Negative electrode material and method for manufacturing the same, and lithium-ion battery

Abstract

The present application relates to a negative electrode material and a method for producing the same, and to a lithium ion battery. [Solution] The negative electrode material includes a carbon material, the carbon material includes a carbon shell layer, and the carbon material has a chamber inside, the chamber is formed so as to be surrounded by the carbon shell layer, and the carbon shell layer has holes, and at least some of the holes penetrate the carbon shell layer. In the negative electrode material of the present application, the carbon material has a chamber located inside and holes located in the carbon shell layer, so that the negative electrode material can secure a sufficient space to withstand the expansion stress of lithium insertion, and improve the expansion resistance and cycle performance of the negative electrode material.

Description

[Technical Field]

[0001] This application claims priority based on a Chinese patent application filed with the China Patent Administration on December 26, 2022, with application number 202211679854.8 and title "Anode material and method for manufacturing the same, and lithium-ion battery," all of which are incorporated herein by reference.

[0002] This application belongs to the technical field of negative electrode materials, and more specifically, to negative electrode materials and manufacturing methods, as well as lithium-ion batteries. [Background technology]

[0003] Porous carbon anode materials are among the most important materials for improving the cycle expansion performance of lithium-ion batteries. Conventional porous carbon anode materials achieve lithium support through their large internal chambers or pore structures, thereby suppressing volume expansion. These porous carbon materials are usually synthesized by simple high-temperature carbonization, and the porous structure directly formed by high-temperature carbonization has a discontinuous graphite crystal lattice structure. Such a structure reduces the van der Waals forces between carbon material particles due to the mechanical properties of the carbon material itself and graphite π-π stacking, and the particle pores and gaps between particles cannot withstand the expansion stress of lithium insertion, requiring the addition of extra adhesive to the anode material, which reduces the energy density of the porous carbon anode material to some extent. At the same time, porous carbon anode materials often require thick pore walls to provide sufficient mechanical strength, which reduces the efficiency of carbon utilization and is disadvantageous for capacity reallocation.

[0004] Therefore, the development of high-capacity, low-expansion anode materials is currently a matter of urgency. [Overview of the project] [Problems that the invention aims to solve]

[0005] This application provides a negative electrode material, a method for manufacturing the same, and a lithium-ion battery. The negative electrode material of this application improves the utilization efficiency of carbon in the material, further improves the capacity and cycle capability of the material, and has excellent resistance to expansion. [Means for solving the problem]

[0006] To achieve the above objective, the first technical proposal of the present application is as follows: an embodiment of the present application provides a negative electrode material comprising a carbon material comprising a carbon shell layer having a chamber inside the carbon material, the chamber being formed to be surrounded by the carbon shell layer, the carbon shell layer having holes, at least some of which penetrate the carbon shell layer.

[0007] The second technical proposal of this application is as follows: The embodiment of this application provides a method for manufacturing a negative electrode material, A mixture containing a silicon-oxygen raw material supported by metal catalyst particles and a carbon source is subjected to a first heat treatment to catalyze the graphitization of the carbon source and obtain a first precursor. The first precursor is etched to obtain a second precursor, and the etching agent for the etching treatment is an oxidizing acid. The method includes the step of reducing at least a portion of the silicon-oxygen raw material in the second precursor to a silicon material to obtain a negative electrode material.

[0008] The third technical proposal of this application is as follows: Embodiments of the present application provide a lithium-ion battery, the lithium-ion battery comprising a negative electrode material described in the first embodiment or a negative electrode material manufactured by the manufacturing method described in the second embodiment. [Effects of the Invention]

[0009] The technical means of the present invention has at least the following beneficial effects.

[0010] In the anode material of the present invention, the carbon material comprises a chamber located inside the carbon shell layer and pores located in the carbon shell layer. The presence of the chamber and pores makes the carbon material a porous hollow housing, and such a structure can ensure sufficient space when the filled silicon material expands. When the silicon material expands and presses against the carbon material, the carbon material releases internal gas or electrolyte through the pores in the carbon shell layer to form strain in order to withstand the expansion stress of lithium insertion. When the silicon material releases lithium and contracts, the strained carbon material absorbs gas or electrolyte through the pores in the carbon shell layer to recover its shape, thereby improving the expansion resistance and cycle performance of the anode material.

[0011] In this invention, by performing a first heat treatment on a mixture containing a silicon oxygen raw material supporting catalyst metal particles and a carbon source, the carbon source undergoes graphitization decomposition during the first heat treatment to generate carbon atoms. Some of the carbon atoms can dissolve inside the catalyst metal particles, dissolve to saturation and precipitate on the catalyst surface, where the precipitated carbon atoms grow into a carbon shell layer. Other carbon atoms can grow along the surface of the metal particles through the catalytic action of the catalyst metal particles to form a carbon shell layer, creating a structure in which the catalyst metal particles are sealed inside the carbon shell layer. On the other hand, because the silicon oxygen raw material has poor catalytic ability with respect to the carbon source material, the silicon oxygen raw material is distributed outside the carbon shell layer and dispersed among the metal particles sealed in the carbon shell layer, thereby obtaining a first precursor. Next, the first precursor is etched, etching the catalyst metal particles inside the carbon shell layer to form chambers. Simultaneously, the etched oxidizing acid undergoes a redox reaction with defects in the carbon shell layer to form bonds such as CO, C=O, CN, and CS, creating pores and forming a porous carbon material with internal voids (i.e., the second precursor). Finally, at least a portion of the silicon-oxygen raw material in the second precursor is reduced to a silicon material to obtain the anode material. In the manufacturing method of the present invention, under the first heat treatment conditions, the carbon source is catalytically grown into a shell layer structure via metal catalyst particles. Further etching creates chambers inside the carbon shell layer structure, and the carbon shell layer becomes porous, thereby improving the expansion resistance of the material. Finally, in the present invention, there is no need to etch the silicon-oxygen raw material; the silicon-oxygen raw material is directly reduced to a silicon material, reducing waste of the silicon-oxygen raw material and improving the capacity of the anode material. [Brief explanation of the drawing]

[0012] The present application will be further described below with reference to the drawings and embodiments. [Figure 1] This is a schematic diagram showing the configuration of the negative electrode material relating to the present invention. [Figure 2] This is a schematic diagram showing the cross-sectional structure of a carbon material. [Figure 3] This is a manufacturing flowchart for the negative electrode material related to the present invention. [Figure 4]This is a process diagram for preparing a first precursor by performing a first heat treatment on a silicon oxygen raw material and a carbon source supported with metal catalyst particles according to the present application. [Figure 5] This is Process Diagram 1 for manufacturing a silicon oxygen raw material supported with metal catalyst particles according to the present application. [Figure 6] This is Process Diagram 2 for manufacturing a silicon oxygen raw material supported with metal catalyst particles according to the present application. [Figure 7] This is a process diagram for obtaining a second precursor by etching the first precursor according to the present application. [Figure 8] This is a process diagram for obtaining a negative electrode material by mixing the second precursor and a reducing agent and performing a third heat treatment. [Figure 9] This is a schematic diagram showing the simulation configuration of the negative electrode material according to the present application.

Embodiments for Carrying out the Invention

[0013] To better understand the technical solution of the present invention, the following will describe the embodiments of the present invention in detail with reference to the accompanying drawings.

[0014] It should be clear that the described embodiments are only some embodiments of the present application and not all embodiments. Based on the embodiments in the present application, all other embodiments that can be achieved by those skilled in the art without creative efforts shall fall within the protection scope of the present application.

[0015] The terms used in the embodiments of the present application are only used for explaining specific embodiments and are not intended to limit the present invention. The singular forms "one", "said", and "the" used in the embodiments and claims of the present invention are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0016] It should be understood that the terms "and / or" used herein only describe the relationship between related objects, indicating that three types of relationships are possible. For example, A and / or B can indicate three situations: A existing alone, A and B existing simultaneously, and B existing alone. Also, the letter " / " in this specification generally indicates that the related objects before and after are in an "or" relationship.

[0017] The present invention provides a negative electrode material 10, as shown in Figure 1, which comprises a carbon material 1, which comprises a carbon shell layer 12, and a chamber 11 is formed inside the carbon material 1, which is formed to surround the carbon shell layer 12. The carbon shell layer 12 has holes 13, and at least some of the holes 13 penetrate the carbon shell layer 12.

