Micron silicon composite material for all-solid-state battery as well as preparation method and application of micron silicon composite material

Abstract

The invention belongs to the field of new material preparation and electrochemical energy storage, and particularly relates to a micron silicon composite material for an all-solid-state battery and a preparation method and application of the micron silicon composite material. The electronic conductor and the micron silicon are calcined to form a conductive framework, then the conductive framework is compounded with the ionic conductor, the electronic / ionic conductivity is synergistically improved, specifically, the electronic conductivity is improved by doping the electronic conductor, and an effective buffer layer is provided for volume expansion of the micron silicon material; the doped ion conductor effectively reduces the diffusion barrier of lithium ions, promotes the rapid transmission of the lithium ions, improves the interface contact between the silicon negative electrode and the electrolyte, reduces the interface resistance, enables the lithium ions to be uniformly embedded, and obtains a stable SEI layer. The fast ion-electron conductor doping method balances the electron conductivity and ion transmission, when the obtained composite material is used as a negative electrode, the discharge capacity of an all-solid-state battery under 10C multiplying power reaches 97.9 mAh / g, the 200-time cycle capacity retention rate is 82.5%, the composite material is obviously superior to a traditional silicon-based negative electrode, and the composite material has a wide application prospect.

Description

Technical Field

[0001] The present invention belongs to the fields of new material preparation and electrochemical energy storage, and particularly relates to a micron silicon composite material for all-solid-state batteries, a preparation method thereof, and an application thereof. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and it is not necessarily regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] The all-solid-state battery system has become a key research direction for next-generation energy storage technologies due to its advantages of high energy density and safety compared to liquid systems. Selecting a suitable anode material is the key to improving the performance of solid-state batteries.

[0004] Silicon is an ideal anode material for solid-state batteries because of its extremely high theoretical capacity (4200 mAh g -1 ) and low cost. However, different from the pulverization phenomenon that occurs due to large volume changes of silicon in liquid electrolytes, the following problems exist in the lithium insertion process of silicon in the all-solid-state battery system:

[0005] (1) Volume expansion occurs (about 300%);

[0006] (2) Poor conductivity: Silicon itself has poor conductivity, and the electron and ion transport are slow, which intensifies the battery polarization and affects the rate performance and cycle stability;

[0007] (3) High interfacial impedance;

[0008] (4) Caking occurs during de-lithiation, resulting in large stress changes, which in turn lead to the failure of the original three-phase interface. In the prior art, directly adding a sulfide electrolyte to the silicon anode for all-solid-state batteries to improve its ionic conductivity and introducing a carbon-based conductive agent to enhance conductivity, but there is an incompatible phenomenon that the carbon-based conductive agent induces the decomposition of the sulfide electrolyte, resulting in poor cycle performance. Therefore, there is an urgent need for a silicon-based composite material that can synergistically improve the ionic / electronic conductivity and relieve volume expansion. Summary of the Invention

[0009] Aiming at the above existing problems, the purpose of the present invention is to provide a micron silicon composite material for all-solid-state batteries, a preparation method thereof, and an application thereof. The novel composite material prepared by the present invention introduces an electron conductor and an ion conductor. This doping method can balance the electron conductivity and ion transport, form a synergistic effect, effectively relieve the interface failure problem caused by volume expansion and contraction during the charge and discharge process of the silicon anode material, and improve the ionic and electronic conductivity. ，Effectively improves the rate performance and cycling performance of silicon anode solid-state batteries, and also considers the compatibility issues of ion conductors and carbon-based electronic conductors.

[0010] Specifically, the present invention provides the following technical solutions:

[0011] In the first aspect of the present invention, a micron-sized silicon composite material for all-solid-state batteries is provided. The micron-sized silicon composite material for all-solid-state batteries includes a porous conductive network structure formed by a micron-sized silicon matrix and an electronic conductor material, and a fast ion conductor material uniformly distributed in the porous conductive network;

[0012] The particle size of the micron-sized silicon matrix is 0.5 - 30 μm;

[0013] The electronic conductor material is selected from one or more of graphene, graphite, carbon nanotubes, vapor-grown carbon fibers, and acetylene black, and accounts for 0.5 - 10 wt% of the total mass of the micron-sized silicon composite material for all-solid-state batteries;

[0014] The fast ion conductor material is selected from one or more of lithium lanthanum zirconium tantalum oxide (Li 6.5 La3Zr 1.5 Ta 0.5 O 12 ), lithium aluminum titanium phosphate (Li 1.4 Al 0.4 Ti 1.6 (PO4)3), β-Li3N, lithium zirconium phosphate (LiZr2(PO4)3), and lithium phosphate (Li3PO4), and accounts for 5 - 30 wt% of the total mass of the micron-sized silicon composite material for all-solid-state batteries.

