A continuous silicon nanowire negative electrode material based on ALD seed layer induced mesoporous confinement and a preparation method thereof

Abstract

This invention discloses a continuous silicon nanowire anode material based on ALD seed layer-induced mesoporous confinement and its preparation method. The material comprises a mesoporous carbon framework with interconnected pore structures, and a one-dimensional silicon nanostructure located within the pores and extending continuously along the axial direction. The one-dimensional silicon nanostructure is connected to the inner wall of the mesoporous carbon through an interface modification layer, forming a continuous electron / ion transport pathway. The interface modification layer is formed by in-situ transformation of a metal oxide seed layer deposited on the inner wall of the pores under a silicon source gas and a reducing atmosphere, and its composition includes elemental metals, metal-silicon alloy phases, or metal silicides. Utilizing the spatial confinement effect of the mesoporous carbon, the radial expansion of the silicon nanostructure is restricted within the pores, reducing mechanical compression on the solid electrolyte; simultaneously, during the delithiation shrinkage process, the axial connectivity of the silicon nanostructure is maintained, alleviating solid-solid interface contact degradation, thereby improving the cycle stability and rate performance of the all-solid-state battery.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery material technology, specifically relating to a continuous silicon nanowire anode material based on ALD seed layer-induced mesoporous carbon confinement, its preparation method and application, and an all-solid-state lithium-ion battery containing the anode material. Background Technology

[0002] New energy vehicles and portable electronic devices place near-stringent demands on the energy density and safety of power batteries. All-solid-state batteries, by completely eliminating flammable and leaky liquid electrolytes and using non-flammable solid electrolytes, are considered the ultimate solution for next-generation high-energy storage systems. Among numerous anode material candidates, silicon, with its theoretical specific capacity of up to 4200 mAh / g (approximately 10 times that of traditional graphite anodes) and suitable lithium intercalation potential, is considered an ideal choice for breaking through current energy density bottlenecks.

[0003] To address the aforementioned issues, existing technologies have proposed various modification strategies. Among them, Chinese patent CN119954159B discloses a silicon-carbon composite anode material prepared using ALD and CVD technologies, its preparation method, and a lithium-ion battery. This technology involves depositing a metal oxide film on a carbon substrate (such as graphite or hard carbon) using ALD, followed by reduction to form metal catalytic nanoparticles, which then induce the growth of extremely fine (<5 nm) silicon nanowires using silane gas. A carbon layer is then coated onto the surface of the silicon nanowires to form carbon-coated silicon nanowires. This structure of "discrete silicon nanowires grown on a carbon surface" utilizes the size effect of the nanowires to alleviate the internal stress of individual silicon wires and improves the rate performance of the material to a certain extent.

[0004] However, although the existing technology represented by CN119954159B has made some progress in liquid electrolyte systems, there are gaps in the carbon substrate. Silicon nanowires grow in the gaps, resulting in a low density of silicon nanowires. Finally, the silicon-carbon anode material obtained after coating the silicon nanowires with a carbon layer has a low silicon-carbon ratio.

[0005] Using natural porous carbon materials as a carrier presents challenges. Because porous carbon materials contain micropores and mesopores of varying sizes, smaller pores are easily blocked by silicon during silicon deposition, hindering the transport of reactant gases. Therefore, the total deposition volume must be reduced, resulting in dispersed silicon particles within the porous carbon material. Forming continuous silicon nanowires is difficult. This type of silicon-carbon anode material faces the following four major challenges: First, the dead silicon phenomenon caused by solid-solid interface contact failure.

[0006] Unlike traditional liquid batteries where the electrolyte can flow and wet the surface, in all-solid-state batteries, the negative electrode active material, solid electrolyte, and conductive agent are all in rigid point contact. During charge-discharge cycles, silicon particles undergo drastic volume expansion and contraction. Especially during the delithiation stage, the silicon particles shrink significantly in volume. Due to the lack of fluidity and high elastic modulus of the solid electrolyte, it cannot promptly follow the deformation of the silicon particles to fill the gaps, resulting in micron- or even nanometer-sized voids at the interface. This physical separation not only cuts off ion transport channels but also causes some active silicon particles to become electrochemically inert dead silicon due to the loss of electrical contact, directly causing rapid and irreversible capacity decay of the battery.

[0007] Second, the vulnerability and risk of interruption of three-dimensional transmission networks.

[0008] Highly efficient electrochemical performance relies on a continuous and stable electron / ion hybrid conduction network. Traditional particle-stacking silicon anodes depend on random contact between particles for their transport paths. Once a local interface peels off due to volume changes, the downstream active material instantly loses its electron or ion supply, causing a break in the entire transport chain. This localized failure has a cascading effect, preventing a large amount of active material inside the battery from participating in the reaction, severely limiting material utilization and rate performance.

[0009] Sulfide all-solid-state battery systems are limited by solid-solid interface contact, ion transport efficiency and positive electrode capacity. The effective discharge specific capacity of the same material in an all-solid-state battery system is only 1 / 10 to 1 / 8 of that in a liquid half-cell. For example, the prior art CN119050259A discloses a method for preparing a negative electrode material for sulfide all-solid-state batteries. The initial charge capacity of this material does not exceed 221 mAh / g, and after 10 charge-discharge cycles, the charge capacity does not exceed 171.2 mAh / g, which is 80% of the initial capacity.

[0010] In summary, there is an urgent need to develop a novel silicon-based anode material and its preparation strategy: the preparation method should be able to achieve the continuity and confinement of silicon structure at the microscale, thereby truly unleashing the high-energy potential of all-solid-state batteries. Summary of the Invention

[0011] This invention aims to provide a silicon-carbon anode material for all-solid-state batteries and its preparation method. By confining mesoporous carbon and continuously constructing one-dimensional silicon nanostructures within the pores, high loading, low external expansion, interface stability and excellent cycle performance are achieved.

[0012] The negative electrode material provided by this invention comprises: a mesoporous carbon framework with interconnected pore structures, and a one-dimensional silicon nanostructure located inside the pores and extending continuously along the pore axis. The one-dimensional silicon nanostructure is connected to the inner wall of the pores through catalytic active centers, thereby forming a continuous electron transport pathway; the mesoporous carbon framework provides confined space for the volume change of silicon, allowing silicon to mainly "breathe" radially within the pores, reducing external compression on the solid electrolyte.

[0013] In this invention, a metal oxide seed layer is formed on the inner wall of a mesoporous channel, and then, under a silicon source gas and a reducing atmosphere, it is transformed into catalytically active centers of a metallic phase, alloy phase, and / or metal silicide phase, thereby inducing the confined growth of silicon within the channel to form a one-dimensional nanostructure. The specific technical solution is as follows: A continuous silicon nanowire anode material based on ALD seed layer-induced mesoporous confinement includes: Mesoporous carbon framework with interconnected mesoporous channels, the average pore size of which is 2-50 nm and the pore volume is 0.5-2.5 cm³. 3 / g; A one-dimensional silicon nanostructure is located inside the mesoporous channels and extends along the axial direction of the mesoporous channels; Nanoscale metal particles are distributed between the one-dimensional silicon nanostructure and the inner wall of the mesoporous channel, and / or distributed at the ends of the one-dimensional silicon nanostructure; the interface modification layer contains a metal element M or its silicide, wherein the metal element M is selected from at least one of Zn, Sn, In, Ga, Cd, Bi, and Pb. And an outer carbon coating layer, which at least continuously covers the outer surface of the one-dimensional silicon nanostructure.

[0014] Furthermore, the mesoporous channels have nanoscale buffer cavities at their openings; the metal element M in the nano-metal particles is Zn.

[0015] Furthermore, the mesoporous carbon framework has an average pore size of 2-50 nm and a pore volume of 0.5-2.5 cm³. 3 / g; The inner wall of the pores of the mesoporous carbon framework is further modified with oxygen-containing functional groups, and the interface functional layer is anchored to the inner wall of the pores through the oxygen-containing functional groups.

