Foam conductive framework material for lithium battery negative electrode material and preparation method thereof

Abstract

This application proposes a foam conductive framework material for lithium-ion battery anode materials and its preparation method. The foam conductive framework material exhibits a porous foam-like structure, with silicon nanowires forming the internal framework. At least a portion of the surface of the framework is covered with a doped carbon layer. The preparation method of the foam conductive framework material includes: coating silicon nanowires with an organic carbon source, then crosslinking the organic carbon-coated silicon nanowires with a crosslinking agent to form a 3D network structure. A foaming agent is adsorbed within the network. A foam-like silicon / carbon composite framework is formed through foaming and carbonization processes. The foam conductive framework material for lithium-ion battery anode materials of this application not only possesses the advantages of high conductivity and low volume expansion rate of traditional carbon-based conductive framework materials, but also has higher specific capacity and better ion conduction ability, which can more effectively improve the cycle performance of anode materials.

Description

Technical Field

[0001] This application relates to the field of secondary battery technology, and in particular to a foamed silicon-carbon composite material, its preparation method, and its application. Background Technology

[0002] The theoretical specific capacity of silicon-based anodes is 4200 mAh / g, ten times that of traditional graphite anodes, which can significantly improve the energy density and battery life of lithium batteries. However, the commercial application of silicon-based anodes faces many challenges. First, the rapid volume expansion and contraction during charging and discharging can cause electrode cracking, pulverization, and even detachment, leading to battery failure. Second, silicon nanowires have very poor conductivity, comparable to activated carbon, far inferior to graphite anodes, affecting the rate performance and capacity utilization of lithium batteries.

[0003] Related technologies attempt to overcome the shortcomings of silicon-based anodes using carbon foam. These technologies generally use asphalt, biomass, or polymer resins as raw materials and employ supercritical methods, template methods, and radiation methods to prepare carbon foam. However, these methods share a common drawback:

[0004] 1. Complex process. Supercritical methods use high-pressure reactors. Template methods typically require a post-processing step of etching to remove the template;

[0005] 2. The raw materials are expensive, especially those using polymer resins.

[0006] Furthermore, the specific capacity, conductivity, and electrochemical performance of carbon foams prepared by these methods still need to be improved, and there have been no reports on carbon foams supported on silicon nanowires. Summary of the Invention

[0007] In view of this, one objective of this application is to provide a foam conductive framework material for lithium-ion battery anode materials. The foam exhibits a porous foam structure with silicon nanowires as the internal framework and a doped carbon layer on the surface. This structural configuration not only possesses the advantages of low volume expansion and good cycle performance of traditional carbon-based frameworks, but also exhibits a higher specific capacity than traditional carbon-based frameworks. Furthermore, the porous foam structure has abundant pores / pores, which can be further loaded with silicon-based anode materials or graphite of different capacities, thereby further improving the capacity and electrochemical performance of silicon-carbon anode materials.

[0008] Another objective of this application is to provide a method for preparing a foam conductive skeleton material for lithium battery anode materials.

[0009] To achieve the above objectives, the first aspect of this application proposes a foam conductive framework material for lithium battery anode materials. The apparent structure of the foam conductive framework material for lithium battery anode materials is a porous foam structure, with silicon nanowires (SiNWs) as the framework inside. At least a portion of the surface layer of the framework is covered with a doped carbon layer.

[0010] The foam conductive framework material for lithium-ion battery anode materials described in this application exhibits a porous foam structure with silicon nanowires as the internal framework and a doped carbon layer on the surface. This structural configuration not only combines the advantages of low volume expansion and good cycle performance of traditional carbon-based frameworks, but also provides a higher specific capacity than traditional carbon-based frameworks. Furthermore, the porous foam structure possesses abundant pores / pores, which can be further loaded with silicon-based anode materials or graphite of varying capacities, thereby further improving the capacity and electrochemical performance of the silicon-carbon anode material.

[0011] In some embodiments, the doping in the doped carbon layer is N-type doping, and the doping element includes, but is not limited to, at least one of phosphorus and nitrogen.

[0012] In some embodiments, the silicon nanowires comprise 1-50% by mass in the foam conductive framework material used as a lithium battery anode material.

[0013] In some embodiments, the doped carbon layer has a mass content of 50-99% in the foam conductive framework material used as a lithium battery anode material.

[0014] In some embodiments, the dopant element in the doped carbon layer has a mass content of 0.01-2% in the doped carbon layer.

[0015] In some embodiments, the doped carbon layer contains microcrystalline graphite. The doped carbon layer on the surface of the silicon nanowire framework contains a large amount of microcrystalline graphite, and the conductive network constructed by this microcrystalline graphite can effectively improve its electronic and ionic conductivity, thereby effectively improving the electrochemical performance of the anode material, such as initial efficiency and specific capacity.

[0016] In some embodiments, the foam conductive skeleton material used for lithium battery anode materials also includes other types of anode materials loaded on the porous foam structure.

[0017] In some embodiments, the other types of negative electrode materials include, but are not limited to, at least one of silicon, tin, and graphite.

[0018] In some embodiments, the silicon material includes, but is not limited to, at least one of silicon nanowires (SiNWs), silicon nanoparticles (SiNPs), silicon nanotubes, silicon nanosheets, silicene, silicon microparticles (SiMPs), and silicon suboxide.

[0019] In some embodiments, the tin material includes, but is not limited to, at least one of elemental tin, tin oxide, etc.

[0020] In some embodiments, the other types of negative electrode materials have a mass content of 0.01-60% in the foam conductive skeleton material used as a negative electrode material for lithium batteries.

[0021] The second aspect of this application discloses a method for preparing a foam conductive framework material for lithium battery anode materials, comprising:

[0022] Silicon nanowires coated with organic carbon were obtained by coating them with an organic carbon source.

[0023] The organic carbon-coated silicon nanowires are cross-linked using a cross-linking agent to form a 3D network structure;

[0024] A foaming agent is adsorbed inside the 3D mesh structure to obtain a 3D network structure containing a foaming agent;

[0025] The 3D network structure containing a foaming agent is foamed and carbonized to form a foam-like silicon / carbon composite skeleton, which is the foam conductive skeleton material used for lithium battery anode materials.

[0026] In some embodiments, the organic carbon source includes, but is not limited to, lignin, organic polymer resins (e.g., at least one of phenolic resins, epoxy resins, etc.), organic acid esters (e.g., at least one of polyurethanes, polyacrylates, etc.), preferably lignin.