[0015] Preferably, the porous conductive network structure has a lamellar morphology, its porosity is 18.1 - 22.5%, and its specific surface area is 14.7 - 19.8 m 2 / g.

[0016] Preferably, the ionic conductivity is (0.982 - 1.56)×10 -4 S cm -1 , and the electronic conductivity is 0.1 - 0.135 mS cm -1 .

[0017] In the second aspect of the present invention, a preparation method of the above-mentioned micron-sized silicon composite material for all-solid-state batteries is provided, including the following steps:

[0018] S1. Mix the micron-sized silicon matrix and the electronic conductor material, ball mill and then calcine to obtain a μSi@G precursor;

[0019] S2. Mix and ball-mill the μSi@G precursor obtained in step S1 with an ionic conductor material to obtain a μSi@G-LLZTO composite material.

[0020] Preferably, in step S1, the mass ratio of the micron silicon matrix to the electronic conductor material is 99.5:0.5 to 90:10.

[0021] Preferably, in step S1, the calcination is carried out by heating to 750 - 850 °C at a heating rate of 3 - 5 °C / min, and the calcination time is 3 - 5 h.

[0022] Preferably, in step S2, the mass ratio of the μSi@G precursor to the ionic conductor material is 95:5 to 70:30.

[0023] In the third aspect of the present invention, there is provided an application of the micron silicon composite material for all-solid-state batteries described in the first aspect in the negative electrode of an all-solid-state battery.

[0024] In the fourth aspect of the present invention, there is provided an all-solid-state battery, the negative electrode of which uses the micron silicon composite material for all-solid-state batteries described in the first aspect.

[0025] Preferably, the electrolyte of the all-solid-state battery is a sulfide or oxide solid electrolyte; more preferably, the electrolyte of the all-solid-state battery is Li6PS5Cl, LLZTO or Li3PO4.

[0026] Preferably, the positive electrode of the all-solid-state battery uses lithium cobaltate, lithium iron phosphate or a ternary material.

[0027] In the fifth aspect of the present invention, there is provided an application of the micron silicon composite material for all-solid-state batteries described in the first aspect in the field of electrochemical energy storage.

[0028] One or more embodiments of the present invention have at least the following beneficial effects:

[0029] (1) The present invention uses a fast ion - electron conductor doping method. Among them, doping an ionic conductor such as LLZTO effectively reduces the diffusion barrier of lithium ions, promotes the rapid transport of lithium ions, and at the same time improves the interfacial contact between the silicon negative electrode and the electrolyte, reduces the interfacial resistance, enables lithium ions to be uniformly embedded and extracted, and obtains a stable solid electrolyte interface (SEI) layer;

[0030] Doping an electronic conductor such as graphene with a lamellar structure provides an effective buffer layer for the volume expansion of the micron silicon material, and at the same time improves the conductivity of the material. The modification method of the fast ion - electron conductor can balance the electronic conductivity and ion transport, and improve the comprehensive electrochemical performance of the silicon-based negative electrode material.

[0031] (2) The fast ion-electron conductor modified micron silicon composite material of the present invention can provide guidance for doping various suitable materials. Meanwhile, the preparation process is simple, the manufacturing cost is low, and it has good practical application prospects.

