Negative electrode material and method for manufacturing the same, battery

Abstract

This application relates to the technology of negative electrode materials, and more particularly to negative electrode materials, methods for manufacturing the same, and batteries. The negative electrode material contains an active material, and the surface density of the negative electrode material is β, where β is ≥ 80%, however, β is measured by the following measurement method: m1 g of negative electrode material is immersed in a hydrofluoric acid solution with a mass fraction of 20%, immersed for 1 hour, washed and dried to obtain m2 g of material, and the surface density of the negative electrode material β = m2 / m1 × 100% is calculated. The negative electrode material of this application has a high surface density, which reduces the amount of negative electrode material dissolved during the cycle process, further reduces the reaction between dissolved silicon particles and the electrolyte, effectively lowers the gas generation value of the negative electrode material, and the total pore volume of the negative electrode material is small and the structure is tighter, which reduces the amount of electrolyte penetration into the negative electrode material during the cycle process and improves the cycle performance of the negative electrode material.

Description

[Technical Field]

[0001] This application relates to the technology of negative electrode materials, and more specifically, to negative electrode materials, methods for manufacturing the same, and batteries. [Background technology]

[0002] Lithium-ion batteries have advantages such as high energy density, long service life, and no environmental pollution, and are widely used in the 3C (Commercial, Consumer, and Electronics) sectors. With the development of the market, lithium-ion batteries are not only widely used in mobile devices such as smartphones and portable computers, but are also being applied to large equipment fields such as electric vehicles and power tools. To improve the energy density of batteries, research and development of silicon-based anode materials are maturing day by day. Silicon-based anode materials include silicon-based active material and a coating layer on its surface, but conventional silicon-based anode materials have poor coating effect, and during the manufacturing process of silicon-based anode materials for lithium-ion batteries, there is a problem in that dissolved silicon particles come into contact with the electrolyte and generate gas.

[0003] Therefore, reducing the reaction between silicon particles and the electrolyte and lowering gas generation is an urgent problem that needs to be solved. [Overview of the project] [Problems that the invention aims to solve]

[0004] This invention provides a negative electrode material, a method for manufacturing the same, and a battery. The surface of the negative electrode material has high density, which reduces the reaction between silicon particles and the electrolyte, lowers the gas generation value, and improves the material's cycle performance. [Means for solving the problem]

[0005] In a first embodiment, the present application provides a negative electrode material comprising an active material, wherein the surface density of the negative electrode material is β, and β is ≥ 80%. Here, the β is measured by the following measurement method: A negative electrode material with a mass of m1g is immersed in a hydrofluoric acid solution with a mass fraction of 20% for 1 hour, then washed and dried to obtain m2g of material. The surface density β of the negative electrode material is then calculated as β = m2 / m1 × 100%.

[0006] In a second embodiment, the present application provides a battery comprising the negative electrode material described above. [Effects of the Invention]

[0007] The present invention's technical solution has at least the following beneficial effects. The negative electrode material provided in this application includes an active material, and the surface density β of the negative electrode material is ≥80%. Within this range, it is possible to reduce the amount of negative electrode material dissolved during the cycle process, further reduce the reaction between the dissolved active material and the electrolyte, effectively lower the gas generation value of the negative electrode material, and reduce side reactions due to contact between the electrolyte and the active material, thereby improving the cycle performance of the lithium-ion battery. [Brief explanation of the drawing]

[0008] [Figure 1] This is a scanning electron microscope (SEM) image of the negative electrode material manufactured in Example 1 of the present application. [Figure 2] This is an XRD diagram of the negative electrode material manufactured in Example 1 of the present application. [Figure 3] This is the initial charge-discharge curve of the negative electrode material manufactured in Example 1 of the present application. [Figure 4] This is the cycle performance curve of the negative electrode material manufactured in Example 1 of the present application. [Modes for carrying out the invention]

[0009] The embodiments described below with reference to the drawings are illustrative and are for interpretation purposes only, and should not be interpreted as limiting the present application.

[0010] Lithium-ion batteries have advantages such as high energy density, long service life, and no environmental pollution, and are widely used in the 3C (Commercial, Consumer, and Electronics) sectors. With the development of the market, lithium-ion batteries are not only widely used in mobile devices such as smartphones and portable computers, but are also being applied to large equipment fields such as electric vehicles and power tools. To improve the energy density of batteries, research and development of silicon-based anode materials are maturing day by day. Silicon-based anode materials include silicon-based active material and a coating layer on its surface, but conventional silicon-based anode materials have poor coating effect, and during the manufacturing process of silicon-based anode materials for lithium-ion batteries, there is a problem in that dissolved silicon particles come into contact with the electrolyte and generate gas.

[0011] In a first embodiment, the present application provides a negative electrode material comprising an active material, wherein the surface density of the negative electrode material is β, and β is ≥ 80%. However, the β mentioned above is measured by the following measurement method: A negative electrode material with a mass of m1g is immersed in a hydrofluoric acid solution with a mass fraction of 20% for 1 hour, then washed and dried to obtain m2g of material. The surface density β of the negative electrode material is then calculated as β = m2 / m1 × 100%.

[0012] In the above-described solution, the negative electrode material contains an active material, and the surface density β of the negative electrode material is ≥80%. Within this range, it is possible to reduce the amount of negative electrode material dissolved during the cycle process, further reduce the reaction between the active material dissolved from the negative electrode material and the electrolyte, effectively lower the gas generation value of the negative electrode material, and reduce side reactions due to contact between the electrolyte and the active material in the negative electrode material, thereby improving the cycle performance of the lithium-ion battery manufactured with the negative electrode material.

[0013] In some embodiments, the surface density of the negative electrode material is ≥80%, specifically 80%, 82%, 85%, 86%, 89%, 90%, 92%, 95%, or 98%, and of course, other values ​​within the above range. As can be understood, ideally, the surface density of the negative electrode material is 100%, in which case the surface density of the negative electrode material is high, and when the negative electrode material is placed in the dissolution solution, the active material in the negative electrode material does not dissolve, and furthermore, the dissolved active material does not come into contact with the dissolution solution and react. However, negative electrode materials manufactured by conventional methods lack sufficient surface density, and the negative electrode material has a certain amount of dissolution in the dissolution solution, and the dissolved active material is contained in the dissolution solution. In this case, the surface density of the negative electrode material can be defined by the amount of dissolved active material, i.e., surface density β = m² / m¹ × 100%.

[0014] Furthermore, the dissolving solution used in this application is a 20% by mass hydrofluoric acid solution, and the amount of dissolving solution is excessive.

[0015] The above measurements allow us to obtain a surface density β ≥ 80% for the anode material of this application. Within this range, during the slurry manufacturing process, the high surface density characteristic of the anode material effectively suppresses direct contact between the active material in the anode material and water in the slurry, reducing the occurrence of side reactions and lowering the gas generation value of the anode material. Furthermore, the anode material can reduce the amount of active material dissolved during the charge-discharge cycle process, and further reduce side reactions between the dissolved active material and the electrolyte, effectively lowering the gas generation value of the anode material.

[0016] In some embodiments, the active material comprises a carbon substrate and silicon particles, and at least some of the silicon particles are located inside the particles of the carbon substrate.

[0017] In some embodiments, the carbon substrate has pores, and the silicon particles are located within the pores of the carbon substrate. As can be understood, the carbon substrate can function as a support framework and have good conductivity, improving the conductivity of the negative electrode material. Furthermore, the silicon particles are located inside the carbon substrate, reducing contact between the silicon particles and the electrolyte, ensuring the stability of the SEI film and improving the initial Coulomb efficiency. Additionally, the porous carbon substrate effectively mitigates the volume expansion of the silicon particles during the cycling process, improving the cycling performance.

[0018] In some embodiments, the carbon substrate comprises at least one of artificial graphite, natural graphite, amorphous carbon, activated carbon, mesocarbon microbeads, carbon nanotubes, carbon nanofibers, porous carbon, and graphene. As can be understood, when the carbon substrate is selected from the above materials, it can all function as a support framework, further possess good conductivity, ensure the conductivity of the anode material, and allow silicon particles to grow inside the carbon substrate, all of which have excellent lithium storage capabilities.

[0019] In some embodiments, the silicon particles include at least one of crystalline silicon, silicon oxide, amorphous silicon, silicon alloy, or crystalline silicon-amorphous silicon composite particles, and the type of carbon substrate and silicon particles can be selected as needed, but are not limited thereto.

[0020] In some embodiments, the silicon oxide contains silicon and oxygen elements, with an atomic ratio of silicon to oxygen being between 0 and 2, and not 0. Specifically, the atomic ratio of silicon to oxygen may be 0.05, 0.11, 0.21, 0.26, 0.31, 0.41, 0.51, 0.59, 0.61, 0.69, 0.71, 0.74, 0.76, 0.79, 0.89, 0.99, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, etc., and is not limited herein. Preferably, the atomic ratio of silicon to oxygen is between 0 and 1, and not 0.

[0021] In some embodiments, the general chemical formula of the silicon oxide is SiO x where 0 < x < 2, and x can specifically be, for example, 0.05, 0.11, 0.21, 0.26, 0.31, 0.41, 0.51, 0.59, 0.61, 0.69, 0.71, 0.74, 0.76, 0.79, 0.89, 0.99, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, and 1.9, etc., and is not limited here. Preferably, 0 < x < 1.

