Silicon-oxygen composite material, preparation method thereof, negative electrode sheet and solid-state battery

Abstract

The application discloses a silicon-oxygen composite material and a preparation method thereof, a negative electrode sheet and a solid-state battery, and belongs to the technical field of batteries.The silicon-oxygen composite material comprises a silicon-oxygen core and an elastic layer, and the elastic layer is attached to the surface of the silicon-oxygen core; the elastic layer comprises a polymer matrix, lithium indium chloride and lithium silicate; the lithium indium chloride and the lithium silicate are dispersed in the polymer matrix.The silicon-oxygen composite material is more suitable for a sulfide solid-state battery system, has a shorter lithium ion transmission path, is beneficial to lithium-silicon alloying, and the fast ion conductor dispersed in the elastic layer has a three-dimensional channel structure, can allow lithium ions to rapidly diffuse from three directions, the soft elastic layer can optimize point contact between a rigid electrode and a rigid solid-state electrolyte, reduce interface impedance, can inhibit lithium dendrite growth, rapidly release expansion stress on the elastic layer, can avoid reaction between carbon and the sulfide solid-state electrolyte, improves battery coulomb efficiency, and enhances battery cycle stability.

Description

Technical Field

[0001] This application relates to the field of materials technology, and more specifically, to a silicon-oxygen composite material and its preparation method, a negative electrode sheet, and a solid-state battery. Background Technology

[0002] Currently, to address energy transition and security bottlenecks, solid-state batteries have become the mainstream direction for next-generation high-energy-density batteries due to their advantages such as the absence of flammable electrolytes, suppression of lithium dendrite formation, and compatibility with high-voltage cathodes. Silicon anodes, with their theoretical specific capacity of up to 4200 mAh / g, low lithium alloying potential, abundant resources, and low cost, are considered ideal materials for overcoming range limitations. However, the carbon layer introduced to improve conductivity in traditional silicon-carbon composite anodes reacts chemically with mainstream sulfide solid electrolytes (such as Li6PS5Cl), generating byproducts like Li2S with low ionic conductivity. This not only consumes active lithium and reduces initial coulombic efficiency but also disrupts solid-solid interface contact, exacerbating interfacial impedance. Furthermore, lithium ions must penetrate the porous carbon layer to react with silicon, significantly extending the transport path and limiting fast-charging performance. Even more serious is the dramatic volume expansion of silicon during charging and discharging (>300%), while the rigid carbon layer lacks buffering capacity, easily leading to electrode pulverization and interfacial delamination. Summary of the Invention

[0003] The main objective of this application is to provide a silicon-oxygen composite material and its preparation method, a negative electrode sheet, and a solid-state battery, in order to solve the problem that silicon-carbon materials and sulfide solid electrolytes are prone to side reactions in the prior art, which degrade the solid-solid contact and consume active lithium, thereby reducing the capacity and initial coulombic efficiency of solid-state batteries.

[0004] To achieve the above objectives, according to one aspect of this application, a silicon-oxygen composite material is provided, comprising a silicon-oxygen core and an elastic layer, wherein the elastic layer is attached to the surface of the silicon-oxygen core; the material of the elastic layer comprises a polymer matrix, lithium indium chloride, and lithium silicate; wherein the lithium indium chloride and lithium silicate are dispersed in the polymer matrix.

[0005] Furthermore, the polymer matrix contains etheroxy groups; at least some of the lithium ions and etheroxy groups in the lithium indium chloride are interconnected through coordination.

[0006] Furthermore, the ratio of the median particle size of the silicon-oxygen core to the thickness of the elastic layer is 1:(0.1~0.2).

[0007] Furthermore, the polymer matrix is ​​at least one of polyethylene oxide, polypropylene oxide, and polyethylene glycol.

[0008] Furthermore, the lithium indium chloride is Li3InCl6.

[0009] Furthermore, the lithium silicates are Li4SiO4 and Li2SiO3.

[0010] Furthermore, the silicon-oxygen core is silicon oxide.

[0011] Furthermore, the median particle size of the silicon-oxygen composite material is 5~10 μm.

[0012] Furthermore, the tap density of the silicon-oxygen composite material is 0.5~1.5 g / cm³. 3 .

[0013] Furthermore, the resistivity of the silicon-oxygen composite material is 0.5~2Ω·cm.

[0014] Furthermore, the specific surface area of ​​the silicon-oxygen composite material is 0.5~2m². 2 / g.

[0015] Furthermore, the median particle size of the silicon-oxygen nuclei is 3~5 μm.

[0016] According to a second aspect of this application, a method for preparing the above-mentioned silicon-oxygen composite material is provided, comprising the following steps:

[0017] Step S1: Calcine silicon suboxide and lithium chloride in a first inactive atmosphere to obtain the first material;

[0018] Step S2: The first material, indium chloride, and polymer matrix are heat-treated under vacuum conditions to obtain a silicon-oxygen composite material; wherein, the silicon-oxygen composite material includes a silicon-oxygen core and an elastic layer, the elastic layer is attached to the surface of the silicon-oxygen core, and the elastic layer includes a polymer matrix, lithium indium chloride, and lithium silicate; wherein, lithium indium chloride and lithium silicate are dispersed in the polymer matrix.

[0019] Furthermore, the weight ratio of silicon suboxide to lithium chloride is 1:(0.1~0.2).

[0020] Furthermore, the molar ratio of indium chloride to lithium chloride is 1:(3~5).

[0021] Furthermore, the weight ratio of the polymer matrix to silicon suboxide is 1:(3~5).

[0022] Furthermore, the calcination temperature is 150~250℃, and the calcination time is 4~6h.

[0023] Furthermore, the heat treatment temperature is 200~300℃, and the heat treatment time is 4~8h.

[0024] Furthermore, the vacuum condition is a vacuum degree ≤ -0.1MPa.

[0025] Furthermore, the indium chloride is anhydrous indium chloride and / or indium chloride tetrahydrate, with a purity ≥99%.

[0026] Furthermore, the median particle size D50 of lithium chloride is 3~5 μm.

[0027] Furthermore, the median particle size D50 of silicon suboxide is 3~5 μm.

[0028] Furthermore, the polymer matrix contains etheroxy groups; at least some of the lithium ions and etheroxy groups in the lithium indium chloride compound are interconnected through coordination.

[0029] Furthermore, the first inactive atmosphere is selected from at least one of argon, nitrogen, helium, neon, and vacuum atmosphere.

[0030] Furthermore, the weight ratio of silicon suboxide to lithium chloride is 1:(0.1~0.15).

[0031] Furthermore, the molar ratio of indium chloride to lithium chloride is 1:(3~4.5).

[0032] Furthermore, the weight ratio of the polymer matrix to the silicon suboxide precursor is 1:(3~4.5).

[0033] Furthermore, the calcination temperature is 180~230℃, and the calcination time is 4~5h.

[0034] Furthermore, the heat treatment temperature is 220~280℃, and the heat treatment time is 4~7h.

[0035] Furthermore, the polymer matrix is ​​at least one of polyethylene oxide, polypropylene oxide, and polyethylene glycol.

[0036] Furthermore, the ratio of the median particle size of the silicon-oxygen core to the thickness of the elastic layer is 1:(0.1~0.2).

[0037] Furthermore, the lithium indium chloride is Li3InCl6.

[0038] Furthermore, the lithium silicates are Li4SiO4 and Li2SiO3.

[0039] Furthermore, the silicon-oxygen core is silicon oxide.

[0040] Furthermore, step S1-2 is included between step S1 and step S2: first, the first material and the solvent are mixed in a second inactive atmosphere to obtain mixture A, and then mixture A, indium chloride and polymer matrix are heat-treated under vacuum conditions.

[0041] Furthermore, the second inactive atmosphere is selected from at least one of argon, nitrogen, helium, neon, and vacuum atmosphere.

