Silicon-carbon negative electrode material, preparation method thereof and lithium ion battery

Abstract

The invention provides a silicon-carbon negative electrode material, a preparation method thereof and a lithium ion battery. The silicon-carbon negative electrode material comprises a three-dimensional mesh cage framework and a silicon material, the three-dimensional mesh cage framework has a pore channel structure, the silicon material is embedded in pore channels of the three-dimensional mesh cage framework, and the three-dimensional mesh cage framework comprises an aluminum phosphate molecular sieve and first carbon layers arranged on the surface of the three-dimensional mesh cage framework and the inner walls of the pore channels of the aluminum phosphate molecular sieve. The three-dimensional mesh cage framework is composed of the aluminum phosphate molecular sieve and the first carbon layer, the aluminum phosphate molecular sieve can support the three-dimensional mesh cage framework on one hand and can provide a pore channel structure for the three-dimensional mesh cage framework on the other hand, an embedding space is provided for a silicon material, and the conductivity of the silicon-carbon negative electrode material can be improved through the arrangement of the first carbon layer. The silicon material is embedded into the pore channel of the three-dimensional mesh cage framework, so that the volume expansion of the silicon material in the charging and discharging process of the lithium ion battery can be effectively inhibited, and the compaction density and the structural stability of the silicon-carbon negative electrode material are improved, thereby improving the cycling stability of the lithium ion battery.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and in particular, to a silicon-carbon negative electrode material, a preparation method thereof, and a lithium-ion battery. Background Art

[0002] At present, the negative electrode active material of lithium-ion batteries is mainly graphite. Although its stability is relatively high, its theoretical specific capacity is only 372 mAh / g, which limits the improvement space of the energy density of lithium-ion batteries. Compared with graphite, the theoretical specific capacity of silicon-based materials is as high as 4200 mAh / g, and at the same time, it has the advantages of environmental friendliness and high abundance of earth elements, making it one of the most promising candidates for negative electrode materials and attracting extensive research. However, the expansion-shrinkage stress generated during the charge and discharge process of silicon-based materials will cause serious cracking of the silicon-based negative electrode material, resulting in irreversible capacity loss and low initial Coulomb efficiency, which limits its practical application.

[0003] At present, a common method to suppress the expansion of silicon-based negative electrode materials is to prepare silicon-carbon negative electrode materials by compounding silicon materials and carbon materials, using the high stability of carbon materials to coat silicon materials or embed silicon materials in carbon materials, so as to suppress the volume change of silicon materials and improve the stability of silicon-carbon negative electrode materials.

[0004] The preparation methods of silicon-carbon negative electrode materials mainly include chemical vapor deposition method and mechanical ball milling method. Although the mechanical ball milling method is simple to operate, it is easy to cause agglomeration of silicon-carbon composite materials, resulting in a decrease in the performance of lithium-ion batteries. The chemical vapor deposition method uses porous carbon as the matrix, embeds silicon materials in the porous carbon matrix, and suppresses the volume expansion of silicon materials through the pore structure of the porous carbon matrix, thereby improving the electrochemical performance of the silicon-carbon negative electrode material. However, the silicon-carbon negative electrode materials prepared by the above methods still have a certain degree of expansion problem, as well as problems of low tap density and poor structural stability, resulting in poor cycle stability in lithium-ion batteries. In addition, the common raw materials for preparing porous carbon matrices mainly come from biomass or resin materials, and there are many uncontrollable factors in the process of preparing porous carbon matrices, resulting in poor stability and consistency of porous carbon matrices, which in turn affects the performance of silicon-carbon negative electrode materials.

[0005] In summary, researching and developing a silicon-carbon negative electrode material with a low volume expansion rate, a high tap density, and good structural stability and its preparation method is of great significance for improving the cycle stability of lithium-ion batteries. Summary of the Invention

[0006] The main object of the present invention is to provide a silicon-carbon negative electrode material, a preparation method thereof, and a lithium-ion battery, so as to solve the problems of high volume expansion rate, low tap density, and poor structural stability of silicon-carbon negative electrode materials in the prior art, and the problem of poor cycle stability of lithium-ion batteries prepared therefrom.

[0007] To achieve the above object, on the one hand, the present invention provides a silicon-carbon negative electrode material, which includes a three-dimensional cage skeleton and a silicon material. The three-dimensional cage skeleton has a pore structure, and the silicon material is embedded inside the pores of the three-dimensional cage skeleton. The three-dimensional cage skeleton includes aluminophosphate molecular sieve and a first carbon layer disposed on the surface of the three-dimensional skeleton of the aluminophosphate molecular sieve and the inner wall of the pores.

[0008] Compared with the silicon-carbon negative electrode materials prepared from biomass or resin porous carbon matrices in the prior art, in this application, the silicon material is embedded inside the pores of the three-dimensional cage skeleton composed of aluminophosphate molecular sieve and the first carbon layer, which can effectively inhibit the volume expansion of the silicon material during the charge and discharge process of the lithium-ion battery and improve the structural stability of the silicon-carbon negative electrode material. In the aluminophosphate molecular sieve, phosphorus-oxygen tetrahedrons and aluminum-oxygen tetrahedrons are connected to each other at the common oxygen vertices to form a three-dimensional cross-cage structure with regular pores. Its skeleton structure has higher strength, can provide stronger support for the three-dimensional cage skeleton, improve its structural stability, and inhibit its fragmentation under high compaction; at the same time, the aluminophosphate molecular sieve can also provide a pore structure for the three-dimensional cage skeleton, provide an embedding space for the silicon material, and cooperate with the first carbon layer disposed on the surface of its three-dimensional skeleton and the inner wall of the pores to improve the conductivity of the silicon-carbon negative electrode material, enhance the binding force between the silicon material and the carbon material, thereby improving the structural stability of the silicon-carbon negative electrode material, inhibiting its volume expansion, increasing the compaction density of the silicon-carbon negative electrode material, and further improving the cycle stability and electrochemical performance of the lithium-ion battery.

[0009] Further, the D of the silicon-carbon negative electrode material 50 is 0.5 to 50 μm, and the specific surface area is 0.5 to 100 m 2 / g.

[0010] Compared with other ranges, limiting the D of the silicon-carbon negative electrode material 50 within the above range is beneficial to improving the lithium-ion transport efficiency, the rate performance and cycle stability of the lithium-ion battery. Compared with other ranges, limiting the specific surface area of the silicon-carbon negative electrode material within the above range is beneficial to increasing the contact area between the silicon-carbon negative electrode material and the electrolyte, reducing the irreversible capacity loss during the first charge and discharge process, and improving the first Coulombic efficiency of the lithium-ion battery.

[0011] Further, the pore volume of the three-dimensional cage skeleton is 0.1 to 2.0 cm 3 / g, the average pore diameter is 0.5 to 50 nm, and the specific surface area is 10 to 3000 m 2 / g.

[0012] Compared with other ranges, limiting the pore volume, average pore diameter, and specific surface area of the three-dimensional cage framework within the above ranges is beneficial to improving the lithium-ion transport efficiency, providing a suitable embedding space for silicon materials, alleviating their volume expansion during charge and discharge, thereby being conducive to improving the stability of the silicon-carbon anode material, and further conducive to improving the cycle stability of lithium-ion batteries.

[0013] Furthermore, the thickness of the first carbon layer is 0.1 - 300 nm.

[0014] Compared with other ranges, limiting the thickness of the first carbon layer within the above range is beneficial to improving the conductivity of the silicon-carbon anode material, and conducive to improving the cycle stability and electrochemical performance of lithium-ion batteries.

[0015] Furthermore, calculated by weight percentage of the silicon-carbon anode material, the content of silicon element is 1 - 80 wt%, and the content of carbon element in the first carbon layer is 1 - 40 wt%.

[0016] Compared with other ranges, limiting the content of silicon element and carbon element in the first carbon layer within the above range is beneficial to alleviating the volume expansion of silicon materials during charge and discharge, and at the same time conducive to obtaining a silicon-carbon anode material with both high specific capacity and good structural stability.

[0017] Furthermore, the pore volume of the aluminophosphate molecular sieve is 0.01 - 3.0 cm 3 / g, the average pore diameter is 0.1 - 300 nm, and the specific surface area is 50 - 3200 m 2 / g.

[0018] Compared with other ranges, limiting the pore volume, average pore diameter, and specific surface area of the aluminophosphate molecular sieve within the above ranges is beneficial to providing a more suitable pore structure for the three-dimensional cage framework, thereby being conducive to providing a more suitable embedding space for silicon materials, alleviating their volume expansion during charge and discharge, and further conducive to improving the structural stability of the silicon-carbon anode material.

[0019] Furthermore, the average particle size of the aluminophosphate molecular sieve is 0.5 - 30 μm.

[0020] Compared with other ranges, limiting the average particle size of the aluminophosphate molecular sieve within the above range is beneficial to inhibiting the agglomeration of the silicon-carbon anode material, conducive to improving the tap density of the silicon-carbon anode material, and thus conducive to improving the energy density and cycle stability of lithium-ion batteries.

[0021] Furthermore, the P / Al ratio of the aluminophosphate molecular sieve is (0.01 - 10):(0.01 - 10), and the P / O ratio is (0.01 - 10):(0.05 - 10).

[0022] The P / Al ratio and P / O ratio of the aluminophosphate molecular sieve include but are not limited to the above ranges. Limiting them within the above ranges is beneficial to improving the pore structure of the aluminophosphate molecular sieve and enhancing the structural stability of the aluminophosphate molecular sieve.

[0023] Furthermore, the aluminophosphate molecular sieve further includes a doped metal element; preferably, the doped metal element is selected from one or more elements of Group IA, Group IIA, Group IIIA, Group IVA, Group IIB, Group IIIB, Group IVB, Group VB, Group VIIB, and Group VIII; more preferably, the doped metal element is selected from one or more elements of the group consisting of Li, Be, Mg, Ga, In, Ge, Sn, Ti, V, Nb, Cr, W, Mn, Co, Ni, Cu, and Zn.