[0032] (3) Experiments show that the fast ion-electron conductor modified micron silicon composite material prepared by the present invention as the anode material of all-solid-state batteries has excellent rate performance and cycle stability. The discharge specific capacity of the composite material reaches 97.9 mAh / g at a rate of 10C, and the capacity retention rate after 200 cycles is 82.5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0034] Figure 1 SEM of the micron silicon composite material for all-solid-state batteries prepared in Example 1 of the present invention;

[0035] Figure 2 Measurement of the electronic conductivity of μSi@G-LLZTO prepared in Example 1 of the present invention in Test Example 1 of the present invention (current-time polarization test);

[0036] Figure 3 Data graph of Battery 1 for testing the ionic conductivity of μSi@G-LLZTO prepared in Example 1 of the present invention in Test Example 1 of the present invention;

[0037] Figure 4 Data graph of Battery 2 for testing the ionic conductivity of μSi@G-LLZTO prepared in Example 1 of the present invention in Test Example 1 of the present invention;

[0038] Figure 5 Rate performance test graph of the micron silicon composite material for all-solid-state batteries prepared in Example 1 of the present invention as the anode material of all-solid-state batteries;

[0039] Figure 6 Cycle performance test graph of the micron silicon composite material for all-solid-state batteries prepared in Example 1 of the present invention as the anode material of all-solid-state batteries. DETAILED DESCRIPTION OF THE INVENTION

[0040] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0041] Aiming at the problems of volume expansion and poor electrochemical performance of silicon-based materials, the present invention provides a preparation method and application of a fast ion-electron conductor modified micron silicon composite material for all-solid-state batteries.

[0042] In a first typical embodiment of the present invention, a micron silicon composite material for all-solid-state batteries is provided. The micron silicon composite material for all-solid-state batteries includes a porous conductive network structure formed by a micron silicon matrix and an electronic conductor material, and a fast ion conductor material uniformly distributed in the porous conductive network;

[0043] The particle size of the micron silicon matrix is 0.5 - 30 μm;

[0044] The electronic conductor material is selected from one or more of graphene, graphite, carbon nanotubes, vapor-grown carbon fibers, and acetylene black, accounting for 0.5 - 10 wt% of the total mass of the micron silicon composite material for all-solid-state batteries;

[0045] The fast ion conductor material is selected from one or more of lithium lanthanum zirconium tantalum oxide (Li 6.5 La3Zr 1.5 Ta 0.5 O 12 ), lithium aluminum titanium phosphate (Li 1.4 Al 0.4 Ti 1.6 (PO4)3), β-Li3N, lithium zirconium phosphate (LiZr2(PO4)3), and lithium phosphate (Li3PO4), accounting for 5 - 30 wt% of the total mass of the micron silicon composite material for all-solid-state batteries.

[0046] In one or more embodiments of this embodiment, the porous conductive network structure has a lamellar morphology, its porosity is 18.1 - 22.5%, and its specific surface area is 14.7 - 19.8 m 2 / g.

[0047] In a second typical embodiment of the present invention, a preparation method of the above-mentioned micron silicon composite material for all-solid-state batteries is provided, including the following steps:

[0048] S1. Mix the micron silicon matrix and the electronic conductor material, ball mill and then calcine to obtain a μSi@G precursor;

[0049] S2. Mix the μSi@G precursor obtained in step S1 with the ion conductor material and ball mill to obtain a μSi@G-LLZTO composite material.

[0050] In one or more embodiments of this embodiment, in step S1, the mass ratio of the micron silicon matrix to the electronic conductor material is 99.5:0.5 - 90:10.

[0051] In one or more embodiments of this embodiment, in step S1, the calcination is carried out by heating to 750 - 850 °C at a heating rate of 3 - 5 °C / min, and the calcination time is 3 - 5 h.

[0052] In one or more embodiments of this embodiment, in step S2, the mass ratio of the μSi@G precursor to the ion conductor material is 95:5 - 70:30.

[0053] The third typical embodiment of the present invention provides an application of the above-mentioned micron silicon composite material for all-solid-state batteries in the negative electrode of all-solid-state batteries.

[0054] The fourth typical embodiment of the present invention provides an all-solid-state battery, the negative electrode of which uses the above-mentioned micron silicon composite material for all-solid-state batteries.

[0055] In one or more embodiments of this embodiment, the electrolyte of the all-solid-state battery is a sulfide or oxide solid electrolyte.

[0056] In one or more embodiments of this embodiment, the electrolyte of the all-solid-state battery is Li6PS5Cl, LLZTO or Li3PO4.

[0057] In one or more embodiments of this embodiment, the positive electrode of the all-solid-state battery uses lithium cobaltate, lithium iron phosphate or ternary materials.

[0058] The fifth typical embodiment of the present invention provides an application of the above-mentioned micron silicon composite material for all-solid-state batteries in the field of electrochemical energy storage.