[0022] In some embodiments, the average particle size of the silicon particles is 0.1 nm to 50 nm. Optionally, the average particle size of the silicon particles can specifically be, for example, 0.1 nm, 10 nm, 20 nm, 30 nm, 40 nm, and 50 nm, etc., or other numerical values within the range, and can be selected according to actual needs and is not limited here. When the silicon particles expand, the mechanical stress decreases with the decrease in the particle size, and when the size decreases, the transport paths of electrons and ions can be shortened. At the same time, when the size of the silicon particles decreases and the gap between adjacent silicon particles increases, space can be reserved for expansion. As can be understood, if the average particle size of the silicon particles is within the above range, the battery capacity of the lithium-ion battery can be guaranteed and the irreversible capacity loss can be reduced. Preferably, the average particle size of the silicon particles is 0.1 nm to 20 nm, and more preferably, the average particle size of the silicon particles is 0.1 nm to 5 nm.

[0023] In some embodiments, the shape of the silicon particles includes at least one of dot-like, spherical, ellipsoidal, and sheet-like, and can be selected according to actual needs and is not limited here.

[0024] In some embodiments, the purity of the silicon particles is greater than 99%. As can be understood, high-purity silicon particles are beneficial for Li-Si alloying with lithium and can improve the cycle performance of the lithium-ion battery.

[0025] In some embodiments, the total pore volume of the negative electrode material is 0.001 cm 3 / g to 0.1 cm 3 / g, specifically, 0.001 cm 3 / g, 0.005 cm 3 / g, 0.006 cm 3 / g, 0.007 cm 3 / g, 0.01 cm 3 / g, 0.02 cm 3 / g, 0.03 cm 3 / g, 0.04 cm 3 / g, 0.05 cm 3 / g, 0.06 cm 3 / g, 0.08 cm 3 / g or 0.1 cm<关于专利文本的翻译,需要注意准确传达技术术语和特定含义。在这个例子中,涉及到负电极材料的孔体积等专业概念。翻译时要确保这些术语的准确性和一致性。例如,“total pore volume”准确翻译为“总孔体积”,“negative electrode material”翻译为“负电极材料”。对于具体的数值范围,如“0.001 cm / g to 0.1 cm / g”,直接按照数学表达习惯进行翻译。同时,要注意保留原文中的特殊符号和格式,如“ 3 ”等,以确保与原文的一致性。这样的翻译方式有助于准确传达专利文本的技术内容,为相关领域的专业人员提供准确的信息参考。 3 / g, etc., and of course, other values within the above range may also be possible, and are not limited here. After filling the silicon particles, the remaining voids reserve space for the volume expansion of the silicon particles, relieve the expansion effect of the negative electrode material, and can improve the cycle stability of the negative electrode material. Furthermore, a very small amount of gas caused by the side reaction between some silicon particles and the electrolyte can be adsorbed or accommodated, and the gas generation phenomenon of the negative electrode material can be improved. Preferably, the total pore volume of the negative electrode material is 0.001 cm 3 / g to 0.02 cm 3 / g. When the total pore volume of the negative electrode material is controlled within this range, the amount of immersion of the electrolyte directly into the interior of the particles of the negative electrode material through the pore structure can be effectively reduced.

[0026] In some embodiments, in the negative electrode material, the volume occupancy rate in the total pore volume of pores with a pore diameter of 10 nm or less is ≧80%, specifically, it may be, for example, 80%, 82%, 85%, 87%, 90%, 93%, 95% or 99%, etc., and of course, other values within the above range may also be possible, and are not limited here.

[0027] In the above solution, while controlling the surface density of the negative electrode material to be ≧80%, the total pore volume of the negative electrode material is 0.001 cm 3 / g to 0.1 cm<关于专利文本的翻译,需要注意准确传达技术术语和特定含义。在这个例子中,涉及到负电极材料的孔体积等专业概念。翻译时要确保这些术语的准确性和一致性。例如,“total pore volume”准确翻译为“总孔体积”,“negative electrode material”翻译为“负电极材料”。对于具体的数值范围,如“0.001 cm / g to 0.1 cm / g”,直接按照数学表达习惯进行翻译。同时,要注意保留原文中的特殊符号和格式,如“ 3 ”等,以确保与原文的一致性。这样的翻译方式有助于准确传达专利文本的技术内容,为相关领域的专业人员提供准确的信息参考。 3By controlling the volume occupancy rate of the total pore volume of pores with a diameter of 10 nm or less to ≥80% during the charge-discharge process, the voids can retain space for the volume expansion of silicon particles during the lithium release process. This invention effectively mitigates the volume expansion of silicon particles during the cycle process by controlling the synergistic effect of the surface density of the negative electrode material and the pores in the negative electrode material, thereby reducing particle fragmentation of the negative electrode material and improving the cycle performance of the negative electrode material. At the same time, the volume occupancy rate of the total pore volume of pores with a diameter of 10 nm or less is ≥80%, meaning that the occupancy rate of pores with a diameter of 10 nm or more is relatively low, and the negative electrode material has very few macropores within the particles, which reduces crack generation in the negative electrode material during the cycle process, reduces the risk of direct contact between silicon particles and the electrolyte, and reduces side reactions. In some embodiments, the surface density β of the negative electrode material is ≥ 80%, and the negative electrode material has pores, the pores including micropores and mesopores, wherein the ratio of the pore volume of the micropores to the pore volume of the mesopores is (1-45):(55-99).

[0028] Specifically, the pore volume occupancy ratio of micropores to mesopores may be 1:99, 5:95, 10:90, 20:80, 30:65, 40:50, or 45:55, and is not limited thereto. In this application, the pore volume occupancy ratio of mesopores is relatively large, the pore volume occupancy ratio of micropores is relatively small, and the molecular size generated by the electrolyte is generally less than or equal to the pore diameter of the micropores. Therefore, the micropores have high capillary force, and the adsorption capacity of the negative electrode material is directly proportional to the pore volume of the micropores to a large extent. That is, as the micropore volume increases, the adsorption capacity of the negative electrode material increases, and thus the side reactions between the negative electrode material and the electrolyte increase.

[0029] In this invention, by controlling the ratio of micropore volume to mesopore volume to (1~45):(55~99), the pore volume occupancy rate of micropores in the anode material is effectively reduced, that is, the number of active sites where side reactions between the anode material and the electrolyte occur is reduced. Furthermore, the thickening of the solid electrolyte film on the surface of the anode material due to the continuous intrusion of the electrolyte can be reduced, which is advantageous in improving the cycle performance of the anode material. In addition, mesopores with increased volume occupancy can retain sufficient buffer space for the volume expansion of silicon particles, which is advantageous in improving the stability of the particle structure of the anode material. In this invention, by controlling the surface density of the anode material and the volume occupancy rate of micropores and mesopores in the anode material, the two are made to act synergistically, reducing the elution of silicon particles, reducing side reactions between the anode material and the electrolyte, effectively mitigating the volume expansion of silicon particles during the cycle process, reducing particle fragmentation of the anode material, and comprehensively improving the cycle performance of the anode material.

[0030] In some embodiments, the pore volume occupancy of mesopores in the negative electrode material is ≥80%, specifically 80%, 82%, 85%, 87%, 90%, 93%, 95%, or 99%, and of course, other values ​​within the above range are also possible and are not limited thereto.

[0031] In some embodiments, the pore volume occupancy of micropores in the negative electrode material is ≤10%, specifically 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or 0%, and of course, other values ​​within the above range are also possible and are not limited thereto.

[0032] In some embodiments, the pore volume occupancy of macropores in the negative electrode material is ≤20%, specifically 20%, 18%, 15%, 12%, 10%, 8%, 7%, 5%, 4%, 3%, or 2%, and of course, other values ​​within the above range are also possible and are not limited thereto.

[0033] To understand this, by controlling the volume occupancy of micropores, mesopores, and macropores in the anode material within the above range, the uniformity of the silicon particle distribution within the anode material can be improved. Since the majority of the pores are mesopores, the volume expansion of silicon particles is effectively mitigated, reducing the risk of the anode material bursting or pulverizing due to excessive local expansion stress caused by non-uniform volume changes of silicon particles during the cycling process, thereby improving the cycle stability of the anode material.

[0034] In some embodiments, the average pore size of the negative electrode material is 0.4 nm to 50 nm, specifically 0.4 nm, 1 nm, 1.5 nm, 2 nm, 3 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, or 50 nm, and of course, other values ​​within the above range are also possible and are not limited thereto.

[0035] In some embodiments, the negative electrode material from which silicon particles have been removed has pores, and these pores include micropores.

[0036] In some embodiments, in a negative electrode material from which silicon particles have been removed, the volume occupancy of the total pore volume of pores with a pore diameter of 2 nm or less is ≥ 70%, and specifically may be 70%, 75%, 80%, 85%, 90%, 95%, or 99%, and of course may be other values ​​within the above range, and are not limited thereto.

[0037] In some embodiments, the anode material from which silicon particles have been removed has pores, which include micropores and mesopores. In the anode material from which silicon particles have been removed, the volume occupancy of the total pore volume of pores with a diameter of 5 nm or less is ≥ 85%, and may be specifically 85%, 87%, 89%, 90%, 92%, 95%, 97%, or 99%, and of course may be other values ​​within the above range, and are not limited thereto.

[0038] In some embodiments, in the negative electrode material from which silicon particles have been removed, the volume occupancy of the total pore volume of pores with a pore diameter of 10 nm or less is ≥ 95%, and specifically may be 95%, 96%, 97%, 98%, or 99%, and of course may be other values ​​within the above range, and are not limited thereto.

[0039] To understand this, in a negative electrode material (i.e., a carbon substrate) from which silicon particles have been removed, if the volume occupancy of the pores is controlled within the above range, the pores can accommodate most of the silicon particles, reducing silicon segregation formed by the growth of silicon particles on the surface of the carbon substrate, improving the silicon particle content and uniformity of silicon particle distribution in the carbon substrate, and further improving the specific capacity and mechanical performance of the negative electrode material.

