Silicon-based negative electrode material and preparation method thereof, negative electrode plate and all-solid-state battery

Abstract

The embodiment of the invention provides a silicon-based negative electrode material and a preparation method thereof, a negative electrode plate and an all-solid-state battery. The silicon-based negative electrode material comprises spherical porous silicon and metal indium, and the metal indium completely fills pores of the spherical porous silicon and coats the surface of the spherical porous silicon to form a continuous coating layer. The technical problems that the internal structure of the battery is damaged and the interface contact fails due to serious volume expansion or shrinkage of the silicon-based negative electrode material in the charging and discharging process, so that the cycle performance of the all-solid-state battery is poor, and the interface contact can be maintained by high voltage are solved.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a silicon-based anode material and its preparation method, an anode sheet, and an all-solid-state battery. Background Technology

[0002] With the ever-growing demand for high-energy-density and high-safety power batteries in the new energy industry, all-solid-state batteries have become the core development direction for next-generation power batteries. As a core component of all-solid-state batteries, the performance of the anode material significantly impacts the overall performance. Currently, graphite is the primary anode material for commercial lithium-ion batteries. However, graphite has a relatively low theoretical specific capacity (only 372 mAh / g), making it difficult to achieve high energy density (>300 Wh / kg) when applied to all-solid-state batteries. Silicon, with its high theoretical specific capacity (3579 mAh / g), low average lithiation potential (~0.4 V), and abundant raw material sources, is one of the ideal choices for anode materials in all-solid-state batteries. However, silicon-based anode materials experience severe volume expansion / contraction during charge and discharge, leading to problems such as damage to the internal structure of the anode sheet and failure of the interface between the anode layer and the electrolyte layer, ultimately causing a sharp decline in battery cycle performance. To maintain long-term stable cycling of silicon-based all-solid-state batteries, stacking pressures of tens or even hundreds of megapascals are typically applied during battery operation to ensure the stability of the internal structure and the integrity of interface contacts. This severely hinders the practical application of silicon-based all-solid-state batteries. Therefore, there is an urgent need to develop a silicon-based anode material that can achieve long-term stable cycling of all-solid-state batteries under low stacking pressure.

[0003] There is currently no good solution to the above problems. Summary of the Invention

[0004] This application provides a silicon-based anode material and its preparation method, anode sheet, and an all-solid-state battery, to at least solve the technical problem that the internal structure of the battery is damaged and the interface contact fails due to the severe volume expansion or contraction of the silicon-based anode material during charging and discharging, resulting in poor cycle performance of the all-solid-state battery and the need for high voltage to maintain interface contact.

[0005] According to one aspect of the embodiments of this application, a silicon-based anode material is provided, comprising: spherical porous silicon and metallic indium; wherein the metallic indium completely fills the pores of the spherical porous silicon and coats the surface of the spherical porous silicon to form a continuous coating layer.

[0006] Furthermore, based on the total weight of the silicon-based anode material, metallic indium is present in an amount of 10wt% to 50wt%.

[0007] Furthermore, the median particle size of the spherical porous silicon is 0.1 μm to 5 μm.

[0008] Furthermore, the porosity of spherical porous silicon is 10% to 50%.

[0009] According to another aspect of the embodiments of this application, a method for preparing a silicon-based anode material is also provided, comprising:

[0010] Step S1: Heat metallic indium to a molten state in an inert atmosphere, then add spherical porous silicon to the molten metallic indium and mix evenly to obtain a first mixture in which metallic indium coats the surface of the spherical porous silicon.

[0011] Step S2: In an inert atmosphere, the first mixture is added to a mold, pressure is applied to the first mixture in the mold and the pressure is maintained until the first mixture cools to room temperature, so as to obtain a second mixture in which metallic indium completely fills the pores of the spherical porous silicon and forms a continuous coating layer on the surface of the spherical porous silicon.

[0012] Step S3: The second mixture is crushed into particles in an inert atmosphere to obtain a silicon-based anode material.

[0013] Furthermore, in step S1, the heating temperature is 180℃~300℃.

[0014] Furthermore, in step S1, the mass ratio of the added spherical porous silicon to metallic indium is 1:1 to 9:1.

[0015] Furthermore, in step S2, the pressure is 20MPa~100MPa.