[0027] In some embodiments, when the organic carbon source comprises lignin, the crosslinking agent includes, but is not limited to, at least one of dialdehyde crosslinking agents. For example, the dialdehyde crosslinking agent includes, but is not limited to, at least one of glutaraldehyde, acetaldehyde, etc.

[0028] In some embodiments, when the organic carbon source comprises an organic polymer resin, the crosslinking agent includes, but is not limited to, at least one of epoxy resin crosslinking agents or phenolic resin crosslinking agents.

[0029] In some embodiments, when the organic carbon source comprises an organic ester and the organic carboxylic acid ester comprises polyurethane and polyacrylate, the crosslinking agent includes, but is not limited to, at least one of diamine crosslinking agents. For example, the diamine crosslinking agent includes, but is not limited to, at least one of hexamethylenediamine and ethylenediamine.

[0030] In some embodiments, the foaming agent includes, but is not limited to, at least one of N-type doped foaming agents.

[0031] In some embodiments, the N-type doped foaming agent includes, but is not limited to, at least one of phosphoric acid, ammonium phosphate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate, preferably phosphoric acid.

[0032] In some embodiments, the mass ratio of the organic carbon source, the silicon nanowires, the foaming agent, and the crosslinking agent is 1:(0.01-0.5):(0.1-1):(0.05-1).

[0033] In some embodiments, coating silicon nanowires with an organic carbon source includes: adding the silicon nanowires to a solvent, followed by adding the organic carbon source and mixing.

[0034] In some embodiments, the solvent includes at least one of water, anhydrous ethanol, N-methylpyrrolidone (NMP), etc.

[0035] In some embodiments, the total mass of the organic carbon source, the silicon nanowires, the crosslinking agent, and the foaming agent is a kg, and the mass of the solvent is b kg, where a is 5-10% of b.

[0036] In some embodiments, the organic carbon-coated silicon nanowires are crosslinked to form a 3D network structure by means of a crosslinking agent, including: adding the crosslinking agent to the organic carbon-coated silicon nanowires, followed by a crosslinking reaction under stirring or ultrasonic dispersion conditions.

[0037] In some embodiments, the crosslinking reaction is carried out at room temperature for 30-60 minutes.

[0038] In some embodiments, adsorbing a foaming agent inside the 3D mesh structure includes: adding the foaming agent dropwise into the 3D network structure containing the foaming agent.

[0039] In some embodiments, the adsorption of the foaming agent inside the 3D mesh structure further includes a drying step after the addition is completed.

[0040] In some embodiments, the foaming method includes: grinding the 3D network structure containing the foaming agent and then heating it.

[0041] In some embodiments, the method for preparing the foam conductive skeleton material for lithium battery anode materials further includes washing and drying steps after carbonization.

[0042] In some embodiments, the method for preparing the foam conductive skeleton material for lithium battery anode materials further includes a step of loading other types of anode materials onto the product obtained after washing and drying following carbonization; the other types of anode materials include at least one of silicon, tin and graphite.

[0043] In some embodiments, the silicon material includes at least one of silicon nanowires, silicon nanoparticles, silicon nanotubes, silicon nanosheets, silicene, silicon micron particles, and silicon suboxide.

[0044] In some embodiments, the tin material includes at least one of elemental tin and tin oxide.

[0045] In some embodiments, the method of loading other types of negative electrode materials onto the dried product includes at least one of in-situ growth, pressure filling, solution adsorption, and physical mixing.

[0046] In some embodiments, the foaming temperature is 110-150°C.

[0047] In some embodiments, the foaming time is 1-5 hours.

[0048] In some embodiments, the carbonization temperature is 200-1000°C.

[0049] In some embodiments, the carbonization time is 0.5-2 hours.

[0050] In some embodiments, the carbonization heating rate is 1-10°C / min.

[0051] In some embodiments, the cooling method after carbonization is natural cooling.

[0052] In some embodiments, the carbonization is carried out in a gaseous atmosphere, the gas including at least one of an inert gas and a mixture of an inert gas and hydrogen.

[0053] In some embodiments, the gas flow rate is 100-800 sccm.

[0054] In some embodiments, the volume fraction of hydrogen in the mixture of inert gas and hydrogen is 3-10%.

[0055] The method for preparing the foam conductive framework material for lithium battery anode materials described in this application can bring at least the following beneficial effects:

[0056] 1. After coating silicon nanowires with an organic carbon source, a crosslinking agent is used to crosslink the organic carbon-coated silicon nanowires to form a 3D network structure. A foaming agent is adsorbed within the network. Through foaming and carbonization processes, a foam-like silicon / carbon composite framework is ultimately formed. The material exhibits a porous foam-like structure, with silicon nanowires forming the internal framework. At least a portion of the framework's surface is covered with a doped carbon layer. Because its framework is composed of silicon nanowires, the material not only possesses the advantage of low volume expansion rate typical of traditional carbon-based frameworks, thus exhibiting better cycle performance, but the constructed foam conductive framework (i.e., the foam-like silicon / carbon composite framework) also has a higher specific capacity than traditional carbon-based frameworks.

[0057] 2. The prepared material has a 3D network structure of silicon / carbon composite framework (i.e., a porous foam structure), which makes it rich in pores / pores. These pores / pores can be further loaded with silicon-based anode materials or graphite of different capacities, thereby further improving the capacity and electrochemical performance of silicon-carbon anode materials.

[0058] 3. The carbon layer (i.e., the doped carbon layer) on the surface of the foam conductive skeleton contains a large amount of microcrystalline graphite. The conductive network constructed by this microcrystalline graphite can effectively improve its electronic and ion conduction capabilities, thereby effectively improving the electrochemical performance of the negative electrode material, such as its first efficiency and specific capacity.

[0059] 4. The main source of organic carbon is industrial waste, which allows for waste recycling and is highly sustainable and environmentally friendly. It also has advantages such as low cost and simple process.

[0060] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0061] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings.

[0062] in:

[0063] Figure 1 This is a flowchart illustrating a method for preparing a foam conductive framework material for a lithium battery anode material, as shown in an exemplary embodiment of this application.

[0064] Figure 2 Photograph of the foam conductive skeleton material for lithium battery anode material prepared in Example 1.

[0065] Figure 3 The images show a comparison of the Raman spectra of the foam conductive framework material for lithium battery anode materials prepared in Example 1 and the carbon material prepared in Comparative Example 1, wherein:

[0066] (a) is the Raman spectrum of the foam conductive framework material for lithium battery anode material prepared in Example 1.

[0067] (b) is the Raman spectrum of the carbon material prepared in Comparative Example 1.