[0040] In some embodiments, the negative electrode material from which silicon particles have been removed further comprises macropores.

[0041] In some embodiments, the total pore volume of all pores in the negative electrode material from which silicon particles have been removed is 0.5 cm³. 3 / g~1.5cm 3 This is per gram, specifically 0.5 cm. 3 / g, 0.6cm 3 / g, 0.7cm 3 / g, 0.8cm³ / g, 0.9cm 3 / g, 1.0cm 3 / g, 1.1cm 3 / g, 1.2cm 3 / g, 1.3cm 3 / g, 1.4cm 3 / g or 1.5cm 3 It may be / g, or of course, any other value within the above range, and is not limited here. To understand this, the anode material from which the silicon particles have been removed has abundant pores, and these pores can accommodate silicon particles and retain space for the volume expansion of the silicon particles. Preferably, the total pore volume of all pores in the anode material from which the silicon particles have been removed is 1.0 cm³. 3 / g~1.5cm 3 It is / g.

[0042] In this application, the negative electrode material containing silicon particles exhibits a significantly reduced total pore volume compared to the negative electrode material from which the silicon particles have been removed. This is because the silicon particles are relatively uniformly packed, resulting in a reduction in the pore volume of most voids after packing. This demonstrates that the specific capacity of the negative electrode material can be improved by efficiently and relatively uniformly filling the pores of the carbon substrate with silicon particles.

[0043] In some embodiments, the specific surface area of ​​the negative electrode material from which silicon particles have been removed is 500 m². 2 / g~2000m 2 The value is / g, and the specific surface area is 500m². 2 / g, 800m 2 / g, 1000m 2 / g, 1200m 2 / g, 1400m 2 / g, 1600m 2 / g, 1800m 2 / g, 1900m 2 / g or 2000m 2 It may be / g, or of course, any other value within the above range, and is not limited here. Preferably, the specific surface area of ​​the negative electrode material from which the silicon particles have been removed is 1200 m². 2 / g~2000m 2 It is / g.

[0044] In some embodiments, at least a portion of the surface of the negative electrode material has a coating layer, and the material of the coating layer includes a carbon material.

[0045] In some embodiments, the carbon material includes at least one of amorphous carbon and graphitized carbon.

[0046] As can be understood, the coating layer located on the outermost layer of the negative electrode material has good conductivity and can improve the conductivity of the negative electrode material. It can also coat the silicon particles exposed on the carbon substrate surface, reducing continuous oxidation of the exposed silicon particles during the standing process, thereby reducing the decrease in the specific capacity and initial Coulomb efficiency (ICE) of the negative electrode material. The coating layer can also reduce direct contact between the active material and the electrolyte, ensuring the stability of the SEI film and thereby improving the initial Coulomb efficiency of the negative electrode material. Furthermore, during the coating process, the material of the coating layer further fills the gaps inside the active material, reducing the total pore volume of the negative electrode material, and effectively reducing the amount of electrolyte that directly penetrates into the particles of the negative electrode material through the pore structure. This reduces side reactions caused by contact between the electrolyte and the active material and improves the cycle performance of ion batteries manufactured with the negative electrode material.

[0047] In some embodiments, the thickness of the coating layer is 1 nm to 300 nm, and optionally, the thickness of the coating layer may be specifically 1 nm, 50 nm, 150 nm, 200 nm, 250 nm, and 300 nm, or other values ​​within the range, and can be selected according to actual needs, and is not limited thereto. As can be understood, the coating layer can reduce the solubility of the anode material and further reduce the amount of gas generated by the reaction between the dissolved silicon particles and the electrolyte. Controlling the thickness of the coating layer within the above range is advantageous for the anode material to maintain the stability of its particle structure during the cycling process, reduces the exposed Si on the surface of the anode material, reduces the generation of a large amount of SEI during the charge-discharge process due to exposed silicon, and can improve the specific capacity and electrochemical performance of the anode material. Preferably, the thickness of the coating layer is 1 nm to 50 nm, and more preferably, the thickness of the coating layer is 1 nm to 30 nm.

[0048] In some embodiments, the mass occupancy of the coating layer in the anode material is ≤10%, specifically 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1%, and of course, other values ​​within the above range are also possible and are not limited thereto. As can be seen, the coating layer can reduce the solubility of the anode material and further reduce the amount of gas generated by the reaction between the dissolved silicon particles and the electrolyte, and setting the mass occupancy of the coating layer in the anode material within the above range can ensure the lithium storage capacity of the anode material and further ensure the charge and discharge capacity of the lithium-ion battery manufactured with the anode material.

[0049] In some embodiments, the median particle size D of the negative electrode material 50 The median particle size is ≤10 μm, and specifically, it may be 10 μm, 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, 3 μm, 2 μm, or 1 μm, and of course, it may be any other value within the above range, and is not limited here. To understand, the median particle size is the size of the negative electrode material particle that is in the middle position when the negative electrode material particles are sorted in descending order of size. When the median particle size of the negative electrode material is within the above range, the time of lithium ion absorption and release can be guaranteed, a state in which the negative electrode material absorbs lithium ions quickly and sufficiently can be achieved, and further guarantees the charge and discharge performance of the lithium-ion battery.

[0050] In some embodiments, the particle size distribution of the negative electrode material satisfies 0.9 ≤ (D90 - D10) / D50 ≤ 5, specifically, it may be 0.9, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4, 4.5, or 5, and of course, it may be any other value within the above range, and is not limited thereto. When the particle size distribution of the negative electrode material is within the above range, the relatively large particles and relatively small particles of the negative electrode material can match each other, and the small particles can fill the gaps between the large particles, thereby improving the tap density of the negative electrode material.

[0051] In some embodiments, the specific surface area of ​​the negative electrode material is ≤10 m². 2 It is / g, specifically 10m 2 / g, 8.9m 2 / g, 6.8m 2 / g, 5.5m 2 / g, 4.2m 2 / g, 4m 2 / g, 3m 2 / g, 2.5m 2 / g, 2m 2 / g or 1m 2 It may be / g, or of course, any other value within the above range, and is not limited here. To understand this, the specific surface area of ​​the negative electrode material affects the contact area between the negative electrode material and the electrolyte, and if the specific surface area of ​​the negative electrode material is within the above range, it can reduce the amount of lithium ions consumed by the SEI film formed during the initial charge-discharge process of the lithium-ion battery, thereby reducing the irreversible capacity loss of the lithium-ion battery. Preferably, the specific surface area of ​​the negative electrode material is ≤5m² 2 It is / g.

[0052] In some embodiments, the density of the compressed powder of the negative electrode material is 0.8 g / cm³. 3 ~1.3g / cm 3 Specifically, 0.8 g / cm³ 3 , 0.9 g / cm³ 3 1.0 g / cm³ 3 , 1.1 g / cm³ 3 , 1.2 g / cm³ 3 Or 1.3 g / cm³ 3 It could be any of the above, or of course, any other value within the above range; it is not limited here.

[0053] In some embodiments, the tap density of the negative electrode material is 0.5 g / cm³. 3 ~1.5g / cm 3 Specifically, 0.5 g / cm³ 3 , 0.6 g / cm³ 3 , 0.7 g / cm³ 3 , 0.8 g / cm³ 3 , 0.9 g / cm³ 3 1.0 g / cm³ 3 , 1.1 g / cm³ 3 , 1.2 g / cm³ 3 1.3 g / cm³ 3 1.4 g / cm³ 3Or 1.5 g / cm³ 3 It could be any of the above, or of course, any other value within the above range; it is not limited here.

[0054] In some embodiments, the powder conductivity of the negative electrode material at a pressure of 20 kN is 0.5 S / cm to 5 S / cm, specifically 0.5 S / cm, 0.8 S / cm, 1.0 S / cm, 1.2 S / cm, 1.5 S / cm, 2 S / cm, 3 S / cm, 4 S / cm, or 5.0 S / cm, and of course, other values ​​within the above range are also possible and are not limited thereto. By controlling the powder conductivity of the negative electrode material within the above range, the electrochemical performance of the negative electrode material can be effectively improved. Preferably, the powder conductivity of the negative electrode material at a pressure of 20 kN is 0.5 S / cm to 2 S / cm.

[0055] In some embodiments, the mass content of carbon in the negative electrode material is 20% to 80%, specifically 20%, 25%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%, and of course, other values ​​within the above range are also possible and are not limited thereto.

[0056] In some embodiments, the mass content of silicon in the negative electrode material is 20% to 60%, specifically 20%, 25%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, 55%, or 60%, and of course, other values ​​within the above range are also possible and are not limited thereto. As can be seen, controlling the mass content of silicon within the above range allows for effective simultaneous control of the volume expansion of the negative electrode material and the capacity of the negative electrode material. Preferably, the mass content of silicon in the negative electrode material is 45% to 55%.

[0057] In some embodiments, the negative electrode material further contains trace metal elements, the trace metal elements comprising at least one of Fe, Co, Ni, Cr, Zn, Cu, and Al.

[0058] In some embodiments, the mass occupancy of trace metal elements in the negative electrode material is ≤200 ppm, specifically 200 ppm, 180 ppm, 160 ppm, 150 ppm, 140 ppm, 130 ppm, 120 ppm, 100 ppm, or 50 ppm, and of course, other values ​​within the above range are also possible and are not limited thereto.