[0016] Furthermore, the diameter of the one-dimensional silicon nanostructure is less than or equal to the average pore size of the mesoporous channels, with a diameter of 1-10 nm. The one-dimensional silicon nanostructure is a single-crystal silicon or polycrystalline silicon nanowire / nanorobar with an aspect ratio greater than 3.

[0017] Furthermore, the outer carbon coating layer is an amorphous carbon or microcrystalline carbon layer with a thickness of 2-20 nm.

[0018] Furthermore, the silicon content in the negative electrode material is 10%-80% by mass.

[0019] Furthermore, an all-solid-state battery includes a positive electrode, a solid electrolyte layer, and a negative electrode; the negative electrode uses the aforementioned negative electrode material, and the metal element M in the nano-metal particles is selected from at least one of Zn, In, Sn, and Ga; the nano-metal particles and lithium form a LixM alloy phase, and the LixM alloy phase exhibits a plastic or liquid state at the battery operating temperature.

[0020] The present invention also proposes a method for preparing the above-mentioned negative electrode material, comprising the following steps: Step S1: Activate the substrate by providing a mesoporous carbon framework and subjecting it to an oxidative heat treatment to introduce oxygen-containing functional groups into the inner wall of the pores of the mesoporous carbon framework. Step S2: Seed layer deposition. Using atomic layer deposition (ALD) technology, the pressure is maintained at a vacuum during ALD. Metal source precursors and oxygen source precursors are introduced into the mesoporous channels of the mesoporous carbon framework in an alternating pulsed manner, reacting to form discretely distributed metal oxide nanoclusters as the seed layer. The metal element in the metal oxide contains at least one metal element M selected from Zn, In, Sn, Ga, Cd, Bi, and Pb. The average particle size of the metal oxide nanoclusters is less than 2 nm. Step S3, confined growth: The product obtained in step S2 is placed in a chemical vapor deposition reactor. First, the metal oxide is reduced to a metallic state in the first temperature range and metal droplets are formed in situ. Then, the precursor containing silicon-hydrogen bonds is cleaved in the second temperature range, so that free silicon and metal droplets form an alloy phase. Silicon grows axially inside the channel to form a one-dimensional silicon nanostructure. Step S4, carbon coating: In an inert or reducing atmosphere, a carbon source gas is introduced, and chemical vapor deposition is performed in the third temperature range to continuously cover at least the outer surface of the one-dimensional silicon nanostructure with an outer carbon coating layer.

[0021] Furthermore, in step S3, the first temperature range and the second temperature range are adjusted according to the type of the metal element M: When the metal element M is a highly volatile metal: Zn or Cd, the first temperature range is 380-420℃, and the second temperature range is 480-520℃. When the metal element M is a low-melting-point metal: In, Sn, Ga, Bi, Pb, the first temperature range is 250-380℃, and the second temperature range is 380-460℃. In step S3, the total pressure of the reaction system is controlled at 10-100 Pa.

[0022] Furthermore, in step S3, when the metal element M is Zn, the first temperature range is 400-420℃ and the second temperature range is 480-500℃; in step S4, the third temperature range is 700-850℃, so that some of the metal element Zn volatilizes in situ, forming a nanoscale buffer cavity in the mesoporous channels at the end of the one-dimensional silicon nanostructure.

[0023] Furthermore, in step S3, when the metal element M is selected from at least one of In, Sn, and Ga, the first temperature range is 300-380℃, and the second temperature range is 400-450℃; in step S4, the third temperature range is controlled at 500-650℃ to suppress the ripening of the metal element M nanodroplets and lock the metal element M or its silicide at the interface or end of the one-dimensional silicon nanostructure.

[0024] Furthermore, in step S3, the silicon-hydrogen bond-containing precursor is one of silane and silane, and its volume fraction in the carrier gas is 1%-5%; in step S4, the carbon source gas is selected from at least one of acetylene, ethylene or propylene; and the thickness of the outer carbon coating layer is 1-20 nm.

[0025] The present invention also proposes an all-solid-state battery, comprising a positive electrode, a solid electrolyte layer and a negative electrode; the negative electrode is prepared using a negative electrode material prepared by the method described above.

[0026] Compared with the prior art, the present invention has at least the following significant advantages: 1. By preparing a one-dimensional silicon nanowire structure that extends continuously along the pore axis, instead of the traditional discrete particle stacking, it is beneficial to maintain the electron / ion transport connectivity in the solid-state system. Even during the charging and discharging process of the all-solid-state battery, when the local interface undergoes slight separation due to volume changes, due to the axial continuity of the silicon nanowire, electrons and lithium ions can still be transported to the depths of the active material through the unbroken pathway. This effectively avoids the phenomenon of "dead siliconization" of downstream materials caused by local contact failure of traditional particle silicon, and significantly improves the utilization rate of the active material and the electrochemical performance at high rates.

[0027] 2. Mechanical damage to solid-state batteries is reduced through mesoporous confinement. The radial expansion of silicon is limited by the internal space of the channels, reducing the overall apparent expansion of the material. This not only effectively alleviates the radial compressive stress of silicon expansion on the surrounding rigid solid electrolyte layer, suppresses the generation of electrolyte microcracks and the risk of lithium dendrite penetration, but also maintains the integrity of the overall electrode structure, significantly improving the safety and cycle life of all-solid-state batteries.

[0028] 3. Based on the universal catalytic mechanism of "in-situ transformation of the seed layer," it possesses excellent process compatibility and broad patent defense. Equivalent substitutability of the catalytic active center: The metal oxide seed layer can be transformed into a metal / alloy / silicide catalytic phase under growth conditions, applicable to various oxide systems and possessing patent layout space to resist element substitution bypass.

[0029] 4. In-situ construction of a "self-healing" flexible interface layer: During the initial charge and discharge process of the battery, the metal nodes at the interface can react with lithium in situ to form a lithium-rich intermetallic compound (LixM) alloy phase. This alloy phase exhibits plastic or even liquid characteristics at the battery operating temperature, forming a flexible interface buffer layer with "self-healing" capability, improving solid-solid contact stability and reducing interface impedance growth.

[0030] 5. This invention overcomes the bottleneck of uniform loading in deep pores and avoids pore blockage. Unlike traditional impregnation methods that easily cause "pore skinning and internal voids," this invention uses atomic layer deposition (ALD) combined with a static exposure mode to introduce a seed layer. The Knudsen diffusion mechanism ensures that the metal precursor is uniformly penetrated into every corner of the mesoporous carbon framework. Subsequent gas-liquid-solid (VLS) or gas-solid-solid (VSS) confined growth modes allow silicon nanowires to grow inwards or bidirectionally from the seed point deep within the pores, rather than accumulating from the pore openings. This growth method fundamentally avoids pore blockage, achieving high uniformity and high loading of silicon within the mesoporous carbon framework, maximizing the porosity utilization of the carbon framework, and laying the material foundation for the fabrication of high energy density electrodes. Attached Figure Description

[0031] Figure 1 These are scanning electron microscope (SEM) images of spherical porous carbon deposited on silicon according to various embodiments; wherein, (a) SEM of Comparative Example 1: The carbon spheres have a rough surface with a large number of protrusions, irregular clusters, and even broken and pulverized silicon that did not enter the channels but directly accumulated and agglomerated on the surface / pore of the carbon spheres, forming large particles that broke the carbon skeleton. (b) SEM of Example 2: The carbon spheres have regular morphology and no obvious clusters on the surface, maintaining the original outline. Silicon preferentially grows in the channels and does not overflow to the surface in large quantities, so no large agglomerates are formed. (c) SEM of Example 1: The carbon spheres have a very smooth and flat surface with no protrusions, cracks or powdering. The silicon grows completely in the channels without accumulating on the surface, and the carbon skeleton remains intact.

[0032] Figure 2 These are the results of the first coulomb efficiency (ICE) and specific capacity tests; Figure 3 The results are from the interface impedance test (EIS - AC impedance). Figure 4These are the results of long-cycle stability tests; Figure 5 These are the results of the rate performance test. Detailed Implementation

[0033] The present invention will be further described below with reference to the embodiments, but the scope of protection of the present invention is not limited to the following embodiments. Process conditions not specifically described can be determined based on conventional techniques in the art.