[0042] Furthermore, the weight ratio of silicon suboxide to solvent is 1:(5~10).

[0043] Furthermore, the solvent is an organic solvent.

[0044] Furthermore, the organic solvent is selected from at least one of acetonitrile, tetrahydrofuran, toluene, and xylene.

[0045] According to a third aspect of this application, a negative electrode sheet is provided, comprising a negative electrode current collector and a negative electrode active coating, wherein the negative electrode active coating is attached to at least one surface of the negative electrode current collector; the negative electrode active coating comprises a negative electrode active material; the negative electrode active material is the aforementioned silicon-oxygen composite material or a silicon-oxygen composite material obtained by the preparation method of the aforementioned silicon-oxygen composite material.

[0046] According to a fourth aspect of this application, a solid-state battery is provided, comprising a negative electrode, a positive electrode, and a solid electrolyte; the negative electrode is the aforementioned negative electrode.

[0047] Compared with the prior art, this application has the following beneficial effects:

[0048] The (pre-lithiated) silicon-oxygen composite material provided in this application is more suitable for sulfide solid-state battery systems. Compared with novel silicon-carbon materials, this silicon-oxygen composite material has a shorter lithium-ion transport path, which is beneficial for lithium-silicon alloying. The fast-ion conductors (such as Li3InCl6) dispersed in the elastic layer have a three-dimensional channel structure, which allows lithium ions to diffuse rapidly from three directions. The soft elastic layer can optimize the point contact between the rigid electrode and the rigid solid electrolyte, reduce the interface impedance, and suppress the growth of lithium dendrites. It can build a stable electrolyte-anode interface and quickly release the expansion stress on the elastic layer. At the same time, compared with traditional carbon coating layers, this silicon-oxygen composite material can avoid the reaction between carbon and sulfide solid electrolyte, improve the coulombic efficiency of the battery, and enhance the cycle stability of the battery. Attached Figure Description

[0049] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0050] Figure 1 This is a schematic diagram of the structure of the silicon-oxygen composite material prepared in Example 1 of this application;

[0051] Figure 2 The X-ray powder diffraction (XRD) pattern of the silicon-oxygen composite material prepared in Example 1 of this application.

[0052] Figure 3 The image shows a scanning electron microscope (SEM) image of the cut surface of the silicon-oxygen composite material prepared in Example 1 of this application.

[0053] Figure label:

[0054] 1. Silicon-oxygen core; 2. Elastic layer. Detailed Implementation

[0055] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present application will now be described in detail with reference to the embodiments.

[0056] The carbon layer introduced into the traditional silicon-carbon composite anode to improve conductivity can react chemically with sulfide solid electrolytes (such as Li6PS5Cl) to generate byproducts. This not only consumes active lithium and reduces the initial coulombic efficiency, but also disrupts the solid-solid interface contact, exacerbating the interface impedance. Furthermore, lithium ions need to penetrate the porous carbon layer to react with silicon, significantly prolonging the transport path and limiting fast-charging performance. At the same time, silicon undergoes dramatic volume expansion (>300%) during charging and discharging, while the carbon layer is rigid and lacks buffering capacity, which can easily lead to electrode pulverization and interface peeling.

[0057] To address the aforementioned problems, according to one aspect of this application, a silicon-oxygen composite material is provided, such as... Figure 1 , Figure 2 and Figure 3 As shown, the silicon-oxygen composite material includes a silicon-oxygen core 1 and an elastic layer 2, with the elastic layer 2 attached to the surface of the silicon-oxygen core 1; the material of the elastic layer 2 includes a polymer matrix and lithium indium chloride and lithium silicate; wherein, lithium indium chloride and lithium silicate are dispersed in the polymer matrix.

[0058] The silicon-oxygen composite material provided in this application can be used as a silicon-oxygen composite anode material for fast-charging solid-state lithium-ion batteries. It is a carbon-free, pre-lithiated, multi-level functional integrated structural material. This silicon-oxygen composite material uses in-situ pre-lithiated silicon oxide as the active core, and the outer layer is a composite coating layer composed of a three-dimensional ion conductor network of lithium indium chloride (such as Li3InCl6) and an elastic polymer matrix. In this structure, the lithium indium chloride (such as Li3InCl6) forms a continuous, interconnected three-dimensional lithium-ion transport channel, significantly shortening the lithium-ion migration path and accelerating the lithium-silicon alloying kinetics. The elastic polymer matrix reacts with Li through its etheroxy groups. + The coordination effect enhances the mobility of ions at the interface, while the flexible mechanical properties effectively buffer the volume deformation of the silicon core, suppressing electrode cracking and interface debonding. The elastic layer is carbon-free, completely avoiding the side reactions that occur between traditional carbon coating layers and sulfide electrolytes, achieving chemical stability and low-resistance contact at the solid-solid interface. Finally, the material achieves a balance between high initial coulombic efficiency, excellent rate performance and long-term cycling stability through a four-fold synergistic mechanism of "pre-lithium compensation - rapid ion transport - stress buffering - interface stabilization".

[0059] To improve the stability of silicon-oxygen composite materials, in some specific embodiments, some lithium ions and silicon-oxygen materials in lithium chloride exist in the form of lithium silicate, forming a stable rigid structure on the material surface, which can suppress the volume expansion of silicon anode materials during charging and discharging to a certain extent; the polymer matrix contains etheroxy groups, and at least some lithium ions (Li3InCl6) in lithium indium chloride (such as Li3InCl6) + The fast ion conductor lithium indium chloride (Li3InCl6) and the ether oxygen group (COC) are combined through coordination, which makes the fast ion conductor lithium indium chloride (Li3InCl6) firmly embedded in the elastic layer and will not fall off. This is conducive to promoting the movement of lithium ions in polymer chain segments and reducing interfacial impedance. At the same time, the three-dimensional network elastic coating layer formed by the lithium indium chloride (Li3InCl6) embedded in the elastic layer can absorb and release the deformation stress on the lithium silicate layer. The carbon-free coating can avoid the side reactions between the traditional carbon coating layer and the sulfide solid electrolyte, thereby improving the battery coulombic efficiency and enhancing the battery cycle stability.

[0060] Since the elastic layer coating effect of the silicon-oxygen composite material affects the overall electrochemical performance of the material, the coating ratio of the elastic layer is controlled. In some specific embodiments, the ratio of the median particle size of the silicon-oxygen core to the thickness of the elastic layer is 1:(0.1~0.2), more preferably 1:(0.1~0.15); the median particle size of the silicon-oxygen core is 3~5μm, preferably 3~3.5μm; the median particle size of the silicon-oxygen composite material is 5~10μm, preferably 5~8μm. By controlling the elastic layer thickness and silicon-oxygen core particle size within the above ratio range, continuous and uniform coating of the elastic layer can be achieved, which can fully absorb expansion stress while minimizing the migration path of lithium ions without affecting the rate performance of the material. Controlling the median particle size of the synthesized silicon-oxygen composite material is to better adapt to the solid-state battery system, optimize the interface contact, reduce the interface impedance, and thus achieve synergistic optimization of the silicon-oxygen material in solid-state batteries in terms of long cycle life, high rate capability, and high first-efficiency performance.

[0061] In some specific embodiments, the polymer matrix is ​​at least one selected from polyethylene oxide (PEO), polypropylene oxide (PPO), and polyethylene glycol (PEG). Preferably, the polymer matrix is ​​a mixture of PEO and PEG. The selected polymer matrices all contain COC ether oxygen bonds, which can coordinate with lithium ions, promoting the migration of lithium ions within the elastic layer. This polymer matrix exhibits excellent flexibility and can absorb the volume expansion stress of silicon.