[0024] Introducing a doped metal element and limiting its type within the above ranges is beneficial to improving the electronic structure of the aluminophosphate molecular sieve, enhancing the conductivity of the silicon-carbon anode material, and at the same time is also beneficial to enhancing the structural stability of the aluminophosphate molecular sieve, providing a stronger supporting effect for the three-dimensional cage framework, and being conducive to alleviating the volume expansion of the silicon material during charge and discharge, thereby being conducive to improving the cycle stability of the lithium-ion battery.

[0025] Furthermore, the surface of the silicon-carbon anode material further includes a second carbon layer, and the second carbon layer is disposed on the surface of the three-dimensional cage framework embedded with the silicon material; preferably, the thickness of the second carbon layer is 0.1 - 100 nm.

[0026] Disposing a second carbon layer on the surface of the three-dimensional cage framework embedded with the silicon material and limiting its thickness within the above ranges is beneficial to improving the conductivity of the silicon-carbon anode material, reducing the direct contact between the silicon material and the electrolyte, and is also beneficial to alleviating the volume expansion of the silicon material, thereby being conducive to improving the structural stability and tap density of the silicon-carbon anode material, and further being conducive to improving the cycle stability and electrochemical performance of the lithium-ion battery.

[0027] Furthermore, based on the weight percentage of the silicon-carbon anode material, the content of silicon element is 1 - 80 wt%, and the total content of carbon element in the first carbon layer and the second carbon layer is 5 - 90 wt%.

[0028] Compared with other ranges, limiting the content of silicon element in the silicon-carbon anode material and the total content of carbon element in the first carbon layer and the second carbon layer within the above ranges is beneficial to obtaining a silicon-carbon anode material with both high specific capacity and good conductivity and structural stability.

[0029] Furthermore, the silicon material is selected from one or more of amorphous silicon, single crystal silicon, and polycrystalline silicon.

[0030] The silicon materials include, but are not limited to, the above types. Using the above types of silicon materials is beneficial to obtaining a silicon-carbon negative electrode material with both high capacity and good structural stability.

[0031] To achieve the above object, another aspect of the present invention further provides a preparation method of the above silicon-carbon negative electrode material provided in the present application. The preparation method includes: Step S1, preparing aluminophosphate molecular sieve by the template method; Step S2, performing a first deposition treatment on the aluminophosphate molecular sieve with a first carbon source in a protective gas atmosphere to obtain a three-dimensional cage framework; Step S3, performing a second deposition treatment on the three-dimensional cage framework with a silicon source in a protective gas atmosphere to obtain a silicon-carbon negative electrode material.

[0032] In the preparation method of the above silicon-carbon negative electrode material provided in the present application, in Step S1, the aluminophosphate molecular sieve with the specific morphology and pore structure as described above in the present application can be obtained by the template method. In Step S2, a first deposition treatment is performed on the aluminophosphate molecular sieve with a first carbon source, and a first carbon layer is formed on the surface of the three-dimensional framework and the inner wall of the pore channels of the aluminophosphate molecular sieve, thereby obtaining a three-dimensional cage framework. The introduction of the first carbon source is beneficial to improving the conductivity of the silicon-carbon negative electrode material. The aluminophosphate molecular sieve can provide support for the three-dimensional cage framework, thereby improving its structural stability, inhibiting its fragmentation under high compaction, and at the same time, the aluminophosphate molecular sieve can also provide a pore structure for the three-dimensional cage framework to provide space for the subsequent embedding of silicon materials. In Step S3, a second deposition is performed on the three-dimensional cage framework with a silicon source to obtain a silicon-carbon negative electrode material. Embedding the silicon material in the pore structure of the three-dimensional cage framework can effectively inhibit the volume expansion of the silicon material during the charge and discharge process of the lithium-ion battery, improve the structural stability of the silicon-carbon negative electrode material, and at the same time can enhance the binding force between the silicon material and the carbon material, further inhibit the volume expansion of the silicon material, and improve the compaction density of the silicon-carbon negative electrode material. Compared with other methods, using the above preparation method provided in the present application can obtain a silicon-carbon negative electrode material with a low volume expansion rate, a high compaction density, and good structural stability, thereby improving the cycle stability and electrochemical performance of the lithium-ion battery.

[0033] Further, in Step S2, the temperature of the first deposition treatment is 500-1000 °C, and the time is 0.5-20 h.

[0034] Compared with other ranges, limiting the temperature and time of the first deposition treatment within the above ranges is beneficial to improving the efficiency of the first deposition treatment, beneficial to forming a first carbon layer on the surface of the three-dimensional framework and the inner wall of the pore channels of the aluminophosphate molecular sieve, and thus beneficial to improving the conductivity of the silicon-carbon negative electrode material.

[0035] Further, the first deposition treatment is performed by chemical vapor deposition, and the feeding rate of the first carbon source is 0.5-50 L / min.

[0036] Performing the first deposition treatment by chemical vapor deposition and limiting the feeding rate of the first carbon source within the above range is conducive to forming a first carbon layer with a more appropriate thickness, and is conducive to improving the uniformity and density of the first carbon layer.

[0037] Further, in step S3, the temperature of the second deposition treatment is 400 - 850 °C, and the time is 0.5 - 20 h.

[0038] Compared with other ranges, limiting the temperature and time of the second deposition treatment within the above range is conducive to uniformly depositing the silicon source inside the pore channels of the three-dimensional cage framework, and is conducive to enhancing the bonding force between the silicon material and the first carbon layer.

[0039] Further, the second deposition treatment is performed by chemical vapor deposition, and the feeding rate of the silicon source is 0.5 - 50 L / min.

[0040] Performing the second deposition treatment by chemical vapor deposition and limiting the feeding rate of the silicon source within the above range is conducive to more uniformly depositing the silicon source inside the pore channels of the three-dimensional cage framework, thereby being conducive to improving the tap density and structural stability of the silicon-carbon anode material.

[0041] Further, the preparation method further includes: in a protective gas atmosphere, performing a third deposition treatment on the product obtained by the second deposition treatment using a second carbon source to obtain the silicon-carbon anode material.

[0042] Using the above method can obtain a silicon-carbon anode material with a second carbon layer. The introduction of the second carbon layer is conducive to improving the conductivity of the silicon-carbon anode material, conducive to reducing the direct contact between the silicon material and the electrolyte, and at the same time conducive to alleviating the volume expansion of the silicon material, thereby being conducive to improving the structural stability and tap density of the silicon-carbon anode material.

[0043] Further, the temperature of the third deposition treatment is 400 - 900 °C, and the time is 0.5 - 20 h.

[0044] Compared with other ranges, limiting the temperature and time of the third deposition treatment within the above range is conducive to forming a more uniform and more appropriately thick second carbon layer.

[0045] Further, the third deposition treatment is performed by chemical vapor deposition, and the feeding rate of the second carbon source is 0.5 - 50 L / min.

[0046] Performing the third deposition treatment by chemical vapor deposition and limiting the feeding rate of the second carbon source within the above range is conducive to forming a second carbon layer with a more appropriate thickness, and is conducive to improving the uniformity and density of the second carbon layer.

[0047] Further, the first carbon source and the second carbon source are each independently selected from one or more of the group consisting of acetylene, methane, ethane, propane, butane, ethylene, propylene, butene, methanol, ethanol, propanol, and benzene.

[0048] Compared with other types, using the first carbon source and the second carbon source of the above types is beneficial to improving the uniformity and density of the first carbon layer and the second carbon layer, thereby being beneficial to improving the electrical conductivity and structural stability of the silicon-carbon anode material.

[0049] Further, the silicon source is selected from one or more of the group consisting of silane, disilane, trisilane, tetrasilane, chlorosilane, dichlorosilane, trichlorosilane, and tetrachlorosilane.

[0050] Compared with other types, using the silicon source of the above types is beneficial to improving the efficiency of the second deposition treatment, beneficial to improving the bonding force between the silicon material and the carbon material, and at the same time, the silicon source of the above types is easily obtained, which is beneficial to reducing the production cost.

[0051] Further, the protective gas is selected from one or more of the group consisting of nitrogen, argon, helium, neon, krypton, and xenon.

[0052] Using the protective gas of the above types is beneficial to suppressing the occurrence of side reactions (such as oxidation reactions) in the first deposition treatment, the second deposition treatment, and the third deposition treatment, thereby being beneficial to improving the structural integrity and purity of the silicon-carbon anode material.

[0053] Further, step S1 includes: mixing an aluminum source, phosphoric acid, a template agent, and a solvent, and obtaining aluminophosphate molecular sieve after crystallization and sintering; preferably, the weight ratio of the aluminum source, phosphoric acid, the template agent to the solvent is (0.1 - 2):(0.1 - 2):(0.1 - 2):(1 - 100).

[0054] Using the above method is beneficial to obtaining an aluminophosphate molecular sieve with a three-dimensional framework structure. Compared with other ranges, limiting the weight ratio of the aluminum source, phosphoric acid, the template agent to the solvent within the above range is beneficial to guiding the formation of aluminophosphate molecular sieve, improving the pore structure of the aluminophosphate molecular sieve, and being beneficial to improving the structural stability of the aluminophosphate molecular sieve.

[0055] Further, the crystallization temperature is 25 - 300 °C and the time is 0.2 - 48 h.

[0056] Compared with other ranges, limiting the crystallization temperature and time within the above range is beneficial to improving the crystallization efficiency, beneficial to improving the pore structure of the aluminophosphate molecular sieve, and being beneficial to improving the structural stability of the aluminophosphate molecular sieve.