[0059] The present invention effectively improves the ionic and electronic conductivities of the material by adding fast ion-electron conductors, reduces the lithium ion diffusion barrier, and promotes the rapid transmission of lithium ions. In addition, carbon-based materials such as graphene have a lamellar structure, so their advantages such as high porosity and large specific surface area can provide more attachment sites for lithium ions, promote the uniform embedding of lithium ions, and improve the conductivity. This advantage can also buffer the volume expansion of the silicon negative electrode material, prevent the electrode material from pulverizing, and thus improve the cycle life of the battery.

[0060] The present invention can remove the oxygen-containing functional groups in graphene by high-temperature calcination to improve the conductivity. In addition, a porous or three-dimensional network structure can be formed to increase the specific surface area and active sites, provide a stable ion / electron transmission channel, and anchor micron silicon as a conductive skeleton to improve the overall mechanical strength of the material.

[0061] The following combines specific embodiments to further elaborate on the present invention in detail. It should be noted that the specific embodiments are explanations rather than limitations of the present invention.

[0062] Example 1: This embodiment provides a micron-sized silicon composite material for all-solid-state batteries and a preparation method thereof.

[0063] Step 1: Weigh 1 g of samples of micron-sized silicon and graphene according to a mass fraction of 95:5 wt%, and use a ball mill to mix them to obtain a uniform precursor.

[0064] Step 2: Place the precursor in a tube furnace under an Ar atmosphere and calcine it at 800 °C for 4 h with a heating rate of 5 °C / min to obtain μSi@G.

[0065] Step 3: Weigh 1 g of samples of μSi@G and lithium lanthanum zirconium tantalum oxide (LLZTO) according to a mass fraction of 80:20 wt%, and use a ball mill to mix them to obtain uniform Si@G-LLZTO, as Figure 1 shown.

[0066] Example 2 : This embodiment provides a micron-sized silicon composite material for all-solid-state batteries and a preparation method thereof.

[0067] The difference between this embodiment and Embodiment 1 is that the doped electronic conductor material is carbon nanotubes. Other components and the preparation method are the same as those in Embodiment 1.

[0068] Example 3 : This embodiment provides a micron-sized silicon composite material for all-solid-state batteries and a preparation method thereof.

[0069] The difference between this embodiment and Embodiment 1 is that the doped ionic conductor is β-Li3N. Since β-Li3N is unstable in air, the mixing and coating operations need to be carried out in a glove box under an Ar atmosphere. Other components and the preparation method are the same as those in Embodiment 1.

[0070] Example 4 : This embodiment provides a micron-sized silicon composite material for all-solid-state batteries and a preparation method thereof.

[0071] The difference between this embodiment and Embodiment 1 is that the proportion of graphene in μSi@G is 10 wt%. Other components and the preparation method are the same as those in Embodiment 1.

[0072] Example 5 : This embodiment provides a micron-sized silicon composite material for all-solid-state batteries and a preparation method thereof.

[0073] The difference between this embodiment and Embodiment 1 is that the proportion of LLZTO in μSi@G-LLZTO is 10 wt%. Other components and the preparation method are the same as those in Embodiment 1.

[0074] Example 6 : This embodiment provides a micron-sized silicon composite material for all-solid-state batteries and a preparation method thereof.

[0075] The difference between this example and Example 1 is that the size of the micron silicon particles used is 10 μm. Other components and the preparation method are the same as those in Example 1.

[0076] Comparative Example 1 :

[0077] The difference between this comparative example and Example 1 is that no electronic conductor material is added. Other components and the preparation method are the same as those in Example 1.

[0078] Comparative Example 2 :

[0079] The difference between this comparative example and Example 1 is that no ionic conductor material is added. Other components and the preparation method are the same as those in Example 1.

[0080] Comparative Example 3 :

[0081] The difference between this comparative example and Example 1 is that the proportion of graphene in μSi@G is 20 wt%. Other components and the preparation method are the same as those in Example 1.

[0082] Comparative Example 4 :

[0083] The difference between this comparative example and Example 1 is that the proportion of graphene in μSi@G is 0.1 wt%. Other components and the preparation method are the same as those in Example 1.

[0084] Comparative Example 5 :

[0085] The difference between this comparative example and Example 1 is that the proportion of LLZTO electrolyte in Si@G-LLZTO is 50 wt%. Other components and the preparation method are the same as those in Example 1.