[0034] The term "mesoporous carbon" as used in this invention refers to porous carbon materials with interconnected pore structures; pore volume and pore size distribution can be determined by nitrogen adsorption-desorption method, and specific surface area can be calculated by BET method, while pore size distribution can be obtained by BJH or DFT method.

[0035] Example 1: Mesoporous carbon-confined silicon nanowire anode material based on ZnO seed layer This embodiment aims to prepare a mesoporous carbon anode composite material with distributed silicon nanowires. One-dimensional selective growth of silicon nanowires deep within the pores is achieved by utilizing the VLS / VS kinetic difference.

[0036] Step 1: Substrate Pretreatment and Activation High specific surface area porous carbon was selected as the substrate. The average pore size of the porous carbon framework was 2-50 nm, preferably 2-10 nm; the pore volume was 0.5-2.5 cm³. 3 / g, preferably greater than 0.8cm 3 / g.

[0037] In this embodiment, the porous carbon used is model FY1400B (purchased from Jiangsu Tanyuan New Material Technology Co., Ltd.), with a pore volume of 1.15 cm³. 3 / g, with an average pore size of 3nm, predominantly mesoporous, the manufacturing process of FY1400B includes: using prepared polystyrene spheres or mesoporous silica material as a template, mixing liquid or solid carbon sources (such as phenolic resin, polyacrylonitrile, sucrose, etc.) with the template material, ensuring uniform dispersion using ultrasound or other methods, and then subjecting the mixture to high-temperature pyrolysis in an inert atmosphere (such as nitrogen or argon), typically at a temperature between 1000℃ and 1200℃. This process converts the carbon source into carbon material. After high-temperature treatment, acid washing is performed to remove the template material. The resulting mesoporous carbon material is then dried and post-treated, containing numerous oxygen-containing functional groups.

[0038] Drying and impurity removal: The porous carbon is placed in a vacuum oven and dried at 200°C for 12 hours to remove physically adsorbed water and impurity gases.

[0039] If the mesoporous carbon material lacks oxygen-containing functional groups, a mild oxidation activation (key pretreatment) is employed: The dried porous carbon is placed in a porous container, which is then placed in the ALD reaction chamber, or the substrate material is placed inside the ALD reaction chamber. Vacuuming and nitrogen purging are performed three times. The reaction chamber is heated to 50-150°C and maintained at a pressure of 10 torr. The substrate material in the reaction chamber is fluidized using nitrogen flow, or the porous container is rotated to achieve material dispersion. The fluidization pressure is 10 torr, and the nitrogen flow rate is 50 sccm. A strong oxidizing gas, carried by N2 at a flow rate of 50 sccm, is pulsed into the ALD reaction chamber. The temperature range is 50-150°C, and the pressure is maintained at 10 torr for half an hour, followed by N2 purging for 90 seconds. The strong oxidizing gas includes any one of O3, H2O2, NO2, or oxygen atoms. Strong oxidizing gas forms an active layer containing oxygen-containing active functional groups at the defects in the inner wall of the porous carbon mesoporous channel. This layer serves as a high-energy nucleation site for the subsequent ALD reaction, inducing ZnO to preferentially and uniformly nucleate deep within the channel, thus avoiding enrichment at the pore opening.

[0040] Step 2, Seed layer formation The porous carbon from the above steps is placed in a porous container, which is then placed in an ALD reaction chamber. The chamber is evacuated and purged with nitrogen three times until the pressure in the ALD reaction chamber is 0.01-0.05 torr. The reaction chamber is then heated to 50-150°C, and the pressure is maintained at 0.01-0.05 torr. The porous container is rotated to achieve substrate material dispersion. Precursors A and B are selected: zinc source (diethylzinc) is used as precursor A, and oxygen source gas is used as precursor B.

[0041] The process parameters (static exposure mode) are as follows: Set the parameters of the ALD reaction chamber as follows: deposition temperature 100℃-400℃, and maintain the deposition pressure at 0.01 torr-0.05 torr before each introduction of reaction precursors A and B; (1) Pulsed zinc source: The precursor A vapor is introduced into the ALD reaction chamber under the carrying of nitrogen or argon gas and held for 10-300 seconds. The flow rate of the carrying gas, nitrogen or argon, is 5-8000 sccm. The amount of carrier gas carrying the precursor is kept equal to the amount of gas pumped by the vacuum pump. The deposition pressure is maintained at 0.01 torr-0.05 torr.

[0042] (2) Static residence: After pulsating precursor A, close the exhaust valve and residence for 10-60 seconds to allow Knudsen diffusion to achieve concentration equilibrium of precursor A inside and outside the deep pores, eliminating the preferential adsorption effect at the pore opening. After residence, slowly open the exhaust valve to evacuate to a pressure of 0.01 torr-0.05 torr.

[0043] (3) Purging: Purge the reaction chamber with nitrogen or argon to remove the remaining precursor A. The flow rate of the carrier gas, nitrogen or argon, is 5-8000 sccm.

[0044] (4) Pulsed water: Under the action of the carrier gas, the precursor B is introduced into the ALD reaction chamber and held for 10-300 seconds; the precursor B is water, hydrogen peroxide, oxygen, ozone, or atomic oxygen, and the carrier gas: nitrogen or argon has a flow rate of 5-8000 sccm. The carrier gas intake is kept equal to the vacuum pump pumping rate, and the deposition pressure is maintained at 0.01 torr-0.05 torr.

[0045] (5) Static hold: Close the inlet and outlet pump valves of the reaction chamber to maintain static pressure and ensure complete hydrolysis reaction.

[0046] (6) Purging: Purge the reaction chamber with nitrogen or argon to remove excess precursor B and byproducts.

[0047] Cyclic control: Repeat the above cycle 1-10 times. Control the number of cycles to form discrete, sub-nanometer-scale ZnO clusters (diameter less than 2 nm) on the inner walls of the mesoporous carbon pores, rather than a continuous film, to facilitate the subsequent formation of ultrafine silicon nanowires (d). NW <2nm growth provides ample catalytic sites.

[0048] As a result, this step yielded ZnO seed layer modified porous carbon with uniform distribution and controllable size inside the pores.

[0049] Step 3, confined growth Porous carbon with deposited ZnO seed layer was placed in the reaction chamber, heated to 420℃, and then SiH4 / Ar mixed gas was introduced. The temperature was then raised to 480-500℃, and silicon was induced to grow in confined space within the pores to form a one-dimensional silicon nanowire structure. The reaction lasted for about 2 hours and was then naturally cooled to room temperature under H2 / Ar atmosphere.

[0050] The first stage is alloying and anchoring at a temperature of 400-420℃.

[0051] Under Ar protection, the tube furnace was heated to 420℃ at a rate of 5℃ / min (slightly higher than the melting point of Zn, 419.5℃, considering the melting point reduction effect of nanoscale). At this temperature, a SiH4 / Ar mixed gas (SiH4 volume fraction 0.5%-2%, pressure 50 torr, duration 20-30 min) was introduced, and the following chemical reaction occurred: SiH4→Si+2H2, ZnO + H2 → Zn(g / l / s) + H2O SiH4 undergoes a thermal decomposition reaction at 420℃, reducing ZnO in situ to liquid Zn nanodroplet seeds. Si atoms dissolve into the Zn droplets to form a Zn-Si metastable alloy. In this step, the silicon source gas can also be silane (Si2H6).

[0052] Zn+SiH4→Zn-Si(Alloy) / Zn2Si(Silicide)+H2.

[0053] Silane readily decomposes on the surface of liquid Zn. The dissolution of Si atoms into liquid Zn significantly reduces the saturated vapor pressure of Zn. Combined with the strong capillary stress within the micropores, the catalytic droplets are anchored within the micropores, preventing them from volatilizing and escaping during subsequent heating.

[0054] In the second stage, VLS grows rapidly to form silicon nanowires.

