1-5 (CE1-CE5). Table 4 Performance test results of Examples 1-13 (E1-E13) and Comparative Examples 1-5 (CE1-CE5) As can be seen from the formulation parameters in Table 3 and the performance test results in Table 4, the solid-state battery anode materials prepared in Examples 1-13 of this invention exhibit good comprehensive performance in terms of volume expansion suppression, specific capacity, cycle stability and interface charge transfer impedance control, and all performance indicators are better than those of Comparative Examples 1-5.

[0106] Specifically, the volume expansion rate of the negative electrode materials in Examples 1-13 was controlled below 65%, with the optimal ratio in Examples 11-13 exhibiting a volume expansion rate as low as 45%-50%. The initial discharge specific capacity of the negative electrode materials in Examples 1-13 all reached 1900-2200 mAh / g, the initial coulombic efficiency was ≥ 91%, the capacity retention rate after 1000 cycles was over 85%, and the interfacial charge transfer impedance was ≤ 35Ω•cm. 2 Furthermore, as the weight ratio of nano-silicon powder to silicon suboxide in the silicon-based active component approaches 2:1-3:1, and the graphite / graphene / carbon nanotube ratio in the carbon-based conductive component becomes (5-10):(1-3):(1-2), all performance characteristics show a significant improvement trend. Example 13 achieved an initial discharge specific capacity of 2200 mAh / g, a cycle capacity retention of 98%, and a capacitance of 15 Ω•cm. 2 The interface charge transfer impedance is reduced to achieve optimal performance.

[0107] The performance of Comparative Examples 1-5 showed significant deterioration. Comparative Example 1 used only nano-silicon powder as the silicon-based active component, lacking the synergistic buffering effect of silicon suboxide, resulting in a surge in volume expansion to 185%, a drop in initial coulombic efficiency to 78.5%, a cycle capacity retention of only 38.1%, and a significant increase in interfacial charge transfer impedance. Comparative Example 2 used only graphite as the conductive component, lacking the conductive network construction effect of graphene and carbon nanotubes, resulting in a significant decrease in specific capacity to 1480 mAh / g, and a substantial decline in both cycle and interfacial performance. Comparative Example 3 used only metallic modifiers, lacking the synergistic effect of non-metallic interfacial modification, resulting in a volume expansion of 98%, and all electrochemical performances failing to meet the requirements of this invention. Comparative Example 4 did not add a binder, leading to poor material structural stability, a volume expansion of 125%, and a cycle retention of less than 50%. Comparative Example 5 has a silicon-based active component ratio exceeding the upper limit of 75% of the present invention, an insufficient carbon-based conductive component ratio, an insufficient conductive network and volume buffer structure, a volume expansion rate of 88%, and a specific capacity and cycle performance that are significantly inferior to Examples 1-13.

[0108] Obviously, those skilled in the art can make various modifications and variations to this disclosure without departing from the spirit and scope of this disclosure. Therefore, if such modifications and variations fall within the scope of this invention, this disclosure is also intended to include such modifications and variations.