[0057] Further, the sintering temperature is 500 - 1000 °C and the time is 0.5 - 48 h.

[0058] Compared with other ranges, limiting the sintering temperature and time within the above ranges is beneficial to improving the removal efficiency of the template agent and to improving the pore structure of the aluminophosphate molecular sieve.

[0059] Further, the aluminum source is selected from one or more of the group consisting of aluminum isopropoxide, aluminum chloride, and pseudoboehmite.

[0060] Compared with other types, the above types of aluminum sources have good solubility and reactivity, which is beneficial to forming an aluminophosphate molecular sieve with the specific morphological structure and pore structure of the present application.

[0061] Further, the template agent is an organic amine, and more preferably the organic amine is selected from one or more of the group consisting of triethylamine, di-n-propylamine, and diisopropylamine.

[0062] Compared with other types, using the above types of template agents is beneficial to guiding the formation of aluminophosphate molecular sieves and to improving the pore structure of aluminophosphate molecular sieves.

[0063] Further, the solvent is selected from one or more of the group consisting of water, ethanol, methanol, and acetone.

[0064] Compared with other solvents, using the above types of solvents is beneficial to improving the dispersibility of the aluminum source, phosphoric acid, and template agent.

[0065] Further, a metal source is also introduced during the mixing process in step S1, and an aluminophosphate molecular sieve doped with a metal element is obtained after crystallization; step S2 further includes: performing a first deposition treatment on the aluminophosphate molecular sieve doped with a metal element with a first carbon source in a protective gas atmosphere to obtain a three-dimensional cage framework.

[0066] Compared with other methods, using the above method can obtain an aluminophosphate molecular sieve doped with a metal element. The introduction of the metal element is beneficial to improving the electronic structure of the aluminophosphate molecular sieve, enhancing the conductivity of the silicon-carbon negative electrode material, and at the same time is also beneficial to improving the structural stability of the aluminophosphate molecular sieve, thereby being beneficial to providing a stronger supporting effect for the three-dimensional cage framework, alleviating the volume expansion of the silicon material during charge and discharge, and further being beneficial to improving the cycle stability of the lithium-ion battery.

[0067] Further, the mass concentration of the metal source is 0.1-10 wt%.

[0068] Compared with other ranges, limiting the mass concentration of the metal source within the above ranges is beneficial to introducing an appropriate amount of metal elements, thereby being beneficial to improving the electronic structure of the aluminophosphate molecular sieve, enhancing the conductivity of the silicon-carbon negative electrode material, and at the same time is also beneficial to improving the structural stability of the aluminophosphate molecular sieve.

[0069] Further, the metal source is selected from one or more of the group consisting of oxides, acids, bases, and salts containing metal elements; preferably, the metal element is selected from one or more of the group consisting of metal elements in Group IA, Group IIA, Group IIIA, Group IVA, Group IIB, Group IIIB, Group IVB, Group VB, Group VIIB, and Group VIII; preferably, the metal element is selected from one or more of the group consisting of Li, Be, Mg, Ga, In, Ge, Sn, Ti, V, Nb, Cr, W, Mn, Co, Ni, Cu, and Zn; preferably, the metal source is selected from one or more of the group consisting of titanium oxide, gallium oxide, tin oxide, copper chloride, tungsten oxide, niobium oxide, magnesium chloride, and nickel oxide.

[0070] Compared with other types, using the above-mentioned type of metal source is beneficial to improving the electronic structure of the aluminophosphate molecular sieve, enhancing the electrical conductivity of the silicon-carbon anode material, and at the same time is also beneficial to improving the structural stability of the aluminophosphate molecular sieve.

[0071] Another aspect of the present invention provides a lithium-ion battery, including a positive electrode, a negative electrode, an electrolyte, and a separator disposed between the positive electrode and the negative electrode, wherein the negative electrode of the lithium-ion battery includes the above-mentioned silicon-carbon anode material provided by this application.

[0072] The above-mentioned silicon-carbon anode material provided by this application embeds silicon materials into the pores of the three-dimensional cage framework composed of aluminophosphate molecular sieve and the first carbon layer, which can effectively inhibit the volume expansion of silicon materials during the charge and discharge process of lithium-ion batteries and improve the structural stability of the silicon-carbon anode material. In the aluminophosphate molecular sieve, phosphorus-oxygen tetrahedrons and aluminum-oxygen tetrahedrons are interconnected by sharing oxygen vertices to form a three-dimensional cross-cage structure with regular pores. Its framework structure has higher strength, can provide stronger support for the three-dimensional cage framework, thereby improving its structural stability and inhibiting its fragmentation under high compaction; at the same time, the aluminophosphate molecular sieve can also provide a pore structure for the three-dimensional cage framework, provide an embedding space for silicon materials, and jointly act with the first carbon layer disposed on the surface of its three-dimensional framework and the inner wall of the pores to improve the electrical conductivity of the silicon-carbon anode material, enhance the binding force between silicon materials and carbon materials, thereby improving the structural stability of the silicon-carbon anode material, inhibiting its volume expansion, and increasing the compaction density of the silicon-carbon anode material. Applying the above-mentioned silicon-carbon anode material as the anode material in a lithium-ion battery can improve the cycle stability and electrochemical performance of the lithium-ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0074] Figure 1The scanning electron microscope image of the silicon-carbon negative electrode material prepared in Example 1 of the present application is shown;

[0075] Figure 2 The transmission electron microscope image of the silicon-carbon negative electrode material prepared in Example 1 of the present application is shown;

[0076] Figure 3 The transmission electron microscope image of the silicon-carbon negative electrode material prepared in Example 1 of the present application is shown;

[0077] Figure 4 The first charge-discharge curve of the button lithium-ion battery prepared in Example 1 of the present application is shown. Detailed implementation manners

[0078] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0079] As described in the background art, the existing silicon-carbon negative electrode materials have problems such as high volume expansion rate, low tap density, and poor structural stability, and the lithium-ion batteries prepared therefrom have poor cycle stability. To solve the above technical problems, the present application provides a silicon-carbon negative electrode material, which includes a three-dimensional cage skeleton and a silicon material. The three-dimensional cage skeleton has a pore structure, and the silicon material is embedded inside the pores of the three-dimensional cage skeleton. The three-dimensional cage skeleton includes aluminophosphate molecular sieve and a first carbon layer provided on the three-dimensional skeleton surface and pore inner wall of the aluminophosphate molecular sieve.

[0080] Compared with the silicon-carbon negative electrode materials prepared from biomass or resin porous carbon matrices in the prior art, in the present application, the silicon material is embedded inside the pores of the three-dimensional cage skeleton composed of aluminophosphate molecular sieve and the first carbon layer, which can effectively inhibit the volume expansion of the silicon material during the charge and discharge process of the lithium-ion battery and improve the structural stability of the silicon-carbon negative electrode material. In aluminophosphate molecular sieve, phosphorus-oxygen tetrahedrons and aluminum-oxygen tetrahedrons are connected by common oxygen vertices to form a three-dimensional cross-cage structure with regular pores. Its skeleton structure has higher strength, can provide stronger support for the three-dimensional cage skeleton, improve its structural stability, and inhibit its fragmentation under high compaction; at the same time, aluminophosphate molecular sieve can also provide a pore structure for the three-dimensional cage skeleton, provide an embedding space for the silicon material, and cooperate with the first carbon layer provided on its three-dimensional skeleton surface and pore inner wall to improve the conductivity of the silicon-carbon negative electrode material, enhance the binding force between the silicon material and the carbon material, thereby improving the structural stability of the silicon-carbon negative electrode material, inhibiting its volume expansion, increasing the tap density of the silicon-carbon negative electrode material, and further improving the cycle stability and electrochemical performance of the lithium-ion battery.

[0081] It should be noted that the three-dimensional framework of the aluminum phosphate (AlPO4) molecular sieve in this application is composed of alternately connected phosphorus-oxygen tetrahedrons and aluminum-oxygen tetrahedrons, forming a three-dimensional network cage structure with regular pores through the common oxygen vertices of the phosphorus-oxygen tetrahedrons and aluminum-oxygen tetrahedrons.

[0082] In a preferred embodiment, the D 50 of the silicon-carbon anode material is 0.5 to 50 μm. The D 50 of the silicon-carbon anode material includes but is not limited to the above range. Limiting it within the above range is beneficial to improving the lithium-ion transport efficiency, thereby being beneficial to improving the rate performance and cycle stability of the lithium-ion battery. Preferably, the D 50 of the silicon-carbon anode material is 3 to 40 μm, or 5 to 20 μm, or 5 to 15 μm. Specifically, the D 50 of the silicon-carbon anode material can be 3 μm, 5 μm, 6 μm, 8 μm or 10 μm.

[0083] In a preferred embodiment, the specific surface area of the silicon-carbon anode material is 0.5 to 100 m 2 / g. The specific surface area of the silicon-carbon anode material includes but is not limited to the above range. Limiting it within the above range is beneficial to increasing the contact area between the silicon-carbon anode material and the electrolyte, being beneficial to forming a stable SEI film, thereby being beneficial to reducing the irreversible capacity loss during the first charge and discharge process and improving the first Coulomb efficiency. Preferably, the specific surface area of the silicon-carbon anode material is 1 to 80 m 2 / g, or 5 to 50 m 2 / g or 10 to 30 m 2 / g. Specifically, the specific surface area of the silicon-carbon anode material can be 1 m 2 / g, 2 m 2 / g, 3 m 2 / g, 5 m 2 / g or 10 m 2 / g.