[0068] Figure 4a The image shows a scanning electron microscope (SEM) image of the electrode sheet after cycling of the foam conductive skeleton material for lithium battery anode material prepared in Example 5.

[0069] Figure 4b Scanning electron microscope (SEM) image of the electrode prepared for Comparative Example 3 after cycling. Detailed Implementation

[0070] The embodiments of this application are described in detail below, with examples of these embodiments illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0071] In this application, the disclosure of numerical ranges includes all values ​​throughout the range and the disclosure of further subdivisions of the range, including the endpoints and subranges given for these ranges.

[0072] Unless otherwise specified, all raw materials and equipment involved in this application are self-made through commercial means or known methods; and all methods involved are conventional methods unless otherwise specified.

[0073] When the term “and / or” is used in a list containing two or more items, it means that any of the listed items can be used alone or in combination with any one or more of the listed items. For example, the expression “A and / or B” is intended to mean A or B or A and B, that is, A only, B only, or a combination of A and B.

[0074] In this application, room temperature refers to 20-30°C.

[0075] <Foam Conductive Skeleton Material for Lithium-ion Battery Anode Materials>

[0076] The foam conductive framework material for lithium battery anode materials of this application embodiment has an apparent structure of porous foam, with silicon nanowires as the framework inside, and at least a portion of the surface layer of the framework is covered with a doped carbon layer.

[0077] The foam conductive framework material for lithium-ion battery anode materials of this application presents a porous foam structure with silicon nanowires as the internal framework and a doped carbon layer on the surface. This structural configuration not only possesses the advantages of low volume expansion and good cycle performance of traditional carbon-based frameworks, but also exhibits a higher specific capacity than traditional carbon-based frameworks. Furthermore, the porous foam structure has abundant pores / pores, which can be further loaded with silicon-based anode materials or graphite of different capacities, thereby further improving the capacity and electrochemical performance of the silicon-carbon anode material.

[0078] It should be noted that, in the embodiments of this application, the porous foam-like structure of the foam conductive framework material used for lithium battery anode materials is essentially a written description of the 3D network structure in the preparation method of the foam conductive framework material used for lithium battery anode materials described later. It can be understood as a 3D network structure, specifically the product of foaming and carbonization after the adsorption of a foaming agent within the 3D network structure in the preparation method, i.e., a foam-like silicon / carbon composite framework. Therefore, in the embodiments of this application, the apparent structure of the foam conductive framework material used for lithium battery anode materials presents as a porous foam-like structure, rather than a 3D network structure itself. Furthermore, in the embodiments of this application, the 3D network structure is a three-dimensional framework structure similar to a spider web, constructed from silicon nanowires, such as a tetrahedral framework structure or an octahedral framework structure.

[0079] In some embodiments, the doping in the doped carbon layer is N-type doping.

[0080] For example, the doping elements in the doped carbon layer include, but are not limited to, at least one of phosphorus and nitrogen, preferably phosphorus. In the embodiments of this application, the doping elements can improve the electrochemical performance of the foam conductive framework material used as a negative electrode material for lithium batteries, for example, by improving the conductivity of the silicon nanowire framework and thus reducing the internal resistance of the battery to meet the requirements of fast charging applications.

[0081] It should be noted that in the foam conductive skeleton material for lithium battery anode materials in the embodiments of this application, the doping elements in the doped carbon layer are mainly introduced by the foaming agent in the preparation method of the foam conductive skeleton material for lithium battery anode materials described later.

[0082] In some embodiments, the silicon nanowires comprise 1-50% by mass in the foam conductive framework material used as a lithium battery anode material.

[0083] For example, the mass content of the silicon nanowires in the foam conductive skeleton material used as a negative electrode material for lithium batteries includes, but is not limited to, 1%, 5%, 10%, 20%, 30%, 40%, or 50%.

[0084] In some embodiments, the mass content of the doped carbon layer in the foam conductive skeleton material used as a negative electrode material for lithium batteries is 50-99%, including but not limited to 50%, 55%, 60%, 70%, 80%, 90%, or 95%.

[0085] In some embodiments, the dopant element in the doped carbon layer has a mass content of 0.01-2% in the doped carbon layer, including but not limited to 0.05%, 0.25%, 0.5%, 0.75%, 1%, 1.25%, 1.5%, 1.75%, or 2%.

[0086] In some embodiments, the foam conductive framework material used for lithium battery anode materials also includes other types of anode materials loaded on the porous foam structure. The porous foam structure has abundant pores / pores, which can be further loaded with silicon-based anode materials, tin materials, graphite, etc., of different capacities, thereby further improving the capacity and electrochemical performance of the silicon-carbon anode material.

[0087] In some embodiments, the other types of negative electrode materials include, but are not limited to, at least one of silicon, tin, and graphite.

[0088] For example, the silicon material includes, but is not limited to, at least one of silicon nanowires (SiNWs), silicon nanoparticles (SiNPs), silicon nanotubes, silicon nanosheets, silicene, silicon microparticles (SiMPs), and silicon suboxide.

[0089] For example, the tin material includes, but is not limited to, at least one of elemental tin, tin oxide, etc.

[0090] In some embodiments, the other types of negative electrode materials are present in the foam conductive skeleton material for lithium battery negative electrode materials (the foam conductive skeleton material for lithium battery negative electrode materials containing other types of negative electrode materials) at a mass content of 0.01-60%, including but not limited to 0.1%, 5%, 10%, 20%, 30%, 40%, 50%, or 55%.

[0091] In some embodiments, the doped carbon layer contains microcrystalline graphite. The doped carbon layer on the surface of the silicon nanowire framework contains a large amount of microcrystalline graphite, and the conductive network constructed by this microcrystalline graphite can effectively improve its electronic and ionic conductivity, thereby effectively improving the electrochemical performance of the anode material, such as initial efficiency and specific capacity.

[0092] As an alternative example, the mass content of microcrystalline graphite in the surface coating layer (i.e., the coated doped carbon layer) is 30-70%, including but not limited to 35%, 40%, 45%, 50%, 55%, 60% or 65%.

[0093] <Preparation Method of Foam Conductive Framework Material for Lithium-ion Battery Anode Material>

[0094] The method for preparing the foam conductive skeleton material for lithium battery anode materials in this application embodiment can be used to prepare the foam conductive skeleton material for lithium battery anode materials in this application embodiment.

[0095] Figure 1 This is a flowchart illustrating a method for preparing a foam conductive framework material for a lithium battery anode material, as shown in an exemplary embodiment of this application.

[0096] like Figure 1 As shown, the preparation method includes the following steps:

[0097] S101. Silicon nanowires are coated with an organic carbon source to obtain organic carbon-coated silicon nanowires.