[0086] Comparative Example 6 :

[0087] The difference between this comparative example and Example 1 is that the proportion of LLZTO electrolyte in Si@G-LLZTO is 1 wt%. Other components and the preparation method are the same as those in Example 1.

[0088] Comparative Example 7 :

[0089] The difference between this comparative example and Example 1 is that micron silicon, graphene, and LLZTO electrolyte are weighed according to the mass ratio and then placed in a mortar and ground for 30 min. Other components and the preparation method are the same as those in Example 1.

[0090] Test Example 1 : This test example is to measure the ionic conductivity and electronic conductivity of the μSi@G-LLZTO prepared in Example 1

[0091] Electronic conductivity measurement method: At a voltage of 5 mV, a current-time polarization test was carried out on a stainless steel foil|μSi@G-LLZTO|stainless steel foil symmetrical cell. The test results are as Figure 2 shown, and the measured current I was 4.5 mA. The thickness L of the sample layer was 1 mm, the solid-state battery mold used for the test was 10 mm in diameter, and the area S was 0.7854 cm 2 . According to the formula Calculated, the electronic conductivity is about 1.14×10 -4 S cm -1 .

[0092] Ionic conductivity measurement method: At a voltage of 100 mV, current-time polarization tests were carried out on two stainless steel foil|Li|Li6PS5Cl|μSi@G-LLZTO|Li6PS5Cl|Li|stainless steel foil symmetrical cells (Cell 1 and Cell 2) respectively. The test results are as Figures 3 - 4 >shown, the measured current I1 was 0.022 mA, I2 was 0.0172 mA, and ΔI was 0.0048 mA. The thickness difference ΔL of the sample layers of the two symmetrical cells was 1 mm, the solid-state battery mold used for the test was 10 mm in diameter, and the area was 0.7854 cm 2 . According to the formula Calculated, the ionic conductivity is about 0.1 mS cm -1 .

[0093] Test Example 2 : In this test example, the electrochemical properties of the materials prepared in Examples 1-7 and Comparative Examples 1-7 were explored.

[0094] Electrochemical performance test method:

[0095] Step 1: The materials prepared in the examples and comparative examples were respectively ground with polyvinylidene fluoride PVDF in a mortar at a mass ratio of 98:2 for 10 min and mixed evenly. The material was transferred to a weighing bottle, 3 drops of NMP were added and stirred for 10 h, then it was coated on the smooth surface of the copper foil and placed in a vacuum oven at 80 °C for 8 h of drying. After drying, it was punched into a negative electrode plate of 10 mm for standby.

[0096] Step 2: Weigh 100 mg of the solid electrolyte Li6PS5Cl into the mold battery and keep the pressure at 1 ton (127 Mpa) for 1 min; place the negative electrode plate on the surface of Li6PS5Cl, keep the pressure at 2-3 tons (254-381 Mpa) for 2-3 min, remove the copper foil and place a Li piece with a mass of 3 / 4 of the mass of the negative electrode active material that has been pre-cut, then place a stainless steel foil and assemble the negative electrode side of the mold battery. Place a pre-rolled 5 mg lithium cobalt oxide positive electrode film on the other side of Li6PS5Cl and assemble the positive electrode side of the mold battery.

[0097] Step 3: Place the mold in an external pressure device and apply a stacking pressure of 254 Mpa. Place it at 60 °C for electrochemical testing, with the voltage range being 2.5 - 4.2 V.

[0098] The electrochemical performance of the all-solid-state battery prepared in Example 1 was tested, and the results are as Figures 5 - 6 shown. It can be seen therefrom that μSi@G-LLZTO exhibits excellent rate performance and cycling stability in the solid-state system.

[0099] Replace the solid electrolyte used in assembling the battery in Example 1 with LLZTO, and designate it as Example 7.

[0100] The specific data are shown in Table 1:

[0101] Table 1

[0102]

[0103] According to the data in Table 1, it can be seen that compared with Examples 1 - 6, the full-cell capacity retention rates of Comparative Examples 1 - 2 without adding electron / ion conductor materials are significantly lower. This is attributed to the poor electron / ion conductivity of silicon itself. Without adding electron / ion conductor materials, the ion transport channels in the silicon-based battery will be blocked during cycling, and the electron conduction network will be missing, resulting in an increase in interfacial impedance and rapid capacity decay.