[0059] In some embodiments, the average gas generation rate of a negative electrode slurry produced with the negative electrode material, when left in a 25°C environment for 7 days, is ≤1 mL / kg / day, specifically 1 mL / kg / day, 0.8 mL / kg / day, 0.6 mL / kg / day, 0.5 mL / kg / day, 0.4 mL / kg / day, 0.3 mL / kg / day, 0.2 mL / kg / day, or 0.1 mL / kg / day, and of course, other values ​​within the above range are also possible and are not limited here. The gas generation value of the negative electrode material of this application is controlled within the above range, and it has been found that most silicon particles can be distributed relatively uniformly within the pores of the carbon substrate, reducing direct contact between silicon particles and the electrolyte, thereby reducing side reactions between eluted silicon particles and the electrolyte (i.e., hydrolysis of silicon into silicate and hydrogen gas), and effectively lowering the gas generation value of the negative electrode material. If the surface density of the negative electrode material is insufficient, the gas generation value of the negative electrode material clearly increases.

[0060] In the second embodiment, the present application is, Step S10 for producing a composite containing an active material and a catalyst, The present invention provides a method for producing a negative electrode material, comprising step S20, which involves coating the composite material to obtain a negative electrode material, wherein the surface density of the negative electrode material is β, and β is ≥ 80%.

[0061] In the above method, a catalyst is added when manufacturing the active material, and during the coating process, the catalyst promotes the formation of a dense coating layer on the surface of the active material. This solves the problem in conventional technology where a high decomposition temperature is used to ensure the complete decomposition of the gas source when manufacturing the coating layer using vapor phase growth, and where highly active silicon particles are consumed by reacting with the carbon substrate, thereby ensuring the charge and discharge capacity of the lithium-ion battery.

[0062] Conventional gas sources commonly used in vapor-phase coating, such as methane and acetylene, require high temperatures (methane > 1000°C, acetylene > 800°C) to completely decompose and form a relatively dense coating layer. However, high temperatures generally lead to the formation of SiC due to the high activity of the grown silicon particles. Therefore, vapor-phase coating is currently generally performed at relatively low temperatures (500°C to 800°C). However, at temperatures of 500°C to 800°C, the decomposition of the gas source precursor is insufficient, resulting in a non-dense carbon coating layer formed on the particle surface. Furthermore, the presence of a large amount of products due to incomplete decomposition prevents a complete resolution of the gas generation problem.

[0063] The manufacturing method of the present invention will be specifically described below with reference to the examples. In step S10, the specific steps for producing the composite include immersing a carbon substrate in a catalyst-containing solution, growing silicon particles on the product after solid-liquid separation, and obtaining the composite.

[0064] In some embodiments, the carbon substrate used in the above manufacturing method includes at least one of artificial graphite, natural graphite, amorphous carbon, activated carbon, mesocarbon microbeads, carbon nanotubes, carbon nanofibers, and graphene. As can be understood, when the carbon substrate is selected from the above materials, it can all function as a support framework and have good conductivity, ensuring the conductivity of the negative electrode material.

[0065] In some embodiments, a pre-fabricated carbon substrate is immersed in a catalyst solution to deposit the catalyst on the surface or inside of the carbon substrate, the catalyst solution being a salt solution containing at least one of Cu, Ni, Co, Fe, and B, and as can be understood, the catalyst contains the above elements, which can reduce the temperature during the coating process and enable obtaining a tight coating layer at a relatively low temperature.

[0066] In some embodiments, the carbon substrate has pores, which include micropores, mesopores, and macropores.

[0067] In some embodiments, the volume occupancy of the total pore volume of pores with a pore diameter of 2 nm or less in the carbon substrate is ≥ 70%, and specifically may be 70%, 75%, 80%, 85%, 90%, 95%, or 99%, and of course, other values ​​within the above range are also possible and are not limited thereto.

[0068] In some embodiments, the volume occupancy of the total pore volume of pores with a pore diameter of 5 nm or less in the carbon substrate is ≥ 85%, and specifically may be 85%, 87%, 89%, 90%, 92%, 95%, 97%, or 99%, and of course, other values ​​within the above range are also possible and are not limited thereto.

[0069] In some embodiments, the volume occupancy of the total pore volume of pores with a pore diameter of 10 nm or less in the carbon substrate is ≥ 95%, and specifically may be 95%, 96%, 97%, 98%, or 99%, and of course may be other values ​​within the above range, and are not limited thereto.

[0070] To understand this, by controlling the volume occupancy of the pores in the carbon substrate within the above range, the pores can accommodate most of the silicon particles, reducing silicon segregation formed by the growth of silicon particles on the carbon substrate surface, improving the silicon particle content and distribution uniformity in the carbon substrate, and further improving the specific capacity and mechanical performance of the anode material.

[0071] In some embodiments, the specific surface area of the carbon matrix is 500 m 2 / g to 2000 m 2 / g, and the specific surface area can be 500 m 2 / g, 800 m 2 / g, 1000 m 2 / g, 1200 m 2 / g, 1400 m 2 / g, 1600 m 2 / g, 1800 m 2 / g, 1900 m 2 / g or 2000 m 2 / g, etc., and of course, other values within the above range are also possible and are not limited here. Preferably, the specific surface area of the carbon matrix is 1200 m 2 / g to 2000 m 2 / g.

[0072] In some embodiments, the total pore volume of all the pores of the carbon matrix is 0.5 cm 3 / g to 1.5 cm 3 / g, specifically, 0.5 cm 3 / g, 0.6 cm 3 / g, 0.7 cm 3 / g, 0.8 cm 3 / g, 0.9 cm 3 / g, 1.0 cm 3 / g, 1.1 cm 3 / g, 1.2 cm 3 / g, 1.3 cm 3 / g, 1.4 cm 3 / g or 1.5 cm 3 / g, etc., and of course, other values within the above range are also possible and are not limited here. As can be understood, the carbon matrix has abundant pores, and these pores can accommodate silicon particles and reserve space for the volume expansion of silicon particles. Preferably, the total pore volume of all the pores in the carbon matrix is 0.6 cm 3 / g to 1.0 cm 3 / g.

[0073] In some embodiments, the concentration of the catalyst-containing solution is 0.1 mol / L to 2.5 mol / L, and optionally, the concentration may be specifically 0.1 mol / L, 0.5 mol / L, 1.2 mol / L, and 2.5 mol / L, or any other value within the range, and can be selected according to actual needs, and is not limited here. As can be understood, when the catalyst concentration is within the above range, it is advantageous for improving the surface density of the anode material. If the catalyst concentration is too high, the catalyst content attached to the carbon substrate becomes too high, and furthermore, the thickness of the surface coating layer of the anode material becomes too high. The excessively high thickness of the coating layer makes it difficult for the electrolyte to effectively penetrate the anode material particles, hindering lithium ion transport and reducing the rate of action of the anode material.

[0074] In some embodiments, the immersion time is 10 min to 60 min, and optionally, the immersion time may be 10 min, 20 min, 30 min, 50 min, and 60 min, or any other value within the range, and can be selected according to actual needs, and is not limited thereto. As can be understood, when the immersion time is within the above range, the amount of catalyst deposited can be increased, which is advantageous in further improving the surface density of the anode material.

[0075] In some embodiments, the drying temperature is 80°C to 120°C, specifically 80°C, 90°C, 100°C, 110°C, or 120°C, or any other value within the range, which can be selected as needed and is not limited thereto.

[0076] In some embodiments, the silicon particles include at least one of crystalline silicon, silicon oxide, amorphous silicon, silicon alloy, or crystalline-amorphous silicon composite particles, and the type of silicon particles can be selected as needed and is not limited thereto. The silicon alloy may be a silicon lithium alloy, a silicon magnesium alloy, a silicon nickel alloy, and the like.

[0077] In some embodiments, the silicon oxide contains silicon element and oxygen element, and the atomic ratio of the silicon element to the oxygen element is from 0 to 2, excluding 0. Specifically, the atomic ratio of the silicon element to the oxygen element may be, for example, 0.05, 0.11, 0.21, 0.26, 0.31, 0.41, 0.51, 0.59, 0.61, 0.69, 0.71, 0.74, 0.76, 0.79, 0.89, 0.99, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2, etc., and is not limited herein. Preferably, the atomic ratio of the silicon element to the oxygen element is from 0 to 1, excluding 0.

[0078] In some embodiments, the general chemical formula of the silicon oxide is SiO x where 0 < x < 2, and x may be specifically, for example, 0.05, 0.11, 0.21, 0.26, 0.31, 0.41, 0.51, 0.59, 0.61, 0.69, 0.71, 0.74, 0.76, 0.79, 0.89, 0.99, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, and 1.9, etc., and is not limited herein. Preferably, 0 < x < 1.

[0079] In some embodiments, the average particle size of the silicon particles is from 0.1 nm to 50 nm. Optionally, the average particle size of the silicon particles may be specifically, for example, 0.1 nm, 10 nm, 20 nm, 30 nm, 40 nm, and 50 nm, etc., or other values within the range, and can be selected according to actual needs, and is not limited herein. When the silicon particles expand, the mechanical stress decreases with the decrease of the particle size, and when the size decreases, the transport paths of electrons and ions can be shortened. At the same time, when the size of the silicon particles decreases and the gap between adjacent silicon particles increases, space can be reserved for expansion. As can be understood, if the average particle size of the silicon particles is within the above range, the battery capacity of the lithium-ion battery can be guaranteed and the irreversible capacity loss can be reduced. Preferably, the average particle size of the silicon particles is from 0.1 nm to 20 nm, and more preferably, the average particle size of the silicon particles is from 0.1 nm to 5 nm.

[0080] In some embodiments, the shape of the silicon particles includes at least one of point-like, spherical, ellipsoidal, and sheet-like shapes, and can be selected as needed, but is not limited thereto.