[0098] S102. The organic carbon-coated silicon nanowires are cross-linked by a cross-linking agent to form a 3D network structure.

[0099] S103. Adsorb foaming agent inside the 3D mesh structure to obtain a 3D network structure containing foaming agent.

[0100] S104. The 3D network structure containing the foaming agent is foamed and carbonized to form a foam-like silicon / carbon composite skeleton, which is the foam conductive skeleton material used for lithium battery anode materials.

[0101] It should be noted that the foam-like silicon / carbon composite framework is the same as the foam conductive framework material used in lithium battery anode materials mentioned above, which has an apparent structure of porous foam, with silicon nanowires as the framework inside, and at least a portion of the surface of the framework being a doped carbon layer.

[0102] In some embodiments, in step S101, the organic carbon source includes, but is not limited to, at least one of lignin, organic polymer resins, and organic acid esters, preferably lignin. Lignin is a major component of waste materials from the papermaking industry (commonly known as "black pulp"). It is typically used as fuel for incineration to generate electricity, resulting in resource waste and poor sustainability. From the perspective of sustainable development, this application aims to use industrial waste such as lignin as organic carbon sources to achieve waste reuse, which is green, environmentally friendly, and highly sustainable, thus making the preparation method have advantages such as low cost and simple process.

[0103] For example, organic polymer resins include, but are not limited to, at least one of epoxy resins, phenolic resins, etc.

[0104] For example, organic esters include, but are not limited to, at least one of polyurethane, polyacrylate, etc.

[0105] In the embodiments of this application, in step S102, the crosslinking agent is a type of crosslinking agent that matches the organic carbon source.

[0106] In some embodiments, when the organic carbon source includes lignin, the crosslinking agent includes, but is not limited to, at least one of dialdehyde crosslinking agents.

[0107] For example, the dialdehyde crosslinking agent includes, but is not limited to, at least one of glutaraldehyde, acetaldehyde, etc.

[0108] In some embodiments, when the organic carbon source comprises an organic polymer resin, the crosslinking agent includes, but is not limited to, at least one of epoxy resin crosslinking agents or phenolic resin crosslinking agents.

[0109] In some embodiments, when the organic carbon source comprises an organic ester and the organic carboxylic acid ester comprises polyurethane and polyacrylate, the crosslinking agent includes, but is not limited to, at least one of diamine crosslinking agents.

[0110] For example, the diamine crosslinking agent includes, but is not limited to, at least one of hexamethylenediamine, ethylenediamine, etc.

[0111] In some embodiments, in step S103, the foaming agent includes, but is not limited to, at least one of N-type doped foaming agents.

[0112] For example, the N-type doped foaming agent includes, but is not limited to, at least one of phosphoric acid, ammonium phosphate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate, preferably phosphoric acid.

[0113] In some embodiments, the mass ratio of the organic carbon source, the silicon nanowires, the foaming agent, and the crosslinking agent is 1:(0.01-0.5):(0.1-1):(0.05-1), including but not limited to 1:0.1:0.1:0.05, 1:0.3:0.1:0.1, 1:0.4:0.1:0.075, 1:0.25:0.5:0.5, 1:0.25:0.3:0.15, 1:0.25:0.7:0.35, or 1:0.25:1:0.75, etc.

[0114] In some embodiments, step S101, coating the silicon nanowires with an organic carbon source, includes: adding the silicon nanowires to a solvent, and then adding the organic carbon source and mixing.

[0115] It should be noted that the process of adding the silicon nanowires to the solvent can also be regarded as the process of raw material dispersion, specifically the process of silicon nanowire dispersion.

[0116] In some embodiments, the solvent includes at least one of water, anhydrous ethanol, N-methylpyrrolidone (NMP), etc.

[0117] As an alternative example, when the organic carbon source comprises an organic polymer resin, the solvent comprises alcohol (e.g., anhydrous ethanol).

[0118] For example, the organic carbon source can be added and mixed in a manner that includes, but is not limited to, stirring, ultrasonic dispersion, etc.

[0119] In some embodiments, the total mass of the organic carbon source, the silicon nanowires, the crosslinking agent, and the foaming agent is a kg, and the mass of the solvent is b kg, where a is 5-10% of b, including but not limited to 5.5%, 6.5%, 7.5%, 8.5%, or 9.5%.

[0120] In some embodiments, step S102, crosslinking the organic carbon-coated silicon nanowires to form a 3D network structure using a crosslinking agent, includes: adding the crosslinking agent to the organic carbon-coated silicon nanowires obtained in step S101, followed by a crosslinking reaction under stirring or ultrasonic dispersion conditions.

[0121] In some embodiments, the crosslinking reaction is carried out at room temperature.

[0122] In some embodiments, the crosslinking reaction takes 30-60 minutes, including but not limited to 35 minutes, 40 minutes, 45 minutes, 50 minutes or 55 minutes, preferably 30 minutes.

[0123] In some embodiments, step S103, adsorbing the foaming agent inside the 3D mesh structure, includes: adding the foaming agent dropwise into the 3D network structure containing the foaming agent.

[0124] In some embodiments, step S103, the adsorption of the foaming agent inside the 3D mesh structure, further includes a drying step after the addition is completed.

[0125] For example, drying methods after the addition is complete include, but are not limited to, rotary evaporation until the solvent has completely evaporated.

[0126] In some embodiments, the foaming method includes: grinding the 3D network structure containing the foaming agent and then heating it. Foaming is achieved by grinding and heating the 3D network structure containing the foaming agent; during the heating process, moisture in the foaming agent, such as phosphoric acid, evaporates (dehydrates), while organic carbon sources, such as lignin, undergo pyrolysis.

[0127] In some embodiments, the preparation method of the foamed silicon-carbon composite material further includes washing and drying steps after carbonization.

[0128] In the embodiments of this application, the purpose of washing is to remove ash and residual foaming agents such as phosphoric acid.

[0129] For example, the washing method described above involves rinsing with deionized water to remove ash and residual foaming agents such as phosphoric acid.

[0130] For example, the drying methods after carbonization include, but are not limited to, baking, spray drying, vacuum drying, etc., such as drying in a constant temperature oven at 80°C to constant weight.

[0131] In some embodiments, the foaming temperature is 110-150°C, including but not limited to 110°C, 120°C, 130°C, 140°C or 150°C, preferably 140°C.

[0132] In some embodiments, the foaming time is 1-5 hours, including but not limited to 1 hour, 2 hours, 3 hours, 4 hours or 5 hours, preferably 3 hours.