[0062] In some specific embodiments, the lithium indium chloride is Li3InCl6; the lithium silicate is Li4SiO4 and Li2SiO3; the silicon-oxygen core is silicon oxide; the median particle size of Li3InCl6 is 1~3 μm, preferably 1.5~2 μm. The tap density of the silicon-oxygen composite material is 0.5~1.5 g / cm³. 3The resistivity of silicon-oxygen composite materials is 0.5~2 Ω·cm; the specific surface area of ​​silicon-oxygen composite materials is 0.5~2 m². 2 / g. Li3InCl6 with the above-mentioned particle size is uniformly distributed in an elastic polymer matrix to form a continuous, interconnected, and high-density three-dimensional ionic conductor network. This network works synergistically with the elastic layer to form a rigid-flexible interfacial protective layer. At the same time, the small-particle-size fast ionic conductor Li3InCl6 improves ionic conductivity, cycle stability, and initial coulombic efficiency. Furthermore, the silicon-oxygen composite material possesses the above-mentioned tap density, conductivity, and specific surface area, which is beneficial to the overall electrochemical performance of the battery.

[0063] According to a second aspect of this application, a method for preparing the above-mentioned silicon-oxygen composite material is provided, comprising the following steps:

[0064] Step S1: Calcine silicon suboxide and lithium chloride in a first inactive atmosphere to obtain the first material;

[0065] Step S2: The first material, indium chloride and polymer matrix are heat-treated under vacuum conditions to obtain a silicon-oxygen composite material; wherein, the silicon-oxygen composite material includes a silicon-oxygen core 1 and an elastic layer 2, the elastic layer 2 is attached to the surface of the silicon-oxygen core 1, and the elastic layer 2 includes a polymer matrix, lithium indium chloride and lithium silicate; wherein, lithium indium chloride and lithium silicate are dispersed in the polymer matrix.

[0066] The pre-lithiated silicon-oxygen composite material synthesized in this application via a liquid-phase method is more suitable for sulfide solid-state battery systems. Compared with novel silicon-carbon materials, the pre-lithiated silicon-oxygen material has a shorter lithium-ion transport path, which is beneficial for lithium-silicon alloying. Simultaneously, the in-situ generated fast-ion conductor (Li3InCl6) has a three-dimensional channel structure, allowing lithium ions to diffuse rapidly from three directions. The ether-oxygen group (-COC-) structure in the elastic matrix powder can interact with lithium ions (Li... + The polymer coating facilitates coordination and promotes the movement of lithium ions within the polymer chain segments. At the same time, the soft polymer coating optimizes the point contact between the rigid electrode and the rigid solid electrolyte, reducing interfacial impedance. Therefore, it has higher initial coulombic efficiency and rate performance.

[0067] The method in this application uses lithium chloride (LiCl) to replenish the irreversible loss of lithium ions during charge and discharge, and to form a structural framework on the surface of the silicon-oxygen composite material. The subsequently added indium chloride (InCl3) and lithium chloride (LiCl) form a three-dimensional network coating layer of fast ion conductor (Li3InCl6), which reduces the volume expansion of the silicon-oxygen composite material during charge and discharge. Due to the introduction of the elastic polymer matrix, this three-dimensional network coating layer is uniformly dispersed in the elastic matrix, forming a "three-dimensional network elastic coating layer." This interface layer suppresses the growth of lithium dendrites, thereby constructing a stable electrolyte-anode interface and rapidly releasing the expansion stress on the coating layer. Compared with traditional carbon coating layers, this avoids the reaction between carbon and sulfide solid electrolytes, improving the coulombic efficiency of the battery and enhancing its cycle stability. This application achieves in-situ pre-lithiation of silicon-oxygen composite materials and improves coating uniformity through a liquid-phase reaction method. The mild liquid-phase reaction environment does not cause the nucleation and growth of silicon grains at high temperatures, reducing the volume expansion of silicon and improving cycle performance.

[0068] In some specific embodiments, the weight ratio of silicon suboxide to lithium chloride is 1:(0.1~0.2), for example, any value or a range between 1:0.1, 1:0.11, 1:0.12, 1:0.13, 1:0.14, 1:0.15, 1:0.16, 1:0.17, 1:0.18, 1:0.19, and 1:0.2; another example is 1:(0.1~0.15). Controlling the ratio within the above range serves two purposes: firstly, it controls the pre-lithiation amount, adjusts the silicon-oxygen ratio of the material to achieve a balance between improving initial efficiency and reducing capacity; secondly, it ensures that the lithium chloride and subsequent indium chloride react to generate a sufficient amount of Li3InCl6, improving coating uniformity.

[0069] In some specific embodiments, the calcination temperature is 150~250℃, for example, any value or a range between 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, and 250℃; another example is 180~230℃; the calcination time is 4~6h, for example, any value or a range between 4, 4.2, 4.5, 4.8, 5, 5.2, 5.5, 5.8, and 6.0h; another example is 4~5h. The aforementioned first inactive atmosphere is an oxygen-free atmosphere, which can be selected from at least one of argon, nitrogen, helium, neon, and vacuum atmosphere. Calcination in this oxygen-free atmosphere can avoid side reactions and ensure the purity of the calcined product. By using the above heat treatment temperature and time, lithium chloride can be stably attached to the material surface without initiating the reaction between lithium chloride and silicon suboxide to form a lithium silicate phase, thus providing stable sites for subsequent reactions.

[0070] In some specific embodiments, the molar ratio of indium chloride to lithium chloride is 1:(3~5), for example, any value or a range between 1:3, 1:3.2, 1:3.5, 1:3.8, 1:4.0, 1:4.2, 1:4.5, 1:4.8, and 1:5.0; another example is 1:(3~4.5). The median particle size D50 of lithium chloride is 3~5 μm. The formation of the fast ion conductor Li3InCl6 consumes 3 mol of lithium chloride per 1 mol of indium chloride. While ensuring the formation of a continuous, non-agglomerated three-dimensional ion-conducting network of Li3InCl6 in the elastic layer, a slight excess of lithium chloride participates in the pre-lithiation process of the material, improving the material's initial efficiency, improving the solid-solid interface impedance, and enhancing the initial coulombic efficiency and cycle stability.

[0071] In some specific embodiments, the weight ratio of the polymer matrix to silicon suboxide is 1:(3~5), for example, any value or a range between 1:3, 1:3.2, 1:3.5, 1:3.8, 1:4.0, 1:4.2, 1:4.5, 1:4.8, and 1:5.0; or, for example, 1:(3~4.5). The median particle size D50 of the silicon suboxide is 3~5 μm. Within the above ratio range, the polymer matrix forms a continuous and reasonably thick coating layer on the silicon oxide surface, which, together with the in-situ generated Li3InCl6, constructs a rigid-flexible three-dimensional network structure, maximizing the suppression of silicon volume expansion while ensuring high ionic conductivity, thereby improving the interfacial contact stability and cycle life of the final electrode.

[0072] In some specific embodiments, the polymer matrix is ​​at least one selected from polyethylene oxide, polypropylene oxide, and polyethylene glycol. The selected polymer matrix can coordinate with lithium ions, promoting their migration within the elastic layer. This polymer matrix also exhibits excellent flexibility, allowing for better absorption of silicon volume expansion stress.

[0073] In some specific embodiments, before heat treatment, silicon suboxide and the calcined product of lithium chloride and a solvent are first mixed in a second inactive atmosphere to obtain mixture A. Then, mixture A, indium chloride, and the polymer matrix are heat-treated under vacuum conditions. The solvent is an organic solvent, specifically selected from at least one of acetonitrile, tetrahydrofuran, toluene, and xylene. The weight ratio of silicon suboxide to solvent is 1:(5~10), for example, 1:(6~9). Solvent dissolution improves the initial dispersibility of mixture A. The second inactive atmosphere is a non-oxygen atmosphere, selected from at least one of argon, nitrogen, helium, neon, and a vacuum atmosphere, which avoids side reactions during mixing. After dissolving to form mixture A, indium chloride, mixture A, and the polymer matrix are stirred and mixed for 4~9 hours at a speed of 400~600 rpm to form a uniform slurry. The slurry is then kept at a constant temperature of 60~90°C until the solvent evaporates to obtain a solid material. Finally, the solid material is heat-treated under vacuum conditions.