[0084] In a preferred embodiment, the pore volume of the three-dimensional network cage framework is 0.1 to 2.0 cm 3 / g, the average pore diameter is 0.5 to 50 nm, and the specific surface area is 10 to 3000 m 2 / g. The pore volume, average pore diameter and specific surface area of the three-dimensional network cage framework include but are not limited to the above range. Limiting them within the above range is beneficial to improving the lithium-ion transport efficiency, providing a suitable embedding space for the silicon material, increasing the specific capacity of the silicon-carbon anode material, thereby being beneficial to improving the energy density of the lithium-ion battery. At the same time, it is also beneficial to provide sufficient buffer space for the volume expansion of the silicon material during the charge and discharge process, inhibiting its rupture, thereby being beneficial to improving the stability of the silicon-carbon anode material and further being beneficial to improving the cycle stability of the lithium-ion battery.

[0085] In a preferred embodiment, the thickness of the first carbon layer is 0.1 to 300 nm. The thickness of the first carbon layer includes but is not limited to the above range. Limiting it within the above range is beneficial to improving the conductivity of the silicon-carbon negative electrode material, thereby being beneficial to improving the cycle stability and electrochemical performance of the lithium-ion battery. Preferably, the thickness of the first carbon layer is 1 to 200 nm, or 5 to 150 nm, or 10 to 100 nm or 20 to 50 nm. Specifically, the thickness of the first carbon layer can be 5 nm, 10 nm, 15 nm, 20 nm or 50 nm.

[0086] In a preferred embodiment, based on the weight percentage of the silicon-carbon negative electrode material, the content of silicon element is 1 to 80 wt%, and the content of carbon element in the first carbon layer is 1 to 40 wt%. Compared with other ranges, limiting the content of silicon element and carbon element in the first carbon layer within the above range is beneficial to improving the conductivity of the silicon-carbon negative electrode material, beneficial to alleviating the volume expansion of silicon material during charge and discharge, and at the same time beneficial to obtaining a silicon-carbon negative electrode material with both high specific capacity and good structural stability. Specifically, the content of silicon element can be 10 wt%, 20 wt%, 40 wt%, 50 wt% or 60 wt%; the content of carbon element can be 1 wt%, 3 wt%, 5 wt%, 10 wt% or 15 wt%.

[0087] In a preferred embodiment, the pore volume of the aluminophosphate molecular sieve is 0.01 to 3.0 cm 3 / g, the average pore diameter is 0.1 to 300 nm, and the specific surface area is 50 to 3200 m 2 / g. The pore volume, average pore diameter and specific surface area of the aluminophosphate molecular sieve include but are not limited to the above range. Limiting them within the above range is beneficial to providing a more suitable pore structure for the three-dimensional cage framework, thereby being beneficial to providing a more suitable embedding space for silicon material, alleviating the volume expansion of silicon material during charge and discharge, and at the same time being beneficial to improving the tap density and structural stability of the silicon-carbon negative electrode material.

[0088] In a preferred embodiment, the average particle size of the aluminophosphate molecular sieve is 0.5 to 30 μm. The average particle size of the aluminophosphate molecular sieve includes but is not limited to the above range. Limiting it within the above range is beneficial to inhibiting the agglomeration of the silicon-carbon negative electrode material, beneficial to improving the tap density of the silicon-carbon negative electrode material, thereby being beneficial to improving the energy density and cycle stability of the lithium-ion battery.

[0089] In a preferred embodiment, the P / Al ratio of the aluminophosphate molecular sieve is (0.01 - 10):(0.01 - 10), and the P / O ratio is (0.01 - 10):(0.05 - 10). The P / Al ratio and P / O ratio of the aluminophosphate molecular sieve include but are not limited to the above ranges. Limiting them within the above ranges is beneficial to improving the pore structure of the aluminophosphate molecular sieve and enhancing the structural stability of the aluminophosphate molecular sieve.

[0090] In a preferred embodiment, the aluminophosphate molecular sieve further includes a doped metal element. The introduction of the doped metal element is beneficial to improving the electronic structure of the aluminophosphate molecular sieve, thereby being conducive to enhancing the conductivity of the silicon-carbon anode material. At the same time, it is also beneficial to improving the structural stability of the aluminophosphate molecular sieve, providing a stronger supporting effect for the three-dimensional cage framework, thus being conducive to suppressing the volume expansion of the silicon material during charge and discharge, and further being conducive to improving the cycle stability of the lithium-ion battery.

[0091] In order to further improve the conductivity of the silicon-carbon anode material, further enhance the structural stability of the aluminophosphate molecular sieve, further provide a stronger supporting effect for the three-dimensional cage framework, thereby further suppressing the expansion of the silicon material, and further improving the cycle stability of the lithium-ion battery, preferably, the doped metal element includes one or more of the elements in Group IA, Group IIA, Group IIIA, Group IVA, Group IIB, Group IIIB, Group IVB, Group VB, Group VIIB, and Group VIII.

[0092] In order to further improve the conductivity of the silicon-carbon anode material, further enhance the structural stability of the aluminophosphate molecular sieve, further provide a stronger supporting effect for the three-dimensional cage framework, thereby further suppressing the expansion of the silicon material, and further improving the cycle stability of the lithium-ion battery, more preferably, the doped metal element includes one or more of the elements in the group consisting of Li, Be, Mg, Ga, In, Ge, Sn, Ti, V, Nb, Cr, W, Mn, Co, Ni, Cu, and Zn. Specifically, the doped metal element can be Ga, Ge, Co, or W.

[0093] In the present application, the three-dimensional cage framework embedded with silicon material refers to a structure formed by embedding the silicon material inside the pores of the three-dimensional cage framework. In a preferred embodiment, the surface of the silicon-carbon anode material further includes a second carbon layer, and the second carbon layer is disposed on the surface of the three-dimensional cage framework embedded with the silicon material. The setting of the second carbon layer is beneficial to improving the conductivity of the silicon-carbon anode material, reducing the direct contact between the silicon material and the electrolyte, thereby suppressing the occurrence of side reactions. At the same time, it is also beneficial to alleviating the volume expansion of the silicon material, improving the structural stability and tap density of the silicon-carbon anode material, and further being conducive to improving the cycle stability and electrochemical performance of the lithium-ion battery.

[0094] In order to further improve the electrical conductivity of the silicon-carbon anode material, further reduce the direct contact between the silicon material and the electrolyte, further inhibit the occurrence of side reactions, and further alleviate the volume expansion of the silicon material, thereby further improving the structural stability and tap density of the silicon-carbon anode material. Preferably, the thickness of the second carbon layer is 0.1 to 100 nm. Preferably, the thickness of the second carbon layer is 1 to 100 nm, or 5 to 80 nm, or 10 to 50 nm, or 15 to 30 nm. Specifically, the thickness of the second carbon layer can be 5 nm, 10 nm, 15 nm, 20 nm, or 30 nm.

[0095] In a preferred embodiment, based on the weight percentage of the silicon-carbon anode material, the content of silicon element is 1 to 80 wt%. The total content of carbon element in the first carbon layer and the second carbon layer is 5 to 90 wt%. The content of silicon element in the silicon-carbon anode material and the total content of carbon element in the first carbon layer and the second carbon layer include but are not limited to the above ranges. Limiting them within the above ranges is beneficial to obtaining a silicon-carbon anode material with both high specific capacity and good electrical conductivity and structural stability. Specifically, the content of silicon element can be 10 wt%, 20 wt%, 40 wt%, 50 wt%, or 60 wt%; the content of carbon element can be 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, or 60 wt%.

[0096] Amorphous silicon has a high lithium ion diffusion rate. Single crystal silicon has excellent mechanical strength and thermal stability, as well as low internal resistance and high energy density. Polycrystalline silicon has good lithium ion diffusion rate and structural stability, and its grain boundaries can absorb the volume expansion during lithium ion charging, improving the cycle stability of the anode material. In a preferred embodiment, the silicon material includes but is not limited to one or more of the group consisting of amorphous silicon, single crystal silicon, and polycrystalline silicon. Compared with other types, using the above types of silicon materials is beneficial to obtaining a silicon-carbon anode material with both high capacity and good structural stability.

[0097] The second aspect of the present application also provides a preparation method of the above silicon-carbon anode material provided by the present application. The preparation method includes: Step S1, preparing aluminophosphate molecular sieve by the template method; Step S2, performing the first deposition treatment on the aluminophosphate molecular sieve with the first carbon source in a protective gas atmosphere to obtain a three-dimensional cage framework; Step S3, performing the second deposition treatment on the three-dimensional cage framework with the silicon source in a protective gas atmosphere to obtain the silicon-carbon anode material.

[0098] In the preparation method of the silicon-carbon anode material provided by the present application, in step S1, the template method can be used to obtain the aluminophosphate molecular sieve with the specific morphology and pore structure described above in the present application. In step S2, a first carbon source is used to perform a first deposition treatment on the aluminophosphate molecular sieve, and a first carbon layer is formed on the surface of the three-dimensional framework and the inner wall of the pore channels of the aluminophosphate molecular sieve, thereby obtaining a three-dimensional cage framework. The introduction of the first carbon source is beneficial to improving the conductivity of the silicon-carbon anode material. The aluminophosphate molecular sieve can provide support for the three-dimensional cage framework, thereby improving its structural stability and inhibiting its fragmentation under high compaction. At the same time, the aluminophosphate molecular sieve can also provide a pore channel structure for the three-dimensional cage framework, providing space for the subsequent embedding of silicon materials. In step S3, a silicon source is used to perform a second deposition on the three-dimensional cage framework to obtain the silicon-carbon anode material. Embedding the silicon material into the pore channel structure of the three-dimensional cage framework can effectively inhibit the volume expansion of the silicon material during the charge and discharge process of the lithium-ion battery, improve the structural stability of the silicon-carbon anode material, and at the same time enhance the binding force between the silicon material and the carbon material, further inhibiting the volume expansion of the silicon material and improving the compaction density of the silicon-carbon anode material.