Claims

1. A method for preparing a solid-state battery anode material, characterized in that... This includes the following steps: (1) The silicon-based active component, the carbon-based conductive component, and the doping modifier are dispersed in a dispersion solvent to prepare a silicon-based active component dispersion, a carbon-based conductive component dispersion, and a doping modifier dispersion; (2) Mix the silicon-based active component dispersion with the carbon-based conductive component dispersion, then add the doping modifier dispersion, then add the binder and interface modifier, mix evenly to obtain a mixed slurry; (3) The mixed slurry is coated onto the substrate and dried to obtain the cured precursor; (4) Under an inert atmosphere, the solidified precursor is subjected to gradient sintering. After cooling, the sintered material is peeled off from the substrate and then crushed to obtain the solid-state battery anode material, wherein: The silicon-based active component is a mixture of nano-silicon powder and silicon suboxide; The carbon-based conductive component is a mixture of graphite, graphene, and carbon nanotubes; The doping modifier is a mixture of metallic and non-metallic element modifiers, wherein the metallic element modifier accounts for 40-70% of the total weight of the doping modifier, and the non-metallic element modifier accounts for 30-60% of the total weight of the doping modifier. The metallic element modifier is a mixture of tetrabutyl titanate, zirconium oxide, tin chloride, and aluminum oxide, and the non-metallic element modifier is a mixture of ammonium dihydrogen phosphate, urea, and boric acid. The binder is selected from at least one of carboxymethyl cellulose, sodium alginate, polyvinylidene fluoride, polyacrylic acid, lithium-ionized polyacrylic acid, and styrene-butadiene rubber; The interface modifier is selected from at least one of lithium fluoride, sodium fluoride, trimethyl borate, and fluoroethylene carbonate; Based on the total weight of silicon-based active components, carbon-based conductive components, doping modifiers, binders, and interface modifiers as 100%, the silicon-based active components account for 40-75%, the carbon-based conductive components account for 15-40%, the doping modifiers account for 3-12%, the binders account for 2-8%, and the interface modifiers account for 0.5-3%.

2. The method for preparing the solid-state battery anode material according to claim 1, characterized in that... , The silicon-based active component is a mixture of nano-silicon powder and silicon suboxide in a weight ratio of 2:1 to 3:1; and / or The average particle size of the nano-silicon powder is 50-200 nm, and the specific surface area is 10-30 m². 2 / g; and / or The silicon suboxide has an average particle size of 100-300 nm and a specific surface area of ​​5-20 m². 2 / g.

3. The method for preparing the solid-state battery anode material according to claim 1, characterized in that... , In the carbon-based conductive component, the weight ratio of graphite, graphene, and carbon nanotubes is (5-10):(1-3):(1-2); and / or The graphite has an average particle size of 1-5 μm and a specific surface area of ​​1-5 m². 2 / g; and / or The graphene has 1-15 layers and an average sheet diameter of 0.5-10 μm; and / or The carbon nanotubes have a diameter of 10-50 nm and a length of 1-10 μm.

4. The method for preparing the solid-state battery anode material according to claim 1, characterized in that... , In the aforementioned metal element modifier, the weight ratio of tetrabutyl titanate, zirconium oxide, tin chloride, and aluminum oxide is (3-5):(2-4):(1-3):(1-2); and / or In the non-metallic element modifier, the weight ratio of ammonium dihydrogen phosphate, urea and boric acid is (4-6):(3-5):(1-2).

5. The method for preparing the solid-state battery anode material according to claim 1, characterized in that... The dispersing solvent is a mixture of deionized water and ethanol in a weight ratio of 2:1 to 1:

2.

6. The method for preparing the solid-state battery anode material according to claim 1, characterized in that... In step (3), the substrate is a copper foil.

7. The method for preparing the solid-state battery anode material according to claim 1, characterized in that... The gradient sintering process includes: (a) Heating stage: Heat to 200-300°C at a heating rate of 5-10°C / min, and hold for 2-4 hours; (b) Intermediate temperature stage: Heat to 400-500°C at a heating rate of 3-5°C / min, and hold for 3-5 hours; (c) High temperature stage: Heat to 600-800°C at a heating rate of 2-3°C / min, and hold for 4-8 hours; (d) Cooling stage: Cool down to room temperature at a cooling rate of 5-8°C / min.

8. The method for preparing the solid-state battery anode material according to claim 1, characterized in that... The particle size of the pulverized solid battery anode material in step (4) is 3-20 μm.

9. A solid-state battery anode material, characterized in that... The solid-state battery anode material is prepared by the method according to any one of claims 1-8.

10. A solid-state battery for new energy vehicles, characterized in that... The solid-state battery for new energy vehicles includes a positive electrode, a solid electrolyte layer, and a negative electrode, wherein the negative electrode comprises the solid-state battery negative electrode material according to claim 9.

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