[0081] In some embodiments, the purity of the silicon particles is greater than 99%, and as can be understood, high-purity silicon particles are advantageous for Li-Si alloying with lithium, improving the cycle performance of lithium-ion batteries.

[0082] In some embodiments, the silicon particle growth method may be vapor phase growth or liquid phase growth, and can be selected as needed, but is not limited thereto.

[0083] Preferably, the silicon particle growth method is vapor-phase chemical growth, which includes the step of introducing a silicon-containing gas source and carrying out a vapor-phase chemical growth reaction with a carbon substrate. In some embodiments, the silicon-containing gas source includes at least one of monosilane, disilane, trisilane, and tetrasilane, and can be selected as needed, but is not limited thereto.

[0084] In some embodiments, the concentration of the silicon-containing gas source is 1% to 80%, and optionally, the concentration of the silicon-containing gas source may be specifically 1%, 13%, 26%, 43%, 55%, 68%, 80%, etc., or any other value within the range, and can be selected according to actual needs, and is not limited thereto.

[0085] In one embodiment, the introduced gas includes a silicon-containing gas source and an auxiliary carrier gas, the auxiliary carrier gas being able to dilute the silicon-containing gas source and help control the residence time of the silicon-containing gas source. The auxiliary carrier gas includes at least one of nitrogen, argon, and helium.

[0086] In some embodiments, the volume ratio of the silicon-containing gas source to the auxiliary carrier gas is 1:(1~10), specifically 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10, or any other value within the range, which can be selected within the above range as needed.

[0087] In some embodiments, the introduced gas may further contain doping gases, specifically NH3 and PH3.

[0088] In some embodiments, the atmospheric pressure for the gas-phase chemical growth reaction is between 10 kPa and atmospheric pressure.

[0089] In some embodiments, the temperature of the vapor phase growth reaction is 300°C to 800°C, and the incubation time is 1 to 15 hours. Optionally, the temperature may be specifically 300°C, 420°C, 500°C, 600°C, 700°C, 750°C, and 800°C, and the time may be specifically 1 hour, 3 hours, 4 hours, 6 hours, 7 hours, 8 hours, 10 hours, 12 hours, and 15 hours, or other values ​​within the range, and can be selected according to actual needs; these are not limited here. Preferably, the temperature of the vapor phase chemical growth reaction is 400°C to 600°C, and the incubation time for the vapor phase chemical growth reaction is 2 to 6 hours.

[0090] By controlling the reaction parameters of vapor-phase chemical growth, a vapor-phase silicon source can be permeated into a carbon substrate, decomposed within the pores of the carbon substrate, and grown to form silicon particles of an appropriate particle size.

[0091] In some embodiments, a liquid-phase silicon source may be used to compound with a carbon substrate, the liquid-phase silicon source comprising at least one of monochlorosilane, dichlorosilane, trichlorosilane, and tetrachlorosilane. When a liquid-phase silicon source is used, the compounding pressure may be 1 to 760 milliliters, and the compounding process temperature may be 300°C to 450°C.

[0092] In some embodiments, the thickness of the coating layer produced in step S20 is 1 nm to 300 nm, and optionally, the thickness of the coating layer may be specifically 1 nm, 50 nm, 150 nm, 200 nm, 250 nm, and 300 nm, or other values ​​within the range, and can be selected according to actual needs, and is not limited herein. As can be understood, the coating layer can reduce the solubility of the anode material and further reduce the amount of gas generated by the reaction between the dissolved silicon particles and the electrolyte. Controlling the thickness of the coating layer within the above range is advantageous for the anode material to maintain the stability of its particle structure during the cycling process, is advantageous for reducing the dissolution of silicon particles, is advantageous for improving lithium ion transport efficiency, and improves the charge-discharge performance of the anode material. Preferably, the thickness of the coating layer is 1 nm to 50 nm, and more preferably, the thickness of the coating layer is 1 nm to 30 nm.

[0093] In some embodiments, the mass occupancy of the coating layer in the anode material is ≤10%. As can be understood, the coating layer reduces the solubility of the anode material and further reduces the amount of gas generated by the reaction between the dissolved silicon particles and the electrolyte. Keeping the mass occupancy of the coating layer in the anode material within the above range ensures the lithium storage capacity of the anode material and further ensures the charge and discharge capacity of the lithium-ion battery manufactured with the anode material.

[0094] In some embodiments, the step of coating a composite includes the step of mixing the composite with a coating material and heat-treating it, wherein the coating material includes a carbon material.

[0095] In some embodiments, the carbon material includes at least one of amorphous carbon and graphitized carbon.

[0096] In some embodiments, the mass ratio of the active material to the coating material is 100:(1~100), and optionally, the mass ratio may be specifically 100:1, 100:10, 100:20, 100:40, 100:60, 100:70, and 100:100, or any other value within the range, and can be selected as needed, but is not limited thereto.

[0097] In some embodiments, the step of coating the composite includes the step of mixing the composite with a coating material and performing a heat treatment, wherein the heat treatment temperature is 400°C to 800°C and the heat treatment holding time is 1 hour to 15 hours.

[0098] In some embodiments, the heat treatment temperature is 400°C to 800°C, and the heat treatment holding time is 1h to 15h. Optionally, the temperature may be specifically 400°C, 500°C, 600°C, and 800°C, and the time may be specifically 1h, 3h, 5h, 6h, 8h, 10h, 11h, 12h, and 15h, or any other value within the range, which can be selected according to actual needs and are not limited thereto.

[0099] In some embodiments, the heat treatment is carried out under a protective gas, which includes, but is not limited to, at least one of nitrogen gas, helium gas, neon gas, argon gas, and krypton gas, and can be selected as needed.

[0100] In the above technical solution, a coating treatment is performed on the surface of the active material to form a coating layer on the surface of the active material. This reduces the decrease in initial Coulomb efficiency and specific capacity caused by side reactions occurring when the electrolyte enters the interior of the negative electrode material. Furthermore, it solves the problem of large volume expansion of the negative electrode material, improves the conductivity of the negative electrode material, reduces the overall volume expansion of the negative electrode material, and reduces swelling of the electrode sheet. During the coating treatment process, a small amount of coating material may enter the pores of the negative electrode material.

[0101] Furthermore, the coating process described in this application is carried out on the premise of reducing the occurrence of changes in the crystal form of the silicon carbon anode material.

[0102] Preferably, in step S20, the composite is subjected to a carbon coating treatment, and the carbon coating treatment includes at least one of solid-phase carbon coating, liquid-phase carbon coating, and gas-phase carbon coating.

[0103] In some embodiments, the carbon coating process is a gas-phase carbon coating and includes the steps of heating the composite, introducing a protective gas and a carbon source gas, thermally decomposing the carbon source gas, and obtaining the negative electrode material.

[0104] In some embodiments, the carbon source gas is a hydrocarbon system.

[0105] In some embodiments, the carbon source gas includes at least one of methane, ethane, propane, ethylene, acetylene, gaseous benzene, gaseous toluene, gaseous xylene, gaseous ethanol, and gaseous acetone.

[0106] In some embodiments, a protective gas and a carbon source gas are introduced to maintain atmospheric pressure within the range of 1 to 10 kPa.

[0107] In some embodiments, the thermal decomposition temperature is 400°C to 800°C, and the holding time is 0.5h to 18h. Optionally, the temperature may be specifically 400°C, 500°C, 600°C, 700°C, and 800°C, and the holding time may be specifically 0.5h, 1.5h, 3h, 5h, 6h, 7h, 8h, 10h, and 18h, or other values ​​within the range, which can be selected according to actual needs and are not limited thereto.

[0108] In some embodiments, the volume ratio of the carbon source gas to the protective gas is 1:(0.1~20), and optionally, the volume ratio may be specifically 1:0.1, 1:1, 1:2, 1:5, 1:10, 1:15, and 1:20, or any other value within the range, and can be selected as needed, but is not limited thereto.

[0109] In some embodiments, the flow rate of the carbon source gas is 100 sccm to 500 sccm, specifically 100 sccm, 200 sccm, 250 sccm, 300 sccm, 350 sccm, 400 sccm, 450 sccm, or 500 sccm, and of course, it may be any other value within the above range, and is not limited thereto. Preferably, the flow rate of the carbon source gas is 200 sccm to 300 sccm.

[0110] By controlling parameters such as the volume ratio of the carbon source gas to the protective gas, the gas flow rate, and the reaction pressure, it is advantageous for the carbon material obtained by the decomposition of the carbon source gas to grow on the surface of the composite.

[0111] In some embodiments, growth coating of a carbon source gas is performed under conditions of a rotating reactor to achieve a homogeneous phase in situ carbon coating on the composite surface.

[0112] In some embodiments, the carbon coating treatment is a solid-phase carbon coating, and includes the step of carbonizing a mixture obtained by mixing a composite with a solid-phase carbon source to obtain a negative electrode material.

[0113] In some embodiments, the carbonization temperature is 400°C to 800°C, and the carbonization time is 1 hour to 15 hours. Optionally, the temperature may be specifically 400°C, 500°C, 600°C, 700°C, and 800°C, and the time may be specifically 1 hour, 2 hours, 4 hours, 6 hours, 8 hours, 9 hours, 11 hours, 12 hours, and 15 hours, or any other value within the range, and can be selected according to actual needs; it is not limited here.

[0114] In some embodiments, the solid-phase carbon source includes at least one of sugars, esters, hydrocarbons, organic acids, and polymers.

[0115] In some embodiments, the solid-phase carbon source includes at least one of the following: polyvinyl chloride, polyvinyl butyral, polyacrylonitrile, polyacrylic acid, polyethylene glycol, polypyrrole, polyaniline, sucrose, glucose, maltose, citric acid, asphalt, furfural resin, epoxy resin, and phenolic resin.