[0099] Compared with other methods, using the above preparation method provided by the present application can obtain a silicon-carbon anode material with a low volume expansion rate, a high compaction density, and good structural stability, thereby improving the cycle stability and electrochemical performance of the lithium-ion battery.

[0100] In a preferred embodiment, in step S2, the temperature of the first deposition treatment is 500-1000 °C, and the time is 0.5-20 h. The temperature and time of the first deposition treatment include but are not limited to the above range. Limiting them within the above range is beneficial to improving the efficiency of the first deposition treatment, beneficial to forming a first carbon layer on the surface of the three-dimensional framework and the inner wall of the pore channels of the aluminophosphate molecular sieve, and thus beneficial to improving the conductivity of the silicon-carbon anode material. Preferably, the temperature of the first deposition treatment is 600-900 °C, and the time is 1-15 h, or the temperature of the first deposition treatment is 700-800 °C, and the time is 5-10 h. Specifically, the temperature of the first deposition treatment can be 500 °C, 600 °C, 800 °C, 900 °C, or 1000 °C, and the time of the first deposition treatment can be 1 h, 2 h, 3 h, 4 h, 5 h, or 6 h.

[0101] In order to make the first carbon source contact the aluminophosphate molecular sieve more fully and uniformly, thereby forming a first carbon layer with a more appropriate thickness and further improving the density and conductivity of the first carbon layer, in a preferred embodiment, the first deposition treatment is carried out by chemical vapor deposition, and the feeding rate of the first carbon source is 0.5-50 L / min. Preferably, the feeding rate of the first carbon source is 5-40 L / min or 10-25 L / min. Specifically, the feeding rate of the first carbon source can be 1 L / min, 2 L / min, 3 L / min, 5 L / min, or 10 L / min.

[0102] In a preferred embodiment, in step S3, the temperature of the second deposition treatment is 400 - 850 °C, and the time is 0.5 - 20 h. The temperature and time of the second deposition treatment include but are not limited to the above ranges. Limiting them within the above ranges is beneficial to improving the efficiency of the second deposition treatment, facilitating the uniform deposition of the silicon source inside the pores of the three-dimensional cage framework, and at the same time is also beneficial to enhancing the bonding force between the silicon material and the first carbon layer. Preferably, the temperature of the second deposition treatment is 400 - 600 °C, and the time is 1 - 15 h, or the temperature of the second deposition treatment is 450 - 550 °C, and the time is 5 - 10 h. Specifically, the temperature of the second deposition treatment can be 400 °C, 450 °C, 500 °C, 550 °C, 600 °C or 850 °C; the time of the second deposition treatment can be 0.5 h, 1 h, 2 h, 3 h, 4 h, 5 h or 6 h.

[0103] In order to make the silicon source contact the three-dimensional cage framework more fully and uniformly, so as to deposit more uniformly inside the pores of the three-dimensional cage framework and further improve the tap density and structural stability of the silicon-carbon negative electrode material, in a preferred embodiment, chemical vapor deposition is used for the second deposition treatment, and the feeding rate of the silicon source is 0.5 - 50 L / min. Preferably, the feeding rate of the silicon source is 5 - 40 L / min or 10 - 25 L / min. Specifically, the feeding rate of the silicon source can be 1 L / min, 2 L / min, 3 L / min, 5 L / min, 10 L / min or 20 L / min.

[0104] In a preferred embodiment, the silicon source includes but is not limited to one or more of the group consisting of silane, disilane, trisilane, tetrasilane, chlorosilane, dichlorosilane, trichlorosilane and tetrachlorosilane. Compared with other types, using the above types of silicon sources is beneficial to improving the efficiency of the second deposition treatment, beneficial to improving the bonding force between the silicon material and the carbon material, and at the same time the above types of silicon sources are easy to obtain, which is beneficial to reducing production costs.

[0105] In order to obtain a silicon-carbon negative electrode material with a second carbon layer, thereby further improving the conductivity of the silicon-carbon negative electrode material, reducing the direct contact between the silicon material and the electrolyte, inhibiting the occurrence of side reactions, and at the same time further alleviating the volume expansion of the silicon material and further improving the structural stability and tap density of the silicon-carbon negative electrode material, in a preferred embodiment, the preparation method further includes: in a protective gas atmosphere, using a second carbon source to perform a third deposition treatment on the product obtained by the second deposition treatment to obtain a silicon-carbon negative electrode material.

[0106] In a preferred embodiment, the temperature of the third deposition treatment is 400 - 900 °C and the time is 0.5 - 20 h. The temperature and time of the third deposition treatment include but are not limited to the above ranges. Limiting them within the above ranges is beneficial to improving the efficiency of the third deposition treatment, forming a more uniform second carbon layer, thus being beneficial to improving the conductivity of the silicon-carbon anode material, reducing the direct contact between the silicon material and the electrolyte, inhibiting the occurrence of side reactions, and at the same time being beneficial to further alleviating the volume expansion of the silicon material, and further being beneficial to improving the structural stability and tap density of the silicon-carbon anode material.

[0107] In order to obtain a second carbon layer with a more suitable thickness, improve the uniformity and denseness of the second carbon layer, thus further improving the conductivity of the silicon-carbon anode material, further reducing the direct contact between the silicon material and the electrolyte, further alleviating the volume expansion of the silicon material, and further improving the structural stability and tap density of the silicon-carbon anode material, in a preferred embodiment, chemical vapor deposition is used for the third deposition treatment, and the feeding rate of the second carbon source is 0.5 - 50 L / min. Preferably, the feeding rate of the second carbon source is 5 - 45 L / min or 10 - 25 L / min. Specifically, the feeding rate of the second carbon source can be 1 L / min, 2 L / min, 3 L / min, 5 L / min or 10 L / min.

[0108] In a preferred embodiment, the first carbon source and the second carbon source independently include but are not limited to one or more of the group consisting of acetylene, methane, ethane, propane, butane, ethylene, propylene, butene, methanol, ethanol, propanol and benzene. Compared with other types, using the above types of the first carbon source and the second carbon source is beneficial to improving the efficiency of the first deposition treatment and the second deposition treatment, and is beneficial to improving the uniformity and denseness of the first carbon layer and the second carbon layer, thus being beneficial to improving the conductivity and structural stability of the silicon-carbon anode material.

[0109] In order to inhibit the occurrence of side reactions (such as oxidation reactions) in the first deposition treatment, the second deposition treatment and the third deposition treatment, and improve the structural integrity and purity of the silicon-carbon anode material, in a preferred embodiment, the protective gas includes but is not limited to one or more of the group consisting of nitrogen, argon, helium, neon, krypton and xenon.

[0110] In a preferred embodiment, step S1 includes: mixing an aluminum source, phosphoric acid, a templating agent and a solvent, and obtaining an aluminophosphate molecular sieve after crystallization and sintering. Compared with other methods, using the above method is beneficial to obtaining an aluminophosphate molecular sieve with a three-dimensional framework structure.

[0111] In a preferred embodiment, the weight ratio of the aluminum source, phosphoric acid, template agent, and solvent is (0.1 - 2):(0.1 - 2):(0.1 - 2):(1 - 100). The weight ratio of the aluminum source, phosphoric acid, template agent, and solvent includes but is not limited to the above range. Limiting it within the above range is beneficial for guiding the formation of aluminophosphate molecular sieve, improving the pore structure of the aluminophosphate molecular sieve, and at the same time is also beneficial for enhancing the structural stability of the aluminophosphate molecular sieve.

[0112] In a preferred embodiment, the crystallization temperature is 25 - 300 °C and the time is 0.2 - 48 h. The crystallization temperature and time include but are not limited to the above range. Limiting them within the above range is beneficial for improving the crystallization efficiency, improving the pore structure of the aluminophosphate molecular sieve, and at the same time is also beneficial for enhancing the stability of the aluminophosphate molecular sieve. Preferably, the crystallization temperature is 25 - 200 °C and the time is 2 - 24 h.

[0113] In a preferred embodiment, the sintering temperature is 500 - 1000 °C and the time is 0.5 - 48 h. The sintering temperature and time include but are not limited to the above range. Limiting them within the above range is beneficial for improving the removal efficiency of the template agent and improving the pore structure of the aluminophosphate molecular sieve. Preferably, the sintering temperature is 500 - 800 °C and the time is 2 - 12 h.

[0114] In a preferred embodiment, the aluminum source includes but is not limited to one or more of the group consisting of aluminum isopropoxide, aluminum chloride, and pseudoboehmite. Compared with other types, the above-mentioned aluminum sources have good solubility and reactivity, which are beneficial for forming aluminophosphate molecular sieves with the specific morphology and pore structure described above in this application.

[0115] In order to guide the formation of aluminophosphate molecular sieve and further improve the pore structure of the aluminophosphate molecular sieve, in a preferred embodiment, the template agent includes but is not limited to organic amines; preferably, the organic amines include but are not limited to one or more of the group consisting of triethylamine, di-n-propylamine, and diisopropylamine.

[0116] In order to improve the dispersibility of the above-mentioned raw materials, in a preferred embodiment, the solvent includes but is not limited to one or more of the group consisting of ethanol, methanol, and acetone.

[0117] In a preferred embodiment, a metal source is further introduced during the mixing process in step S1, and an aluminophosphate molecular sieve doped with a metal element is obtained after crystallization; step S2 further includes: in a protective gas atmosphere, the aluminophosphate molecular sieve doped with a metal element is subjected to a first deposition treatment with a first carbon source to obtain a three-dimensional cage framework. Compared with other methods, the above method can obtain an aluminophosphate molecular sieve doped with a metal element. The introduction of the metal element is beneficial to improving the electronic structure of the aluminophosphate molecular sieve, thereby being beneficial to improving the conductivity of the silicon-carbon anode material. At the same time, it is also beneficial to improving the structural stability of the aluminophosphate molecular sieve, providing a stronger supporting effect for the three-dimensional cage framework, alleviating the volume expansion of the silicon material during charge and discharge, and further being beneficial to improving the cycle stability of the lithium-ion battery.