[0133] In some embodiments, the carbonization temperature is 200-1000°C, including but not limited to 200°C, 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C or 1000°C, preferably 850°C.

[0134] In the embodiments of this application, excessively high carbonization temperatures (e.g., exceeding 1000°C) may cause the material to gradually lose its toughness and become brittle.

[0135] In some embodiments, the carbonization time is 0.5-2 hours, including but not limited to 0.5 hours, 1 hour, 1.5 hours or 2 hours, preferably 1 hour.

[0136] In some embodiments, the heating rate of the carbonization is 1-10°C / min, including but not limited to 2°C / min, 5°C / min, 7°C / min or 10°C / min, preferably 5°C / min.

[0137] In some embodiments, the cooling method after carbonization is natural cooling.

[0138] In some embodiments, the carbonization is carried out in a gaseous atmosphere, the gas including at least one of an inert gas and a mixture of an inert gas and hydrogen.

[0139] For example, inert gases include, but are not limited to, at least one of nitrogen, argon, helium, etc.

[0140] For example, the volume fraction of hydrogen in the mixture of inert gas and hydrogen is 3-10%, including but not limited to 4%, 5%, 6%, 7%, 8% or 9%.

[0141] In some embodiments, the gas flow rate is 100-800 sccm, including but not limited to 200 sccm, 400 sccm, 500 sccm or 700 sccm, preferably 500 sccm.

[0142] In some embodiments, carbonization is carried out in a quartz tube furnace, but is not limited to a quartz tube furnace; it can also be any other reactor in the art capable of carrying out a carbonization reaction.

[0143] As an optional example, the method for preparing a foam conductive framework material for lithium battery anode materials according to embodiments of this application includes the following steps:

[0144] (1) Disperse silicon nanowires in a solvent, add an organic carbon source and mix well, then add a crosslinking agent and carry out a crosslinking reaction under stirring or ultrasonic dispersion conditions. After the crosslinking reaction, add a foaming agent dropwise, and then dry the mixture to obtain a mixture (i.e., a 3D network structure containing a foaming agent).

[0145] (2) Grind the mixture obtained in step (1) evenly and then heat it to foam to obtain the foamed product.

[0146] (3) Carbonize the foamed product obtained in step (2) to form a foamed silicon / carbon composite skeleton, which is a foamed conductive skeleton material used for lithium battery anode materials.

[0147] It should be noted that in some cases, step (1) can also be: dispersing silicon nanowires in a solvent, then adding an organic carbon source, a crosslinking agent and a foaming agent in sequence, and then drying to obtain a mixture.

[0148] In some embodiments, the method for preparing the foam conductive skeleton material for lithium battery anode materials further includes the step of loading other types of anode materials onto the dried product; the other types of anode materials include, but are not limited to, at least one of silicon, tin and graphite.

[0149] In some embodiments, the silicon material includes, but is not limited to, at least one of silicon nanowires (SiNWs), silicon nanosheets, silicene, silicon nanotubes, silicon nanoparticles (SiNPs), silicon microparticles (SiMPs), and silicon suboxide powder.

[0150] In some embodiments, the tin material includes, but is not limited to, at least one of elemental tin, tin oxide, etc.

[0151] In some embodiments, the method of loading other types of anode materials onto the product obtained after washing and drying following carbonization includes at least one of in-situ growth, pressure filling, solution adsorption, and physical mixing.

[0152] For example, physical mixing is performed using an ultrasonic method. The specific steps are as follows: other types of negative electrode materials are added to a solvent such as dimethyl sulfoxide (DMSO) and ultrasonically dispersed evenly to obtain a suspension. Then, the dried product is placed in the suspension and ultrasonically sonicated for a period of time (e.g., 5-15 min). The foam conductive skeleton material for lithium battery negative electrode materials loaded with other types of negative electrode materials is then removed and air-dried.

[0153] In some embodiments, other types of negative electrode materials comprise 0.01-60% of the dried foam conductive skeleton material for lithium battery negative electrode materials (i.e., the final product, with a total mass equal to the mass of the other types of negative electrode materials and the dried product after drying), preferably 10-50%, for example 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or 55%, etc.

[0154] The method for preparing the foam conductive framework material for lithium battery anode materials according to the embodiments of this application can bring at least the following beneficial effects:

[0155] 1. After coating silicon nanowires with an organic carbon source, a crosslinking agent is used to crosslink the organic carbon-coated silicon nanowires to form a 3D network structure. A foaming agent is adsorbed within the network. Through foaming and carbonization processes, a foam-like silicon / carbon composite framework is ultimately formed. The material exhibits a porous foam-like structure, with silicon nanowires forming the internal framework. At least a portion of the framework's surface is covered with a doped carbon layer. Because its framework is composed of silicon nanowires, the material not only possesses the advantage of low volume expansion rate typical of traditional carbon-based frameworks, thus exhibiting better cycle performance, but the constructed foam conductive framework (i.e., the foam-like silicon / carbon composite framework) also has a higher specific capacity than traditional carbon-based frameworks.

[0156] 2. The prepared material has a 3D network structure of silicon / carbon composite framework (i.e., a porous foam structure), which gives it a rich pore / pore structure. This pore / pore structure can further load silicon-based anode materials of different forms with different capacities, thereby further improving the capacity and electrochemical performance of silicon-carbon anode materials.

[0157] 3. The carbon layer (i.e., the doped carbon layer) on the surface of the foam conductive skeleton contains a large amount of microcrystalline graphite. The conductive network constructed by this microcrystalline graphite can effectively improve its electronic and ion conduction capabilities, thereby effectively improving the electrochemical performance of the negative electrode material, such as its first efficiency and specific capacity.

[0158] 4. The main source of organic carbon is industrial waste, which allows for waste recycling and is highly sustainable and environmentally friendly. It also has advantages such as low cost and simple process.

[0159] The following non-limiting embodiments further illustrate certain features of the present technology.

[0160] I. Examples and Comparative Examples

[0161] Example 1 (Organic carbon source: silicon nanowires: foaming agent: crosslinking agent = 1:0.3:0.6:0.6, organic carbon source + silicon nanowires + crosslinking agent + foaming agent: solvent = 6.25%)

[0162] The method for preparing the foam conductive framework material for lithium battery anode materials in this embodiment includes the following steps:

[0163] (1) Add 0.3 parts by mass of silicon nanowires to 40 parts by mass of deionized water, then add 1 part by mass of lignin and stir for 15 min. Then add 0.6 parts by mass of glutaraldehyde and keep stirring mechanically for 30 min. Add 0.6 parts by mass of 85 wt% phosphoric acid dropwise and rotary evaporate at 80°C until the solvent deionized water is completely evaporated to obtain a mixture.