[0016] According to another aspect of the embodiments of this application, a negative electrode sheet is also provided, including silicon-based negative electrode materials of various embodiments of this application or silicon-based negative electrode materials prepared by the methods of various embodiments of this application.

[0017] According to another aspect of the embodiments of this application, an all-solid-state battery is also provided, including the negative electrode sheet in the embodiments of this application.

[0018] In this embodiment, a silicon-based anode material comprising spherical porous silicon and metallic indium is used. The metallic indium completely fills the pores of the spherical porous silicon and coats the surface of the spherical porous silicon to form a continuous coating layer. This significantly reduces stress concentration during the volume expansion of the silicon-based anode material and maintains good interfacial contact between anode material particles and the anode-electrolyte interface under low stacking pressure (≤5MPa) during battery cycling. This achieves the technical effect of enabling all-solid-state batteries to achieve long-term stable cycling under low pressure conditions, thereby solving the technical problems of poor cycle performance of all-solid-state batteries caused by severe volume expansion or contraction of silicon-based anode materials during charging and discharging, and the need for high voltage to maintain interfacial contact. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0020] Figure 1 This is a schematic diagram of the structure of the silicon-based anode material according to this application. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0022] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] According to an embodiment of this application, a silicon-based anode material is provided, comprising: spherical porous silicon and metallic indium; wherein, metallic indium completely fills the pores of the spherical porous silicon and coats the surface of the spherical porous silicon to form a continuous coating layer.

[0024] In the silicon-based anode material provided in this application embodiment, metallic indium completely fills the pores of spherical porous silicon and coats the surface of the spherical porous silicon to form a continuous coating layer. The spherical porous silicon, as the main contributor to capacity, can achieve uniform and rapid lithium alloying during battery charging due to its regular shape and large specific surface area. This significantly reduces stress concentration during the volume expansion of the silicon-based anode material and improves the cycle stability of the all-solid-state battery prepared from the silicon-based anode material. The metallic indium filling the pores of the spherical porous silicon and continuously coating the surface of the spherical porous silicon can not only provide part of the capacity as an active material, but also, as a good lithium-ion / electron hybrid conductor, can replace the electrolyte and conductive agent to provide a uniform and rapid lithium-ion / electron transport channel for the spherical porous silicon particles. In addition, the low yield strength of metallic indium allows the anode material particles and the anode layer-electrolyte layer interface to maintain good interfacial contact under low stacking pressure (≤5MPa) during battery cycling, thereby enabling the all-solid-state battery to achieve long-term stable cycling under low pressure conditions.

[0025] Furthermore, the silicon-based anode material preparation process provided in this application embodiment is simple and easy to scale up, and no electrolyte or additives are required during the anode sheet preparation process. At the same time, the all-solid-state battery prepared by silicon-based anode material has advantages such as low operating pressure requirements and long cycle life.

[0026] Figure 1 This is a structural schematic diagram of the silicon-based anode material according to this application, wherein the silicon-based anode material is composed of spherical porous silicon and metallic indium, wherein the metallic indium completely fills the pores of the spherical porous silicon and coats the surface of the spherical porous silicon to form a continuous coating layer.

[0027] Preferably, the silicon-based anode material is composed of spherical porous silicon and metallic indium, wherein the metallic indium completely fills the pores of the spherical porous silicon and coats the surface of the spherical porous silicon to form a continuous coating layer.

[0028] Preferably, the spherical porous silicon is a primary particle. Primary particles typically have a relatively uniform shape and size, which helps to uniformly insert and extract lithium ions during battery charging and discharging, reduces local stress concentration, and thus further improves the cycle stability of silicon-based anode materials.

[0029] Preferably, based on the total weight of the silicon-based anode material, metallic indium can be present in an amount of 10wt% to 50wt%. By controlling the mass ratio of metallic indium in the silicon-based anode material, the expansion or contraction of the silicon-based anode material can be further controlled while better maintaining high conductivity.

[0030] For example, the amount of metallic indium can be 10wt%, 20wt%, 30wt%, 40wt%, or 50wt%.

[0031] Preferably, the median particle size of the spherical porous silicon can be 0.1 μm to 5 μm. By controlling the median particle size of the spherical porous silicon within this range, it is easier to reduce stress concentration during charge-discharge cycles and further improve the cycle performance of the battery.