[0118] In a preferred embodiment, the mass concentration of the metal source is 0.1-10 wt%. The mass concentration of the metal source includes but is not limited to the above range. Limiting it within the above range is beneficial to introducing an appropriate amount of metal element, thereby being beneficial to improving the electronic structure of the aluminophosphate molecular sieve, improving the conductivity of the silicon-carbon anode material, and at the same time being beneficial to improving the structural stability of the aluminophosphate molecular sieve.

[0119] In a preferred embodiment, the metal source includes but is not limited to one or more of the group consisting of oxides, acids, bases, and salts containing metal elements. Compared with other types, using the above types of metal sources is beneficial to introducing metal elements into the aluminophosphate molecular sieve, thereby being beneficial to improving the structural stability of the aluminophosphate molecular sieve, being beneficial to improving the electronic structure of the aluminophosphate molecular sieve, and improving the conductivity of the silicon-carbon anode material.

[0120] In order to further improve the conductivity of the silicon-carbon anode material and further improve the structural stability of the aluminophosphate molecular sieve, in a preferred embodiment, the metal element includes but is not limited to one or more of the group consisting of metal elements in Group IA, Group IIA, Group IIIA, Group IVA, Group IIB, Group IIIB, Group IVB, Group VB, Group VIIB, and Group VIII; preferably, the metal element includes but is not limited to one or more of the group consisting of Li, Be, Mg, Ga, In, Ge, Sn, Ti, V, Nb, Cr, W, Mn, Co, Ni, Cu, and Zn.

[0121] In order to further improve the conductivity of the silicon-carbon anode material and further improve the structural stability of the aluminophosphate molecular sieve, more preferably, the metal source includes but is not limited to one or more of the group consisting of titanium oxide, gallium oxide, tin oxide, copper chloride, tungsten oxide, niobium oxide, magnesium chloride, and nickel oxide.

[0122] The third aspect of the present application also provides a lithium-ion battery, which includes a positive electrode, a negative electrode, an electrolyte, and a separator disposed between the positive electrode and the negative electrode. Among them, the negative electrode includes the above-mentioned silicon-carbon negative electrode material provided by the present application.

[0123] The above-mentioned silicon-carbon negative electrode material provided by the present application embeds silicon material into the pores of the three-dimensional cage framework composed of aluminophosphate molecular sieve and the first carbon layer, which can effectively inhibit the volume expansion of silicon material during the charge and discharge process of the lithium-ion battery and improve the structural stability of the silicon-carbon negative electrode material. In the aluminophosphate molecular sieve, phosphorus-oxygen tetrahedrons and aluminum-oxygen tetrahedrons are connected by shared oxygen vertices to form a three-dimensional cross-cage structure with regular pores. Its framework structure has higher strength, can provide stronger support for the three-dimensional cage framework, thereby improving its structural stability and inhibiting its fragmentation under high compaction; at the same time, the aluminophosphate molecular sieve can also provide a pore structure for the three-dimensional cage framework, provide an embedding space for the silicon material, and cooperate with the first carbon layer disposed on the surface of its three-dimensional framework and the inner wall of the pores to improve the conductivity of the silicon-carbon negative electrode material, enhance the binding force between the silicon material and the carbon material, thereby improving the structural stability of the silicon-carbon negative electrode material, inhibiting its volume expansion, and increasing the compaction density of the silicon-carbon negative electrode material. Applying the above-mentioned silicon-carbon negative electrode material as the negative electrode material in a lithium-ion battery can improve the cycle stability and electrochemical performance of the lithium-ion battery.

[0124] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application.

[0125] It should be noted that in the present application: (1) An automatic specific surface area and pore size analyzer (Quantachrome, Autosorb-iQ) is used and fitting analysis is carried out through the DFT model to measure the pore volume, pore size and specific surface area of the aluminophosphate molecular sieve and the three-dimensional cage framework and the specific surface area of the silicon-carbon negative electrode material; (2) A laser particle size analyzer (Malvern Panalytical, 3000) is used to measure the average particle size of the aluminophosphate molecular sieve and the D 50 of the silicon-carbon negative electrode material; (3) A compaction density tester (Yuaneng Technology, PRCD3100) is used to measure the compaction density of the silicon-carbon negative electrode material, and the test pressure is 5 tons; (4) A focused ion beam scanning electron microscope (FIB-SEM, Thermo Fisher Scientific, Scois2) is used to slice the three-dimensional cage framework and the silicon-carbon negative electrode material to measure the thickness of the first carbon layer and the second carbon layer, and a scanning electron microscope (Thermo Fisher Scientific, NANO SEM 450) is used to observe the microscopic morphology of the material; (5) An inductively coupled plasma emission spectrometer (Agilent, 5800ICP-OES) is used to measure the silicon element content in the silicon-carbon negative electrode material, and a carbon-sulfur analyzer (LECO, CS844) is used to measure the carbon element content in the silicon-carbon negative electrode material.

[0126] Example 1

[0127] A preparation method of a silicon-carbon anode material specifically includes the following steps:

[0128] (1) Mix 1000 g of aluminum isopropoxide with 2000 g of water, stir for 0.5 h to obtain an aluminum hydroxide sol, add 700 g of phosphoric acid to the aluminum hydroxide sol, stir for 0.5 h to obtain an aluminum phosphate sol, and then add 600 g of the template agent triethylamine to the obtained aluminum phosphate sol. After mixing evenly, crystallize at 25 °C for 5 h, then calcine at 600 °C for 4 h. After cooling, wash twice with water, dry and crush to obtain an aluminum phosphate molecular sieve with an average particle size of 7.9 μm. The pore volume of this aluminum phosphate molecular sieve is 1.15 cm 3 / g, the average pore diameter is 3.2 nm, and the specific surface area is 2006.1 m 2 / g;

[0129] (2) Place the aluminum phosphate molecular sieve prepared in step (1) in a fluidized bed device, heat it to 800 °C under nitrogen protection, introduce acetylene at a flow rate of 3 L / min and carry out deposition treatment for 3 h to form a carbon layer with a thickness of 23 nm on the surface of the three-dimensional framework and the inner wall of the pores of the aluminum phosphate molecular sieve. After cooling, a three-dimensional cage framework is obtained; among them, the pore volume of the three-dimensional cage framework is 0.83 cm 3 / g, the average pore diameter is 1.89 nm, and the specific surface area is 1983 m 2 / g;

[0130] (3) Place the three-dimensional cage framework prepared in step (2) in a fluidized bed device, heat it to 550 °C under nitrogen protection, introduce silane at a flow rate of 3 L / min and carry out deposition treatment for 4 h. After cooling, a three-dimensional cage framework embedded with silicon material is obtained;

[0131] (4) Place the three-dimensional cage framework embedded with silicon material prepared in step (3) in a fluidized bed device, heat it to 550 °C under nitrogen protection, introduce acetylene at a flow rate of 3 L / min and carry out deposition treatment for 3 h to form a carbon coating layer with a thickness of 10 nm on the surface of the three-dimensional cage framework embedded with silicon material. After cooling, a silicon-carbon anode material is obtained; among them, the D 50 of the silicon-carbon anode material is 8 μm, the specific surface area is 1.6 m 2 / g, the content of silicon element is 48.2 wt%, and the content of carbon element is 40.1 wt%.

[0132] The scanning electron microscope image of the silicon-carbon anode material prepared in Example 1 is as shown in Figure 1 shown, and the transmission electron microscope images are as shown in Figure 2 and Figure 3 shown. It can be seen from Figure 1 that the silicon-carbon anode material is granular, and the surface of the particles is flat and the sizes are uniform; fromFigure 2 It can be seen that there is a carbon coating layer on the surface of the silicon-carbon anode material, and its thickness is 10 nm; Figure 3 It can be seen that the silicon material is uniformly distributed in the three-dimensional cage framework.

[0133] Example 2

[0134] The difference from Example 1 is that in step (1), 5 g of titanium oxide is dissolved in 100 g of water to obtain a mixed solution, and the mixed solution is mixed with an aluminum phosphate sol to obtain an aluminum phosphate sol containing Ti element. Subsequently, the same amount of template agent triethylamine is added to the above-mentioned aluminum phosphate sol containing Ti element, and after mixing evenly, crystallization is carried out. The remaining steps are the same as those in Example 1.

[0135] Example 3

[0136] The difference from Example 1 is that in step (2), the temperature of the deposition treatment is 1000 °C, and the remaining steps are the same as those in Example 1.

[0137] Example 4

[0138] The difference from Example 1 is that in step (2), the temperature of the deposition treatment is 400 °C, and the remaining steps are the same as those in Example 1.

[0139] Example 5

[0140] The difference from Example 1 is that in step (2), the time of the deposition treatment is 0.5 h, and the remaining steps are the same as those in Example 1.

[0141] Example 6

[0142] The difference from Example 1 is that in step (2), the time of the deposition treatment is 0.3 h, and the remaining steps are the same as those in Example 1.

[0143] Example 7

[0144] The difference from Example 1 is that in step (2), the feeding rate of acetylene is 0.5 L / min, and the remaining steps are the same as those in Example 1.

[0145] Example 8

[0146] The difference from Example 1 is that in step (2), the feeding rate of acetylene is 50 L / min, and the remaining steps are the same as those in Example 1.

[0147] Example 9

[0148] The difference from Example 1 is that in step (2), the feeding rate of acetylene is 0.3 L / min, and the remaining steps are the same as those in Example 1.

[0149] Example 10

[0150] The difference from Example 1 is that: the temperature of the deposition treatment in step (3) is 400 °C, and the remaining steps are the same as those in Example 1.