[0018] In the above-described technical proposal, the negative electrode material 10 of the present application comprises a chamber 11 located inside the carbon shell layer 12 and a hole 13 located in the carbon shell layer 12. Due to the presence of the chamber 11 and the hole 13, the carbon material 1 becomes a porous hollow housing. Such a structure can retain sufficient space when the filled silicon material expands. When the silicon material expands and presses against the carbon material 1, the carbon material 1 releases internal gas or electrolyte through the hole 13 on the carbon shell layer 12, forming strain in order to withstand the expansion stress of lithium insertion. When the silicon material releases lithium and contracts, the strained carbon material 1 absorbs gas or electrolyte through the hole 13 on the carbon shell layer 12, restoring its shape. Thus, the negative electrode material 10 can retain sufficient space to withstand the expansion stress of lithium insertion, improving the expansion resistance and cycle performance of the negative electrode material 10.

[0019] Furthermore, the negative electrode material 10 further contains silicon material 2, which is distributed within the carbon material 1. The carbon material 1 provides sufficient space for the expansion of the filled silicon material 2, and the filled silicon material 2 can improve the usable space of the negative electrode material 10 and increase the capacity of the negative electrode material 10.

[0020] Preferably, at least some of the silicon material 2 is distributed between the carbon shell layers 12.

[0021] As shown in Figure 2, in one embodiment, the carbon material 1 is spherical, the carbon shell layer 12 contains a graphitized carbon material 14, the graphitized carbon material 14 has a layered structure, and the layered structure of the graphitized carbon material 14 is installed in a stacked manner along the radial direction of the carbon material 1. As a result, the carbon shell layer 12 has excellent elastic modulus and tensile strength, and when the carbon shell layer 12 experiences strain, it shrinks without decomposing and recovers its shape.

[0022] Referring to Figure 2, a schematic diagram showing the composition of carbon material 1, the layering direction of the layered structure of graphitized carbon material 14 extends along the radial direction of carbon material 1. That is, the length direction of the layered structure of graphitized carbon material 14 is perpendicular to the radial direction of carbon material 1, and the thickness direction (i.e., layering direction) of graphitized carbon material 14 is perpendicular to the direction in which the carbon shell layer 12 extends and coincides with the radial direction of carbon material 1.

[0023] The graphitized carbon material comprises at least one of graphite and graphene. Preferably, the graphitized carbon material is graphene, and the number of layers in the layered structure of the graphene is less than 20, specifically, it may be 1, 2, 3, 5, 8, 10, 12, 15, 18, or 19 layers, and of course, it may be any other value within the above range, and is not limited thereto.

[0024] In one embodiment, the graphitized carbon material is graphite, the graphite is a deposition of multiple layers of graphene, and the number of layers in the layered structure of the graphite is 20 or more, specifically 20, 30, 50, 80, 100, 120, 150, 180, or 200 layers, and of course other values ​​within the above range are also acceptable and are not limited thereto.

[0025] In some embodiments, a portion of the silicon material is located in the chamber 11 and / or the pore 13, which can improve the capacity of the negative electrode material 10.

[0026] In some embodiments, graphite (not shown in the drawings) is provided between the carbon materials 1. Due to the presence of the graphite structure, the conductive network of the negative electrode material 10 is strengthened, thereby improving the conductivity of the negative electrode material 10.

[0027] In some embodiments, for the carbon material, the median diameter of the carbon material 1 is 5 nm to 200 nm. Specifically, the median diameter of the carbon material 1 may be, for example, 5 nm, 10 nm, 20 nm, 50 nm, 80 nm, 100 nm, 120 nm, 150 nm, 180 nm, 200 nm, etc. Of course, other values within the above range may also be possible, and the present application is not limited here.

[0028] In some embodiments, the thickness of the carbon shell layer 12 is 1.2 nm to 5.2 nm. Specifically, the thickness of the carbon shell layer 12 may be, for example, 1.2 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 5 nm, 5.2 nm, etc. Of course, other values within the above range may also be possible, and the present application is not limited here.

[0029] In the present application, the thickness of the carbon shell layer 12 is 1.2 nm to 5.2 nm, and the graphitized carbon material 14 has a layered structure. It shows that the carbon shell layer 12 of the present application has a certain rigidity and a certain elasticity, and can resist the volume expansion due to the insertion of lithium into the material.

[0030] In some embodiments, the negative electrode material is shown in the Raman spectrum obtained by Raman spectroscopy using a measurement light source with a wavelength of 532 nm, and a D band is observed at 1300 cm -1 ~1400 cm -1 and a G band is observed at 1500 cm -1 ~1600 cm -1 The ratio I D of the peak intensity I G of the D band to the peak intensity I G / I D of the G band is greater than 0.5. Specifically, I G / ID This value may be 0.6, 0.7, 0.8, 0.9, etc., and of course, it may be any other value within the above range, and this application is not limited thereto. Within the above limited range, the degree of graphitization of the negative electrode material of this application is high, and strong π-π stacking van der Waals forces are present between the carbon material 1. Such a structure can resist expansion stress due to lithium insertion, thereby allowing the lithium insertion capacity of the pores between the carbon material 1 to be exhibited and increasing the efficiency of carbon utilization.

[0031] In some embodiments, the average inner diameter of the chamber 11 is 3.8 nm to 198.8 nm, specifically, the average inner diameter of the chamber 11 may be, for example, 3.8 nm, 10 nm, 30 nm, 50 nm, 80 nm, 100 nm, 120 nm, 150 nm, 180 nm, and 198.8 nm, and of course, it may be any other value within the above range, and is not limited herein. It is understood that the carbon material 1 is spherical, the chamber 11 is also spherical, and the average inner diameter of the chamber 11 refers to the average value of the inner circle diameter in the spherical chamber 11.

[0032] In some embodiments, the average pore diameter of the holes 13 is 0.42 nm to 2 nm, specifically, the average pore diameter of the holes 13 may be 0.42 nm, 0.5 nm, 1 nm, 1.5 nm, 1.8 nm, and 2 nm, and of course, it may be any other value within the above range, and this application is not limited thereto.

[0033] In some embodiments, the distance between adjacent carbon materials 1 is 0 nm to 40 nm, specifically, the distance between adjacent carbon materials 1 may be, for example, 0.34 nm, 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, and 40 nm, and of course, it may be any other value within the above range, and is not limited herein. It is understood that in the negative electrode material 10 of this application, a close distance between adjacent carbon materials 1 is advantageous in reducing the formation of bulk lithium during the lithium insertion process of the material and the leakage of silicon material 2 during the lithium release process, and that the distance between some adjacent carbon materials 1 may be 0 nm.

[0034] In some embodiments, the sphericity of the carbon material 1 is 0.6 to 1.0, specifically, the sphericity of the carbon material 1 may be 0.6, 0.7, 0.8, 0.9, and 1.0, and of course, it may be other values ​​within the above range, and this application is not limited thereto. The high sphericity of the carbon material 1 in this application is advantageous for improving the processing performance of the material.

[0035] In some embodiments, the mass ratio of silicon material 2 in the negative electrode material 10 is 5% to 80%, and specifically, the mass ratio of silicon material 2 in the negative electrode material 10 may be, for example, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, and 80%, and of course, it may be any other value within the above range, and this application is not limited thereto.

[0036] In some embodiments, the median diameter of silicon material 2 is 1 nm to 15 nm, and exemplary, the median diameter of silicon material 2 may be 1 nm, 3 nm, 5 nm, 8 nm, 10 nm, 12 nm, 14 nm, and 15 nm, and of course, it may be other values ​​within the above range, and is not limited herein.

[0037] In some embodiments, the silicon material 2 includes at least one of crystalline silicon and amorphous silicon.

[0038] In some embodiments, the elastic modulus of carbon material 1 is 0.1TPa to 0.8TPa, specifically, the elastic modulus of carbon material 1 may be, for example, 0.1TPa, 0.2TPa, 0.3TPa, 0.4TPa, 0.5TPa, 0.6TPa, 0.7TPa, and 0.8TPa, and of course, it may be any other value within the above range, and is not limited to this application. If the elastic modulus of carbon material 1 is 0.1TPa or less, carbon material 1 is prone to collapse, and if the elastic modulus of carbon material 1 is 0.8TPa or more, the rigidity of carbon material 1 increases, making it difficult to provide space for the expansion of lithium insertion.