[0074] In some specific embodiments, the heat treatment temperature is 200~300℃, for example, any value or a range between 200℃, 220℃, 240℃, 260℃, 280℃, and 300℃; or, for example, 150~220℃; the heat treatment time is 4~8h, for example, any value or a range between 4, 5, 6, 7, and 8h; or, for example, 4~7h. The vacuum degree is ≤-0.1MPa. Indium chloride, calcined products, and polymer matrix solutions are first stirred until the solvent evaporates, and then placed in a vacuum drying oven for low-temperature heating. By controlling the heating temperature within the above-mentioned range, Li3InCl6 can be synthesized in situ from lithium chloride in indium chloride and calcined products, and an elastic layer is formed in the polymer matrix. During this process, some lithium ions fixed in the calcined products that are in contact with the polymer matrix are tightly bound together with the ether oxygen bonds in the chain segment through coordination. Some lithium ions that are in contact with the material surface participate in the lithiation of silicon suboxide to form a dense and stable lithium silicate phase. Finally, a dense, crack-free, three-dimensionally connected elastic-ionic conductor integrated interface layer is formed, which significantly reduces the solid-solid interface impedance, inhibits electrode expansion and lithium dendrite growth, and improves the initial coulombic efficiency and cycle stability.

[0075] In some specific embodiments, indium chloride is anhydrous indium chloride and / or indium chloride tetrahydrate (InCl3·4H2O) with a purity ≥99%. Choosing this type of indium chloride raw material allows for the gradual release of In into the solvent. 3+ Ions, avoiding localized high concentrations, and slow release of In 3+ The nucleation rate of ions and LiCl fixed on the material surface is controllable, ensuring that Li3InCl6 crystals form a nanoscale, continuous, three-dimensional interconnected ionic conductive network in the elastic matrix, which significantly improves the coating uniformity and electrolytic interface stability.

[0076] According to a third aspect of this application, a negative electrode sheet is provided, comprising a negative electrode current collector and a negative electrode active coating, wherein the negative electrode active coating is attached to at least one surface of the negative electrode current collector; the negative electrode active coating comprises a negative electrode active material; the negative electrode active material is the aforementioned silicon-oxygen composite material or a silicon-oxygen composite material obtained by the preparation method of the aforementioned silicon-oxygen composite material.

[0077] In some specific embodiments, the negative electrode active layer is attached to two opposite surfaces of the negative electrode current collector; wherein the negative electrode current collector is selected from at least one of copper foil, nickel foil, and stainless steel foil. Specifically, the negative electrode active slurry includes the above-mentioned silicon-oxygen negative electrode material, conductive agent, binder, solvent and solid electrolyte slurry, which is coated on the surface of the negative electrode current collector and dried to obtain a solid battery silicon-oxygen negative electrode sheet; furthermore, the weight ratio of the above-mentioned silicon-oxygen negative electrode material, conductive agent, binder, solvent and solid electrolyte is 4:(0.08~0.12):(1.2~1.8):(4~5):(0.8~1.2).

[0078] In some specific embodiments, solid-state half-cells are assembled using the aforementioned silicon-oxygen anode material. In the half-cell, this anode material acts as the positive electrode, and lithium indium serves as the negative electrode. The silicon-oxygen anode material is first intercalated with lithium and then discharged. Conventional additives such as binders and solid electrolytes in the anode sheet can be of conventional types in the art. For example, the conductive agent is selected from at least one of superconducting carbon black (super-P), natural graphite, artificial graphite, acetylene black, Ketjen black, and carbon fiber. The binder is selected from at least one of polyvinylidene fluoride (PVDF), polyvinyl alcohol, hydroxypropyl cellulose, polyvinylpyrrolidone, and polytetrafluoroethylene. The solvent is selected from isobutyl isobutyrate or N-methylpyrrolidone (NMP). The solid electrolyte includes at least one of sulfide electrolytes such as Li6PS5Cl electrolyte, oxide electrolytes such as lithium lanthanum zirconium oxide (LLZO), and polymer electrolytes such as polyethylene oxide (PEO). The aforementioned anode sheet exhibits high initial coulombic efficiency, long cycle stability, high rate performance, and good safety, thus enabling the solid-state battery to exhibit superior overall performance.

[0079] According to a fourth aspect of this application, a solid-state battery is provided, including a negative electrode sheet; the negative electrode sheet is the aforementioned negative electrode sheet. For example, the aforementioned solid-state battery includes a negative electrode sheet, a positive electrode sheet, and a solid electrolyte; further for example, the aforementioned solid-state battery is an all-solid-state battery or a semi-solid-state battery, which exhibits high initial efficiency, stable cycle performance, and excellent rate performance.

[0080] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0081] The raw materials used in the embodiments of this application are all existing technologies and are commercially available.

[0082] Example 1

[0083] (1) Preparation of silicon-oxygen anode materials:

[0084] Step S1 Raw material weighing: Accurately weigh 100g of silicon suboxide (purity 99.9%, particle size 4μm) and 15g of anhydrous lithium chloride (particle size 4μm, weight ratio 1:0.15); separately weigh indium chloride tetrahydrate (InCl3·4H2O, purity ≥99%), the amount of which must ensure that the molar ratio of indium chloride (anhydrous) to lithium chloride is 1:4; weigh approximately 25.9g of indium chloride tetrahydrate (assuming a lithium chloride molar mass of 42.4g / mol and an indium chloride molar mass of 221.2g / mol); at the same time, weigh 25g of polyethylene oxide (PEO, brand name Aladdin, molecular weight 300,000, PEO:silicon suboxide weight ratio 1:4).

[0085] Step S2 calcination treatment:

[0086] Mixing: Place the weighed silica powder and anhydrous lithium chloride powder in a ball mill jar and mechanically ball mill them for 30 minutes under argon protection to ensure that the two are fully and evenly mixed.

[0087] Calcination: Transfer the uniformly mixed material to a corundum boat and place it in a tube furnace; introduce high-purity argon as the first inactive atmosphere at a flow rate of 200 mL / min, and exhaust the air in the tube for 30 minutes; then heat to 200°C at a heating rate of 5°C / min and calcine at 200°C for 5 hours.

[0088] Post-processing: After calcination, the material was naturally cooled to room temperature to obtain a grayish-black material A. The first material was ground through a 200-mesh sieve in an argon-protected glove box for later use.

[0089] Step S3 Heat Treatment:

[0090] Mixing: Add all of the material A obtained in step S2, the weighed indium chloride tetrahydrate and polyethylene oxide (PEO) into the mixer and mechanically stir under argon protection to ensure that the three are fully mixed and uniform.

[0091] Heat treatment: Transfer the mixed materials to a vacuum oven; first, evacuate to a vacuum degree ≤ -0.1MPa, then introduce high-purity argon gas to atmospheric pressure, repeat this process three times to ensure that the air in the reaction environment is completely replaced; finally, maintain the vacuum state (vacuum degree ≤ -0.1MPa), heat to 250℃ at a heating rate of 3℃ / min, and heat-treat at 250℃ for 6 hours.

[0092] Crushing and screening: After heat treatment, the furnace is naturally cooled to room temperature; the resulting blocky solid material is mechanically crushed and pulverized under a protective atmosphere and passed through a 300-mesh sieve to obtain the silicon-oxygen composite material.