[0151] Example 11

[0152] The difference from Example 1 is that: the temperature of the deposition treatment in step (3) is 300 °C, and the remaining steps are the same as those in Example 1.

[0153] Example 12

[0154] The difference from Example 1 is that: the time of the deposition treatment in step (3) is 20 h, and the remaining steps are the same as those in Example 1.

[0155] Example 13

[0156] The difference from Example 1 is that: the time of the deposition treatment in step (3) is 0.3 h, and the remaining steps are the same as those in Example 1.

[0157] Example 14

[0158] The difference from Example 1 is that: in step (3), the feeding rate of silane is 0.5 L / min, and the remaining steps are the same as those in Example 1.

[0159] Example 15

[0160] The difference from Example 1 is that: in step (3), the feeding rate of silane is 50 L / min, and the remaining steps are the same as those in Example 1.

[0161] Example 16

[0162] The difference from Example 1 is that: in step (3), the feeding rate of silane is 0.2 L / min, and the remaining steps are the same as those in Example 1.

[0163] Example 17

[0164] The difference from Example 1 is that: step (4) is omitted, and the three-dimensional cage framework embedded with silicon material prepared in step (3) is the silicon-carbon negative electrode material prepared in this example, and its surface does not contain a carbon coating layer, and the remaining steps are the same as those in Example 1.

[0165] Example 18

[0166] The difference from Example 1 is that: the temperature of the deposition treatment in step (4) is 900 °C, and the remaining steps are the same as those in Example 1, wherein the thickness of the carbon coating layer obtained in step (4) is 20 nm.

[0167] Example 19

[0168] The difference from Example 1 is that: in step (4), the temperature of the deposition treatment is 350 °C, and the remaining steps are the same as those in Example 1. Among them, the thickness of the carbon coating layer obtained in step (4) is 5 nm.

[0169] Example 20

[0170] The difference from Example 1 is that: in step (4), the time of the deposition treatment is 0.5 h, and the remaining steps are the same as those in Example 1. Among them, the thickness of the carbon coating layer obtained in step (4) is 6 nm.

[0171] Example 21

[0172] The difference from Example 1 is that: in step (4), the time of the deposition treatment is 0.3 h, and the remaining steps are the same as those in Example 1. Among them, the thickness of the carbon coating layer obtained in step (4) is 3 nm.

[0173] Example 22

[0174] The difference from Example 1 is that: in step (4), the feeding rate of acetylene is 0.5 L / min, and the remaining steps are the same as those in Example 1. Among them, the thickness of the carbon coating layer obtained in step (4) is 7 nm.

[0175] Example 23

[0176] The difference from Example 1 is that: in step (4), the feeding rate of acetylene is 50 L / min, and the remaining steps are the same as those in Example 1. Among them, the thickness of the carbon coating layer obtained in step (4) is 32 nm.

[0177] Example 24

[0178] The difference from Example 1 is that: in step (4), the feeding rate of acetylene is 0.3 L / min, and the remaining steps are the same as those in Example 1. Among them, the thickness of the carbon coating layer obtained in step (4) is 4 nm.

[0179] Comparative Example 1

[0180] A method for preparing a silicon-carbon anode material specifically includes the following steps:

[0181] (1) Place the resin matrix porous carbon (Shenquan Group, ZLS) in a fluidized bed device, heat it to 550 °C under nitrogen protection, feed silane at a feeding rate of 3 L / min and carry out deposition treatment for 4 h, and obtain porous carbon embedded with silicon material after cooling;

[0182] (2) Place the porous carbon embedded with silicon material prepared in step (2) in a fluidized bed device, heat it to 550 °C under nitrogen protection, introduce acetylene at an inlet rate of 3 L / min and carry out deposition treatment for 3 h to form a carbon coating layer with a thickness of 10 nm on the surface of the porous carbon embedded with silicon material, and obtain a silicon-carbon negative electrode material after cooling; wherein, the D of the silicon-carbon negative electrode material 50 is 8.1 m, and the specific surface area is 1.7 m 2 / g, the content of silicon element is 48.2 wt%, and the content of carbon element is 50.4 wt%.

[0183] In Examples 1 to 9 of this application, the carbon layer thickness, pore volume, average pore diameter and specific surface area of the three-dimensional cage-like skeleton prepared in step (2) are shown in Table 1.

[0184] Table 1

[0185]

[0186] The D of the silicon-carbon negative electrode materials prepared in Examples 1 to 24 and Comparative Example 1 of this application 50 , specific surface area, silicon element content, carbon element content and compaction density are shown in Table 2.

[0187] Table 2

[0188]

[0189] Respectively mix the silicon-carbon negative electrode materials, conductive carbon black and binder LA133 (purchased from Sichuan Yindi Le) prepared in Examples 1 to 24 and Comparative Example 1 above according to a weight ratio of 8:1:1 to obtain a negative electrode slurry, apply the above negative electrode slurry to a copper foil with a thickness of 9 μm, and dry it at 80 °C to obtain a negative electrode sheet; use metallic lithium as the counter electrode; the composition of the electrolyte: 1 mol / L LiPF6, the solvent is ethylene carbonate (EC) and ethyl methyl carbonate (EMC), and the volume ratio of EC to EMC is 1:2; use a polypropylene (PP) / polyethylene (PE) composite diaphragm as the diaphragm, and assemble a button-type lithium-ion battery.

[0190] Use a battery test cabinet (Wuhan Landian, CT3002A) to conduct the following electrochemical performance tests on the button-type lithium-ion batteries prepared in Examples 1 to 24 and Comparative Example 1:

[0191] (1) First reversible capacity and first Coulomb efficiency test: Let it stand for 10 hours, discharge at 0.1C to 5 mV, and then charge at 0.1C to 1.5V;

[0192] (2) Full charge expansion rate: Calculate the full charge expansion rate of the button-type lithium-ion battery according to the formula shown in formula (I), Among them, m0 is the thickness of the negative electrode sheet before assembling the battery, m1 is the thickness of the negative electrode sheet after being fully charged (the negative electrode sheet is disassembled from the button-type lithium-ion battery to measure its thickness), and m2 is the thickness of the copper foil;

[0193] (3) 100-cycle capacity retention rate: Under the condition of 25 °C, the voltage range is 0.005 to 1.5 V, and it is cycled 100 times.

[0194] The test results are shown in Table 3. The first charge-discharge curve of the button-type lithium-ion battery prepared in Example 1 is as Figure 4 shown. It can be Figure 4 seen that the capacity of the prepared silicon-carbon negative electrode material is 1806 mAh / g, and the first efficiency is 91.9%.

[0195] Table 3

[0196]

[0197] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0198] Comparative Example 1 is a currently mainstream preparation method of a vapor deposition silicon-carbon negative electrode material. The first reversible capacity and first efficiency of the silicon-carbon negative electrode material prepared by it are relatively high. However, the tap density of the silicon-carbon negative electrode material prepared from a porous carbon matrix is usually low, and it is easy to break during the rolling process of the negative electrode sheet, resulting in a high expansion rate of the silicon-carbon negative electrode material, and further leading to a decline in the cycle performance of the lithium-ion battery. Comparing Example 1 and 2 with Comparative Example 1, it can be seen that the full-charge expansion rate of the button-type lithium-ion batteries prepared in Examples 1 and 2 is much lower than that of Comparative Example 1, and the 100-cycle capacity retention rate is much higher than that of Comparative Example 1. It can be seen from this that compared with the silicon-carbon negative electrode material prepared from a resin porous carbon matrix in the prior art, in the present application, the silicon material is embedded inside the pores of the three-dimensional cage framework composed of aluminophosphate molecular sieve and the first carbon layer, which can effectively relieve the volume expansion of the silicon material during the charge and discharge process of the lithium-ion battery, improve the structural stability and tap density of the silicon-carbon negative electrode material, and thus improve the cycle stability of the lithium-ion battery.

[0199] Comparing Examples 1, 3 to 6, it can be seen that compared with other ranges, limiting the temperature and time of the first deposition treatment within the above ranges is beneficial to form a more suitable first carbon layer on the surface and inner wall of the pores of the three-dimensional framework of the aluminophosphate molecular sieve, which is beneficial to providing sufficient buffer space for the volume expansion of the silicon material during the charge and discharge process, and thus is beneficial to reducing the full-charge expansion rate of the lithium-ion battery and improving its cycle stability.

[0200] Comparing Examples 1, 7 to 9, it can be seen that compared with other ranges, limiting the feeding rate of the first carbon source within the above range is beneficial to forming a first carbon layer with a more suitable thickness, improving the uniformity and density of the first carbon layer, alleviating the volume expansion of the silicon material, thereby reducing the full-charge expansion rate of the lithium-ion battery and improving its cycle stability.

[0201] Comparing Examples 1, 10 to 13, it can be seen that the first reversible capacities and first Coulombic efficiencies of Examples 11 and 13 are relatively low. This is because less silicon material is deposited in Examples 11 and 13, which limits the exertion of their high-capacity characteristics and reduces the effective storage of lithium ions, resulting in the reduction of their first reversible capacities and first Coulombic efficiencies. At the same time, the full-charge expansion rates and cycle capacity retention rates of Examples 11 and 13 are also relatively low. It can be seen from this that compared with other ranges, limiting the temperature and time of the second deposition treatment within the above range is beneficial to uniformly depositing the silicon source inside the pore channels of the three-dimensional cage framework, enhancing the bonding force between the silicon material and the first carbon layer, thereby alleviating the volume expansion of the silicon material, further improving the electrochemical performance of the lithium-ion battery, reducing the full-charge expansion rate of the lithium-ion battery, and improving its cycle stability.