[0039] In some embodiments, the tensile strength of the carbon material 1 is 15 GPa to 110 GPa. Specifically, the tensile strength of the carbon material 1 may be, for example, 15 GPa, 30 GPa, 50 GPa, 60 GPa, 80 GPa, 100 GPa, and 110 GPa, and of course, it may be other values ​​within the above range, and this application is not limited thereto. Within the above range, the carbon material 1 of this application has excellent mechanical properties. This is because the shell layer thickness of the carbon material 1 in this application is thin, the degree of graphitization is high, and the distance between the carbon materials 1 is short, resulting in strong π-π stacking van der Waals forces. As a result, the gap structure between the carbon materials 1 has good stability. This stability can resist the expansion stress caused by lithium insertion, exhibits the lithium insertion capacity of the pores between particles, and improves the efficiency of carbon utilization. If the tensile strength of the carbon material 1 is less than 15 GPa, the carbon material is prone to fracturing during lithium insertion expansion, and if the tensile strength of the carbon material 1 exceeds 110 GPa, it is difficult to provide space for lithium insertion expansion.

[0040] In some embodiments, the porosity of the carbon material 1 is 65% to 96%, specifically, the porosity of the carbon material 1 may be, for example, 65%, 70%, 75%, 80%, 85%, 90%, and 96%, and of course, it may be any other value within the above range, and is not limited herein. It is understood that the porosity of the carbon material 1 refers to the volume ratio of chambers 11 and holes 13 in the carbon material 1.

[0041] In some embodiments, the porosity of the negative electrode material 10 is 7% to 50%, specifically, the porosity of the negative electrode material 10 may be, for example, 7%, 10%, 15%, 20%, 30%, 40%, and 50%, and of course, it may be any other value within the above range, and is not limited to the present application. It is understood that the porosity of the negative electrode material 10 refers to the volume ratio of the voids between the chamber 11, the holes 13, and the carbon material 1 to the negative electrode material 10. Due to the high porosity of the negative electrode material 10 in the present application, the negative electrode material 10 has excellent expansion resistance.

[0042] In some embodiments, the π-π stacking van der Waals force between adjacent carbon materials 1 is 1 kJ / mol to 50 kJ / mol, specifically, the π-π stacking van der Waals force between adjacent carbon materials 1 is 1 kJ / mol, 5 kJ / mol, 10 kJ / mol, 20 kJ / mol, 30 kJ / mol, 40 kJ / mol, and 50 kJ / mol, and of course, it may be other values ​​within the above range, and the present application is not limited thereto. By having strong π-π stacking van der Waals forces between the carbon materials 1 of the present application, the gaps between the carbon materials 1 can withstand the expansion stress of lithium insertion, and the energy density of the negative electrode material 10 can be improved without adding additional adhesives.

[0043] This application further provides a method for manufacturing the negative electrode material 10, and as shown in Figure 3, is a flowchart for manufacturing the negative electrode material 10 of this application. A mixture containing a silicon-oxygen raw material supported by metal catalyst particles and a carbon source is subjected to a first heat treatment to catalyze the graphitization of the carbon source and obtain a first precursor. The first precursor is etched to obtain the second precursor, and the etching agent for the etching process contains an oxidizing acid. The process includes the step of reducing at least a portion of the silicon-oxygen raw material in the second precursor to a silicon material to obtain the negative electrode material 10.

[0044] In the above proposed technology, the present invention provides a first heat treatment to a mixture containing a silicon oxygen raw material supporting catalyst metal particles and a carbon source. During the first heat treatment, the carbon source undergoes graphitization decomposition to generate carbon atoms. Some of these carbon atoms can dissolve inside the catalyst metal particles, dissolve to saturation, and precipitate on the catalyst surface. These precipitated carbon atoms grow into a carbon shell layer 12. Other carbon atoms can grow along the surface of the metal particles through the catalytic action of the catalyst metal particles to form a carbon shell layer 12, creating a structure in which the catalyst metal particles are sealed inside the carbon shell layer 12. On the other hand, because the silicon oxygen raw material has poor catalytic ability with respect to the carbon source material, the silicon oxygen raw material is distributed outside the carbon shell layer 12 and dispersed among the metal particles sealed in the carbon shell layer 12, thereby obtaining a first precursor. Next, the first precursor is etched, etching the catalyst metal particles inside the carbon shell layer to form chambers 11. Simultaneously, the etched oxidizing acid undergoes a redox reaction with defects in the carbon shell layer 12, gradually exfoliating carbon atoms to form pores 13. At the end of the redox reaction, bonds such as CO, C=O, CN, and CS are formed at the edges of the pores, forming a porous carbon material 1 (i.e., the second precursor) with chambers 11 inside. Finally, at least a portion of the silicon-oxygen raw material in the second precursor is reduced to a silicon material to obtain the anode material 10. In the manufacturing method of the present invention, under the first heat treatment conditions, the carbon source is catalytically grown into a shell layer structure via metal catalyst particles. The shell layer structure has a large pore volume and lithium insertion capacity. Furthermore, the carbon shell layer 12 structure has chambers 11 inside due to the etching process, and the carbon shell layer 12 has pores 13, thereby improving the expansion resistance of the material. Finally, in the present invention, there is no need to etch the silicon-oxygen raw material, as the silicon-oxygen raw material is directly reduced to the silicon material 2, reducing waste of silicon-oxygen raw material and improving the capacity of the anode material 10.

[0045] The manufacturing method of the present invention will be described in detail below, along with examples. In step S100, as shown in Figure 4, a mixture containing a silicon oxygen raw material supported by metal catalyst particles and a carbon source is subjected to a first heat treatment to catalyze the graphitization of the carbon source and obtain a first precursor. In some embodiments, the carbon source includes a gaseous carbon source and a solid carbon source.

[0046] In some embodiments, the gaseous carbon source includes at least one of methane, ethane, and acetylene.

[0047] In some embodiments, the solid-phase carbon source includes at least one of pitch, glucose, sucrose, cellulose, glycine, alanine, and phenylalanine. When the first heat treatment is performed using a solid carbon source, the solid carbon source has poorer uniformity compared to a gaseous carbon source, resulting in an excess of local carbon sources. This leads to the formation of a layered graphite structure between the carbon materials 1, and the presence of this layered graphite structure strengthens the conductive network of the anode material 10, thereby improving the conductivity of the anode material 10.

[0048] In some embodiments, the mass ratio of the solid-phase carbon source to the metal catalyst particles is 1:(10~10000), specifically, it may be, for example, 1:10, 1:50, 1:100, 1:500, 1:1000, 1:5000, and 1:10000, and of course, it may be any other value within the above range, and this application is not limited thereto. Within the above range, a large amount of metal catalyst particles is added, and the carbon source contributes to the formation of a thin shell layer structure on the surface of the metal catalyst particles. If the mass ratio of the solid-phase carbon source to the metal catalyst particles is greater than 1:10, excess amorphous carbon is generated, which is detrimental to improving the performance of the material. If the mass ratio of the solid-phase carbon source to the metal catalyst particles is less than 1:10000, the amount of carbon source added is too small, and the carbon source cannot completely coat the metal catalyst particles.

[0049] In some embodiments, the introduction flow rate of the gas phase carbon source is 10 sccm to 250 sccm, specifically, 10 sccm, 30 sccm, 50 sccm, 100 sccm, 150 sccm, 200 sccm, and 250 sccm, and of course, it may be other values ​​within the above range, and this application is not limited thereto. It is understood that increasing the introduction flow rate of the gas phase carbon source increases the thickness of the carbon shell layer 12, and further increases the tensile strength and modulus of elasticity of the carbon shell layer 12, and when the introduction flow rate exceeds 250 sccm, the growth of the carbon shell layer 12 becomes faster, there are more defects, and the tensile modulus and modulus of elasticity decrease.

[0050] In some embodiments, the temperature of the first heat treatment is 600°C to 1000°C, and specifically, the temperature of the first heat treatment may be, for example, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, and 1000°C, and of course, it may be any other value within the above range, and this application is not limited thereto.