[0032] For example, the median particle size of spherical porous silicon can be 0.1 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm or 5 μm.

[0033] Preferably, the porosity of the spherical porous silicon can be 10% to 50%. By controlling the porosity of the spherical porous silicon within this range, it is easier to promote uniform and rapid lithium alloying / dealloying of the porous silicon during charge-discharge cycles, thereby reducing stress concentration and further improving the cycle performance of the battery.

[0034] For example, the porosity of spherical porous silicon can be 10%, 20%, 30%, 40%, or 50%.

[0035] Preferably, the pores of the spherical porous silicon can all be pores with a diameter > 50 nm.

[0036] Preferably, the purity of metallic indium can be ≥99.99%.

[0037] By giving the spherical porous silicon a macroporous structure and ensuring high purity of indium, it is possible to better ensure that indium completely fills and coats the spherical porous silicon, forming a uniform and rapid lithium-ion / electron transport channel, thereby further improving the cycle performance of the battery.

[0038] According to another aspect of the embodiments of this application, a method for preparing a silicon-based anode material is also provided, the method comprising:

[0039] Step S1: Heat metallic indium to a molten state in an inert atmosphere, then add spherical porous silicon to the molten metallic indium and mix evenly to obtain a first mixture in which metallic indium coats the surface of the spherical porous silicon.

[0040] Step S2: In an inert atmosphere, the first mixture is added to a mold, pressure is applied to the first mixture in the mold and the pressure is maintained until the first mixture cools to room temperature, so as to obtain a second mixture in which metallic indium completely fills the pores of the spherical porous silicon and forms a continuous coating layer on the surface of the spherical porous silicon.

[0041] Step S3: The second mixture is crushed into particles in an inert atmosphere to obtain a silicon-based anode material.

[0042] In the method for preparing silicon-based anode materials provided in this application embodiment, metallic indium completely fills the pores of spherical porous silicon and coats the surface of the spherical porous silicon to form a continuous coating layer. The spherical porous silicon, as the main contributor to capacity, has a regular shape and large specific surface area, enabling uniform and rapid lithium alloying during battery charging. This significantly reduces stress concentration during the volume expansion of the silicon-based anode material and improves the cycle stability of the all-solid-state battery prepared from the silicon-based anode material. The metallic indium filling the pores of the spherical porous silicon and continuously coating its surface not only provides some capacity as an active material but also, as a good lithium-ion / electron hybrid conductor, can replace the electrolyte and conductive agent to provide a uniform and rapid lithium-ion / electron transport channel for the spherical porous silicon particles. Furthermore, the low yield strength of metallic indium allows for good interfacial contact between the anode material particles and the anode-electrolyte layer interface under low stacking pressure (≤5MPa) during battery cycling, enabling the all-solid-state battery to achieve long-term stable cycling under low pressure conditions.

[0043] Furthermore, the silicon-based anode material preparation process provided in this application embodiment is simple and easy to scale up, and no electrolyte or additives are required during the anode sheet preparation process. At the same time, the all-solid-state battery prepared by silicon-based anode material has advantages such as low operating pressure requirements and long cycle life.

[0044] Preferably, in steps S1-S3, the inert atmosphere can be one or more of argon, helium, or nitrogen. Inert atmospheres include, but are not limited to, these. Performing steps S1-S3 under an inert atmosphere ensures that the structural integrity and electrochemical performance of the material are not affected by oxidation.

[0045] Preferably, in step S1, the heating temperature can be between 180°C and 300°C. This temperature range better ensures that the indium metal melts and has sufficient fluidity so that it can more fully fill the pores of the spherical porous silicon and form a continuous layer on its surface.

[0046] For example, in step S1, the heating temperature can be 180°C, 220°C, 250°C, or 300°C.

[0047] Preferably, in step S1, the mass ratio of the added spherical porous silicon to metallic indium can be 1:1 to 9:1. By controlling the mass ratio of metallic indium to spherical porous silicon, the expansion or contraction of the silicon-based anode material can be further controlled while better maintaining high conductivity.

[0048] For example, in step S1, the mass ratio of the added spherical porous silicon to metallic indium can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, or 9:1.