[0055] The temperature was further increased to 480-500℃, maintaining a SiH4 gas flow (SiH4: 2-5%, pressure: 10-50 torr, duration: 60-120 min). Within this temperature range, the VLS growth rate induced by the catalytic decomposition of SiH4 by Zn-Si alloy droplets was significantly higher than the rate at which SiH4 decomposed on mesoporous surfaces without Zn-Si alloy to generate amorphous silicon. Silicon preferentially precipitated at the microporous Zn seed droplets, growing axially to form one-dimensional silicon nanowires that extended into the mesopores, even reaching the pore openings, while almost no amorphous silicon was deposited on the carbon walls at the pore openings. This selective catalytic growth completely avoided pore closure. The Zn droplets after the first stage of reduction are extremely small. Even if the Zn droplets aggregate at high temperatures, their maximum size is limited by the physical boundaries of the pore walls within rigid microporous carbon channels smaller than 2 nm. This fundamentally limits the diameter of the catalyzed silicon nanowires to <2 nm. This mechanism ensures that the silicon nanowires can extend smoothly within the channels without cracking the carbon framework due to excessive lateral growth. Because the grown silicon nanowires are extremely fine (1-2 nm in diameter) and exhibit one-dimensional extension rather than two-dimensional layered coverage, they have ample free space within mesopores of 3-5 nm and even macropores >10 nm. This fundamental change in geometry and growth pattern completely eliminates the pore-clogging bias caused by the rapid accumulation of amorphous silicon at the pore openings in traditional CVD processes.

[0056] In this step, the one-dimensional silicon nanostructure is a monocrystalline silicon or polycrystalline silicon nanowire / nanorobar with an aspect ratio greater than 3.

[0057] Cooling: Stop the flow of SiH4 and allow it to cool naturally to room temperature under an H2 / Ar atmosphere to prevent high-temperature oxidation.

[0058] Step 4: Functional carbon coating and in-situ pore formation.

[0059] The product from the above steps is heated again to approximately 750-800°C, and a carbon source gas (methane, ethylene, or propylene) is introduced for chemical vapor deposition (CVD) carbon coating for approximately 30-60 minutes, resulting in a carbon coating layer thickness of 1-20 nm. A dense, conductive amorphous carbon shell is formed on the outer surface of the silicon nanowires and the mesoporous carbon, constructing a continuous electron transport network. A portion of the Zn phase is retained in the silicon nanowire connection region. During the initial lithium insertion process in the battery, Zn reacts in situ with Li to form a Li-Zn intermetallic compound. The Li-Zn phase exhibits good ductility; when the silicon nanowires shrink, the ductile Li-Zn alloy on the silicon nanowires can undergo a certain degree of plastic deformation. The Li-Zn alloy can elongate along with the deformation of the silicon nanowires, preventing the formation of nanoscale or even micrometer-scale voids between the solid electrolyte and the silicon nanowires, thus solving the problem of contact failure between rigid electrolytes and silicon anodes.

[0060] At a high temperature of 750℃, some metallic Zn (boiling point 907℃, but with significantly higher vapor pressure at the nanoscale and in alloy states) remaining at the tips or gaps of silicon nanowires undergoes in-situ volatilization or sublimation due to the increased vapor pressure, escaping from the micropores or defects of the carbon shell. As a result, a nanoscale buffer cavity spontaneously forms between the tip of the silicon nanowire and the carbon shell. This cavity is an adaptive structure that traditional high-boiling-point metal seeds such as Cu and Fe cannot achieve, specifically designed to accommodate the volume expansion of silicon during charging and discharging. This cavity provides a dedicated buffer space for the volume expansion of silicon during charging and discharging, preventing the carbon framework from being broken.

[0061] Product characteristics and functional descriptions: The composite anode material obtained in this embodiment has mesopores, within which one-dimensional silicon nanowires coated with an outer carbon shell are distributed. The mesopores or their openings have cavities with increased diameters. The silicon nanowires have a diameter of <3 nm.

[0062] Interfacial chemistry function: The trace amounts of Zn or Zn-Si phase remaining in the composite anode material will react in situ with Li during the first lithium insertion process of the battery to form Li-Zn intermetallic compounds. This Li-Zn phase has excellent lithium-ion conductivity (fast ion conductor) and good ductility, and acts as a flexible interface layer in all-solid-state batteries, effectively reducing solid-solid interface impedance and buffering stress.

[0063] Example 2: Porous carbon-confined silicon nanowire anode material based on In2O3 seed layer Designed specifically for sulfide-based all-solid-state batteries, it utilizes the low melting point and excellent alloying ability of indium (In) to construct a liquid-like flexible solid-solid interface, solving the problem of contact failure between rigid electrolyte and silicon anode.

[0064] Step 1, substrate pretreatment and activation, is the same as in Example 1.

[0065] Step 2, Seed layer formation, is the same as in Example 1, except that precursor A is replaced with trimethylindium (TMI) or indium chloride (InCl3). The deposition temperature is reduced to 180°C, and the deposition pressure is maintained at 0.01 torr-0.05 torr before each introduction of reaction precursors A and B.

[0066] The process parameters are as follows: (1) Pulsed indium source: The precursor A vapor is introduced into the ALD reaction chamber under nitrogen or argon gas and held for 10-300 seconds. The flow rate of the carrier gas, nitrogen or argon, is 5-8000 sccm. The carrier gas intake is kept equal to the vacuum pump pumping rate, and the deposition pressure is maintained at 0.01 torr-0.05 torr.

[0067] (2) Static residence: After pulsating precursor A, close the exhaust valve and residence for 10-60 seconds to allow Knudsen diffusion to achieve concentration equilibrium of precursor A inside and outside the deep pores, eliminating the preferential adsorption effect at the pore opening. After residence, slowly open the exhaust valve to evacuate to a pressure of 0.01 torr-0.05 torr.

[0068] (3) Purging: Purge the reaction chamber with nitrogen or argon to remove the remaining precursor A. The flow rate of the carrier gas, nitrogen or argon, is 5-8000 sccm.

[0069] (4) Pulsed water: Under the action of the carrier gas, the precursor B is introduced into the ALD reaction chamber and held for 10-300 seconds; the precursor B is water, hydrogen peroxide, oxygen, ozone, or atomic oxygen, and the carrier gas: nitrogen or argon has a flow rate of 5-8000 sccm. The carrier gas intake is kept equal to the vacuum pump pumping rate, and the deposition pressure is maintained at 0.01 torr-0.05 torr.

[0070] (5) Static hold: Close the inlet and outlet pump valves of the reaction chamber to maintain static pressure and ensure complete hydrolysis reaction.

[0071] (6) Purging: Purge the reaction chamber with nitrogen or argon to remove excess precursor B and byproducts.

[0072] Cyclic control: Repeat the above cycle 5 times. Because indium has a large atomic radius and a low diffusion coefficient, the number of cycles is appropriately increased to ensure the formation of sufficiently dense and discretely distributed In₂O₃ clusters (diameter less than 2 nm) deep within the pores, rather than a continuous thin film, which is beneficial for the subsequent formation of ultrafine silicon nanowires (d). NW <2nm growth provides ample catalytic sites.

[0073] As a result, this step yielded a uniformly distributed and controllable In2O3 seed layer modified mesoporous carbon within the pores.

[0074] Step 3, confined growth.

[0075] Porous carbon with deposited In2O3 seed layer was placed in the reaction chamber, heated to 350℃, and then H2 / Ar mixed gas was introduced. The temperature was then raised to 450℃, and SiH4 / Ar was introduced to induce silicon to grow in confined space within the pores to form a one-dimensional silicon nanowire structure. The reaction lasted for about 1.5-2.5 hours and was then naturally cooled to room temperature under H2 / Ar atmosphere.

[0076] The first stage involves the reduction and alloying reaction of the seed layer.

[0077] Porous carbon carrying an In₂O₃ seed layer was transferred to CVD and heated to 350-400℃ under Ar protection. A H₂ / Ar mixture (H₂ volume fraction 5%-10%) was introduced as a reducing carrier gas, and In₂O₃ was rapidly reduced in situ to metallic In. Due to the low melting point of In, highly fluid liquid nanodroplets were formed at this point.

[0078] Immediately introduce silicon source gas (silane SiH4 concentration of 1%-5%, the rest is Ar, pressure: 200Pa (1.5Torr)) to form In-Si liquid alloy, and use the strong capillary stress in the micropores to anchor the catalytic droplets in the micropores.