[0104] In Comparative Examples 3 - 4, the proportion of graphene in μSi@G was changed. The addition of excessive electron conductor will cause a decrease in active substances and a reduction in the overall capacity. In addition, excessive electron conductor can lead to an increase in side reactions between the electrode and the electrolyte, consuming active lithium ions and exacerbating capacity decay. The reason for the rapid capacity decay with too little electron conductor added is the same as that of Comparative Example 1 without adding electron conductor;

[0105] In Comparative Examples 5 - 6, the proportion of LLZTO electrolyte in Si@G-LLZTO was changed. The addition of excessive ion conductor will cover the surface of silicon particles, hinder the direct contact between lithium ions and silicon, reduce the effective reaction area, and lead to a decrease in battery capacity. The reason for the rapid capacity decay with too little ion conductor added is the same as that of Comparative Example 2 without adding ion conductor;

[0106] In Comparative Example 7, only micron silicon, graphene, and LLZTO electrolyte were physically mixed. Comparing with the operation of ball-milling, mixing, and sintering in Example 1, through this operation, graphene can be coated on the surface of micron silicon to achieve the purpose of accelerating electron conduction and suppressing volume expansion. However, this simple process of physical mixing does not achieve the modification of silicon and cannot effectively improve the electrochemical performance of the silicon-based anode.

[0107] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A micron-sized silicon composite material for all-solid-state batteries, characterized in that, The micron-sized silicon composite material for all-solid-state batteries comprises a porous conductive network structure formed by a micron-sized silicon matrix and an electronic conductor material, and a fast ion conductor material uniformly distributed in the porous conductive network; The particle size of the micron-sized silicon matrix is 0.5 - 30 μm; The electronic conductor material is selected from one or more of graphene, graphite, carbon nanotubes, vapor-grown carbon fibers, and acetylene black, and accounts for 0.5 - 10 wt% of the total mass of the micron-sized silicon composite material for all-solid-state batteries; The fast ion conductor material is selected from one or more of lithium lanthanum zirconium tantalum oxide, lithium aluminum titanium phosphate, β-Li3N, lithium zirconium phosphate, and lithium phosphate, and accounts for 5 - 30 wt% of the total mass of the micron-sized silicon composite material for all-solid-state batteries.

2. The micron silicon composite material for all-solid-state batteries according to claim 1, wherein, The porous conductive network structure has a lamellar morphology, with a porosity of 18.1-22.5% and a specific surface area of 14.7-19.8 m 2 / g.

3. A method for preparing the micron silicon composite material for all-solid-state batteries according to any one of claims 1 to 2, characterized in that, It includes the following steps: S1. Mix the micron-sized silicon matrix and the electronic conductor material, grind them by ball milling, and then calcine to obtain a μSi@G precursor; S2. Mix and ball mill the μSi@G precursor obtained in step S1 with the ion conductor material to obtain a μSi@G-LLZTO composite material.

4. The preparation method according to claim 3, characterized in that, In step S1, the mass ratio of the micron-sized silicon matrix to the electronic conductor material is 99.5:0.5 - 90:

10.

5. The preparation method according to claim 3, characterized in that, In step S1, the calcination is carried out by heating at a heating rate of 3 - 5 °C / min to 750 - 850 °C, and the calcination time is 3 - 5 h.

6. The preparation method according to claim 3, characterized in that In step S2, the mass ratio of the μSi@G precursor to the ion conductor material is 95:5 - 70:

30.

7. Application of the micron-sized silicon composite material for all-solid-state batteries according to any one of claims 1 - 2 in the negative electrode of an all-solid-state battery.

8. A all-solid-state battery, characterized in that, The negative electrode thereof uses the micron-sized silicon composite material for all-solid-state batteries according to any one of claims 1 - 2.

9. The all-solid-state battery according to claim 8, characterized in that, The electrolyte of the all-solid-state battery is a sulfide or oxide solid electrolyte; Preferably, the electrolyte of the all-solid-state battery is Li6PS5Cl, LLZTO, or Li3PO4; Preferably, the positive electrode of the all-solid-state battery uses lithium cobaltate, lithium iron phosphate, or a ternary material.

10. Application of the micron-sized silicon composite material for all-solid-state batteries according to any one of claims 1 - 2 in the field of electrochemical energy storage.

Images