[0049] Preferably, in step S2, the pressure can be between 20 MPa and 100 MPa. This pressure range ensures that indium metal completely fills the pores of the spherical porous silicon and forms a continuous coating layer on its surface without causing excessive physical damage or altering its chemical properties. Furthermore, precise pressure control more effectively promotes uniform contact and fusion between indium metal and the spherical porous silicon, forming a stable structure, enhancing the stability of the silicon-based anode material during charge and discharge, reducing interfacial contact failures caused by volume expansion or contraction, and thus improving the cycle performance of the all-solid-state battery.

[0050] For example, in step S2, the pressure can be 20MPa, 30MPa, 40MPa, 50MPa, 60MPa, 70MPa, 80MPa, 90MPa or 100MPa.

[0051] Preferably, in step S2, the mold can be a stainless steel mold. The mold includes, but is not limited to, a stainless steel mold, and those skilled in the art can select a suitable mold as needed.

[0052] Preferably, in step S2, a stainless steel plunger can be used to apply pressure to the first mixture in the mold. The method of applying pressure in this step is not particularly limited, as long as the required pressure can be achieved. Those skilled in the art can select a suitable method of applying pressure as needed.

[0053] Preferably, in step S3, an air jet mill can be used to break the second mixture into particles. Due to its unique pulverizing mechanism, the air jet mill can not only effectively control the particle size of the powder but also largely retain the original properties of the material. However, the pulverizing method in this application is not limited to an air jet mill; those skilled in the art can choose a suitable pulverizing method.

[0054] Preferably, in step S3, the pulverizing pressure of the air jet mill can be 0.2 MPa to 2 MPa; the feed rate of the air jet mill can be 2 kg / h to 10 kg / h; the classifier speed of the air jet mill can be 2000 r / min to 8000 r / min; and the pulverizing medium of the air jet mill can be nitrogen. The optimization of the pulverizing conditions, including the application of nitrogen as the pulverizing medium in step S3, aims to refine the particle size of the silicon-based anode material while ensuring the integrity of the material structure. Specifically, controlling the crushing pressure within the range of 0.2 MPa to 2 MPa helps to achieve a gentle force on the silicon-based composite material particles during the crushing process, avoiding the degradation of material properties due to over-crushing. Setting the feed rate to 2 kg / h to 10 kg / h helps maintain the continuity and efficiency of the crushing process, while ensuring the residence time of each batch of material in the crushing chamber, thus affecting its particle size distribution and microstructure. Adjusting the classifier wheel speed between 2000 r / min and 8000 r / min allows for precise adjustment of the particle size of the crushed material, ensuring that the final silicon-based composite material has an ideal particle size distribution, which is crucial for improving the compaction density and electrochemical performance of the electrode material. By optimizing the crushing conditions, not only can the effective refinement of silicon-based anode material particles be achieved better, but the structural stability of the material can also be better guaranteed, thereby significantly improving the cycle stability of the all-solid-state battery.

[0055] According to another aspect of the embodiments of this application, a negative electrode sheet is also provided, including silicon-based negative electrode materials of various embodiments of this application or silicon-based negative electrode materials prepared by the methods of various embodiments of this application.

[0056] In the negative electrode sheet comprising silicon-based negative electrode material provided in this application embodiment, metallic indium completely fills the pores of spherical porous silicon and coats the surface of the spherical porous silicon to form a continuous coating layer. The spherical porous silicon, as the main contributor to capacity, due to its regular shape and large specific surface area, can achieve uniform and rapid lithium alloying during battery charging, thereby significantly reducing stress concentration generated during the volume expansion of the silicon-based negative electrode material and improving the cycle stability of the all-solid-state battery prepared from the silicon-based negative electrode material. The metallic indium filling the pores of the spherical porous silicon and continuously coating its surface not only provides some capacity as an active material, but also, as a good lithium-ion / electron hybrid conductor, can replace the electrolyte and conductive agent to provide a uniform and rapid lithium-ion / electron transport channel for the spherical porous silicon particles. Furthermore, the low yield strength of metallic indium allows the negative electrode material particles and the negative electrode layer-electrolyte layer interface to maintain good interfacial contact under low stacking pressure (≤5MPa) during battery cycling, thus enabling the all-solid-state battery to achieve long-term stable cycling under low pressure conditions.