[0079] In the second stage, VLS-directed growth forms silicon nanowires.

[0080] Continue heating to 450℃ (at this temperature, the VLS growth rate caused by the catalytic cracking of SiH4 by In-Si alloy droplets is much higher than the rate at which SiH4 cracks to generate amorphous silicon on a mesoporous surface without In-Si alloy), and continuously introduce SiH4 and Ar gas flow (SiH4 concentration: 0.2%, total pressure: 200Pa), and the reaction lasts for 1.5-2.5 hours.

[0081] Liquid In-Si droplets, confined within 3 nm mesopores, induce silicon to grow axially into one-dimensional nanowires. The high fluidity of In allows it to perfectly adapt to the pore shape, resulting in silicon wires with high crystallinity and few defects.

[0082] After the reaction is complete, cool to room temperature under an H2 / Ar atmosphere to prevent high-temperature oxidation.

[0083] Step 4: Functional carbon coating and interface retention.

[0084] The product from the above steps is heated to approximately 600°C, and a carbon source gas (methane, ethylene, or propylene) is introduced for chemical vapor deposition (CVD) carbon coating for about 20-30 minutes. A dense, conductive amorphous carbon shell is formed on the outer surface of the silicon nanowires and the outer surface of the mesoporous carbon, constructing a continuous electron transport network. Part of the In phase is retained in the silicon nanowire connection region, solving the problem of contact failure between the rigid electrolyte and the silicon anode.

[0085] While In has a high boiling point, controlling the temperature at 600℃ is crucial. Excessive temperatures at the nanoscale can exacerbate surface diffusion and Ostwald ripening of In atoms, causing fine In catalytic particles to agglomerate into larger particles, and even migrate from deep within the pores to the outer surface, disrupting the uniformly dispersed interfacial structure. Simultaneously, a suitable amount of metallic In or In-Si alloy phase is frozen and retained at the tips, roots, and contact areas with the carbon walls of the silicon nanowires. These residual phases are key precursors for subsequent construction of flexible interfaces.

[0086] Product characteristics and compatibility with solid-state batteries: The resulting composite anode material has mesopores containing one-dimensional silicon nanowires coated with an outer carbon shell. The mesopores or their openings contain cavities with increased diameters. The silicon nanowires have a diameter of <3 nm. The silicon content can be controlled between 35% and 45%.

[0087] In-situ flexible interface formation mechanism: After the negative electrode material is assembled with lithium metal (or pre-lithiation process) and sulfide electrolyte, a lithium-containing alloy phase interface layer can be formed. The residual In phase will rapidly alloy with Li to form Li-In intermetallic compounds (such as LiIn, Li2In, etc.), that is, a flexible interface is formed in situ. When the silicon nanowires shrink, the Li-In alloy with ductility on the silicon nanowires can undergo a certain degree of plastic deformation. The Li-In alloy can follow the deformation of the silicon nanowires to elongate, preventing the generation of nanoscale or even microscale gaps between the solid electrolyte and the silicon nanowires, thus solving the problem of contact failure between rigid electrolyte and silicon negative electrode.

[0088] In sulfide all-solid-state batteries, the flexible interface layer of this material helps maintain solid-solid contact, has an extremely low apparent volume expansion rate, and reduces the growth rate of interface impedance, thus significantly improving long-cycle stability.

[0089] Example 3: Porous carbon-confined silicon nanowire anode material based on SnO2 seed layer Step 1, substrate pretreatment and activation, is the same as in Example 1.

[0090] Step 2, Seed layer formation, is the same as in Example 1, except that precursor A is replaced with tetrakis(NMe2)4. The deposition temperature is reduced to 120-150°C, and the deposition pressure is maintained at 0.01 torr-0.05 torr before each introduction of reaction precursors A and B.

[0091] Process parameters: (1) Pulsed tin source: The precursor A vapor is introduced into the ALD reaction chamber under the carrying of nitrogen or argon gas and held for 10-300 seconds. The carrying gas, nitrogen or argon gas, has a flow rate of 5-8000 sccm. The carrier gas intake is kept equal to the vacuum pump pumping rate, and the deposition pressure is maintained at 0.01 torr-0.05 torr.

[0092] (2) Static dwell time: After pulse precursor A, close the exhaust valve and dwell for 10-60 seconds. Use Knudsen diffusion to achieve concentration balance of precursor A inside and outside the deep pores, eliminate the preferential adsorption effect at the pore opening. After dwell time ends, slowly open the exhaust valve to evacuate to a pressure of 0.01 torr-0.05 torr.

[0093] (3) Purging: Purge the reaction chamber with nitrogen or argon to remove the remaining precursor A. The flow rate of the carrier gas, nitrogen or argon, is 5-8000 sccm.

[0094] (4) Pulsed water: Under the action of the carrier gas, the precursor B is introduced into the ALD reaction chamber and held for 10-300 seconds; the precursor B is water, hydrogen peroxide, oxygen, ozone, or atomic oxygen, and the carrier gas: nitrogen or argon has a flow rate of 5-8000 sccm. The carrier gas intake is kept equal to the vacuum pump pumping rate, and the deposition pressure is maintained at 0.01 torr-0.05 torr.

[0095] (5) Static hold: Close the inlet and outlet pump valves of the reaction chamber to maintain static pressure and ensure complete hydrolysis reaction.

[0096] (6) Purging: Purge the reaction chamber with nitrogen or argon to remove excess precursor B and byproducts.

[0097] Cyclic control: Repeat the above cycle 3-8 times. Ensure sufficient density and discrete distribution of SnO2 clusters (diameter less than 2 nm) are formed deep within the pores, rather than a continuous thin film, to facilitate the subsequent formation of ultrafine silicon nanowires (d). NW <2nm growth provides ample catalytic sites.

[0098] As a result, this step yielded SnO2 seed layer modified porous carbon with uniform distribution and controllable size inside the pores.

[0099] Step 3: Confined growth (low-temperature catalytic induction).

[0100] Porous carbon with a SnO2 seed layer was placed in a reaction chamber and heated to 300°C. Then, an H2 / Ar mixed gas was introduced, and the temperature was further increased to 450°C. SiH4 / Ar was introduced, and silicon was induced to grow in confined space within the pores to form a one-dimensional silicon nanowire structure. The reaction lasted for about 1.5-2.5 hours and was then naturally cooled to room temperature under an H2 / Ar atmosphere.

[0101] The first stage involves the reduction and alloying reaction of the seed layer.

[0102] Mesoporous carbon carrying a SnO2 seed layer was transferred to CVD and heated to 300-350℃ (above the melting point of Sn, 232℃) under Ar protection. A H2 / Ar mixture (5%-10% H2 volume fraction) was introduced as a reducing carrier gas, and SnO2 was rapidly reduced in situ to metallic Sn. Due to the low melting point of In, highly fluid liquid nanodroplets were formed at this point.

[0103] A low partial pressure silicon source gas (silane SiH4 concentration of 1%-5%, the remainder being Ar) is immediately introduced to form a Sn-Si liquid alloy. The strong capillary stress within the micropores is used to anchor the catalytic droplets within the micropores.

[0104] In the second stage, VLS-directed growth is used to form silicon nanowires.

[0105] Continue heating to 400-450℃ (at this temperature, the VLS rate is extremely fast, while the VS thermal decomposition is extremely slow, resulting in significant kinetic selectivity), and continuously introduce SiH4 and H2 gas streams for 1.5-2.5 hours.

[0106] Liquid Sn-Si droplets, confined within 3 nm mesopores, induce silicon to grow axially into one-dimensional nanowires. Some Sn dissolves in the silicon wires or remains at the interface, forming a Si-Sn nanocomposite structure.

[0107] After the reaction is complete, cool to room temperature under an H2 / Ar atmosphere to prevent high-temperature oxidation.

[0108] Step 4: Functional carbon coating.