[0164] (2) Grind the mixture obtained in step (1) evenly in a quartz crucible and heat it at 140°C for 3 hours to obtain the foamed product.

[0165] (3) Take out the foamed product obtained in step (2) and place it in a quartz tube furnace. In a nitrogen atmosphere of 500 sccm, heat it to 1000℃ at 5℃ / min and hold it for 4 hours to carbonize it. Then cool it down naturally to obtain the carbonized product.

[0166] (4) The carbonized product obtained in step (3) is rinsed with deionized water to remove ash and residual phosphoric acid, and dried in a constant temperature oven at 80°C to constant weight to obtain the foam conductive skeleton material for lithium battery anode material in this embodiment.

[0167] Figure 2A photograph of the foam conductive framework material prepared for lithium-ion battery anode materials in Example 1. From... Figure 2 As can be seen, the foam conductive skeleton material for lithium battery anode materials prepared in Example 1 is black with a slight metallic luster.

[0168] Example 2 (Organic carbon source: silicon nanowires: foaming agent: crosslinking agent = 1:0.01:0.1:0.05, organic carbon source + silicon nanowires + crosslinking agent + foaming agent: solvent = 5.8%)

[0169] This embodiment is basically the same as embodiment 1, except that:

[0170] Step (1) is as follows: 0.01 parts by mass of silicon nanowires are added to 20 parts by mass of deionized water, then 1 part by mass of lignin is added and stirred for 15 min, then 0.05 parts by mass of glutaraldehyde is added, mechanical stirring is maintained for 30 min, 0.1 parts by mass of 85 wt% phosphoric acid is added dropwise, and the mixture is rotary evaporated at 80°C until the solvent deionized water is completely evaporated to obtain a mixture.

[0171] Example 3 (Organic carbon source: silicon nanowires: foaming agent: crosslinking agent = 1:0.5:1:1, organic carbon source + silicon nanowires + crosslinking agent + foaming agent: solvent = 6.25%)

[0172] This embodiment is basically the same as embodiment 1, except that:

[0173] Step (1) is as follows: 0.5 parts by mass of silicon nanowires are added to 56 parts by mass of deionized water, then 1 part by mass of lignin is added and stirred for 15 min, then 1 part by mass of glutaraldehyde is added and mechanical stirring is maintained for 30 min, then 1 part by mass of 85 wt% phosphoric acid is added dropwise, and the solvent deionized water is evaporated at 80°C to obtain a mixture.

[0174] Example 4 (Organic carbon source: silicon nanowires: foaming agent: crosslinking agent = 1:0.3:1:0.75, organic carbon source + silicon nanowires + crosslinking agent + foaming agent: solvent = 10%)

[0175] This embodiment is basically the same as embodiment 1, except that:

[0176] Step (1) is as follows: 0.3 parts by mass of silicon nanowires are added to 30.5 parts by mass of deionized water, then 1 part by mass of lignin is added and stirred for 15 min. After that, 0.75 parts by mass of glutaraldehyde is added and mechanical stirring is maintained for 30 min. 1 part by mass of 85 wt% phosphoric acid is added dropwise and the mixture is rotary evaporated at 80°C until the solvent deionized water is completely evaporated to obtain the mixture.

[0177] Example 5 (Based on Example 1, nano-silicon powder is loaded using a physical loading process)

[0178] This embodiment is basically the same as embodiment 1, except that:

[0179] It also includes step (5), which is: the foam conductive skeleton material for lithium battery anode material obtained in step (4) is physically mixed with 0.5 parts by mass of nano silicon powder (average particle size of 100nm) to obtain the foam conductive skeleton material for lithium battery anode material of this embodiment.

[0180] The physical mixing process employs an ultrasonic method. Specifically, 0.5 parts by mass of nano-silicon powder (average particle size of 100 nm) is added to dimethyl sulfoxide (DMSO) solvent and ultrasonically dispersed to obtain a DMSO suspension. Then, the foam conductive framework material for lithium battery anode materials obtained in step (4) is placed in the DMSO suspension and ultrasonically sonicated for 10 minutes. Finally, the foam conductive framework material for lithium battery anode materials loaded with nano-silicon powder is removed and dried.

[0181] Example 6 (Based on Example 1, nano-silica powder is loaded using a physical loading process)

[0182] This embodiment is basically the same as embodiment 1, except that:

[0183] It also includes step (5), which is: the foam conductive skeleton material for lithium battery anode material obtained in step (4) is physically mixed with 0.5 parts by mass of nano-silica powder (average particle size of 100nm) to obtain the foam conductive skeleton material for lithium battery anode material in this embodiment.

[0184] The physical mixing process employs an ultrasonic method. Specifically, 0.5 parts by mass of nano-silica powder (average particle size of 100 nm) is added to dimethyl sulfoxide (DMSO) solvent and ultrasonically dispersed to obtain a DMSO suspension. Then, the foam conductive framework material for lithium battery anode materials obtained in step (4) is placed in the DMSO suspension and ultrasonically sonicated for 10 minutes. Finally, the foam conductive framework material for lithium battery anode materials loaded with nano-silica powder is removed and dried.

[0185] Example 7 (Based on Example 1, nano-flake graphite powder is loaded using a physical loading process)

[0186] This embodiment is basically the same as embodiment 1, except that:

[0187] It also includes step (5), which is: the foam conductive skeleton material for lithium battery anode material obtained in step (4) is physically mixed with 0.5 parts by mass of nano-scale graphite powder (average particle size of 800nm) to obtain the foam conductive skeleton material for lithium battery anode material in this embodiment.

[0188] The physical mixing process employs an ultrasonic method. Specifically, 0.5 parts by mass of nano-flake graphite powder (average particle size of 800 nm) is added to dimethyl sulfoxide (DMSO) solvent and ultrasonically dispersed to obtain a DMSO suspension. Then, the foam conductive framework material for lithium battery anode materials obtained in step (4) is placed in the DMSO suspension and ultrasonically sonicated for 10 minutes. Finally, the foam conductive framework material for lithium battery anode materials loaded with nano-flake graphite powder is removed and dried.

[0189] Comparative Example 1

[0190] The preparation method of the carbon material in this comparative example includes the following steps:

[0191] Polyurethane nanofibers (average diameter 150 nm ± 10 nm) were used as the carbon source and subjected to carbonization heat treatment in a general-purpose high-temperature vacuum furnace. The carbonization process parameters were as follows: argon atmosphere; heating rate of 25 °C / min; carbonization temperature of 600 °C and 2000 °C; holding time of 1 hour; and natural cooling to room temperature to obtain glass carbon fibers.