[0093] The final schematic diagram of the silicon-oxygen composite material structure for fast-charging solid-state lithium-ion batteries is shown in Figure 1; the phase composition of the silicon-oxygen composite material was determined by XRD (…). Figure 2 Characterization was performed using SEM (Sequencing). The microstructure and layered structure were analyzed. Figure 3 Observation results show that the material exhibits a typical core-shell structure, with a silicon-oxygen core 1 as the core and an elastic layer 2 covering the surface of the silicon-oxygen core 1. Li3InCl6 is dispersed in the PEO elastomer. The thickness of the elastic layer 2 is about 0.65μm, which is uniformly covered on the surface of the silicon-oxygen particles without peeling or cracking, and the interface is tightly bonded.

[0094] (2) Preparation of negative electrode sheet: The above-mentioned silicon-oxygen negative electrode material, conductive agent super-P, binder PVDF, solvent isobutyl isobutyrate, and sulfide solid electrolyte L6PS5Cl are mixed in a weight ratio of 4:0.1:1.5:4.5:1 to obtain a negative electrode slurry; the slurry is coated on both sides of copper foil, dried and cured to obtain a negative electrode sheet, which is used as the original negative electrode sheet.

[0095] Example 2

[0096] (1) Preparation of silicon-oxygen anode materials:

[0097] Step S1 Raw material weighing: Accurately weigh 100g of silicon suboxide (purity 99.9%, median particle size 4μm) and 10g of anhydrous lithium chloride (particle size 4μm, weight ratio 1:0.1); separately weigh anhydrous indium chloride (InCl3, purity ≥99%), the amount of which must ensure that the molar ratio of indium chloride to lithium chloride is 1:3; approximately 17.4g of anhydrous indium chloride; at the same time, weigh 33.3g of polyethylene glycol (PEG, molecular weight 20000, PEG to silicon suboxide weight ratio 1:3).

[0098] Step S2 calcination treatment:

[0099] Mixing: Place the weighed silica powder and anhydrous lithium chloride powder in a ball mill jar and mechanically ball mill them for 30 minutes under nitrogen protection to ensure that they are fully mixed.

[0100] Calcination: Transfer the uniformly mixed material to a corundum boat and place it in a tube furnace; introduce high-purity nitrogen as the first inactive atmosphere at a flow rate of 200 mL / min, and exhaust the air in the tube for 30 minutes; then heat to 150°C at a heating rate of 5°C / min and calcine at 150°C for 6 hours.

[0101] Post-processing: After calcination, the material was allowed to cool naturally to room temperature to obtain material A. The first material was then ground through a 200-mesh sieve in a nitrogen-protected glove box for later use. At this point, the mass of the first material was approximately 110g.

[0102] Step S3 Heat Treatment:

[0103] Mixing: Add all of the material A (approximately 110g) obtained in step S2, the weighed 17.4g of anhydrous indium chloride, and 33.3g of polyethylene glycol (PEG) to the mixer and mechanically stir under nitrogen protection to ensure that the three are thoroughly mixed.

[0104] Heat treatment: Transfer the mixed materials to a vacuum oven. First, evacuate to a vacuum level ≤ -0.1 MPa, then introduce high-purity nitrogen to atmospheric pressure. Repeat this process three times to ensure that the air in the reaction environment is completely replaced. Finally, maintain the vacuum state (vacuum level ≤ -0.1 MPa) and heat to 200℃ at a heating rate of 3℃ / min, then maintain the temperature at 200℃ for 8 hours.

[0105] Crushing and screening: After heat treatment, the furnace is naturally cooled to room temperature. The resulting blocky solid material is mechanically crushed and pulverized under a protective atmosphere and then passed through a 300-mesh sieve to obtain the silicon-oxygen composite material.

[0106] The final fast-charging solid-state lithium-ion battery silicon-oxygen composite material structure is similar to the silicon-oxygen composite material prepared in Example 1. The core-shell structure of the elastic layer 2 is about 0.50 μm thick. The elastic layer is uniformly coated on the surface of silicon-oxygen particles without peeling or cracking, and the interface is tightly bonded.

[0107] (2) Preparation of negative electrode sheet: The above-mentioned silicon-oxygen negative electrode material, conductive agent super-P, binder PVDF, solvent isobutyl isobutyrate, and sulfide solid electrolyte L6PS5Cl are mixed in a weight ratio of 4:0.1:1.5:4.5:1 to obtain a negative electrode slurry; the slurry is coated on both sides of copper foil, dried and cured to obtain a negative electrode sheet, which is used as the original negative electrode sheet.

[0108] Example 3

[0109] (1) Preparation of silicon-oxygen anode materials:

[0110] Step S1 Raw material weighing: Accurately weigh 100g of silicon suboxide (purity 99.9%, median particle size 5μm) and 20g of anhydrous lithium chloride (particle size 5μm, weight ratio 1:0.2); separately weigh anhydrous indium chloride (InCl3, purity ≥99%), the amount of which must ensure that the molar ratio of indium chloride to lithium chloride is 1:5; approximately 20.9g of anhydrous indium chloride; at the same time, weigh 20g of polypropylene oxide (PPO, molecular weight 100,000, PPO to silicon suboxide weight ratio 1:5).

[0111] Step S2 calcination treatment:

[0112] Mixing: Place the weighed silica powder and anhydrous lithium chloride powder in a ball mill jar and mechanically ball mill them for 30 minutes under argon protection to ensure that they are fully mixed.

[0113] Calcination: Transfer the uniformly mixed material to a corundum boat and place it in a tube furnace; introduce high-purity argon as the first inactive atmosphere at a flow rate of 200 mL / min, and exhaust the air in the tube for 30 minutes; then heat to 250°C at a heating rate of 5°C / min and calcine at 250°C for 4 hours.

[0114] Post-processing: After calcination, the mixture was allowed to cool naturally to room temperature to obtain material A. Material A was then ground through a 200-mesh sieve in an argon-protected glove box for later use. At this point, the mass of mixture A was approximately 120g.

[0115] Step S3 Heat Treatment:

[0116] Mixing: Add all of the material A (approximately 120g) obtained in step S2, the weighed 20.9g of anhydrous indium chloride, and 20g of polypropylene oxide (PPO) to the mixer and mechanically stir under argon protection to ensure that the three are thoroughly mixed.

[0117] Heat treatment: Transfer the mixed materials to a vacuum oven. First, evacuate to a vacuum level ≤ -0.1 MPa, then introduce high-purity argon gas to atmospheric pressure. Repeat this process three times to ensure that the air in the reaction environment is completely replaced. Finally, maintain the vacuum state (vacuum level ≤ -0.1 MPa) and heat to 300℃ at a heating rate of 3℃ / min, then maintain the temperature at 300℃ for 4 hours.

[0118] Crushing and screening: After heat treatment, the furnace is naturally cooled to room temperature. The resulting blocky solid material is mechanically crushed and pulverized under a protective atmosphere and then passed through a 300-mesh sieve to obtain the silicon-oxygen composite material.

[0119] The final fast-charging solid-state lithium-ion battery silicon-oxygen composite material structure is similar to the silicon-oxygen composite material prepared in Example 1, exhibiting a core-shell structure; the thickness of the elastic layer 2 is approximately 0.82 μm, and the elastic layer uniformly coats the surface of the silicon-oxygen particles without peeling or cracking, with a tight interface bond.

[0120] (2) Preparation of negative electrode sheet: The above-mentioned silicon-oxygen negative electrode material, conductive agent super-P, binder PVDF, solvent isobutyl isobutyrate, and sulfide solid electrolyte L6PS5Cl are mixed in a weight ratio of 4:0.10:1.5:4.5:1.0 to obtain a negative electrode slurry; the slurry is coated on both sides of copper foil, dried and cured to obtain a negative electrode sheet, which is used as the original negative electrode sheet.