[0051] In some embodiments, the holding time for the first heat treatment is 1 min to 30 min, and specifically, the holding time for the first heat treatment may be, for example, 1 min, 5 min, 10 min, 20 min, and 30 min, and of course, it may be any other value within the above range, and this application is not limited thereto.

[0052] In some embodiments, hydrogen gas is introduced in the first heat treatment process, and the hydrogen gas introduction flow rate is 10 ccm to 290 sccm, and exemplary, the hydrogen gas introduction flow rate may be 10 sccm, 30 sccm, 50 sccm, 80 sccm, 90 sccm, 150 sccm, 200 sccm, 250 sccm and 290 sccm, and of course, it may be other values ​​within the above range, and is not limited thereto. By controlling the hydrogen gas introduction flow rate within the above range, the decomposition of the carbon source is reduced, the concentration of decomposed carbon atoms is reduced, and the rate at which carbon atoms form a carbon shell layer is slowed down, the content of defect sites is reduced, and the I of the negative electrode material D / I GIt can be controlled to a value greater than 0.5.

[0053] In some embodiments, a silicon-oxygen raw material supporting metal catalyst particles is obtained by subjecting a mixture containing the silicon-oxygen raw material and a metal salt catalyst to a second heat treatment in a reducing atmosphere. Specifically, as shown in Figure 5, the mixed material containing the silicon-oxygen raw material and the metal salt catalyst is The process includes the steps of mixing a solvent, a silicon-oxygen raw material, and a metal salt catalyst to obtain a mixture, drying and polishing the mixture to obtain a silicon-oxygen raw material supported by metal catalyst particles, and understanding that the material obtained after the drying process is a bulk solid and needs to be further polished into a powder for reserve use.

[0054] In this step, as shown in Figure 6, by reducing the catalytic metal ions in a mixture containing a silicon-oxygen raw material and a metal salt catalyst to catalytic metal nanoparticles in a reducing gas atmosphere, on the one hand, the silicon-oxygen raw material can act as a template agent, providing support sites for the metal salt catalyst, and on the other hand, the silicon-oxygen raw material can act as a dispersant, limiting the fusion of metal nanoparticles during the process in which the catalytic metal ions are reduced to metal nanoparticles and grow, resulting in catalytic metal nanoparticles having a relatively uniform and controllable size. Of course, the present invention may also provide a silicon-oxygen raw material supporting metal catalyst particles by other conventional methods, exemplified by directly mixing the metal catalyst particles and the silicon-oxygen raw material by a dry or wet process, and the present invention is not limited thereto, but the metal catalyst particles include at least one of iron, cobalt, nickel, copper, gold, iron alloys, cobalt alloys, nickel alloys, copper alloys and gold alloys.

[0055] In some embodiments, the silicon-oxygen raw material includes at least one of silicon dioxide and silicon monoxide.

[0056] In some embodiments, the median diameter of the silicon-oxygen raw material is 5 nm to 200 nm, and specifically, the median diameter of the silicon-oxygen raw material may be, for example, 5 nm, 10 nm, 20 nm, 50 nm, 80 nm, 100 nm, 120 nm, 150 nm, 180 nm, and 200 nm, and of course, it may be any other value within the above range, and this application is not limited thereto.

[0057] In some embodiments, the metal salt catalyst is Fe 3+ Co 2+ Ni 2+ Cu 2+ and Au 3+ It includes at least one of the following. For example, the metal salt catalyst includes at least one of Fe(NO3)3, FeCl3, Co(NO3)2, CoCl2, Ni(NO3)2, NiCl2, Cu(NO3)2, CuCl2, and HAuCl4.

[0058] In some embodiments, the mass ratio of the silicon oxygen raw material to the metal salt catalyst is 1:(0.08~5), and specifically, the mass ratio of the silicon oxygen raw material to the metal salt catalyst may be 1:0.08, 1:0.1, 1:0.5, 1:1, 1:2, 1:3, 1:4, and 1:5, etc., and may be other values ​​within the above range, and this application is not limited thereto.

[0059] In some embodiments, the solvent comprises at least one of methanol, ethanol, propanol, and water.

[0060] In some embodiments, the amount of solvent added is 50 to 1000 times the total mass of the silicon oxygen raw material and the metal salt catalyst. Specifically, the amount of solvent added is 50, 100, 200, 500, 700, 800, 900, and 1000 times the total mass of the silicon oxygen raw material and the metal salt catalyst, and of course, it may be other values ​​within the above range, and this application is not limited thereto.

[0061] In some embodiments, the mixing method includes at least one of polishing and ultrasonic waves, and exemplary the ultrasonic power is 40W to 50W, and the ultrasonic power may be, for example, 40W, 42W, 45W, 48W and 50W, and of course other values ​​within the above range, and is not limited herein. The ultrasonic heating time is 0.5h to 5h, and the ultrasonic heating time may be, for example, 0.5h, 1h, 2h, 3h, 4h and 5h, and of course other values ​​within the above range, and is not limited herein. Within the above range, sufficient mixing of the silicon oxygen raw material and the metal salt catalyst can be ensured, which is advantageous for forming a silicon oxygen raw material that uniformly supports metal salt catalyst particles.

[0062] In some embodiments, the drying method includes evaporative drying.

[0063] In some embodiments, the reducing gas atmosphere includes at least one of hydrogen gas and ammonia gas.

[0064] In some embodiments, the introduction flow rate of the reducing gas atmosphere is 10 sccm to 150 sccm, and specifically, the introduction flow rate of the reducing gas atmosphere may be, for example, 10 sccm, 30 sccm, 50 sccm, 80 sccm, 100 sccm, 120 sccm, and 150 sccm, and of course, it may be any other value within the above range, and this application is not limited thereto.

[0065] In some embodiments, the temperature of the second heat treatment is 400°C to 1000°C, specifically, the temperature of the second heat treatment may be, for example, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, and 1000°C, and of course, it may be any other value within the above range, and is not limited herein.

[0066] In some embodiments, the holding time for the second heat treatment is 5 min to 30 min, and specifically, the holding time for the second heat treatment may be, for example, 5 min, 10 min, 15 min, 20 min, 25 min, and 30 min, and of course, it may be any other value within the above range, and the present application is not limited thereto.

[0067] In some embodiments, the heating rate of the second heat treatment is 100°C / h to 1200°C / h, specifically, the heating rate of the second heat treatment is 100°C / h, 300°C / h, 500°C / h, 800°C / h, 1000°C / h, and 1200°C / h, and of course, it may be any other value within the above range, and this application is not limited thereto.

[0068] In step S200, as shown in Figure 7, the first precursor is etched to obtain a second precursor, and the etching agent for the etching process contains an oxidizing acid. The second precursor contains a carbon material 1, which contains a carbon shell layer 12, the carbon shell layer 12 has a chamber 11, the carbon shell layer 12 has pores 13, and silicon oxygen raw material is filled between the carbon materials 1.

[0069] In this step, the first precursor is etched so that the catalyst metal particles inside the carbon shell layer 12 are etched, thereby forming the chamber 11 and the pores 13, and during the etching process, some of the silicon oxygen raw material can enter the chamber 11 and / or the pores 13.

[0070] In some embodiments, the oxidizing acid includes at least one of sulfuric acid, nitric acid, and hydrogen peroxide. On the one hand, the oxidizing acid can be used to etch the catalyst metal particles inside the carbon shell layer 12 to form the chamber 11, and on the other hand, the oxidizing acid can undergo oxidation-reduction reactions with defects in the carbon material 1 to form bonds such as CO, C=O, CN, and CS, thereby forming pores 13. Exemplarily, for metal catalyst particles made of corrosion-resistant materials such as iron, cobalt, iron alloys, and cobalt alloys, etching can be performed using a mixed acid of sulfuric acid and nitric acid as an etching agent, and the corrosion effect can be improved by performing heat treatment during the etching process as needed.

[0071] In some embodiments, the concentration of sulfuric acid in the mixed acid is 0.1 mol / L to 4 mol / L, specifically, the concentrations of sulfuric acid in the mixed acid are 0.1 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, and 4 mol / L, and of course, other values ​​within the above range are also possible and are not limited to this application.