[0192] It should be noted that Comparative Example 1 is actually two preparation examples. In one preparation example, the carbonization temperature was 600℃, and in the other preparation example, the carbonization temperature was 2000℃.

[0193] Comparative Example 2 (Compared to Example 1, silicon nanowires were not added in step (1))

[0194] This comparative example is basically the same as Example 1, except that:

[0195] In step (1), no silicon nanowires are added.

[0196] Step (1) is as follows: Add 1 part by mass of lignin to 40 parts by mass of deionized water and stir for 15 min. Then add 0.6 parts by mass of glutaraldehyde and keep mechanically stirring for 30 min. Add 0.6 parts by mass of 85wt% phosphoric acid dropwise and rotary evaporate at 80℃ until the solvent deionized water is completely evaporated to obtain a mixture.

[0197] Comparative Example 3 (compared to Example 5, using carbon nanotubes instead of silicon nanowires)

[0198] This comparative example is basically the same as Example 5, except that:

[0199] In step (1), carbon nanotubes are used instead of silicon nanowires.

[0200] Step (1) is as follows: 0.3 parts by mass of carbon nanotubes are added to 40 parts by mass of deionized water, then 1 part by mass of lignin is added and stirred for 15 min, then 0.6 parts by mass of glutaraldehyde is added, mechanical stirring is maintained for 30 min, 0.6 parts by mass of 85 wt% phosphoric acid is added dropwise, and the mixture is rotary evaporated at 80°C until the solvent deionized water is completely evaporated to obtain a mixture.

[0201] Comparative Example 4 (using NaCl as the foaming agent compared to Example 1)

[0202] This comparative example is basically the same as Example 1, except that:

[0203] In step (1), 85 wt% phosphoric acid is replaced with NaCl.

[0204] Step (1) is as follows: 0.3 parts by mass of silicon nanowires are added to 40 parts by mass of deionized water, then 1 part by mass of lignin is added and stirred for 15 min, then 0.6 parts by mass of glutaraldehyde is added, mechanical stirring is maintained for 30 min, 0.6 parts by mass of NaCl is added dropwise, and the solvent deionized water is evaporated at 80℃ to obtain a mixture.

[0205] II. Material Characterization and Performance Testing

[0206] 1. Material Characterization

[0207] The foam conductive framework material for lithium battery anode materials prepared in Example 1 and the carbon material prepared in Comparative Example 1 were tested using Raman spectroscopy. The test results are as follows: Figure 3 As shown.

[0208] from Figure 3 It can be seen that the Raman shift exhibits three characteristic peaks in the 0-5000 wavenumber range: the D peak, the G peak, and the 2D peak. These peaks appear at 1577.8 cm⁻¹. -1 1352.3cm -1 and 2698.3cm -1 The D and G peaks describe amorphous carbon (or defects) and graphite in carbon materials, respectively. Additionally, the 2D peak is a characteristic peak of graphite crystals. The higher the microcrystalline graphite content in the carbon material, the stronger and sharper the 2D peak. Conversely, the higher the amorphous carbon content (or defects) in the carbon material, the weaker the 2D peak, the wider the peak, and it may even disappear. (Comparison) Figure 3 (a) and (b) it is not difficult to see that the graphite microcrystal composition of the foam conductive skeleton material for lithium battery anode material prepared in Example 1 of this application at a carbonization process temperature of 1000°C is equivalent to the carbon material prepared in Prior Art Document 1 at a process temperature of 2000°C.

[0209] 2. Electrochemical performance testing

[0210] The materials prepared in each embodiment or comparative example were mixed with the binder polyvinylidene fluoride (PVDF) and the conductive agent Super-P in a mass ratio of 8:1:1, ground, coated, and slurried, and then prepared into coin half-cells with lithium sheets. The capacity, first efficiency, and cycle performance of the materials were tested.

[0211] The electrochemical performance test results are shown in Table 1.

[0212] Table 1. Results of density, resistivity and electrochemical performance tests

[0213]

[0214]

[0215] As can be seen from Table 1, Examples 1-4 exhibit superior capacity, first-efficiency performance, and cycle performance. Compared to Comparative Example 1, the carbonization temperature of Example 1 is only 1000℃, while its graphite characteristic peak 2D peak (approximately 2698.3 cm⁻¹) is significantly higher. -1 The carbonization effect at 2000℃ is comparable to that of Comparative Example 1, which is sufficient to indicate that it contains a high content of microcrystalline graphite. In Examples 5-6, after loading nano-silicon and silicon suboxide, the capacity of the foam conductive framework material used as a lithium battery anode material was further improved, and the cycle life was not significantly affected. In Example 7, after loading nano-graphite powder, the first-efficiency and cycle performance were significantly improved. Compared with Comparative Example 2, Example 1 had a relatively lower capacity because silicon nanowires were not introduced into the reaction process of Comparative Example 2. Compared with Example 5, Comparative Example 3 showed a certain difference in capacity under the same loading of nano-silicon powder, and the cycle life of Comparative Example 3 rapidly declined. This is because the microcrystalline graphite, without being combined with the silicon nanowire framework, has poorer structural stability, leading to structural collapse during cycling. Figure 4a and Figure 4b As shown in the comparison, Comparative Example 4 used NaCl as a pore-forming agent instead of the 85wt% phosphoric acid foaming agent in Example 1. Its carbonization process was not doped, resulting in lower electronic and ionic conductivity, which led to lower capacity and first-time efficiency.

[0216] In summary, this application utilizes lignin and other industrial waste, the main component of "black pulp" waste from the paper industry, as an organic carbon source to prepare a foam conductive framework material for lithium-ion battery anode materials. This allows for the reuse of industrial waste, ensuring the green and environmentally friendly production process of the foam conductive framework material and its sustainability, while also significantly reducing raw material costs. The carbon yield of this application is between 40-50%, which, compared to traditional processes, offers advantages of low cost and high output. Furthermore, the foam conductive framework material prepared in this application for lithium-ion battery anode materials exhibits a porous foam structure with silicon nanowires as the internal framework. At least a portion of the framework's surface is covered with a doped carbon layer. Because its internal framework consists of silicon nanowires, the material not only possesses the advantage of low volume expansion rate inherent in traditional carbon-based frameworks, resulting in better cycle performance, but the constructed foam conductive framework (i.e., a foam-like silicon / carbon composite framework) also exhibits a higher specific capacity than traditional carbon-based frameworks. The silicon / carbon composite framework with a 3D network structure (i.e., a porous foam-like structure) possesses abundant pores / pores. These pores / pores can further support silicon-based anode materials of varying capacities, thereby enhancing the capacity and electrochemical performance of the silicon-carbon anode material. Furthermore, the carbon layer (i.e., the doped carbon layer) on the surface of the foam conductive framework contains a large amount of microcrystalline graphite. The conductive network constructed by this microcrystalline graphite effectively improves its electronic and ionic conductivity, thus significantly enhancing the electrochemical performance of the anode material, such as its initial efficiency and specific capacity.