[0116] In some embodiments, the mass ratio of the solid-phase carbon source to the active material is 100:(10~200), and optionally, the mass ratio may be specifically 100:10, 100:40, 100:60, 100:100, 100:130, 100:160, and 100:200, or any other value within the range, and can be selected according to actual needs, and is not limited thereto.

[0117] In some embodiments, the carbon coating process is a liquid-phase carbon coating process, which includes the step of carbonizing a mixture obtained by mixing a composite material with a liquid-phase carbon source to obtain a negative electrode material.

[0118] In some embodiments, the mass ratio of the liquid phase carbon source to the active material is 100:(5~300), and optionally, the mass ratio may be specifically 100:5, 100:10, 100:60, 100:150, 100:200, 100:240, and 100:300, or any other value within the range, which can be selected as needed and is not limited thereto.

[0119] In some embodiments, the liquid-phase carbon source includes at least one of n-hexane, toluene, benzene, xylene, methanol, ethanol, propanol, butanol, pentanol, acetone, methyl ethyl ketone, 2-pentanone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, and amyl acetate.

[0120] In some embodiments, the carbonization temperature is 400°C to 800°C, and the carbonization time is 1 hour to 15 hours. Optionally, the temperature may be specifically 400°C, 500°C, 600°C, 700°C, and 800°C, and the time may be specifically 1 hour, 3 hours, 5 hours, 7 hours, 9 hours, 10 hours, 12 hours, 13 hours, and 15 hours, or any other value within the range, which can be selected according to actual needs and are not limited thereto.

[0121] In a third embodiment, the present invention provides a battery comprising the above-described negative electrode material or a negative electrode material manufactured by the above-described manufacturing method. The battery may be, but is not limited to, an electrochemical device such as a lithium-ion battery or a sodium-ion battery.

[0122] As those skilled in the art will understand, the lithium-ion battery manufacturing method described above is merely an example. Other methods commonly used in the art may be employed without departing from the disclosure herein.

[0123] The embodiments of this application will be further described below in the form of several examples. However, the embodiments of this application are not limited to the following specific examples. They may be modified and implemented as appropriate without altering the sovereign right.

[0124] Measurement method: 1. Measurement of density β: A negative electrode material with a mass of m1g is immersed in a hydrofluoric acid solution with a mass fraction of 20% for 1 hour, then washed and dried to obtain m2g of material. The surface density β of the negative electrode material is then calculated as β = m2 / m1 × 100%.

[0125] 2. Thickness of the coating layer: The material is cut using a FIB-SEM device, and the average thickness of the coating layer is obtained by measuring it with a SEM.

[0126] 3. Method for measuring the pore volume and ratio between the carbon substrate and the negative electrode material from which silicon particles have been removed: The pore volume of a carbon substrate is the total pore volume per unit mass of the carbon substrate, and this can be measured by gas adsorption measurements. Nitrogen gas adsorption is a technique that characterizes the porosity and pore size distribution of a material by condensing gas within the voids of a solid. As the pressure increases, the gas first condenses in the voids with the smallest diameter, and the pressure rises until it reaches a saturation point, at which point all voids are filled with liquid. Subsequently, the pressure of the nitrogen gas gradually decreases, causing the liquid to evaporate from the system. By analyzing adsorption-desorption isotherms, the distribution of pore volume and void size, as well as the proportion of the pore volumes of micropores, mesopores, and macpores in the total pore volume, can be determined. However, as a method for removing silicon particles from the negative electrode material, a 1M nitric acid solution is added to the negative electrode material and it is immersed for 4 hours. Subsequently, a 20% mass fraction HF acid solution is added drop by drop to the negative electrode material, and this process is repeated several times until yellow smoke is generated and no more yellow smoke is generated in the solution. Finally, the residue is decomposed again with a 1M nitric acid solution, followed by washing and drying to obtain the negative electrode material after the active material has been removed.

[0127] 4. Gas generation measurement: Carboxymethylcellulose (CMC) is dispersed in water at a mass ratio of 1.4% to form an adhesive. After uniform dispersion, 10 g of the adhesive solution is taken and mixed with 10 g of negative electrode material to obtain a slurry. The slurry is placed in an aluminum plastic film bag, its mass is recorded, and then the bag is sealed to form a sealed aluminum plastic film bag. The sealed aluminum-plastic film bag is fixed to the bottom of the container and completely immersed in water. The volume of the aluminum-plastic film bag is recorded, and after a certain period of time (24 hours), the volume of the aluminum-plastic film bag is recorded again. The amount of gas generated by the silicon anode material is calculated based on the change in volume of the aluminum-plastic film bag, in units of mL / g.

[0128] 5. Type of silicon particles: The type of silicon particles is determined by measuring the diffraction peak using an X-ray diffractometer (XRD).

[0129] 6. Measurement of the mass content of silicon in the negative electrode material: Using a box-type atmosphere furnace (brand: Nanyo Kinyu, model number: SA2-9-17TP), the sample is calcined under an oxygen gas atmosphere to react silicon with silicon oxy-oxide to form silica. After combustion, the carbon is emitted as carbon dioxide, and the silica in the negative electrode material is weighed. Calculate the mass content of n.

[0130] 8. Powder resistivity measurement: The volume resistivity of the sample is measured using the four-probe method. The instrument measures the resistance of the powder at five pressure points of 4, 8, 12, 16, and 20 kN, and then the computer automatically calculates the conductivity and resistivity of the powder.

[0131] 9. Measurement of the mass content of trace metal elements in carbon substrates: The mass content of each trace metallic element (Fe, Co, Ni, Cr, Zn, Cu, Al, etc.) in the carbon substrate was measured using ICP emission spectroscopy, with the model number of the measuring instrument being PEoptima8000.

[0132] 10. Measurement of the mass content of carbon element in the negative electrode material: Using a German Bruker / Ertra infrared carbon-sulfur analyzer G4ICARUSHF / CS-i, the sample is burned under high-temperature, oxygen-enriched conditions, causing the contained carbon elements to oxidize to carbon dioxide. This carbon dioxide enters the infrared detector along with the carrier gas, and the carbon content is calculated by quantitatively statistically measuring the change in the infrared absorption wavelength intensity of the carbon dioxide signal.

[0133] 11. Electrical characteristics measurement: The electrochemical cycle performance is measured using the following method: The negative electrode material, conductive agent, and binder are dissolved and mixed in a solvent at a mass percentage of 94:1:5, the solid content is controlled to 50%, and the mixture is applied to a copper foil current collector, vacuum-dried to obtain a negative electrode sheet. Subsequently, a ternary positive electrode sheet manufactured using a conventional, well-established process, a 1 mol / L LiPF6 / EC+DMC+EMC (v / v=1:1:1) electrolyte, a Celgard 2400 separator, and a case are assembled into an 18650 cylindrical cell using a conventional manufacturing process. Charge and discharge measurements of the cylindrical cell are performed using the LAND battery measurement system of Wuhan Jinnuo Electronics Co., Ltd., under room temperature conditions, charging and discharging are performed with a constant current of 0.2C, and the charge and discharge voltage is limited to 2.75~4.2V. In the following examples, the average particle size of the silicon particles grown within the carbon substrate is 0.1 nm to 50 nm, the purity of the silicon particles is greater than 99%, the thickness of the coating layer is 1 nm to 300 nm, and the mass occupancy of the coating layer in the negative electrode material is ≤10%.

[0134] (Example 1) (1) Using bamboo charcoal as a raw material, carbonization treatment is performed, followed by acid pickling to obtain a porous carbon substrate. (2) A carbon substrate having pores is added to a 2 mol / L copper nitrate solution, immersed for 0.5 hours, and then vacuum-dried at 80°C to obtain a carbon substrate containing a catalyst. (3) Place the catalyst-containing carbon substrate in the CVD reaction cavity, repeatedly blow air through the reaction cavity with nitrogen gas for 3-5 minutes, then close the nitrogen gas and introduce argon gas, set the flow rate to 400 sccm, raise the temperature to 500°C, raise the heating rate to 8°C / min, and after remaining at this temperature for 1 hour, open the monosilane and introduce a mixed gas of monosilane and argon gas into the CVD apparatus, set the volume concentration ratio of monosilane to argon gas to 1:3 (silicon-containing gas concentration is 25%), set the total gas concentration to 100 sccm, maintain the temperature for 5 hours, then close the silane gas and cool to room temperature to obtain the composite. (4) The phenolic resin and composite material are mixed in a mass ratio of 1:4, and after mixing for 10 minutes in a VC mixing machine, the mixed material is placed in a high-temperature box-type furnace, vacuumed to 5kPa, nitrogen gas is introduced, and carbonization is performed at 580°C and 5kPa, and after being kept warm for 2 hours, the temperature is lowered, the product is pulverized, screened, and then classified to obtain the anode material. The negative electrode material manufactured in this embodiment comprises a carbon substrate, silicon particles, and a coating layer located on the surface of a silicon-based active material, wherein some of the silicon particles are located within the pores of the carbon substrate, and the coating layer comprises a carbon layer.

[0135] (Example 2) The differences from Example 1 are as follows: (2) A porous carbon substrate is added to a 2 mol / L iron nitrate solution, immersed for 0.5 hours, and then vacuum-dried at 80°C to obtain a carbon substrate containing a catalyst. The negative electrode material manufactured in this embodiment comprises a carbon substrate, silicon particles, and a coating layer located on the surface of a silicon-based active material, wherein some of the silicon particles are located within the pores of the carbon substrate, and the coating layer comprises a carbon layer.