[0072] In some embodiments, the concentration of nitric acid in the mixed acid is 0.1 mol / L to 4 mol / L, specifically, the concentrations of nitric acid in the mixed acid are 0.1 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, and 4 mol / L, and of course, other values ​​within the above range are also possible, and this application is not limited thereto.

[0073] In some embodiments, the etching time is 2 to 24 hours, specifically 2 hours, 5 hours, 10 hours, 12 hours, 15 hours, 18 hours, 20 hours, and 24 hours, and of course, other values ​​within the above range are also possible, and this application is not limited thereto.

[0074] In some embodiments, the material obtained after etching is a solid-liquid mixed phase, and it is necessary to separate the material obtained by etching into solid and liquid phases. The resulting solid is then subjected to a first water wash and a first drying to obtain a second precursor. The second precursor contains a carbon material 1, in which a chamber 11 is etched into the shell layer structure of the carbon material 1, and holes 13 are etched into the shell layer structure of the carbon material 1, ensuring sufficient space to withstand the expansion stress into which lithium is inserted, thereby improving the expansion resistance of the negative electrode material 10.

[0075] In some embodiments, solid-liquid separation may be performed, for example, by centrifugation or filtration.

[0076] In some embodiments, the number of first rinses is one or more, preferably three to ten times.

[0077] In some embodiments, the first drying temperature is 50°C to 80°C, specifically, the first drying temperature may be 50°C, 60°C, 70°C, and 80°C, and of course, it may be any other value within the above range, and is not limited thereto.

[0078] In some embodiments, the first drying time is 6h to 24h, specifically, the first drying time is 6h, 8h, 10h, 12h, 15h, 18h, 20h, and 24h, and of course, it may be any other value within the above range, and this application is not limited thereto.

[0079] In step S300, at least a portion of the silicon-oxygen raw material in the second precursor is reduced to a silicon material to obtain the anode material 10. Specifically, as shown in Figure 8, the silicon-oxygen raw material in the second precursor can be reduced to a silicon material 2 by mixing it with a reducing agent in the second precursor and then performing the third heat treatment. The simulated structure of the obtained anode material 10 is shown in Figure 9.

[0080] In some embodiments, the reducing agent includes at least one of magnesium powder and aluminum powder, and under the reducing action of the reducing agent, the silicon-oxygen raw material in the second precursor is reduced to silicon material 2, eliminating the need to etch the silicon-oxygen raw material, thereby improving the capacity of the negative electrode material 10 and reducing resource waste.

[0081] In some embodiments, the mass ratio of the second precursor to the reducing agent is (1.25 to 2.00):1, and specifically, the mass ratio of the second precursor to the reducing agent may be 1.25:1, 1.50:1, 1.75:1, and 2.00:1, and of course, it may be any other value within the above range, and this application is not limited thereto. Within the above range, the silicon oxygen raw material can be reduced to silicon material 2 as much as possible, contributing to an improvement in the capacity of the negative electrode material 10.

[0082] In some embodiments, the third heat treatment is performed in an inert gas atmosphere.

[0083] In some embodiments, the inert gas includes at least one of nitrogen gas and argon gas.

[0084] In some embodiments, the temperature of the third heat treatment is 600°C to 800°C, and specifically, the temperature of the third heat treatment may be 600°C, 630°C, 650°C, 680°C, 700°C, 730°C, 750°C, 780°C, 790°C, and 800°C, and of course, it may be any other value within the above range, and this application is not limited thereto.

[0085] In some embodiments, the holding time for the third heat treatment is 0.5h to 5h, and specifically, the holding time for the third heat treatment may be 0.5h, 1h, 2h, 3h, 4h, and 5h, and of course, it may be any other value within the above range, and this application is not limited thereto.

[0086] In some embodiments, after the third heat treatment, the material obtained in the third heat treatment is further deactivated to deactivate the silicon material 2, reduce oxidation of the silicon material 2, and improve the capacity of the material.

[0087] In some embodiments, the gas to be deactivated includes ammonia gas.

[0088] In some embodiments, the method further includes the steps of pickling the material obtained by the deactivation treatment, second washing with water, and second drying, after the deactivation treatment.

[0089] In some embodiments, the pickling reagent includes hydrochloric acid.

[0090] In some embodiments, the pickling time is 2 to 24 hours, specifically, it may be, for example, 2 hours, 5 hours, 8 hours, 10 hours, 12 hours, 15 hours, 18 hours, and 24 hours, and of course, it may be any other value within the above range, and this application is not limited thereto.

[0091] In some embodiments, the number of second rinses is 5 to 10 times.

[0092] In some embodiments, the second drying method includes freeze-drying.

[0093] In a third embodiment, the present application provides a lithium-ion battery comprising the negative electrode material 10 described above or a negative electrode material 10 manufactured by the above manufacturing method.

[0094] As will be apparent to those skilled in the art, the methods for manufacturing lithium-ion batteries described above are merely examples. Other methods commonly used in the art can be employed without departing from the scope of the present invention.

[0095] The embodiments of the present invention will be further described below by dividing them into several examples. However, the present invention is not limited to the following specific embodiments. The main claims may be modified as appropriate without changing their scope.

[0096] Example 1

[0097] (1) Add 1 g SiO2 to 800 mL methanol, then add 2.10 g Co(NO3) 2· After adding 6H2O to obtain a mixed solution, the mixed solution is ultrasonically treated with 40W ultrasonic power for 4 hours. Next, the ultrasonically treated mixed solution is evaporated and dried for 12 hours to obtain a solid mass, and finally, the solid mass is pulverized into a powder to obtain the catalyst Co 2+ Silicon dioxide (SiO2@Co) supported with [the substance] is obtained.

[0098] (2) The SiO2@Co powder from (1) is placed in a CVD tubular furnace, and in an H2 environment with a flow rate of 90 sccm, the temperature is raised to 800°C at a heating rate of 1200°C / h, then the temperature is maintained for 20 minutes to reduce the SiO2@Co and form silicon dioxide SiO2-CoNPs powder on which cobalt nanoparticles are supported.

[0099] (3) Under high temperature conditions of 800°C, the H2 flow rate is adjusted to 10 sccm, methane is introduced at a flow rate of 150 sccm, and after 10 minutes of introduction, the H2 and methane are turned off, Ar gas is introduced, and the temperature is lowered to room temperature to obtain silicon dioxide SiO2-Co@GNPs powder supported with multiple layers of graphite-encapsulated cobalt nanoparticles.

[0100] (4) The SiO2-Co@GNPs powder is placed in a mixed acid solution of 1 mol / L sulfuric acid and 1 mol / L nitric acid, etched for 8 hours, and centrifuged to obtain a silicon dioxide SiO2-MGNPs precipitate supported with porous hollow graphite. After washing with water multiple times and drying for 8 hours, the SiO2-MGNPs powder is obtained.

[0101] (5) SiO2-MGNPs powder and magnesium powder are mixed in a mass ratio of 1.5:1 and placed in a high-temperature tubular furnace. A high-temperature reduction reaction is carried out in an Ar gas atmosphere at 650°C for 2 hours, after which the temperature is lowered to room temperature. Next, ammonia gas is introduced for 1 hour, then the ammonia gas is shut off. After introducing Ar gas for another 0.5 hours, the Ar gas is shut off, and the mixed powder is removed. Finally, the mixed powder is pickled in 1 mol / L hydrochloric acid for 2 hours, washed with water by centrifugation, and freeze-dried to obtain Si-MGNPs powder.

[0102] The negative electrode material manufactured in this embodiment comprises a spherical carbon material and a silicon material positioned between the carbon materials. The carbon material includes a carbon shell layer, which surrounds and forms a chamber. The carbon shell layer has pores, and the carbon shell layer comprises multiple layers of graphitized carbon material, which are stacked along the radial direction of the carbon material. Table 1 shows the number of layers of graphitized carbon material in the carbon shell layer, the thickness of the carbon shell layer, the average inner diameter of the chamber, the average pore diameter, and the porosity and thickness of the negative electrode material.

[0103] Example 2

[0104] The difference from Example 1 is the Co(NO3) in step (1) 2· This involves replacing 6H2O with Cu(NO3)2.