[0202] Comparing Examples 1, 14 to 16, it can be seen that the first reversible capacity and first Coulombic efficiency of Example 16 are relatively low. This is because less silicon material is deposited in Example 16, which limits the exertion of its high-capacity characteristics and reduces the effective storage of lithium ions, resulting in the reduction of its first reversible capacity and first Coulombic efficiency. At the same time, its full-charge expansion rate and cycle capacity retention rate are also relatively low. It can be seen from this that compared with other ranges, limiting the feeding rate of the first carbon source within the above range is beneficial to more uniformly depositing an appropriate amount of silicon source inside the pore channels of the three-dimensional cage framework, thereby improving the compaction density and structural stability of the silicon-carbon negative electrode material, alleviating the volume expansion of the silicon material, improving the electrochemical performance of the lithium-ion battery, reducing the full-charge expansion rate of the lithium-ion battery, and improving its cycle stability.

[0203] Comparing Example 1 and 17, it can be seen that compared with the silicon-carbon negative electrode material without the second carbon layer coating, the introduction of the second carbon layer is beneficial to improving the conductivity of the silicon-carbon negative electrode material, reducing the direct contact between the silicon material and the electrolyte, and at the same time is also beneficial to alleviating the volume expansion of the silicon material, thereby reducing the full-charge expansion rate of the lithium-ion battery and improving its cycle stability.

[0204] Comparing Examples 1, 18 to 21, it can be seen that limiting the temperature and time of the third deposition process within the above ranges is beneficial to forming a more uniform and appropriately thick second carbon layer, which is conducive to reducing the direct contact between the silicon material and the electrolyte, and at the same time is conducive to providing sufficient buffer space for the volume expansion of the silicon material during charge and discharge, thereby being conducive to reducing the full-charge expansion rate of the lithium-ion battery and improving its cycle stability.

[0205] Comparing Examples 1, 22 to 24, it can be seen that compared with other ranges, limiting the introduction rate of the second carbon source within the above range is beneficial to forming a second carbon layer with an appropriately thick thickness, which is conducive to improving the uniformity and denseness of the second carbon layer, conducive to reducing the direct contact between the silicon material and the electrolyte, and at the same time is also conducive to alleviating the volume expansion of the silicon material, thereby being conducive to reducing the full-charge expansion rate of the lithium-ion battery and improving its cycle stability.

[0206] It should be noted that the terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects and do not necessarily have to be used to describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented, for example, in an order other than those described herein.

[0207] 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, the present invention can have various modifications and changes. 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 silicon-carbon anode material, characterized in that, The silicon-carbon negative electrode material includes a three-dimensional cage framework and a silicon material. The three-dimensional cage framework has a pore structure, and the silicon material is embedded inside the pores of the three-dimensional cage framework. The three-dimensional cage framework includes aluminophosphate molecular sieve and a first carbon layer disposed on the surface of the three-dimensional framework and the inner wall of the pores of the aluminophosphate molecular sieve.

2. The silicon-carbon anode material according to claim 1, wherein The D of the silicon-carbon anode material 50 is 0.5 to 50 μm, and the specific surface area is 0.5 to 100 m 2 / g; Preferably, the pore volume of the three-dimensional cage skeleton is 0.1 to 2.0 cm 3 / g, the average pore diameter is 0.5 to 50 nm, and the specific surface area is 10 to 3000 m 2 / g; Preferably, the thickness of the first carbon layer is 0.1 - 300 nm; Preferably, calculated by weight percentage of the silicon-carbon negative electrode material, the content of silicon element is 1 - 80 wt%, and the content of carbon element in the first carbon layer is 1 - 40 wt%.

3. The silicon-carbon negative electrode material according to claim 1 or 2, characterized in that, The pore volume of the aluminophosphate molecular sieve is 0.01 to 3.0 cm 3 / g, the average pore diameter is 0.1 to 300 nm, and the specific surface area is 50 to 3200 m 2 / g; Preferably, the average particle size of the aluminophosphate molecular sieve is 0.5 - 30 μm; Preferably, the P / Al ratio of the aluminophosphate molecular sieve is (0.01 - 10):(0.01 - 10), and the P / O ratio is (0.01 - 10):(0.05 - 10); Preferably, the aluminophosphate molecular sieve further includes a doped metal element; Preferably, the doped metal element is selected from one or more of the elements in Group IA, Group IIA, Group IIIA, Group IVA, Group IIB, Group IIIB, Group IVB, Group VB, Group VIIB, and Group VIII; More preferably, the doped metal element is selected from one or more of the group consisting of Li, Be, Mg, Ga, In, Ge, Sn, Ti, V, Nb, Cr, W, Mn, Co, Ni, Cu, and Zn.

4. The silicon-carbon negative electrode material according to any one of claims 1 to 3, characterized in that, The surface of the silicon-carbon negative electrode material further includes a second carbon layer, and the second carbon layer is disposed on the surface of the three-dimensional cage framework embedded with the silicon material; Preferably, the thickness of the second carbon layer is 0.1 - 100 nm; Preferably, calculated by weight percentage of the silicon-carbon negative electrode material, the content of silicon element is 1 - 80 wt%, and the total content of carbon element in the first carbon layer and the second carbon layer is 5 - 90 wt%; More preferably, the silicon material is selected from one or more of the group consisting of amorphous silicon, single crystal silicon, and polycrystalline silicon.

5. A method for preparing the silicon-carbon negative electrode material according to any one of claims 1 to 4, characterized in that, The preparation method includes: Step S1, preparing aluminophosphate molecular sieve by the template method; Step S2, in an inert gas atmosphere, performing a first deposition treatment on the aluminophosphate molecular sieve with a first carbon source to obtain a three-dimensional cage framework; Step S3, in an inert gas atmosphere, performing a second deposition treatment on the three-dimensional cage framework with a silicon source to obtain the silicon-carbon negative electrode material.

6. The preparation method of the silicon-carbon anode material according to claim 5, characterized in that, In the step S2, the temperature of the first deposition treatment is 500 - 1000 °C, and the time is 0.5 - 20 h; Preferably, the first deposition treatment is performed by chemical vapor deposition, and the feeding rate of the first carbon source is 0.5 - 50 L / min; Preferably, in the step S3, the temperature of the second deposition treatment is 400 - 850 °C, and the time is 0.5 - 20 h; Preferably, the second deposition treatment is performed by chemical vapor deposition, and the feeding rate of the silicon source is 0.5 - 50 L / min.

7. The preparation method of the silicon-carbon anode material according to claim 5 or 6, characterized in that, The preparation method further includes: in an inert gas atmosphere, performing a third deposition treatment on the product obtained by the second deposition treatment with a second carbon source to obtain the silicon-carbon negative electrode material; Preferably, the temperature of the third deposition treatment is 400 - 900 °C, and the time is 0.5 - 20 h; Preferably, the third deposition treatment is carried out by chemical vapor deposition, and the feeding rate of the second carbon source is 0.5 - 50 L / min; Preferably, the first carbon source and the second carbon source are each independently selected from one or more of the group consisting of acetylene, methane, ethane, propane, butane, ethylene, propylene, butene, methanol, ethanol, propanol, and benzene; Preferably, the silicon source is selected from one or more of the group consisting of silane, disilane, trisilane, tetrasilane, chlorosilane, dichlorosilane, trichlorosilane, and tetrachlorosilane; Preferably, the protective gas is selected from one or more of the group consisting of nitrogen, argon, helium, neon, krypton, and xenon.

8. The preparation method of the silicon-carbon anode material according to claim 5, characterized in that, The step S1 includes: mixing an aluminum source, phosphoric acid, a template agent, and a solvent, and obtaining the aluminophosphate molecular sieve after crystallization and sintering; Preferably, the weight ratio of the aluminum source, the phosphoric acid, the template agent to the solvent is (0.1 - 2):(0.1 - 2):(0.1 - 2):(1 - 100); Preferably, the temperature of the crystallization is 25 - 300 °C, and the time is 0.2 - 48 h; Preferably, the temperature of the sintering is 500 - 1000 °C, and the time is 0.5 - 48 h; Preferably, the aluminum source is selected from one or more of the group consisting of aluminum isopropoxide, aluminum chloride, and pseudo-boehmite; Preferably, the template agent is an organic amine, and more preferably the organic amine is selected from one or more of the group consisting of triethylamine, di-n-propylamine, and diisopropylamine; Preferably, the solvent is selected from one or more of the group consisting of water, ethanol, methanol, and acetone.

9. The preparation method of the silicon-carbon anode material according to claim 8, wherein, In the step S1, a metal source is further introduced during the mixing process, and an aluminophosphate molecular sieve doped with a metal element is obtained after crystallization; the step S2 further includes: in an atmosphere of a protective gas, performing the first deposition treatment on the aluminophosphate molecular sieve doped with the metal element with the first carbon source to obtain the three-dimensional cage framework; Preferably, the mass concentration of the metal source is 0.1 - 10 wt%; Preferably, the metal source is selected from one or more of the group consisting of oxides, acids, bases, and salts containing the metal element; Preferably, the metal element is selected from one or more of the group consisting of metal elements in Group IA, Group IIA, Group IIIA, Group IVA, Group IIB, Group IIIB, Group IVB, Group VB, Group VIIB, and Group VIII; more preferably the metal element is selected from one or more of the group consisting of Li, Be, Mg, Ga, In, Ge, Sn, Ti, V, Nb, Cr, W, Mn, Co, Ni, Cu, and Zn; Preferably, the metal source is selected from one or more of the group consisting of titanium oxide, gallium oxide, tin oxide, copper chloride, tungsten oxide, niobium oxide, magnesium chloride, and nickel oxide.

10. A lithium-ion battery, comprising a positive electrode, a negative electrode, an electrolyte, and a separator disposed between the positive electrode and the negative electrode, characterized in that, The negative electrode includes the silicon-carbon negative electrode material according to any one of claims 1 to 4.

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