[0136] (Example 3) The differences from Example 1 are as follows: (2) A porous carbon substrate is added to a 0.7 mol / L boric acid solution, immersed for 0.5 hours, and then treated at 900°C to obtain a carbon substrate containing a catalyst. The negative electrode material manufactured in this embodiment comprises a carbon substrate, silicon particles, and a coating layer located on the surface of a silicon-based active material, wherein some of the silicon particles are located within the pores of the carbon substrate, and the coating layer comprises a carbon layer.

[0137] (Example 4) The differences from Example 1 are as follows: (2) A carbon substrate having pores and nickel carbonate are mixed in a mass ratio of 100:2, then dried and treated at 960°C to obtain a carbon substrate containing a catalyst. The negative electrode material manufactured in this embodiment comprises a carbon substrate, silicon particles, and a coating layer located on the surface of a silicon-based active material, wherein some of the silicon particles are located within the pores of the carbon substrate, and the coating layer comprises a carbon layer.

[0138] (Example 5) The differences from Example 1 are as follows: (4) The epoxy resin and composite material are mixed in a mass ratio of 1:3, and after mixing for 10 minutes in a VC mixing machine, the mixed material is placed in a high-temperature box-type furnace, vacuumed to 5kPa, nitrogen gas is introduced, and carbonization is performed at 580°C and 5kPa, and after being kept warm for 2 hours, the temperature is lowered, the product is pulverized, screened, and then classified to obtain the anode material. The negative electrode material manufactured in this embodiment comprises a carbon substrate, silicon particles, and a coating layer located on the surface of a silicon-based active material, wherein some of the silicon particles are located within the pores of the carbon substrate, and the coating layer comprises a carbon layer.

[0139] (Example 6) The differences from Example 1 are as follows: (4) The phenolic resin and composite material are mixed in a mass ratio of 1:4, and after mixing for 10 minutes in a VC mixing machine, the mixed material is placed in a high-temperature box-type furnace, vacuumed to 5 kPa, nitrogen gas is introduced, and carbonization is performed at 680°C and 5 kPa, and after being kept warm for 2 hours, the temperature is lowered, the product is pulverized, screened, and then classified to obtain the anode material. The negative electrode material manufactured in this embodiment comprises a carbon substrate, silicon particles, and a coating layer located on the surface of a silicon-based active material, wherein some of the silicon particles are located within the pores of the carbon substrate, and the coating layer comprises a carbon layer.

[0140] (Example 7) The differences from Example 1 are as follows: (4) The phenolic resin and composite material are mixed in a mass ratio of 1:4, and after mixing for 10 minutes in a VC mixing machine, the mixed material is placed in a high-temperature box-type furnace, vacuumed to 5 kPa, nitrogen gas is introduced, and carbonization is performed at 720°C and 5 kPa, and after being kept warm for 2 hours, the temperature is lowered, the product is crushed, screened, and then classified to obtain the anode material.

[0141] (Example 8) The differences from Example 1 are as follows: (4) The phenolic resin and composite material are mixed in a mass ratio of 1:4 and mixed for 10 minutes in a VC mixing machine. Subsequently, the mixed material is placed in a high-temperature box furnace, vacuumed to 5 kPa, nitrogen gas is introduced, and carbonization is performed at 800°C and 5 kPa. After being kept warm for 2 hours, the temperature is lowered, the product is crushed, screened, and then classified to obtain the anode material. The negative electrode material manufactured in this embodiment comprises a carbon substrate, silicon particles, and a coating layer located on the surface of a silicon-based active material, wherein some of the silicon particles are located within the pores of the carbon substrate, and the coating layer comprises a carbon layer.

[0142] (Example 9) The differences from Example 1 are as follows: (3) A carbon substrate containing a catalyst is placed in a CVD reaction cavity, the reaction cavity is repeatedly air-blown with nitrogen gas for 3 to 5 minutes, then the nitrogen gas is closed and argon gas is introduced, the flow rate is set to 400 sccm, the temperature is raised to 500°C, the heating rate is set to 8°C / min, and after remaining at this temperature for 1 hour, the monosilane is opened and a mixed gas of monosilane and argon gas is introduced into the CVD apparatus, the volume concentration ratio of monosilane to argon gas is set to 1:8 (silicon-containing gas concentration is 11.1%), the total gas concentration is set to 100 sccm, the temperature is maintained for 5 hours, then the monosilane gas is closed and the temperature is lowered to room temperature to obtain the composite. The negative electrode material manufactured in this embodiment comprises a carbon substrate, silicon particles, and a coating layer located on the surface of a silicon-based active material, wherein some of the silicon particles are located within the pores of the carbon substrate, and the coating layer comprises a carbon layer.

[0143] (Example 10) The differences from Example 1 are as follows: (3) A carbon substrate containing a catalyst is placed in a CVD reaction cavity, the reaction cavity is repeatedly air-blown with nitrogen gas for 3 to 5 minutes, then the nitrogen gas is closed and argon gas is introduced, the flow rate is set to 400 sccm, the temperature is raised to 500°C, the heating rate is set to 8°C / min, and after remaining at this temperature for 1 hour, the silane is opened and a mixed gas of silane and argon gas is introduced into the CVD apparatus, the volume concentration ratio of silane and argon gas is set to 1:5 (silicon-containing gas concentration is 16.7%), the total gas concentration is set to 100 sccm, the temperature is maintained for 5 hours, then the silane gas is closed and the temperature is lowered to room temperature to obtain the composite. The negative electrode material manufactured in this embodiment comprises a carbon substrate, silicon particles, and a coating layer located on the surface of a silicon-based active material, wherein some of the silicon particles are located within the pores of the carbon substrate, and the coating layer comprises a carbon layer.

[0144] (Example 11) The differences from Example 1 are as follows: (3) A carbon substrate containing a catalyst is placed in a CVD reaction cavity, the reaction cavity is repeatedly air-blown with nitrogen gas for 3 to 5 minutes, then the nitrogen gas is closed and argon gas is introduced, the flow rate is set to 400 sccm, the temperature is raised to 500°C, the heating rate is set to 8°C / min, and after remaining at this temperature for 1 hour, the silane is opened and a mixed gas of silane and argon gas is introduced into the CVD apparatus, the volume concentration ratio of silane to argon gas is set to 1:3 (silicon-containing gas concentration is 25%), the total gas concentration is set to 100 sccm, the temperature is maintained for 5 hours, then the silane gas is closed and the temperature is lowered to room temperature to obtain the composite. The negative electrode material manufactured in this embodiment comprises a carbon substrate, silicon particles, and a coating layer located on the surface of a silicon-based active material, wherein some of the silicon particles are located within the pores of the carbon substrate, and the coating layer comprises a carbon layer.

[0145] (Example 12) The differences from Example 1 are as follows: (3) A carbon substrate containing a catalyst is placed in a CVD reaction cavity, the reaction cavity is repeatedly air-blown with nitrogen gas for 3 to 5 minutes, then the nitrogen gas is closed and argon gas is introduced, the flow rate is set to 400 sccm, the temperature is raised to 500°C, the heating rate is set to 8°C / min, and after remaining at this temperature for 1 hour, the silane is opened and a mixed gas of silane and argon gas is introduced into the CVD apparatus, the volume concentration ratio of silane to argon gas is set to 1:4 (silicon-containing gas concentration is 20%), the total gas concentration is set to 100 sccm, the temperature is maintained for 8 hours, then the silane gas is closed and the temperature is lowered to room temperature to obtain the composite. The negative electrode material manufactured in this embodiment comprises a carbon substrate, silicon particles, and a coating layer located on the surface of a silicon-based active material, wherein some of the silicon particles are located within the pores of the carbon substrate, and the coating layer comprises a carbon layer.

[0146] (Comparative Example 1) (1) Using bamboo charcoal as a raw material, carbonization treatment is performed, followed by acid pickling to obtain a porous carbon substrate. (2) A carbon substrate having pores is added to a 2 mol / L copper nitrate solution, immersed for 0.5 hours, and then vacuum-dried at 80°C to obtain a carbon substrate containing a catalyst. (3) A carbon substrate containing a catalyst is placed in a CVD reaction cavity, the reaction cavity is repeatedly air-blown with nitrogen gas for 3 to 5 minutes, then the nitrogen gas is closed and argon gas is introduced, the flow rate is set to 400 sccm, the temperature is raised to 500°C, the heating rate is set to 8°C / min, and after remaining at this temperature for 1 hour, the monosilane is opened and a mixed gas of silane and argon gas is introduced into the CVD apparatus, the volume concentration ratio of monosilane to argon gas is set to 1:3 (silicon-containing gas concentration is 25%), the total gas concentration is set to 100 sccm, the temperature is maintained for 5 hours, then the silane gas is closed and the temperature is lowered to room temperature to obtain the composite. The negative electrode material produced in this embodiment includes a carbon substrate and silicon particles.

[0147] (Comparative Example 2) (1) Using bamboo charcoal as a raw material, carbonization treatment is performed, followed by acid pickling to obtain a porous carbon substrate. (2) Place the carbon substrate in the CVD reaction cavity, blow the reaction cavity with nitrogen gas repeatedly for 3-5 minutes, then close the nitrogen gas and introduce argon gas, set the flow rate to 400 sccm, raise the temperature to 500°C, raise the heating rate to 8°C / min, and after remaining at this temperature for 1 hour, open the silane and introduce a mixed gas of silane and argon gas into the CVD apparatus, set the volume concentration ratio of silane to argon gas to 1:3 (silicon-containing gas concentration is 25%), set the total gas concentration to 100 sccm, maintain the temperature for 5 hours, then close the silane gas and cool to room temperature to obtain the composite. (3) The phenolic resin and composite material are mixed in a mass ratio of 1:4, and after mixing for 10 minutes in a VC mixing machine, the mixed material is placed in a high-temperature box-type furnace, vacuumed to 5kPa, nitrogen gas is introduced, and carbonization is performed at 580°C and 5kPa, and after being kept warm for 2 hours, the temperature is lowered and the product is crushed, screened, and then classified to obtain the anode material. The negative electrode material manufactured in this embodiment comprises a carbon substrate, silicon particles, and a coating layer located on the surface of a silicon-based active material, wherein some of the silicon particles are located within the pores of the carbon substrate, and the coating layer comprises a carbon layer.