[0105] The negative electrode material manufactured in this embodiment comprises a carbon material and a silicon material positioned between the carbon materials. The carbon material includes a carbon shell layer, which surrounds and forms a chamber. The carbon shell layer has pores, and the carbon shell layer contains a graphitized carbon material, which has a layered structure. The layered structure of the graphitized carbon material is arranged in layers along the radial direction of the carbon material. Table 1 shows the number of layers of graphitized carbon material in the carbon shell layer, the thickness of the carbon shell layer, the average inner diameter of the chamber, the average pore diameter, and the porosity and thickness of the negative electrode material.

[0106] Example 3

[0107] The difference from Example 1 is the Co(NO3) in step (1) 2· This involves replacing 6H2O with Fe(NO3)3.

[0108] The negative electrode material manufactured in this embodiment comprises a carbon material and a silicon material positioned between the carbon materials. The carbon material includes a carbon shell layer, which surrounds and forms a chamber. The carbon shell layer has pores, and the carbon shell layer contains a graphitized carbon material, which has a layered structure. The layered structure of the graphitized carbon material is arranged in layers along the radial direction of the carbon material. Table 1 shows the number of layers of graphitized carbon material in the carbon shell layer, the thickness of the carbon shell layer, the average inner diameter of the chamber, the average pore diameter, and the porosity and thickness of the negative electrode material.

[0109] Example 4

[0110] The difference from Example 1 is the Co(NO3) in step (1) 2· This involves replacing 6H2O with NiCl2.

[0111] The negative electrode material manufactured in this embodiment comprises a carbon material and a silicon material positioned between the carbon materials. The carbon material includes a carbon shell layer, which surrounds and forms a chamber. The carbon shell layer has pores, and the carbon shell layer contains a graphitized carbon material, which has a layered structure. The layered structure of the graphitized carbon material is arranged in layers along the radial direction of the carbon material. Table 1 shows the number of graphene layers in the carbon shell layer, the thickness of the carbon shell layer, the average inner diameter of the chamber, the average pore diameter, and the porosity and thickness of the negative electrode material.

[0112] Example 5

[0113] The difference from Example 1 is that steps (1) and (2) were omitted, and 1 g of silicon dioxide, 0.43 g of cobalt metal nanoparticles, and 800 ml of methanol were mixed, then ultrasonically treated with 40 W of ultrasonic power for 4 hours, and after drying, silicon dioxide SiO2-CoNPs powder supported with cobalt nanoparticles was obtained. Steps (3) to (5) of Example 1 were further performed on the obtained SiO2-CoNPs.

[0114] The negative electrode material manufactured in this embodiment comprises a carbon material and a silicon material positioned between the carbon materials. The carbon material includes a carbon shell layer, which surrounds and forms a chamber. The carbon shell layer has pores, and the carbon shell layer contains a graphitized carbon material, which has a layered structure. The layered structure of the graphitized carbon material is arranged in layers along the radial direction of the carbon material. Table 1 shows the number of graphene layers in the carbon shell layer, the thickness of the carbon shell layer, the average inner diameter of the chamber, the average pore diameter, and the porosity and thickness of the negative electrode material.

[0115] Example 6

[0116] (1) Add 1 g SiO2 to 800 mL methanol, then add 2.10 g Co(NO3) 2· 6H2O and 20 mg of phenylalanine (Phe) are added to obtain a mixed solution, and the mixed solution is ultrasonically treated with 40 W of ultrasonic power for 4 hours. Next, the ultrasonically treated mixed solution is evaporated and dried for 12 hours to obtain a solid mass, and finally, the solid mass is pulverized into a powder to obtain the catalyst Co 2+ And silicon dioxide SiO2@Co-Phe supported with a solid carbon source Phe is obtained.

[0117] (2) The SiO2@Co-Phe powder from (1) is placed in a CVD tubular furnace and heated to 800°C at a heating rate of 1200°C / h in an H2 environment with a flow rate of 90 sccm. After heating for 20 minutes, the temperature is maintained to reduce the SiO2@Co and form silicon dioxide SiO2-CoNPs powder supported with cobalt nanoparticles (during this process, the solid carbon source Phe has already begun to decompose).

[0118] (3) Under high temperature conditions of 800°C, the H2 flow rate is adjusted to 10 sccm, the Phe decomposition process is continued, and after 10 mins, the H2 is turned off, Ar gas is introduced, and the temperature is lowered to room temperature to obtain silicon dioxide SiO2-Co@GNPs powder supported with multiple layers of graphite-encapsulated cobalt nanoparticles.

[0119] (4) The SiO2-Co@GNPs powder is placed in a mixed acid solution of 1 mol / L sulfuric acid and 1 mol / L nitric acid, etched for 8 hours, and centrifuged to obtain a silicon dioxide SiO2-MGNPs precipitate supported with porous hollow graphite. After washing with water multiple times and drying for 8 hours, the SiO2-MGNPs powder is obtained.

[0120] (5) SiO2-MGNPs powder and magnesium powder are mixed in a mass ratio of 1.5:1 and placed in a high-temperature tubular furnace. A high-temperature reduction reaction is carried out in an Ar gas atmosphere at 650°C for 2 hours, after which the temperature is lowered to room temperature. Next, ammonia gas is introduced for 1 hour, then the ammonia gas is shut off. After introducing Ar gas for another 0.5 hours, the Ar gas is shut off, and the mixed powder is removed. Finally, the mixed powder is pickled in 1 mol / L hydrochloric acid for 2 hours, washed with water by centrifugation, and freeze-dried to obtain Si-MGNPs powder.

[0121] The negative electrode material manufactured in this embodiment comprises a carbon material and a silicon material positioned between the carbon materials. The carbon material includes a carbon shell layer, which surrounds and forms a chamber. The carbon shell layer has pores, and the carbon shell layer contains a graphitized carbon material, which has a layered structure. The layered structure of the graphitized carbon material is arranged in layers along the radial direction of the carbon material. Table 1 shows the number of graphene layers in the carbon shell layer, the thickness of the carbon shell layer, the average inner diameter of the chamber, the average pore diameter, and the porosity and thickness of the negative electrode material.

[0122] Example 7

[0123] The difference from Example 1 is that the methane introduction flow rate is 8 sccm and the introduction and heating time is 5 min.

[0124] The negative electrode material manufactured in this embodiment comprises a carbon material and a silicon material positioned between the carbon materials. The carbon material includes a carbon shell layer, which surrounds and forms a chamber. The carbon shell layer has pores, and the carbon shell layer contains multiple layers of graphene, which are stacked along the radial direction of the carbon material. Table 1 shows the number of graphene layers in the carbon shell layer, the thickness of the carbon shell layer, the average inner diameter of the chamber, the average pore diameter, and the porosity and thickness of the negative electrode material.

[0125] Example 8

[0126] The difference from Example 1 is that the methane introduction flow rate is 10 sccm and the introduction and heating time is 30 min.

[0127] The negative electrode material manufactured in this embodiment comprises a carbon material and a silicon material positioned between the carbon materials. The carbon material includes a chamber carbon shell layer, the carbon shell layer has a chamber, and the carbon shell layer has pores. The carbon shell layer also contains a graphitized carbon material, which has a layered structure, and the layered structure of the graphitized carbon material is arranged in layers along the radial direction of the carbon material. Table 1 shows the number of graphene layers in the carbon shell layer, the thickness of the carbon shell layer, the average inner diameter of the chamber, the average pore diameter, and the porosity and thickness of the negative electrode material.

[0128] Example 9

[0129] The difference from Example 1 is that the methane introduction flow rate is 50 sccm and the introduction and heating time is 20 min.

[0130] The negative electrode material manufactured in this embodiment comprises a carbon material and a silicon material positioned between the carbon materials. The carbon material includes a chamber carbon shell layer, the carbon shell layer has a chamber, and the carbon shell layer has pores. The carbon shell layer also contains a graphitized carbon material, which has a layered structure, and the layered structure of the graphitized carbon material is arranged in layers along the radial direction of the carbon material. Table 1 shows the number of graphene layers in the carbon shell layer, the thickness of the carbon shell layer, the average inner diameter of the chamber, the average pore diameter, and the porosity and thickness of the negative electrode material.