[0109] The product from the above steps is heated to approximately 600-650°C, and a carbon source gas (acetylene or ethylene) is introduced for chemical vapor deposition (CVD) carbon coating for about 20-30 minutes. A dense, conductive amorphous carbon shell is formed on the outer surface of the silicon nanowires and the outer surface of the mesoporous carbon, constructing a continuous electron transport network. Part of the Sn phase is retained in the silicon nanowire connection region, solving the problem of contact failure between the rigid electrolyte and the silicon anode.

[0110] The temperature is controlled below 650℃ to prevent severe Ostwald ripening (agglomeration) of Sn particles. While forming a conductive carbon shell, appropriate amounts of metallic Sn or Sn-Si alloy phase are retained at the roots, tips, and interfaces of the silicon nanowires. These residual phases are the source of subsequent self-healing functionality.

[0111] Product characteristics and compatibility with solid-state batteries: The resulting composite anode material has mesopores containing one-dimensional silicon nanowires coated with an outer carbon shell. The mesopores or their openings contain cavities with increased diameters. The silicon nanowires have a diameter of <3 nm. The silicon content can be controlled between 35% and 45%.

[0112] In-situ self-healing interface: During the initial lithium insertion, the residual Sn phase transforms into a Li-Sn alloy (such as Li7Sn2, Li...). 13 (e.g., Sn5). The Li-Sn phase exhibits high ionic / electronic conductivity and good plasticity / rheology at temperatures ranging from room temperature to 60°C. When silicon nanowires undergo volume shrinkage and generate microcracks, the plastic Li-Sn phase can flow and elongate, preventing voids, restoring electrical contact, achieving in-situ self-healing, significantly improving conductivity and interface stability, and effectively extending the cycle life of all-solid-state batteries.

[0113] Application advantages: It is particularly suitable for all-solid-state battery systems with extremely high requirements for rate performance and long-cycle stability.

[0114] Example 4: Preparation of mesoporous carbon-confined silicon nanowire anode material based on Ga2O3 seed layer Step 1, substrate pretreatment and activation, is the same as in Example 1.

[0115] Step 2, Seed layer formation, is the same as in Example 1, except that precursor A is replaced with tetradimethylgallium (TMGa) or triethylgallium (TEGa). The deposition temperature is reduced to 150-180°C, and the deposition pressure is maintained at 0.01 torr-0.05 torr before each introduction of reaction precursors A and B.

[0116] Process parameters: (1) Pulsed gallium source: The precursor A vapor is introduced into the ALD reaction chamber under nitrogen or argon gas and held for 10-300 seconds. The flow rate of the carrier gas, nitrogen or argon, is 5-8000 sccm. The carrier gas intake is kept equal to the vacuum pump pumping rate, and the deposition pressure is maintained at 0.01 torr-0.05 torr.

[0117] (2) Static residence: After pulsating precursor A, close the exhaust valve and residence for 10-60 seconds to allow Knudsen diffusion to achieve concentration equilibrium of precursor A inside and outside the deep pores, eliminating the preferential adsorption effect at the pore opening. After residence, slowly open the exhaust valve to evacuate to a pressure of 0.01 torr-0.05 torr.

[0118] (3) Purging: Purge the reaction chamber with nitrogen or argon to remove the remaining precursor A. The flow rate of the carrier gas, nitrogen or argon, is 5-8000 sccm.

[0119] (4) Pulsed water: Under the action of the carrier gas, the precursor B is introduced into the ALD reaction chamber and held for 10-300 seconds; the precursor B is water, hydrogen peroxide, oxygen, ozone, or atomic oxygen, and the carrier gas: nitrogen or argon has a flow rate of 5-8000 sccm. The carrier gas intake is kept equal to the vacuum pump pumping rate, and the deposition pressure is maintained at 0.01 torr-0.05 torr.

[0120] (5) Static hold: Close the inlet and outlet pump valves of the reaction chamber to maintain static pressure and ensure complete hydrolysis reaction.

[0121] (6) Purging: Purge the reaction chamber with nitrogen or argon to remove excess precursor B and byproducts.

[0122] Cyclic control: Repeat the above cycle 1-10 times. Ensure the formation of sufficiently dense and discretely distributed Ga2O3 clusters (diameter less than 2 nm) deep within the pores, rather than a continuous thin film, to facilitate the subsequent formation of ultrafine silicon nanowires (d). NW <2nm growth provides ample catalytic sites.

[0123] As a result, this step yielded Ga2O3 seed layer modified mesoporous carbon with uniform distribution and controllable size inside the pores.

[0124] Step 3: Confined growth (low-temperature catalytic induction).

[0125] Porous carbon with a Ga2O3 seed layer was placed in a reaction chamber and heated to 250°C. Then, an H2 / Ar mixed gas was introduced, and the temperature was further increased to 350°C. SiH4 / Ar was introduced, and silicon was induced to grow in confined space within the pores to form a one-dimensional silicon nanowire structure. The reaction lasted for about 1-2 hours and was then naturally cooled to room temperature under an H2 / Ar atmosphere.

[0126] The first stage involves the reduction and alloying reaction of the seed layer.

[0127] Mesoporous carbon carrying a Ga2O3 seed layer was transferred to CVD at a heating rate of 5℃ / min, and heated to 250-300℃ (above the melting point of Ga, 29.8℃) under Ar protection for approximately 50 min. A H2 / Ar mixture (H2 volume fraction 5%-10%) was then introduced as a reducing carrier gas, and Ga2O3 was rapidly reduced in situ to metallic Ga. Due to the low melting point of Ga2O3, highly fluid liquid nanodroplets were formed at this point.

[0128] A low partial pressure silicon source gas (silane SiH4 concentration of 1%-5%, the remainder being Ar) is immediately introduced to form a Ga-Si liquid alloy. The strong capillary stress within the micropores is used to anchor the catalytic droplets within the micropores.

[0129] In the second stage, VLS-directed growth forms silicon nanowires.

[0130] Maintain the temperature at 300-350℃ (at this temperature, the VLS growth rate caused by the catalytic decomposition of SiH4 by Ga-Si alloy droplets is much higher than the rate at which SiH4 decomposes on the mesoporous surface without Ga-Si alloy to generate amorphous silicon), and continuously introduce SiH4 and H2 gas streams for 1-2 hours.

[0131] Liquid Ga exhibits extremely high catalytic activity for the decomposition of silanes, rapidly growing highly crystalline one-dimensional silicon nanowires within mesoporous confinement. Due to Ga's high fluidity, the droplets perfectly adapt to the pore morphology, ensuring continuous and uniform growth of silicon nanowires along the pore direction.

[0132] After the reaction is complete, cool to room temperature under an H2 / Ar atmosphere to prevent high-temperature oxidation.

[0133] Step 4: Functional carbon coating.

[0134] The product from the above steps is heated to approximately 500-550°C, and a carbon source gas (acetylene or ethylene) is introduced to perform chemical vapor deposition (CVD) carbon coating for approximately 20-30 minutes. A dense, conductive amorphous carbon shell is formed on the outer surface of the silicon nanowires and the outer surface of the mesoporous carbon, constructing a continuous electron transport network. Part of the Ga phase is retained in the silicon nanowire connection region, solving the problem of contact failure between the rigid electrolyte and the silicon anode.

[0135] Although Ga has a high boiling point, high temperatures at the nanoscale can exacerbate the surface migration and aggregation of Ga atoms, leading to the agglomeration and growth of Ga particles, and even causing them to seep out from the nanopores, disrupting the uniformly dispersed interfacial structure. Therefore, the temperature needs to be strictly controlled below 550℃. A thin and tough carbon shell is formed on the surface of silicon nanowires and mesoporous carbon frameworks, encapsulating the liquid / semi-liquid Ga-Si alloy phase between the silicon wires and the carbon framework. This prevents aggregation before assembly while maintaining its fluidity.

[0136] Product characteristics and compatibility with solid-state batteries: The resulting composite anode material has mesopores containing one-dimensional silicon nanowires coated with an outer carbon shell. The mesopores or their openings contain cavities with increased diameters. The silicon nanowires have a diameter of <3 nm. The silicon content can be controlled between 35% and 45%.