[0057] Furthermore, the silicon-based anode material preparation process provided in this application embodiment is simple and easy to scale up, and no electrolyte or additives are required during the anode sheet preparation process. At the same time, the all-solid-state battery prepared by silicon-based anode material has advantages such as low operating pressure requirements and long cycle life.

[0058] According to another aspect of the embodiments of this application, an all-solid-state battery is also provided, including the negative electrode sheet in the embodiments of this application.

[0059] In the all-solid-state battery including a negative electrode provided in this application embodiment, metallic indium completely fills the pores of spherical porous silicon and coats the surface of the spherical porous silicon to form a continuous coating layer. The spherical porous silicon, as the main contributor to capacity, can achieve uniform and rapid lithium alloying during battery charging due to its regular shape and large specific surface area. This significantly reduces stress concentration caused by the volume expansion of silicon-based negative electrode materials and improves the cycle stability of the all-solid-state battery prepared from silicon-based negative electrode materials. The metallic indium filling the pores of the spherical porous silicon and continuously coating the surface of the spherical porous silicon can not only provide part of the capacity as an active material, but also, as a good lithium-ion / electron hybrid conductor, can replace the electrolyte and conductive agent to provide a uniform and rapid lithium-ion / electron transport channel for the spherical porous silicon particles. In addition, the low yield strength of metallic indium allows the negative electrode material particles and the negative electrode layer-electrolyte layer interface to maintain good interfacial contact under low stacking pressure (≤5MPa) during battery cycling, thereby enabling the all-solid-state battery to achieve long-term stable cycling under low pressure conditions.

[0060] Furthermore, the silicon-based anode material preparation process provided in this application embodiment is simple and easy to scale up, and no electrolyte or additives are required during the anode sheet preparation process. At the same time, the all-solid-state battery prepared by silicon-based anode material has advantages such as low operating pressure requirements and long cycle life.

[0061] An embodiment of this application also provides a vehicle including the all-solid-state battery described in the embodiments of this application.

[0062] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0063] Example

[0064] Preparation of silicon-based anode materials

[0065] Example 1

[0066] Step S1: In an argon atmosphere, 10g of indium foil is added to a crucible and heated to 300°C and maintained at the heating temperature. Then, 90g of spherical porous silicon (median particle size of 0.1μm and porosity of 10%) is added to molten metallic indium and mixed evenly to obtain a first mixture with metallic indium coating the surface of spherical porous silicon.

[0067] Step S2: In an argon atmosphere, the first mixture is added to a cylindrical stainless steel mold. The first mixture in the mold is pressurized to 20 MPa using a stainless steel plunger and the pressure is maintained until the first mixture cools to room temperature to obtain a second mixture in which metallic indium completely fills the pores of the spherical porous silicon and forms a continuous coating layer on the surface of the spherical porous silicon.

[0068] Step S3: The second mixture is crushed into particles in an argon atmosphere using an airflow pulverizer at a pulverizing pressure of 0.2 MPa, a feed rate of 2 kg / h, and a classifier speed of 2000 r / min to obtain silicon-based anode material.

[0069] Example 2

[0070] Step S1: In a helium atmosphere, 50g of indium foil is added to a crucible and heated to 180°C and maintained at the heating temperature. Then, 50g of spherical porous silicon (median particle size of 5μm and porosity of 50%) is added to molten metallic indium and mixed evenly to obtain a first mixture with metallic indium coating the surface of spherical porous silicon.

[0071] Step S2: In a helium atmosphere, the first mixture is added to a cylindrical stainless steel mold. The first mixture in the mold is pressurized to 100 MPa using a stainless steel plunger and held under pressure until the first mixture cools to room temperature to obtain a second mixture in which metallic indium completely fills the pores of the spherical porous silicon and forms a continuous coating layer on the surface of the spherical porous silicon.

[0072] Step S3: The second mixture is crushed into particles in a helium atmosphere using an air jet mill at a crushing pressure of 2 MPa, a feed rate of 10 kg / h, and a classifier speed of 8000 r / min to obtain silicon-based anode material.