[0148] [Table 1]

[0149] [Table 2]

[0150] [Table 3]

[0151] [Table 4]

[0152] As can be seen from the data in Tables 1 to 4, Examples 1 to 4 mainly explored the relationship between the surface density of the anode material and the catalyst in the carbon substrate when the silicon content is similar. As can be seen from the data, Example 3 has a larger total pore volume in the anode material from which silicon particles have been removed compared to Examples 1 to 2 or Example 4, allowing more pores to accommodate the catalyst. In the subsequent carbon coating process, the thickness of the coating layer is also affected. The surface density of the anode material in Example 3 is relatively high, and the influence of the different catalysts on the coating layer on the surface of the anode material is not significant.

[0153] As is clear from the data in Tables 1-4, Examples 5-8 primarily explore the relationship between the surface density of the anode material and the thickness of the coating layer when the silicon content is similar. As can be seen from the data, among Examples 1 and 5-8, Example 5 increased the amount of coating material added compared to Example 1, resulting in increased surface density of the anode material. In Example 6, compared to Example 1, the carbonization temperature during the carbon coating process was higher, resulting in increased surface density of the anode material. However, as the carbonization temperature continuously increased, the surface density of the anode material slightly decreased with increasing temperature. This is because excessively high temperatures cause partial gasification of the carbon material. Preferably, the carbonization temperature during the carbon coating process is 580°C to 720°C. The presence of an appropriate amount of catalyst in the carbon substrate can lower the carbonization temperature during the carbon coating process, making it possible to obtain a dense coating layer at a relatively low temperature.

[0154] As can be seen from the data in Tables 1-4, Examples 9-12 primarily explored the effect of changes in silicon content on the anode material. As the silicon content increases, the specific capacity of the anode material increases, and the expansion effect also increases. Because the surface of the anode material has a coating layer, the difference in surface density between them is not large, and the gas generation value of the anode material also fluctuates only slightly.

[0155] In Comparative Example 1, compared to Example 1, no coating treatment was performed, resulting in a significant decrease in the surface density of the negative electrode material. The solid electrolyte film formed by the side reaction between the negative electrode material and the electrolyte became thicker, and a large amount of active lithium ions were consumed. This led to a significant decrease in the initial Coulomb efficiency of the battery, a significant increase in the volume expansion rate after the battery cycle, and an increase in gas generation.

[0156] In Comparative Example 2, the anode material produced lacked a catalyst, and since the catalyst was not present in the carbon substrate, the carbon material had difficulty filling the voids within the carbon substrate. As a result, the carbon material mainly coated the surface of the anode material, and the total pore volume of the anode material clearly increased. Furthermore, the surface density of the anode material decreased, and the gas generation value of the anode material also clearly increased.

[0157] The above describes in detail the structure, features, and effects of the present application based on the embodiments shown in the drawings. The above description is merely a preferred embodiment of the present application, and the scope of the present application is not limited to those shown in the drawings. Modifications made based on the concept of the present application, or equivalent embodiments amended to equivalent modifications, should still fall within the scope of protection of the present application, provided that they do not deviate from the spirit contained in the specification and drawings.

[0158] [Cross-reference of related applications] This application claims priority rights to three Chinese patent applications: application number 202311289564.7, filed with the China National Intellectual Property Administration on September 28, 2023, with the application title "Anode material and method for manufacturing the same, lithium-ion battery"; application number 202311832248.X, filed with the China National Intellectual Property Administration on December 27, 2023, with the application title "Anode material and battery"; and application number 202410205115.8, filed with the China National Intellectual Property Administration on February 23, 2024, with the contents of all of these applications incorporated into this application by reference.

Claims

1. A negative electrode material, wherein the negative electrode material contains an active material, the surface density of the negative electrode material is β, and β is ≥ 80%. However, the β mentioned above is measured by the following measurement method: Mass m １ The negative electrode material g is immersed in a hydrofluoric acid solution with a mass fraction of 20%, immersed for 1 hour, washed, and dried. ２ Obtain material g and calculate the surface density β = m of the negative electrode material. ２ / m １ A negative electrode material characterized by achieving ×100%.

2. The negative electrode material according to claim 1, characterized in that the active material comprises a carbon substrate and silicon particles, and at least some of the silicon particles are located inside the particles of the carbon substrate.

3. The negative electrode material according to claim 1, characterized in that the negative electrode material has pores, the pores include micropores and mesopores, wherein the ratio of the pore volume of the micropores to the pore volume of the mesopores is (1 to 45):(55 to 99).

4. The aforementioned negative electrode material is (1) The characteristic of micropores is that the pore volume occupancy is ≤10%, (2) The characteristic of mesopores is that the pore volume occupancy rate is ≥ 80%, (3) The negative electrode material according to claim 3, characterized in that it has at least one of the following features: the pore volume occupancy rate of the macropores is ≤20%.

5. The negative electrode material has holes, and the negative electrode material is (1) The total pore volume of the negative electrode material is 0.001 cm³. ３ / g ~ 0.1cm ３ The characteristic of being / g, (2) The negative electrode material has the characteristic that the average pore size is 0.4 nm to 50 nm, (3) The negative electrode material according to claim 1, characterized in that it has at least one of the following features: (3) The volume occupancy rate of the total pore volume of pores with a pore diameter of 10 nm or less in the negative electrode material is ≥ 80%.

6. The aforementioned negative electrode material is (1) In the negative electrode material from which silicon particles have been removed, the volume occupancy rate in the total pore volume of pores with a pore size of 2 nm or less is ≥ 70%, (2) The negative electrode material from which silicon particles have been removed has the characteristic that the volume occupancy rate of the total pore volume of pores with a pore size of 5 nm or less is ≥ 85%, (3) The negative electrode material from which silicon particles have been removed has the characteristic that the volume occupancy rate of the total pore volume of pores with a pore diameter of 10 nm or less is ≥ 95%, (4) The specific surface area of ​​the negative electrode material from which the silicon particles have been removed is 500 m². ２ / g to 2000m ２ The characteristic of being / g, (5) The total pore volume of all pores in the negative electrode material from which silicon particles have been removed is 0.5 cm ３ / g to 1.5 cm ３ / g, and the negative electrode material according to claim 5, characterized by having at least one of the above features.

7. The aforementioned negative electrode material is (1) The silicon particles are characterized by containing at least one of the following: crystalline silicon, silicon oxide, amorphous silicon, silicon alloy, and crystalline silicon / amorphous silicon composite particles. (2) The average particle size of the silicon particles is 0.1 nm to 50 nm, (3) The anode material according to claim 2, characterized in that the carbon substrate contains at least one of the following: artificial graphite, natural graphite, amorphous carbon, activated carbon, mesocarbon microbeads, carbon nanotubes, carbon nanofibers, porous carbon, and graphene.

8. The aforementioned negative electrode material is (1) The negative electrode material has a characteristic of having a mass content of silicon element of 20% to 60%, (2) The negative electrode material is characterized in that the mass content of carbon is 20% to 80%, (3) The negative electrode material contains trace metal elements, and the trace metal elements are characterized by containing at least one of Fe, Co, Ni, Cr, Zn, Cu, and Al. (4) The negative electrode material according to claim 2, characterized in that the negative electrode material has at least one of the following characteristics: containing trace metal elements with a mass occupancy of ≤200 ppm.

9. The anode material according to claim 1, characterized in that the average gas generation amount when the anode slurry produced from the anode material is left in a 25°C environment for 7 days is ≤1 mL / g / day.

10. The anode material according to any one of claims 1 to 9, characterized in that the surface of the anode material has a coating layer, and the material of the coating layer includes a carbon material.

11. The aforementioned negative electrode material is (1) The carbon material is characterized by containing at least one of amorphous carbon and graphitized carbon, (2) The coating layer has the characteristic of having a thickness of 1 nm to 300 nm, (3) The anode material according to claim 10, characterized in that the mass occupancy rate of the coating layer in the anode material is ≤10%.

12. The aforementioned negative electrode material is (1) The negative electrode material has the characteristic that the median particle size is ≤ 10 μm, (2) The particle size distribution of the negative electrode material is 0.9 ≤ (D ９０ -D １０ ) / D ５０ The negative electrode material according to any one of claims 1 to 9, characterized in that it has at least one of the features that satisfy ≤ 5.

13. The aforementioned negative electrode material is (1) The specific surface area of ​​the negative electrode material is ≤ 10 m² ２ The characteristic of being / g, (2) The density of the compacted negative electrode material is 0.8 g / cm³ ３ ~1.3 g / cm ３ The characteristics of, (3) The tap density of the negative electrode material is 0.5 g / cm³ ３ ~1.5 g / cm ３ The negative electrode material according to any one of claims 1 to 9, characterized by having at least one of the following features.

14. The negative electrode material according to claim 1, characterized in that the powder conductivity of the negative electrode material at a pressure of 20 kN is 0.5 S / cm to 5 S / cm.

15. A battery comprising the negative electrode material according to any one of claims 1 to 14.

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