[0137] The room-temperature liquid interface layer occurs after the battery is assembled and a lithium source is injected. The remaining Ga phase then forms a Li-Ga alloy with Li. Due to Ga's low melting point, the Li-Ga alloy often exists in a liquid or semi-liquid (paste-like) state at the battery's operating temperature (or even room temperature). During the dramatic volume expansion / contraction of the silicon anode, this liquid layer can flow and deform freely, maintaining physical contact and completely eliminating contact separation caused by volume changes. The Li-Ga alloy is an excellent ion / electron hybrid conductor, significantly reducing interfacial charge transfer resistance.

[0138] Therefore, when this anode material comes into contact with lithium, it can form a flexible interface layer containing lithium alloy phase, which helps to alleviate solid-solid interface contact changes and suppress impedance growth.

[0139] Comparative Example 1: Porous carbon composite material with direct thermal decomposition deposition of silicon without seed layer This comparative example prepares a negative electrode material without a seed layer through direct deposition, used to verify the decisive role of the ALD seed layer in inducing the growth of one-dimensional silicon nanowires within porous carbon channels, preventing pore blockage, and constructing a continuous conductive network. This comparative example simulates the traditional CVD direct deposition process.

[0140] Step 1, substrate preparation, same as in Example 1.

[0141] Step 2: Direct silicon deposition. The porous carbon material described above is placed in a CVD reactor, Ar carrier gas is introduced, the temperature is raised to 500°C, and SiH4 (silane concentration 1%-5%, the remainder is argon) is introduced. No hydrogen reducing gas is added, and the reaction continues for 2 hours. The silicon flow rate is controlled in the same way as in Example 1 to make the silicon loading similar to that obtained in Example 1.

[0142] Due to the lack of low activation energy catalytic centers, silanes mainly rely on high-temperature thermal decomposition (VS mechanism) for reaction. Due to diffusion limitations, the concentration of silane molecules is highest at the pore opening, and they preferentially nucleate and accumulate rapidly on the outer surface and at the pore opening.

[0143] Step 3: Carbon coating, same as in Example 1.

[0144] The temperature is raised to 750℃, and acetylene is introduced to perform carbon coating for approximately 30-60 minutes. This process involves encapsulating the deposited silicon particles with an external carbon layer. The final product is a seed-layer-free silicon / carbon composite material.

[0145] The materials in this comparative example exhibit significant defects in both microstructure and electrochemical performance, as detailed below: 1. The microstructure has obvious defects. When the pore openings are blocked, and without a uniformly distributed ALD seed layer, the thermal decomposition reaction of SiH4 is diffusion-controlled. It takes time for silane molecules to enter the mesoporous channels, while the concentration and contact probability are highest at the outer surface and pore openings. For example... Figure 1 As shown, silicon preferentially nucleates and grows rapidly on the outer surface and pores of mesoporous carbon, forming a dense silicon shell or large particle aggregates.

[0146] The hollow interior of the mesoporous carbon quickly seals the pores, blocking the diffusion path of silane gas into the deeper channels, ultimately forming a "thick outside, hollow inside" structure. The outer surface is covered with a thick amorphous silicon layer, while most of the pores inside the mesoporous carbon remain empty, or have only a very small amount of silicon deposited. The high specific surface area advantage of the mesoporous carbon is completely unutilized.

[0147] Disordered stacking and lack of one-dimensional interconnected structures. Due to the absence of uniformly dispersed liquid / solid catalytic active centers within the pores, silicon cannot undergo VLS / VSS directional growth. The deposited silicon is in the form of amorphous particles or discontinuous films, randomly stacked at the pore openings and on the outer surface, causing pore blockage, insufficient silicon loading deep within the pores, and difficulty in forming axially continuous one-dimensional interconnected structures within the pores. These particles lack one-dimensional physical connections and electronic pathways like "nanowires" between themselves and between particles and the carbon framework.

[0148] 2. Electrochemical performance failure, interface degradation, and increased impedance.

[0149] Solid-solid contact failure. During charging and discharging, the large amorphous silicon on the outer surface undergoes huge isotropic volume expansion. Due to the lack of mesoporous channels to confine and restrain the silicon particles, they are easily pulverized and broken, and separate from the surrounding solid electrolyte particles. The physical contact area between the active material and the electrolyte decreases, resulting in rapid capacity decay.

[0150] Interfacial side reactions and impedance growth. The disordered stacking of silicon on the outer surface has an extremely high specific surface area (relative to nanowires) and numerous surface defects, making it prone to continuous chemical side reactions with the solid electrolyte (especially sulfides), generating a high-resistivity interfacial layer. Due to structural pulverization and the continuous exposure of new surfaces, side reactions continue, leading to an exponential increase in the battery's internal resistance with the number of cycles. EIS testing shows that after 10 cycles, the charge transfer impedance (Rct) increases exponentially (more than 10 times), indicating complete destruction of the solid-solid contact.

[0151] Capacity decay: Low capacity in the first week (due to low payload), capacity retention rate <50% after 50 cycles, leading to rapid failure.

[0152] Performance test results and analysis of all-solid-state batteries.

[0153] 1. Experimental setup Battery configuration: coin cell solid-state battery.

[0154] Positive electrode: From top to bottom, it includes a high-nickel ternary material (NCM811) layer, a sulfide solid electrolyte (Li6PS5Cl, LPSCl) sheet, and a conductive carbon composite cathode (capacity ~3.0 mAh / cm³). 2 ).

[0155] Electrolyte layer: Pure Li6PS5Cl cold-pressed sheet (thickness ~60μm, density ~1.6g / cm³) 3 ).

[0156] Negative electrode: The sample to be tested (Example 1 / Example 2 / Comparative Example 1) was mixed with a small amount of LPSCl and coated onto copper foil (area capacity matching positive electrode, N / P ratio ~1.1).

[0157] Current collector: positive electrode aluminum foil, negative electrode copper foil.

[0158] 2. Test conditions Stack Pressure: 10MPa (simulating the actual working conditions of a pouch cell, where solid-state interface contact is particularly critical under this pressure).

[0159] Temperature: 25°C.

[0160] Voltage window: 2.5V-4.3V (vs. Li / Li) + ).

[0161] Ratio: 0.1C~2C (1C = theoretical capacity current).

[0162] 3. Test Items (1) Long cycle performance: 0.5C charge-discharge cycle 1~80 cycles, capacity retention rate was recorded, and the results are as follows: Figure 2 and Figure 4 .

[0163] (2) Electrochemical impedance spectroscopy (EIS): Tests were performed after assembly (Initial), after 10 cycles, and after 50 cycles, with a frequency range of 0.1 Hz to 1 MHz. The results are as follows: Figure 3 .

[0164] (3) Evaluate the battery under constant current charging at different charge / discharge current densities (0.1C, 0.2C, 0.5C, 1C, 2C rates), followed by 5 charge / discharge cycles. Record the discharge specific capacity for each cycle. The results are as follows: Figure 5 .

[0165] Electrode thickness expansion rate: The change in electrode thickness before and after the cycle is measured using a micrometer or in-situ thickness gauge.

[0166] The discharge specific capacity and retention rate of the three materials after 50 cycles at 0.5C are shown in the table below: Table 1 Comparison of Long-Cycle Stability By fitting the mid-frequency semicircle in the Nyquist plot, the change in charge transfer impedance (Rct, which mainly reflects the characteristics of the negative electrode / electrolyte interface) was obtained. This is shown in Table 2 below.

[0167] Table 2. Changes in interfacial charge transfer impedance during cycling for each sample / (Rct / Ω) The thickness change rate (relative to the initial compaction thickness) of the negative electrode sheet was measured in the fully charged state (100% SOC). The results are shown in Table 3 below.

[0168] Table 3 From the above test results, we can conclude that: Examples 1-4 utilize ALD to form discrete seed layers of ZnO / In2O3 / SnO2 / Ga2O3 deep within the pores, enabling preferential, uniform, and one-dimensional silicon growth within the pores via the VLS mechanism. The silicon nanowires have a diameter <3nm, without pore blockage or agglomeration. Comparative Example 1 lacks a seed layer; silicon rapidly accumulates at the pore openings and outer surfaces solely through VS thermal decomposition, forming a dense silicon shell. The pore interior is almost devoid of silicon, resulting in an ineffective "thick outside, hollow inside" structure. Figure 1 and 2 As shown.