[0073] Example 3

[0074] Step S1: In a nitrogen atmosphere, 35g of indium foil is added to a crucible and heated to 250°C and maintained at the heating temperature. 65g of spherical porous silicon (median particle size of 3μm and porosity of 30%) is added to molten metallic indium and mixed evenly to obtain a first mixture with metallic indium coating on the surface of spherical porous silicon.

[0075] Step S2: In a nitrogen atmosphere, the first mixture is added to a cylindrical stainless steel mold. The first mixture in the mold is pressurized to 30 MPa using a stainless steel plunger and the pressure is maintained until the first mixture cools to room temperature to obtain a second mixture in which metallic indium completely fills the pores of the spherical porous silicon and forms a continuous coating layer on the surface of the spherical porous silicon.

[0076] Step S3: The second mixture is crushed into particles in a nitrogen atmosphere using an air jet mill at a crushing pressure of 1 MPa, a feed rate of 6 kg / h, and a classifier speed of 5000 r / min to obtain silicon-based anode material.

[0077] Example 4

[0078] Step S1: In a nitrogen atmosphere, 20g of indium foil is added to a crucible and heated to 220°C and maintained at the heating temperature. Then, 80g of spherical porous silicon (median particle size of 1μm and porosity of 20%) is added to molten metallic indium and mixed evenly to obtain a first mixture with metallic indium coating on the surface of spherical porous silicon.

[0079] Step S2: In a nitrogen atmosphere, the first mixture is added to a cylindrical stainless steel mold. The first mixture in the mold is pressurized to 50 MPa using a stainless steel plunger and the pressure is maintained until the first mixture cools to room temperature to obtain a second mixture in which metallic indium completely fills the pores of the spherical porous silicon and forms a continuous coating layer on the surface of the spherical porous silicon.

[0080] Step S3: The second mixture is crushed into particles in a nitrogen atmosphere using an air jet mill at a crushing pressure of 0.5 MPa, a feed rate of 3 kg / h, and a classifier speed of 3000 r / min to obtain silicon-based anode material.

[0081] Comparative Example 1

[0082] The only difference between Comparative Example 1 and Example 4 is that the spherical porous silicon added in step S1 is replaced with non-porous spherical silicon with a median particle size of 1 μm.

[0083] Comparative Example 2

[0084] The only difference between Comparative Example 2 and Example 4 is that the spherical porous silicon added in step S1 is replaced with commercially available block silicon powder with a median particle size of 1 μm.

[0085] Comparative Example 3

[0086] The silicon-based anode material is only spherical porous silicon with a median particle size of 1 μm and a porosity of 20%.

[0087] Comparative Example 4

[0088] Silicon-based anode materials are only commercially available bulk silicon powder with a median particle size of 1 μm.

[0089] Preparation of solid-state mold half-cell

[0090] The silicon-based anode materials provided in Examples 1-4 and Comparative Examples 1-4 were assembled into solid-state mold half-cells (mold inner diameter was 10 mm) according to the following steps:

[0091] Weigh 100 mg of solid electrolyte powder (LPSCl (lithium phosphorus sulfur chloride) electrolyte: median particle size = 5 μm, ionic conductivity = 6 mS / cm). Hold the solid electrolyte powder at 150 MPa for 2 min. After holding the pressure, uniformly disperse 2 mg of silicon-based anode material on one side of the electrolyte sheet and hold it at 100 MPa for 2 min. After holding the pressure, place indium foil (diameter 9.8 mm, thickness 100 μm) and lithium foil (diameter 6 mm, thickness 150 μm) on the other side of the electrolyte sheet and hold it at 100 MPa for 2 min. After holding the pressure, unload the pressure to 5 MPa to obtain a solid mold half cell.

[0092] Electrochemical performance testing

[0093] (1) Measurement of specific capacity during the first 0.1C charge

[0094] The solid-state mold half-cell was subjected to a first charge-discharge specific capacity test at room temperature at a 0.1C rate (test voltage range: 0.900V to -0.595V), and the first 0.1C charge specific capacity of the solid-state half-cell was recorded.