[0121] Example 4

[0122] (1) Preparation of silicon-oxygen anode materials:

[0123] Step S1 Raw material weighing: Accurately weigh 100g of silicon suboxide (purity 99.9%, median particle size 3μm) and 12g of anhydrous lithium chloride (particle size 3μm, weight ratio 1:0.12); separately weigh indium chloride tetrahydrate (InCl3·4H2O, purity ≥99%), the amount of which must ensure that the molar ratio of anhydrous indium chloride to lithium chloride is 1:3.5; weigh 23.7g of indium chloride tetrahydrate; at the same time, weigh 12.5g of polyethylene oxide (PEO, molecular weight 300,000) and 12.5g of polyethylene glycol (PEG, molecular weight 20,000) (total weight of both is 25g, the weight ratio of polymer matrix to silicon suboxide is 1:4).

[0124] Step S2 calcination treatment:

[0125] Mixing: Place the weighed silica powder and anhydrous lithium chloride powder in a ball mill jar and mechanically ball mill them for 30 minutes under helium protection to ensure that the two are fully mixed and homogeneous.

[0126] Calcination: Transfer the uniformly mixed material to a corundum boat and place it in a tube furnace; introduce high-purity helium as the first inactive atmosphere at a flow rate of 200 mL / min, and exhaust the air in the tube for 30 minutes. Then heat to 180°C at a heating rate of 5°C / min and calcine at 180°C for 5.5 hours.

[0127] Post-processing: After calcination, the material was allowed to cool naturally to room temperature to obtain material A. Material A was then ground through a 200-mesh sieve in a helium-protected glove box for later use; at this point, the mass of material A was approximately 112g.

[0128] Step S3 Heat Treatment:

[0129] Mixing: Add all of the material A (approximately 112g) obtained in step S2, the weighed 23.7g of indium chloride tetrahydrate, 12.5g of polyethylene oxide (PEO), and 12.5g of polyethylene glycol (PEG) to the mixer and mechanically stir under helium protection to ensure that the three are thoroughly mixed.

[0130] Heat treatment: Transfer the mixed materials to a vacuum oven. First, evacuate to a vacuum level ≤ -0.1 MPa, then introduce high-purity helium to atmospheric pressure. Repeat this process three times to ensure that the air in the reaction environment is completely replaced. Finally, maintain the vacuum state (vacuum level ≤ -0.1 MPa) and heat to 220°C at a heating rate of 3°C / min, then maintain the temperature at 220°C for 7 hours.

[0131] Crushing and Screening: After heat treatment, the furnace is allowed to cool naturally to room temperature. The resulting blocky solid material is then mechanically crushed and pulverized under a protective atmosphere and passed through a 300-mesh sieve to obtain the silicon-oxygen composite material.

[0132] The final fast-charging solid-state lithium-ion battery silicon-oxygen composite material structure is similar to the silicon-oxygen composite material prepared in Example 1, exhibiting a core-shell structure; the thickness of the elastic layer 2 is approximately 0.45 μm, and the elastic layer uniformly coats the surface of the silicon-oxygen particles without peeling or cracking, with a tight interface bond.

[0133] (2) Preparation of negative electrode sheet: The above-mentioned silicon-oxygen negative electrode material, conductive agent super-P, binder PVDF, solvent isobutyl isobutyrate, and sulfide solid electrolyte L6PS5Cl are mixed in a weight ratio of 4:0.1:1.5:4.5:1.0 to obtain a negative electrode slurry; the slurry is coated on both sides of copper foil, dried and cured to obtain a negative electrode sheet, which is used as the original negative electrode sheet.

[0134] Example 5

[0135] (1) Preparation of silicon-oxygen anode materials:

[0136] Raw material weighing: Accurately weigh 100g of silicon suboxide (purity 99.9%, median particle size 5μm) and 18g of anhydrous lithium chloride (particle size 4μm, weight ratio 1:0.18); separately weigh indium chloride tetrahydrate (InCl3·4H2O, purity ≥99%), the amount of which must ensure that the molar ratio of anhydrous indium chloride to lithium chloride is 1:4.5; weigh approximately 27.7g of tetrahydrate; at the same time, weigh 22.2g of polyethylene oxide (PEO, molecular weight 300,000, PEO to silicon suboxide weight ratio 1:4.5).

[0137] Step S2 calcination treatment:

[0138] Mixing: Place the weighed silica powder and anhydrous lithium chloride powder in a ball mill jar and mechanically ball mill them in a vacuum glove box for 30 minutes to ensure they are fully and evenly mixed (note that a vacuum environment should be maintained).

[0139] Calcination: Transfer the uniformly mixed material to a corundum boat and place it in a vacuum tube furnace. First, evacuate to a vacuum degree ≤ -0.095MPa and maintain this vacuum atmosphere as the first inactive atmosphere. Then, heat to 220℃ at a heating rate of 5℃ / min and calcine at 220℃ for 4.5 hours.

[0140] Post-processing: After calcination, allow it to cool naturally to room temperature. Then, purge with argon gas to restore atmospheric pressure and remove the material to obtain material A. Grind material A through a 200-mesh sieve in an argon-protected glove box for later use. At this point, material A weighs approximately 118g.

[0141] Step S3 Heat Treatment:

[0142] Mixing: Add all of the material A (approximately 118g) obtained in step S2, the weighed 27.7g of indium chloride tetrahydrate, and 22.2g of polyethylene oxide (PEO) to the mixer and mechanically stir under argon protection to ensure that the three are thoroughly mixed.

[0143] Heat treatment: Transfer the mixed materials to a vacuum oven. First, evacuate to a vacuum level ≤ -0.1 MPa, then introduce high-purity argon gas to atmospheric pressure. Repeat this process three times to ensure that the air in the reaction environment is completely replaced. Finally, maintain the vacuum state (vacuum level ≤ -0.1 MPa) and heat to 280℃ at a heating rate of 3℃ / min, then maintain the temperature at 280℃ for 5 hours.

[0144] Crushing and screening: After heat treatment, the furnace is naturally cooled to room temperature. The resulting blocky solid material is mechanically crushed and pulverized under a protective atmosphere and then passed through a 300-mesh sieve to obtain the silicon-oxygen composite material.

[0145] The final fast-charging solid-state lithium-ion battery silicon-oxygen composite material structure is similar to the silicon-oxygen composite material prepared in Example 1, exhibiting a core-shell structure. The thickness of the elastic layer 2 is approximately 0.9 μm. The elastic layer uniformly coats the surface of the silicon-oxygen particles without shedding or cracking, and the interface is tightly bonded.

[0146] (2) Preparation of negative electrode sheet: The above-mentioned silicon-oxygen negative electrode material, conductive agent super-P, binder PVDF, solvent isobutyl isobutyrate, and sulfide solid electrolyte L6PS5Cl are mixed in a weight ratio of 4:0.1:1.5:4.5:1 to obtain a negative electrode slurry; the slurry is coated on both sides of copper foil, dried and cured to obtain a negative electrode sheet, which is used as the original negative electrode sheet.

[0147] Example 6

[0148] The difference between Example 6 and Example 1 is that the weight of polyethylene oxide in step S1 is replaced with 28.5g, and the weight ratio of polyethylene oxide to silicon dioxide is 1:3.5; the other steps are the same.

[0149] Example 7

[0150] The difference between Example 7 and Example 1 is that the polyethylene oxide in step S1 is replaced with 12.5g of polyethylene oxide and 12.5g of polypropylene oxide (PPO, molecular weight 100,000); the other steps are the same.

[0151] Example 8

[0152] The difference between Example 8 and Example 1 is that the polyethylene oxide in step S1 is replaced with 12.5g of polyethylene glycol (PEG, molecular weight 20,000) and 12.5g of polypropylene oxide (PPO, molecular weight 100,000); the other steps are the same.