[0169] The anode material in Example 1 maintained a capacity retention of 89.1% after 50 cycles, Example 2 reached 90.1%, and Examples 3 and 4 also maintained above 85%, with a coulombic efficiency stable at 99.3%-99.4%. In contrast, Comparative Example 1 only achieved 55.6%, experiencing a rapid decline in efficiency during the later stages of cycling. This is because the silicon in Examples 1-4 was one-dimensional crystalline nanowires, which have a stable structure and are not easily pulverized; the comparative example used amorphous silicon particles, which expanded and broke during charge and discharge, leading to rapid failure of the active material.

[0170] Initial impedance test data showed that Example 1 had an impedance of 45.2Ω, Example 2 had an impedance of 40.3Ω, and Comparative Example 1 had an impedance as high as 110.6Ω. After 50 cycles: Example 1 had an impedance of only 72.3Ω, Example 2 had an impedance of 65.1Ω, showing a slow increase; Comparative Example 1 surged to 780.9Ω, an increase of more than 10 times. This is because Example 1 has a built-in nano-buffer cavity, and Examples 2-4 respectively formed a Li-In flexible interface, a Li-Sn self-healing interface, and a Li-Ga room temperature liquid interface, maintaining good solid-solid contact. In contrast, the comparative example showed silicon particle pulverization, interface separation, violent side reactions, and uncontrolled impedance.

[0171] Example 1 showed a thickness expansion of 20.5% with a recovery rate of 96.3%; Example 2 showed an expansion of only 15.6% with a recovery rate of 97.1%; Comparative Example 1 showed an expansion as high as 88.8% with a recovery rate of only 67.9%, resulting in severe electrode bulging and carbon shell cracking. This is because the silicon nanowires in Examples 1-4 were doubly constrained by a mesoporous carbon framework and carbon shell, with Example 1 providing additional nanocavities to buffer the expansion; the silicon nanodots in the comparative example expanded freely on the surface without constraint or buffering, leading to complete structural collapse.

[0172] In summary, Examples 1-4, through the synergistic effect of confined growth of silicon nanowires within pores, nano-buffer cavities (Example 1), and in-situ flexible / self-healing / liquid interfaces (Examples 2-4), comprehensively outperform Comparative Example 1 in terms of 50-week capacity retention, interface impedance growth, and electrode expansion rate. They fundamentally solve the three major problems of solid-solid contact failure, uncontrolled volume expansion, and dramatic increase in interface impedance in silicon anodes of sulfide all-solid-state batteries, fully demonstrating the significant progress and superior effects of the technical solution of this invention.

Claims

1. A continuous silicon nanowire anode material based on ALD seed layer-induced mesoporous confinement, characterized in that, include: Mesoporous carbon framework with interconnected mesoporous channels, the average pore size of which is 2-50 nm and the pore volume is 0.5-2.5 cm³. 3 / g; A one-dimensional silicon nanostructure is located inside the mesoporous channels and extends along the axial direction of the mesoporous channels; Nanoscale metal particles are distributed between the one-dimensional silicon nanostructure and the inner wall of the mesoporous channel, and / or distributed at the ends of the one-dimensional silicon nanostructure; the nanoscale metal particles contain a metal element M or its silicide, wherein the metal element M is selected from at least one of Zn, Sn, In, Ga, Cd, Bi, and Pb; And an outer carbon coating layer, which at least continuously covers the outer surface of the one-dimensional silicon nanostructure.

2. The negative electrode material according to claim 1, characterized in that, The mesoporous channels have nanoscale buffer cavities at their openings; the metal element M in the nano-metal particles is Zn.

3. The negative electrode material according to claim 2, characterized in that, The diameter of the one-dimensional silicon nanostructure is less than or equal to the average pore size of the mesoporous channel, with a diameter of 1-10 nm. The one-dimensional silicon nanostructure is a single-crystal silicon or polycrystalline silicon nanowire / nanorobar with an aspect ratio greater than 3.

4. The negative electrode material according to claim 1, characterized in that, The outer carbon coating layer is an amorphous carbon or microcrystalline carbon layer with a thickness of 2-20 nm.

5. The negative electrode material according to claim 1, characterized in that, The silicon content in the negative electrode material is 10%-80% by mass.

6. An all-solid-state battery, characterized in that, It includes a positive electrode, a solid electrolyte layer, and a negative electrode; the negative electrode adopts the negative electrode material as described in any one of claims 1-5, and the metal element M in the nano-metal particles is selected from at least one of Zn, In, Sn, and Ga; the nano-metal particles form a LixM alloy phase with lithium, and the LixM alloy phase exhibits a plastic state or a liquid state at the battery operating temperature.

7. A method for preparing a mesoporously confined continuous silicon nanowire anode material as described in any one of claims 1-5, characterized in that, Includes the following steps: Step S1: Activate the substrate by providing a mesoporous carbon framework and subjecting it to an oxidative heat treatment to introduce oxygen-containing functional groups into the inner wall of the pores of the mesoporous carbon framework. Step S2: Seed layer deposition. Using atomic layer deposition (ALD) technology, the pressure is maintained at a vacuum during ALD. Metal source precursors and oxygen source precursors are introduced into the mesoporous channels of the mesoporous carbon framework in an alternating pulsed manner, reacting to form discretely distributed metal oxide nanoclusters as the seed layer. The metal element in the metal oxide contains at least one metal element M selected from Zn, In, Sn, Ga, Cd, Bi, and Pb. The average particle size of the metal oxide nanoclusters is less than 2 nm. Step S3, confined growth: The product obtained in step S2 is placed in a chemical vapor deposition reactor. First, the metal oxide is reduced to a metallic state in the first temperature range and metal droplets are formed in situ. Then, the precursor containing silicon-hydrogen bonds is cleaved in the second temperature range, so that free silicon and metal droplets form an alloy phase. Silicon grows axially inside the channel to form a one-dimensional silicon nanostructure. Step S4, carbon coating: In an inert or reducing atmosphere, a carbon source gas is introduced, and chemical vapor deposition is performed in the third temperature range to continuously cover at least the outer surface of the one-dimensional silicon nanostructure with an outer carbon coating layer.

8. The preparation method according to claim 7, characterized in that: In step S3, the first temperature range and the second temperature range are adjusted according to the type of the metal element M: When the metal element M is a highly volatile metal: Zn or Cd, the first temperature range is 380-420℃, and the second temperature range is 480-520℃. When the metal element M is a low-melting-point metal: In, Sn, Ga, Bi, Pb, the first temperature range is 250-380℃, and the second temperature range is 380-460℃. In step S3, the total pressure of the reaction system is controlled at 10-100 Pa.

9. The preparation method according to claim 8, characterized in that: In step S3, when the metal element M is Zn, the first temperature range is 400-420℃ and the second temperature range is 480-500℃. In step S4, the third temperature range is 700-850℃, so that some of the metal element Zn volatilizes in situ, forming a nanoscale buffer cavity in the mesoporous channels at the end of the one-dimensional silicon nanostructure.

10. The preparation method according to claim 8, characterized in that: In step S3, when the metal element M is selected from at least one of In, Sn, and Ga, the first temperature range is 300-380℃ and the second temperature range is 400-450℃; in step S4, the third temperature range is controlled at 500-650℃ to suppress the ripening of the metal element M nanodroplets and lock the metal element M or its silicide at the interface or end of the one-dimensional silicon nanostructure.

11. The preparation method according to claim 8, characterized in that: In step S3, the silicon-hydrogen bond-containing precursor is one of silane and disilane, and its volume fraction in the carrier gas is 1%-5%; in step S4, the carbon source gas is selected from at least one of acetylene, ethylene or propylene; the thickness of the outer carbon coating layer is 1-20 nm.

12. An all-solid-state battery, characterized in that, It includes a positive electrode, a solid electrolyte layer, and a negative electrode; the negative electrode is prepared by the preparation method according to any one of claims 7-11.

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