[0131] Example 10

[0132] The difference from Example 1 is that the methane introduction flow rate is 250 sccm and the introduction and heating time is 1 min.

[0133] The negative electrode material manufactured in this embodiment comprises a carbon material and a silicon material positioned between the carbon materials. The carbon material includes a chamber carbon shell layer, the carbon shell layer has a chamber, and the carbon shell layer has pores. The carbon shell layer also contains a graphitized carbon material, which has a layered structure, and the layered structure of the graphitized carbon material is arranged in layers along the radial direction of the carbon material. Table 1 shows the number of graphene layers in the carbon shell layer, the thickness of the carbon shell layer, the average inner diameter of the chamber, the average pore diameter, and the porosity and thickness of the negative electrode material.

[0134] Example 11

[0135] The difference from Example 1 is that the methane introduction flow rate is 300 sccm and the introduction and heating time is 10 min.

[0136] The negative electrode material manufactured in this embodiment comprises a carbon material and a silicon material positioned between the carbon materials. The carbon material includes a chamber carbon shell layer, the carbon shell layer has a chamber, and the carbon shell layer has pores. The carbon shell layer also contains a graphitized carbon material, which has a layered structure, and the layered structure of the graphitized carbon material is arranged in layers along the radial direction of the carbon material. Table 1 shows the number of graphene layers in the carbon shell layer, the thickness of the carbon shell layer, the average inner diameter of the chamber, the average pore diameter, and the porosity and thickness of the negative electrode material.

[0137] Comparative Example 1

[0138] (1) After uniformly mixing 1 g SiO2 powder and 0.5 g pitch powder, the mixed powder is placed in a high-temperature box-type furnace and heated to 800°C at a heating rate of 1200°C / h under an N2 atmosphere, and then carbonized by maintaining a constant temperature for 10 min to form carbon-sealed silicon dioxide SiO2-C powder.

[0139] (2) The SiO2-C powder is placed in a mixed acid solution of 1 mol / L sulfuric acid and 1 mol / L nitric acid, etched for 8 hours, and centrifuged to obtain a porous carbon-coated silicon dioxide SiO2-MCNPs precipitate. Then, the SiO2-MCNPs precipitate is placed in 20 wt% hydrofluoric acid and the silicon dioxide is etched for 8 hours to obtain a porous carbon material MCNPs powder.

[0140] (3) MGNPs powder, SiO2, and magnesium powder are mixed in a mass ratio of 1:2:2 and placed in a high-temperature tubular furnace. A high-temperature reduction reaction is carried out for 2 hours in an N2 atmosphere at 650°C, and then the temperature is lowered to room temperature. Next, ammonia gas is introduced for 1 hour, then the ammonia gas is shut off, and then N2 is introduced for 0.5 hours, then the N2 is shut off, and the mixed powder is removed. Finally, the mixed powder is pickled in 1 mol / L hydrochloric acid for 2 hours, washed with water by centrifugation, and freeze-dried to obtain Si-MCNPs powder.

[0141] The negative electrode material produced in this comparative example comprises a carbon material and a silicon material positioned between the carbon materials. The carbon material includes a carbon shell layer, which has chambers and pores, and the carbon shell layer is amorphous carbon. Table 1 shows the values ​​for the thickness of the carbon shell layer, the average inner diameter of the chambers, the average pore diameter, the porosity of the negative electrode material, and its thickness.

[0142] Comparative Example 2

[0143] The difference from Example 1 is that in step (4), the mixed acid solution of 1 mol / L sulfuric acid and 1 mol / L nitric acid is replaced with HF.

[0144] The negative electrode material manufactured in this comparative example includes graphite particles and silicon material positioned between the graphite particles, and the graphite particles include a solid metal core and a graphite shell layer located on the surface of the solid metal core. The measurement parameters for each of the negative electrode materials are shown in Table 1.

[0145] Performance measurement

[0146] (1) Using the BET pore distribution, measure the pore volume dimensions of the chamber and holes, calculate the porosity of the carbon material and the anode material, and before measuring the porosity of the carbon material, it is necessary to etch and remove the silicon material in the anode material with HF.

[0147] (2) Before etching the silicon material in the negative electrode material, the mass M1 of the negative electrode material is measured, and the mass of the negative electrode material measured after etching the silicon material with HF is M2, and (M2-M1) / M2 is the mass ratio of the silicon material in the negative electrode material.

[0148] (3) The number of graphene layers in the carbon shell layer, the thickness of the carbon shell layer, and the distance between adjacent carbon materials are measured using a high-resolution transmission electron microscope.

[0149] (4) After etching the silicon material in the negative electrode material using HF, the sphericity and median diameter of the carbon material are measured using a zetasizer.

[0150] (5) After etching the silicon material in the negative electrode material using HF, the elastic modulus and tensile strength of the carbon material are measured using a nanoindenter.

[0151] (6) Measuring π-π stacking van der Waals forces between carbon materials using a bipolar interferometer.

[0152] (7) Method for measuring the average pore size of the chambers: The pore sizes of 200 chambers in the carbon material in transmission electron microscope images are mathematically statistically analyzed to calculate the average value.

[0153] (8) Method for measuring the average pore size: After etching the silicon material in the negative electrode material using HF, the average pore size is measured using a Micromeritics ASAP 2460 fully automated specific surface and porosity analyzer, with CO2 being the gas used during measurement.

[0154] (9) Method for measuring the median diameter of silicon materials: The diameter of silicon materials in transmission electron microscope images is mathematically statistically determined.

[0155] (10) Measure the electrochemical properties of the negative electrode material using the following method. The manufactured silicon-carbon negative electrode material, conductive agent, and adhesive are mixed in a solvent in a mass ratio of 94:1:5 to form a slurry (solid content of 50%), which is then applied to a copper foil current collector and vacuum-dried to produce a negative electrode piece. Next, the negative electrode piece, a ternary positive electrode piece manufactured by a conventional maturation process, a 1 mol / L LiPF6 / ethylene carbonate + dimethyl carbonate + ethyl methyl carbonate (v / v=1:1:1) electrolyte, a Celgard 2400 separator, and a battery housing are assembled into an 18650 cylindrical cell using a normal manufacturing process. Charge and discharge tests of the cylindrical cell are performed using a LAND battery test system manufactured by Wuhan LAND electronics Co., Ltd., under the conditions of constant current charge and discharge at 0.2C at room temperature, with a charge and discharge voltage of 2.75V to 4.2V. The test results are shown in Tables 1 and 2.

[0156] [Table 1]

[0157] [Table 2]

[0158] As shown in Tables 1 and 2, in the manufacturing methods described in Examples 1 to 11 of this application, under the first heat treatment conditions, the carbon source is catalytically grown into the carbon shell layer 12 via metal catalyst particles, and further etching treatment creates a chamber 11 inside the structure of the carbon shell layer 12, forming pores 13 in the carbon shell layer 12, so that the carbon material has a large pore volume and lithium insertion capacity, thereby improving the expansion resistance of the carbon material. In addition, in the manufacturing method of this application, there is no need to etch the silicon oxygen raw material, and the silicon oxygen raw material is directly reduced to the silicon material, reducing waste of the silicon oxygen raw material and improving the capacity of the negative electrode material.

[0159] In Examples 1, 7 to 11, the present invention adjusts the thickness of the generated carbon shell layer 12 (i.e., the number of graphene layers in the carbon shell layer 12) by adjusting the flow rate of the gas phase carbon source introduced in step (3) and the holding time of the first heat treatment. In Example 7, the flow rate of the gas phase carbon source introduced is low, resulting in a thinner carbon shell layer 12 and a decrease in the tensile strength of the carbon material 1, which in turn reduces the cycle performance and expansion resistance of the anode material 10. In Example 11, the flow rate of the gas phase carbon source introduced is too high, resulting in a thicker carbon shell layer 12 and an increase in the tensile strength of the carbon material 1, but a decrease in flexibility, a reduction in the gaps between the carbon materials 1, a decrease in the amount of silicon material 2, and a decrease in the capacity of the anode material 10.

[0160] In the negative electrode material manufactured in Comparative Example 1, since catalyst metal particles were not added, the resulting carbon material became amorphous carbon without a continuous graphite crystal lattice structure, resulting in poor mechanical performance of the resulting negative electrode material, as well as poor expansion resistance and cycle stability.