[0095] (2) Measurement of specific capacity during the first 1C charge and the specific capacity after 500 1C charge cycles

[0096] The prepared solid-state mold half-cell was subjected to one charge-discharge cycle at room temperature at a 0.1C rate, followed by a room temperature cycling test at a 1C rate (test voltage range: 0.900V to -0.595V). The specific capacity of the solid-state mold half-cell at the first 1C charge and the specific capacity after 500 1C cycles were recorded. Then, based on the following formula, the capacity retention rate (%) after 500 1C cycles was calculated using the specific capacity at the first 1C charge and the specific capacity after 500 1C cycles.

[0097] Capacity retention rate after 500 1C charging cycles (%) = (Specific capacity after 500 1C charging cycles / Specific capacity after the first 1C charging cycle) × 100%.

[0098] Please refer to Table 1 for the test results of the solid-state mold half-cells of silicon-based anode materials prepared in each embodiment and comparative example.

[0099] Table 1

[0100]

[0101] By comparing the experimental results of the embodiments of the present invention and the comparative examples, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0102] The differences between Examples 1, 2, 3, and 4 are: the particle size and porosity of spherical porous silicon in the silicon-based anode material, the mass ratio of spherical porous silicon to metallic indium, and the preparation process parameters. The data from Examples 1, 2, 3, and 4 in Table 1 show that optimizing the particle size and porosity of spherical porous silicon, the mass ratio of spherical porous silicon to metallic indium, and the preparation process parameters can yield the anode material with the best performance.

[0103] - Comparing the data of Comparative Examples 1 and 2 in Table 1 with the data of Example 4, it can be seen that the use of spherical porous silicon is beneficial to the efficient utilization of the specific capacity of silicon-based anode materials and the improvement of cycle stability.

[0104] - Comparing the data of Comparative Examples 3 and 4 in Table 1 with the data of Example 4, it can be seen that the structural design of filling the pores of spherical porous silicon with indium metal and coating the surface of spherical porous silicon to form a continuous coating layer can significantly improve the capacity performance and cycle stability of silicon-based all-solid-state batteries under low stacking pressure (5MPa).

[0105] Furthermore, the silicon-based anode material preparation process provided in this application is simple and easy to scale up, and no electrolyte or additives are required during the electrode preparation process. At the same time, the all-solid-state battery prepared by the silicon-based anode material has advantages such as low operating pressure requirements (≤5MPa) and long cycle life, and has high application value and broad development prospects in the field of all-solid-state batteries.

[0106] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A silicon-based anode material, characterized in that, include: Spherical porous silicon; and Metallic indium; The indium metal completely fills the pores of the spherical porous silicon and coats the surface of the spherical porous silicon to form a continuous coating layer.

2. The silicon-based anode material according to claim 1, characterized in that, Based on the total weight of the silicon-based anode material, the metallic indium is present in an amount of 10wt% to 50wt%.

3. The silicon-based anode material according to claim 1 or 2, characterized in that, The median particle size of the spherical porous silicon is 0.1 μm to 5 μm.

4. The silicon-based anode material according to claim 1 or 2, characterized in that, The porosity of the spherical porous silicon is 10% to 50%.

5. A method for preparing silicon-based anode materials, characterized in that, include: Step S1: In an inert atmosphere, indium metal is heated to a molten state, and then spherical porous silicon is added to the molten indium metal and mixed evenly to obtain a first mixture in which the indium metal coats the surface of the spherical porous silicon. Step S2: In an inert atmosphere, the first mixture is added to a mold, pressure is applied to the first mixture in the mold and the pressure is maintained until the first mixture cools to room temperature, so as to obtain a second mixture in which the indium metal completely fills the pores of the spherical porous silicon and coats the surface of the spherical porous silicon to form a continuous coating layer. Step S3: The second mixture is crushed into particles in an inert atmosphere to obtain a silicon-based anode material.

6. The method according to claim 5, characterized in that, In step S1, the heating temperature is 180℃~300℃.

7. The method according to claim 5 or 6, characterized in that, In step S1, the mass ratio of the added spherical porous silicon to the metallic indium is 1:1 to 9:

1.

8. The method according to claim 5 or 6, characterized in that, In step S2, the pressure is 20MPa~100MPa.

9. A negative electrode sheet, characterized in that, The silicon-based anode material includes any one of claims 1-4 or a silicon-based anode material prepared by any one of claims 5-8.

10. An all-solid-state battery, characterized in that, Includes the negative electrode sheet as described in claim 9.

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