[0153] Example 9

[0154] Example 9 differs from Example 1 in that the polyethylene oxide in step S1 is replaced with 10g of polyethylene oxide, 10g of polyethylene glycol (PEG, molecular weight 20,000), and 5g of polypropylene oxide (PPO, molecular weight 100,000); the other steps are the same.

[0155] Example 10

[0156] The difference between Example 10 and Example 1 is that the calcination temperature in step S2 is replaced with 230°C and the calcination time is 4 hours; the other steps are the same.

[0157] Example 11

[0158] The difference between Example 11 and Example 1 is that all of the material A obtained in step S2 is first mixed with the solvent tetrahydrofuran under argon protection to obtain mixture A. Then, mixture A, indium chloride tetrahydrate and polyethylene oxide (PEO) are added to a mixer and mechanically stirred under argon protection to ensure that the three are fully mixed and homogeneous. The other steps are the same.

[0159] Example 12

[0160] The difference between Example 12 and Example 1 is that all of the material A obtained in step S2 is first mixed with the solvent toluene under argon protection to obtain mixture A. Then, mixture A, indium chloride tetrahydrate and polyethylene oxide (PEO) are added to a mixer and mechanically stirred under argon protection to ensure that the three are fully mixed and homogeneous. The other steps are the same.

[0161] Comparative Example 1

[0162] Step S1: Take 500g of petroleum coke particles with a D50 of 10μm and pack them into the fluidized bed reactor;

[0163] Step S2: Silane is preheated to 80°C and fed into the fluidized bed reactor at 30 mL / min. The temperature is then raised to 600°C in a helium protective atmosphere and held for 10 h.

[0164] Step S3: Preheat acetylene gas to 80°C and deliver it to the fluidized bed reactor at 30 mL / min. In a helium protective atmosphere, the temperature is raised to 600°C and held for 2 hours to obtain a silicon-oxygen composite material with a carbon layer coating the silicon surface.

[0165] Comparative Example 2

[0166] Step S1: Take 500g of petroleum coke particles with a D50 of 10μm and pack them into the CVD reactor (chemical vapor deposition);

[0167] Step S2: Silane is preheated to 80°C and fed into the CVD reactor at 30 mL / min. The temperature is then raised to 600°C in a helium protective atmosphere and held for 10 h.

[0168] Step S3: Preheat acetylene gas to 80°C and deliver it to the CVD reactor at 30 mL / min. In a helium protective atmosphere, the temperature is raised to 600°C and held for 2 hours to obtain a silicon-oxygen composite material with a carbon layer coating the silicon surface.

[0169] Performance testing

[0170] The performance of the silicon-oxygen composite material and solid-state battery in each embodiment and comparative example was tested; wherein, a semi-solid-state battery was assembled from silicon-oxygen composite material (positive electrode), lithium indium (negative electrode) and L6PS5Cl solid electrolyte; the test results are shown in Table 1 and Table 2.

[0171] 1. Structural testing:

[0172] Composition of silicon-oxygen composite materials: Qualitative testing was performed using X-ray diffraction (XRD) with a German Bruker D8 ADVANCE X-ray diffractometer, scanning angle 2θ, range: 10~80°, using Cu target Kα1 rays; the test method refers to GB / T 30904-2014; Quantitative testing was performed using ICP testing, the test method refers to GB / T 20975.25-2020 Chemical Analysis Methods for Aluminum and Aluminum Alloys Part 25: Determination of Elemental Content by Inductively Coupled Plasma Atomic Emission Spectrometry.

[0173] 2. Performance Testing:

[0174] (1) The particle size, tap density, specific surface area, silicon grains, powder resistivity and specific capacity of the silicon-oxygen composite material were tested in accordance with the national standard GB / T 38823-2020.

[0175] (2) Electrochemical performance of solid-state batteries:

[0176] The anode material, super-P (superconducting carbon black) conductive agent, Li6PS5Cl (LPSC) electrolyte, PVDF (polyvinylidene fluoride) binder, and C8H are used. 16 O2 (isobutyl isobutyrate) solvent was mixed in a weight ratio of 4:0.1:1:1.5:4.5, and 30g of zirconium beads were added for ball milling and slurry preparation. The slurry was then coated onto an 8μm copper foil and dried to obtain a negative electrode sheet. The negative electrode sheet, lithium indium sheet, and solid electrolyte (0.1g Li6PS5Cl (LPSC)) were assembled into a solid-state battery.

[0177] a: After conducting the first week of charge-discharge testing of the solid-state battery at 0.1C, calculate the initial lithium-depletion capacity and initial coulombic efficiency;

[0178] Initial lithium removal capacity = charging capacity ÷ mass of active material; where the active material is the silicon-oxygen composite material of solid-state battery.

[0179] Initial coulombic efficiency = charging capacity ÷ discharging capacity.

[0180] b: The solid-state battery was subjected to rate performance testing and cycle performance testing at 0.1C. The testing steps and calculation methods are as follows:

[0181] Rate performance test: Discharge to -0.61V at 0.1C, charge to 0.9V at 1C, and the capacity is calculated as C1; then charge at a constant voltage of 0.9V until the charging current is less than 0.05C and the capacity is calculated as C2; Rate performance = C1 / (C1+C2)×100%.

[0182] Cyclic performance test: Discharge at 0.1C to -0.61V, charge at 0.1C to 0.9V, cycle for 3 times, and calculate the average charge capacity as C3; then discharge at 0.5C to -0.61V, charge at 0.5C to 0.9V, cycle for 200 times, and calculate the charge capacity on the 200th cycle as C200; calculate the capacity retention rate after 200 cycles, capacity retention rate = C200 / C3 × 100%.

[0183] (3) Expansion performance of the negative electrode sheet: The negative electrode sheets of the above embodiments and comparative examples were measured using a micrometer. The measurement points were the center, the middle ring, and the outer ring. The thickness data was recorded as D1 (including the distance from the center point to the middle ring point and the distance from the center point to the outer ring point; the average of the test results will be taken later, as long as the in-situ test is ensured before and after disassembly). After the first week of charge-discharge test (condition: 55℃), the solid-state battery was disassembled and in-situ measurements were performed. The thickness data was recorded as D2. The average of the measurement results was taken, and the expansion rebound rate of the electrode sheet was calculated. The expansion rebound rate = (D2-D1) / D1×100%.

[0184] Table 1

[0185]

[0186] Table 2

[0187]

[0188] As shown in Table 2, the solid-state battery performance test results indicate that the first lithium-depletion capacity and electrode expansion rate of the solid-state batteries assembled from the silicon-oxygen composite materials prepared in each embodiment of this application are significantly lower than those of the conventional silicon-carbon anode materials in Comparative Examples 1-2, while the first coulombic efficiency, rate performance, and cycle retention rate are significantly higher than those in Comparative Examples 1-2.

[0189] Depend on Figure 2 Si, Li4SiO4 and Li2SiO3 were detected in the XRD, and PDF#04-009-9027 is a characteristic peak of Li3InCl6, indicating that silicon, lithium silicate and lithium indium chloride were generated in the prepared silicon-oxygen composite material.

[0190] Depend on Figure 3 The SEM images also clearly show that the structure of the silicon-oxygen composite material includes a silicon-oxygen core 1, an elastic layer 2, and the elastic layer 2 wrapping around the surface of the silicon-oxygen core 1.

[0191] The comparative example, commercial homogeneous silicon-carbon, lacks the "three-dimensional network elastic coating layer" structure of this application. Side reactions between the sulfide and carbon layers lead to the continuous decomposition and consumption of the sulfide electrolyte, reducing the high ionic conductivity of Li2S and affecting the ionic conductivity of the sulfide electrolyte during electrochemical testing, thus impacting its initial efficiency and rate performance. Furthermore, the absence of an elastic matrix fails to mitigate the volume expansion of silicon, further affecting electrode expansion and cycle life.