[0161] In Comparative Example 2, etching is performed using HF, and the carbon shell layer can block the HF. As a result, the carbon material has no chambers or pores, and the silicon content in the material is reduced by etching with HF, further worsening the specific capacity of the material. Although the absence of chambers and pores increases the volume expansion of the material, the amount of silicon in the negative electrode material obtained in this comparative example is small, so the overall volume expansion is relatively small.

[0162] The foregoing is merely a preferred embodiment of the present application and is not intended to limit it, and to those skilled in the art, the present application may have various modifications and changes. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present application should be included within the scope of protection of the present application. [Explanation of Symbols]

[0163] 10-Negative electrode material 1-Carbon materials 11-Chamber 12-Carbon shell layer 13-hole 14-Graphitized carbon materials 2-Silicon materials

Claims

1. It is a negative electrode material, The negative electrode material comprises a carbon material and a silicon material, the carbon material comprises a carbon shell layer, the carbon shell layer comprises a graphitized carbon material, the carbon material has a chamber inside, the chamber is formed so as to be surrounded by the carbon shell layer, the carbon shell layer has holes, at least some of the holes penetrate the carbon shell layer, and at least some of the silicon material is located between the carbon shell layers.

2. The negative electrode material according to claim 1, characterized in that the carbon material is spherical, the graphitized carbon material has a layered structure, and the layered structure of the graphitized carbon material is arranged in layers along the radial direction of the carbon material.

3. The negative electrode material according to claim 1, characterized in that a portion of the silicon material is located in the chamber and / or the hole.

4. The anode material according to claim 1, characterized in that the anode material satisfies at least one of the following features (1) to (4). (1) The median diameter of the carbon material is 5 nm to 200 nm; (2) The number of layers of graphitized carbon material in the carbon shell layer shall be less than 20; (3) The thickness of the carbon shell layer shall be 1.2 nm to 5.2 nm; (4) The negative electrode material is shown in the Raman spectrum obtained by Raman spectroscopy using a measurement light source with a wavelength of 532 nm, and at 1300 cm⁻¹ －１ ~1400cm －１ A D-band was observed at 1500 cm. －１ ~1600cm －１ A G band was observed, and the peak intensity of the D band was I Ｄ and the peak intensity of the G band I Ｇ Ratio I Ｇ / I Ｄ The value must be greater than 0.

5.

5. The anode material according to claim 1, characterized in that the anode material satisfies at least one of the following features (1) to (3). (1) The average inner diameter of the chamber shall be between 3.8 nm and 198.8 nm; (2) The average pore size of the holes shall be 0.42 nm to 2 nm; (3) The porosity of the carbon material shall be 65% to 96%.

6. The anode material according to claim 1, characterized in that the anode material satisfies at least one of the following features (1) to (2). (1) The distance between adjacent carbon materials shall be between 0 nm and 40 nm; (2) The sphericity of the carbon material shall be 0.6 to 1.

7. The anode material according to claim 1, characterized in that the anode material satisfies at least one of the following features (1) to (3). (1) The silicon material is present in an amount of 5% to 80% by mass relative to the negative electrode material; (2) The median diameter of the silicon material is 1 nm to 15 nm; (3) The silicon material comprises at least one of crystalline silicon and amorphous silicon.

8. The anode material according to claim 1, characterized in that the anode material satisfies at least one of the following features (1) to (3). (1) The elastic modulus of the carbon material is 0.1 TPa to 0.8 TPa; (2) The tensile strength of the carbon material shall be 15 GPa to 110 GPa; (3) The π-π stacking van der Waals force between adjacent carbon materials is 1 kJ / mol to 50 kJ / mol.

9. A method for manufacturing a negative electrode material, A mixture containing a silicon oxygen raw material supporting metal catalyst particles and a carbon source is subjected to a first heat treatment to catalyze the graphitization of the carbon source and obtain a first precursor. The first precursor is etched to obtain a second precursor, and the etching agent for the etching process is an oxidizing acid. A method for producing a negative electrode material, characterized by comprising the step of reducing at least a portion of the silicon-oxygen raw material in the second precursor to a silicon material to obtain a negative electrode material.

10. The manufacturing method according to claim 9, characterized in that the silicon oxygen raw material supporting the metal catalyst particles is manufactured by the following method. A mixture containing a silicon-oxygen raw material and a metal salt catalyst is subjected to a second heat treatment in a reducing atmosphere to obtain the silicon-oxygen raw material supporting the metal catalyst particles.

11. The aforementioned silicon oxygen raw material includes at least one of silicon dioxide and silicon monoxide. The median diameter of the aforementioned silicon-oxygen raw material is 5 nm to 200 nm. The metal salt catalyst contains at least one of Fe ３＋ , Co ２＋ , Ni ２＋ , Cu ２＋ and Au ３＋ and contains at least one kind of them. The mass ratio of the silicon-oxygen raw material to the metal salt catalyst is 1:(0.08 to 5.00). The mixture containing the silicon oxygen raw material and the metal salt catalyst further contains a solvent, the solvent comprising at least one of methanol, ethanol, propanol, and water, and the amount of solvent added is 50 to 1000 times the total mass of the silicon oxygen raw material and the metal salt catalyst. The mixture comprising the silicon oxygen raw material and the metal salt catalyst further comprises the steps of drying and polishing the mixture before the second heat treatment. The reducing atmosphere includes at least one of hydrogen gas and ammonia gas. The flow rate of the reducing atmosphere introduced is 10 sccm to 150 sccm. The temperature of the second heat treatment is 400°C to 1000°C. The holding time for the second heat treatment is 5 min to 30 min. The manufacturing method according to claim 10, characterized in that the heating rate of the second heat treatment is 100°C / h to 1200°C / h.

12. The carbon source includes a gas-phase carbon source and a solid-phase carbon source, and the gas-phase carbon source includes at least one of methane, ethane, and acetylene. The solid-phase carbon source comprises at least one of pitch, glucose, sucrose, cellulose, glycine, alanine, and phenylalanine. The mass ratio of the solid-phase carbon source to the metal catalyst particles is 1:(10 to 10000), and the introduction flow rate of the gas-phase carbon source is 10 sccm to 250 sccm. The temperature of the first heat treatment is 600°C to 1000°C. The holding time for the first heat treatment is 1 min to 30 min. The manufacturing method according to claim 9, further comprising passing hydrogen gas through the mixture containing the silicon oxygen raw material and carbon source containing the metal catalyst particles before performing a first heat treatment on the mixture containing the silicon oxygen raw material and carbon source containing the metal catalyst particles, wherein the flow rate of the hydrogen gas introduced is 10 sccm to 90 sccm.

13. The oxidizing acid includes a mixed acid of sulfuric acid and nitric acid, and the concentration of sulfuric acid in the mixed acid is 0.1 mol / L to 4 mol / L. The concentration of nitric acid in the mixed acid is 0.1 mol / L to 4 mol / L. The etching process time is 2 to 24 hours. The manufacturing method according to claim 9, further comprising the step of performing a solid-liquid separation of the second precursor, and a first water washing and first drying of the obtained solid, before reducing at least a portion of the silicon-oxygen raw material in the second precursor to a silicon material.

14. Reducing at least a portion of the silicon-oxygen raw material in the second precursor to a silicon material includes the step of mixing the second precursor with a reducing agent and then performing a third heat treatment. The reducing agent comprises at least one of metallic magnesium and metallic aluminum. The mass ratio of the second precursor to the reducing agent is (1.25 to 2.00):

1. The third heat treatment is carried out in an inert gas atmosphere, and the inert gas includes at least one of nitrogen gas and argon gas. The temperature of the third heat treatment is 600°C to 800°C. The heat retention time for the third heat treatment is 0.5h to 5h. The process further includes a step of performing a third heat treatment on the second precursor and the reducing agent, followed by an inactivation treatment on the material obtained from the third heat treatment, wherein the gas used in the inactivation treatment includes ammonia gas. The manufacturing method according to claim 9, further comprising the steps of pickling, second washing, and second drying the material obtained by the deactivation treatment.

15. A lithium-ion battery characterized by comprising the negative electrode material described in any one of claims 1 to 8.

Images