[0217] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0218] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A foam conductive framework material for lithium battery anode materials, characterized in that, The apparent structure of the foam conductive framework material used for lithium battery anode materials is a porous foam structure, with silicon nanowires as the framework inside, and at least a portion of the surface of the framework is covered with a doped carbon layer.

2. The foam conductive skeleton material according to claim 1, characterized in that, The doping in the carbon layer is N-type doping, and the doping element includes at least one of phosphorus and nitrogen.

3. The foam conductive skeleton material according to claim 1, characterized in that, The silicon nanowires comprise 1-50% by mass in the foam conductive framework material used as a negative electrode material for lithium batteries; and / or, The doped carbon layer has a mass content of 50-99% in the foam conductive framework material used as a negative electrode material for lithium batteries; and / or, The doping element in the doped carbon layer has a mass content of 0.01-2% in the doped carbon layer; and / or, The doped carbon layer contains microcrystalline graphite.

4. The foam conductive skeleton material according to any one of claims 1 to 3, characterized in that, It also includes other types of negative electrode materials; said other types of negative electrode materials are loaded on the porous foam structure; said other types of negative electrode materials include at least one of silicon, tin and graphite; Preferably, the silicon material includes at least one of silicon nanowires, silicon nanoparticles, silicon nanotubes, silicon nanosheets, silicene, silicon micron particles, and silicon suboxide; and / or, the tin material includes at least one of elemental tin and tin oxide; and / or, the other types of anode materials have a mass content of 0.01-60% in the foam conductive framework material used as a lithium battery anode material.

5. A method for preparing a foam conductive framework material for lithium battery anode materials, characterized in that, include: Silicon nanowires coated with organic carbon were obtained by coating them with an organic carbon source. The organic carbon-coated silicon nanowires are cross-linked using a cross-linking agent to form a 3D network structure; A foaming agent is adsorbed inside the 3D mesh structure to obtain a 3D network structure containing a foaming agent; The 3D network structure containing a foaming agent is foamed and carbonized to form a foam-like silicon / carbon composite skeleton.

6. The preparation method according to claim 5, characterized in that, The organic carbon source includes one of lignin, organic polymer resin, and organic acid ester; and / or, When the organic carbon source comprises lignin, the crosslinking agent comprises at least one of dialdehyde crosslinking agents; preferably, the dialdehyde crosslinking agent comprises at least one of glutaraldehyde and acetaldehyde; and / or, when the organic carbon source comprises an organic polymer resin, the crosslinking agent comprises at least one of an epoxy resin crosslinking agent or a phenolic resin crosslinking agent; and / or, when the organic carbon source comprises an organic acid ester and the organic carboxylic acid ester comprises polyurethane and polyacrylate, the crosslinking agent comprises at least one of diamine crosslinking agents; preferably, the diamine crosslinking agent comprises at least one of hexamethylenediamine and ethylenediamine; and / or, The foaming agent includes at least one of N-type doped foaming agents; preferably, the N-type doped foaming agent includes at least one of phosphoric acid, ammonium phosphate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate. Preferably, the organic carbon source is lignin; and / or, the foaming agent is phosphoric acid.

7. The preparation method according to claim 5, characterized in that, The mass ratio of the organic carbon source, the silicon nanowires, the foaming agent, and the crosslinking agent is 1:(0.01-0.5):(0.1-1):(0.05-1); And / or, Coating silicon nanowires with an organic carbon source includes: adding the silicon nanowires to a solvent, followed by adding the organic carbon source and mixing thoroughly; and / or, The organic carbon-coated silicon nanowires are cross-linked to form a 3D network structure using a cross-linking agent, comprising: adding the cross-linking agent to the organic carbon-coated silicon nanowires, followed by a cross-linking reaction under stirring or ultrasonic dispersion conditions; and / or, Adsorbing a foaming agent within the 3D mesh structure includes: dropwise addition of the foaming agent into the 3D network structure containing the foaming agent; and / or, The foaming method includes: grinding the 3D network structure containing the foaming agent and then heating it; and / or, The method for preparing the foam conductive skeleton material for lithium battery anode materials further includes washing and drying steps after carbonization.

8. The preparation method according to claim 7, characterized in that, The solvent includes at least one of water, anhydrous ethanol, and N-methylpyrrolidone; and / or, The total mass amount of the organic carbon source, the silicon nanowires, the crosslinking agent, and the foaming agent is a kg, and the mass amount of the solvent is b kg, where a is 5-10% of b; and / or, The crosslinking reaction is carried out at room temperature for 30-60 minutes; and / or, The adsorption of the foaming agent within the 3D mesh structure further includes a drying step after the dripping is completed; and / or, The method for preparing the foam conductive skeleton material for lithium battery anode materials further includes the step of loading other types of anode materials onto the product obtained after carbonization by washing and drying; the other types of anode materials include at least one of silicon, tin and graphite.

9. The preparation method according to claim 8, characterized in that, The silicon material includes at least one of silicon nanowires, silicon nanoparticles, silicon nanotubes, silicon nanosheets, silicene, silicon micron-sized particles, and silicon suboxide; and / or, The tin material includes at least one of elemental tin and tin oxide; and / or, The method of loading other types of negative electrode materials onto the dried product includes at least one of in-situ growth, pressure filling, solution adsorption, and physical mixing.

10. The preparation method according to claim 5, characterized in that, The foaming temperature is 110-150℃; and / or, The foaming time is 1-5 hours; and / or, The carbonization temperature is 200-1000℃; and / or, The carbonization time is 0.5-2 hours; and / or, The carbonization heating rate is 1-10°C / min; and / or, The cooling method following carbonization is natural cooling; and / or, The carbonization is carried out in a gaseous atmosphere, the gas including at least one of an inert gas, a mixture of an inert gas and hydrogen; and / or, the gas flow rate is 100-800 sccm. Preferably, the volume fraction of hydrogen in the mixture of inert gas and hydrogen is 3-10%.

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