[0192] The pre-lithiated silicon-oxygen composite material synthesized in this application via a liquid-phase method is more suitable for sulfide solid-state battery systems. Compared with novel silicon-carbon materials, the pre-lithiated silicon-oxygen material has a shorter lithium-ion transport path, which is beneficial for lithium-silicon alloying. Simultaneously, the in-situ generated fast-ion conductor (Li3InCl6) has a three-dimensional channel structure, allowing lithium ions to diffuse rapidly from three directions. The ether-oxygen group (-COC-) structure in the elastic matrix powder can interact with lithium ions (Li... +The polymer coating layer coordinates with the lithium ions, promoting their movement within the polymer chain. Simultaneously, the flexible polymer coating optimizes the point contact between the rigid electrode and the rigid solid electrolyte, reducing interfacial impedance and resulting in higher initial coulombic efficiency and rate performance. In this application, LiCl is used to replenish the irreversible lithium ion loss during charge and discharge, while simultaneously forming a structural framework on the surface of the silicon-oxygen composite material. The subsequently added InCl3 forms a fast-ion conductor (Li3InCl6) three-dimensional network coating layer with LiCl, reducing the volume expansion of the silicon-oxygen composite material during charge and discharge. Due to the introduction of the elastic polymer matrix, this three-dimensional network coating layer is uniformly dispersed within the elastic matrix, forming a "three-dimensional network elastic coating layer." This interfacial layer suppresses lithium dendrite growth, thereby constructing a stable electrolyte-anode interface and rapidly releasing the expansion stress on the coating layer. Compared to traditional carbon coating layers, this avoids the reaction between carbon and the sulfide solid electrolyte, improving the battery's coulombic efficiency and enhancing its cycle stability. This application achieves in-situ pre-lithiation of silicon-oxygen composite materials and improves coating uniformity through a liquid-phase reaction method. The mild liquid-phase reaction environment does not cause silicon grains to nucleate and grow at high temperatures, reducing silicon volume expansion and improving cycle performance.

[0193] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0194] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A silicon-oxygen composite material, characterized in that, The silicon-oxygen composite material includes a silicon-oxygen core and an elastic layer, wherein the elastic layer is attached to the surface of the silicon-oxygen core; the material of the elastic layer includes a polymer matrix, lithium indium chloride, and lithium silicate; wherein the lithium indium chloride and the lithium silicate are dispersed in the polymer matrix.

2. The silicon-oxygen composite material according to claim 1, characterized in that, The polymer matrix contains etheroxy groups; at least some of the lithium ions in the lithium indium chloride are interconnected with the etheroxy groups through coordination. And / or, the ratio of the median particle size of the silicon-oxygen core to the thickness of the elastic layer is 1:(0.1~0.2).

3. The silicon-oxygen composite material according to claim 1 or 2, characterized in that, The polymer matrix is ​​at least one of polyethylene oxide, polyethylene oxide, and polyethylene glycol; And / or, the lithium indium chloride is Li3InCl6; And / or, the lithium silicate is Li4SiO4 and Li2SiO3; And / or, the silicon-oxygen core is silicon oxide.

4. The silicon-oxygen composite material according to any one of claims 1 to 3, characterized in that, The median particle size of the silicon-oxygen composite material is 5~10μm; And / or, the tap density of the silicon-oxygen composite material is 0.5~1.5 g / cm³. 3 ; And / or, the resistivity of the silicon-oxygen composite material is 0.5~2Ω·cm; And / or, the specific surface area of ​​the silicon-oxygen composite material is 0.5~2m². 2 / g; And / or, the median particle size of the silicon-oxygen core is 3~5 μm.

5. A method for preparing a silicon-oxygen composite material according to any one of claims 1 to 4, characterized in that, The preparation method includes the following steps: Step S1: Calcine silicon suboxide and lithium chloride in a first inactive atmosphere to obtain the first material; Step S2: The first material, indium chloride, and polymer matrix are heat-treated under vacuum conditions to obtain the silicon-oxygen composite material; wherein the silicon-oxygen composite material includes a silicon-oxygen core and an elastic layer, the elastic layer is attached to the surface of the silicon-oxygen core, and the elastic layer includes a polymer matrix, lithium indium chloride, and lithium silicate; wherein the lithium indium chloride and the lithium silicate are dispersed in the polymer matrix.

6. The method for preparing the silicon-oxygen composite material according to claim 5, characterized in that, The weight ratio of silicon suboxide to lithium chloride is 1:(0.1~0.2). And / or, the molar ratio of indium chloride to lithium chloride is 1:(3~5); And / or, the weight ratio of the polymer matrix to the silicon suboxide is 1:(3~5). And / or, the calcination temperature is 150~250℃, and the calcination time is 4~6h; And / or, the heat treatment temperature is 200~300℃, and the heat treatment time is 4~8h; And / or, the vacuum condition is a vacuum degree ≤ -0.1 MPa; And / or, the indium chloride is anhydrous indium chloride and / or indium chloride tetrahydrate, with a purity ≥99%; And / or, the median particle size D50 of the lithium chloride is 3~5 μm; And / or, the median particle size D50 of the silicon suboxide is 3~5 μm; And / or, the polymer matrix contains etheroxy groups; at least some of the lithium ions in the lithium indium chloride compound are interconnected with the etheroxy groups through coordination; And / or, the first inactive atmosphere is selected from at least one of argon, nitrogen, helium, neon, and vacuum atmosphere.

7. The method for preparing the silicon-oxygen composite material according to claim 5, characterized in that, The weight ratio of silicon suboxide to lithium chloride is 1:(0.1~0.15). And / or, the molar ratio of indium chloride to lithium chloride is 1:(3~4.5). And / or, the weight ratio of the polymer matrix to the silicon suboxide precursor is 1:(3~4.5). And / or, the calcination temperature is 180~230℃, and the calcination time is 4~5h; And / or, the heat treatment temperature is 220~280℃, and the heat treatment time is 4~7h; And / or, the polymer matrix is ​​at least one of polyethylene oxide, polypropylene oxide, and polyethylene glycol; And / or, the ratio of the median particle size of the silicon-oxygen core to the thickness of the elastic layer is 1:(0.1~0.2). And / or, the lithium indium chloride is Li3InCl6; And / or, the lithium silicate is Li4SiO4 and Li2SiO3; And / or, the silicon-oxygen core is silicon oxide.

8. The method for preparing the silicon-oxygen composite material according to any one of claims 5 to 7, characterized in that, Between step S1 and step S2, there is also step S1-2: first, the first material and the solvent are mixed in a second inactive atmosphere to obtain the mixture A, and then the mixture A, the indium chloride and the polymer matrix are subjected to the heat treatment under the vacuum conditions; Preferably, the second inactive atmosphere is selected from at least one of argon, nitrogen, helium, neon, and vacuum atmosphere; Preferably, the weight ratio of silicon suboxide to the solvent is 1:(5~10). Preferably, the solvent is an organic solvent; more preferably, the organic solvent is selected from at least one of acetonitrile, tetrahydrofuran, toluene, and xylene.

9. A negative electrode sheet, comprising a negative electrode current collector and a negative electrode active coating, wherein the negative electrode active coating is attached to at least one surface of the negative electrode current collector; the negative electrode active coating comprises a negative electrode active material; characterized in that, The negative electrode active material is the silicon-oxygen composite material according to any one of claims 1 to 4 or the silicon-oxygen composite material according to any one of claims 5 to 8, obtained by the preparation method of the silicon-oxygen composite material.

10. A solid-state battery, comprising a negative electrode, a positive electrode, and a solid electrolyte; characterized in that, The negative electrode sheet is the negative electrode sheet as described in claim 9.

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