Lithium ion battery negative electrode material and preparation method and application thereof

Abstract

The invention discloses a lithium ion battery negative electrode material as well as a preparation method and application thereof, relates to the technical field of new materials, and particularly relates to a preparation method of a lithium ion battery negative electrode material by taking a graphene nanobelt as a raw material, or mixing the graphene nanobelt with silicon, tin, boron, phosphorus or oxides thereof or lithiates thereof according to a certain mass ratio, and performing supercritical reaction, spheroidizing granulation and surface coating. And finally, the graphene nanobelt self-toughened, high-capacity and high-power negative electrode material is obtained. The production process is simple, low in production cost and suitable for large-scale production, the obtained negative electrode material has the advantages of being high in sphericity degree, controllable in particle size, high in tap density, high in mechanical strength and the like, and the problems that the negative electrode material is low in volumetric specific energy density, low in power density, unstable in circulation, violent in volume expansion and the like are fundamentally solved.

Description

Technical Field

[0001] This invention relates to the field of new materials technology, specifically to a lithium-ion battery anode material, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries are widely used in 3C portable products, electric vehicles, and energy storage. Among these applications, the anode material plays a crucial role in the energy density, power density, and safety of lithium-ion batteries. Currently, graphite is generally used as the anode material in lithium-ion batteries; however, the low specific capacity of graphite (theoretical capacity 372 mAh / g) severely limits the performance of lithium-ion batteries.

[0003] To improve the energy density and power density of lithium-ion batteries, relevant research has been conducted on lithium-ion battery anode materials. For example, regarding the composites of graphene nanoribbons with silicon, tin and their oxides, titanium oxide, etc., patent numbers ZL2015101920918, ZL2020102956157, ZL2015101920706, ZL2016104157650, etc., all of the above invention patents utilize the electrostatic adhesion of graphene nanoribbons to composite them with silicon and its oxides, or SnO2 or TiO2 and other materials, which requires long-term drying and high-temperature sintering. However, the final products obtained by the above patents have non-spherical and irregular shapes, and the particle size of the powder is uncontrollable, resulting in uncontrollable coating quality. In addition, the volumetric energy density and power density are low, which greatly limits the application fields. Moreover, the mechanical strength is low, and it is easy to break and pulverize, which seriously affects the performance and lifespan. Furthermore, the production process requires long-term drying and high-temperature sintering, which reduces the efficiency of large-scale production and seriously hinders the efficiency of large-scale production and market application.

[0004] Therefore, how to provide a lithium-ion battery anode material with high sphericity, high energy density / power density, and long cycle life is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a lithium-ion battery anode material, its preparation method, and its application.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a lithium-ion battery anode material specifically includes the following steps: (1) Graphene nanoribbons and active materials are dispersed in a solvent and mixed evenly to obtain a mixed slurry A; (2) The mixed slurry A is subjected to a supercritical reaction to obtain mixed slurry B; (3) The mixed slurry B is granulated by gas-liquid insoluble phase to obtain spherical bodies C; (4) A lithium-ion battery anode material is obtained by sequentially plating lithium and magnesium onto the surface of the spherical body C.

[0008] The preparation method of this invention uses supercritical reaction to enhance the dispersion and exfoliation of graphene nanoribbons, and can modify the surface functional groups of graphene nanoribbons, such as reducing carboxyl and hydroxyl groups and increasing nitrogen content; at the same time, spheroidization treatment can improve the homogenization and coating effect, and increase the mass specific capacity and volume specific capacity of the negative electrode; in addition, surface lithium and magnesium plating can improve the first cycle efficiency of the negative electrode, reduce irreversible reactions, and enhance cycle stability.

[0009] Preferably, the mass ratio of the graphene nanoribbons to the active material in step (1) is (1-100):(0-99).

[0010] Preferably, the graphene nanoribbons are obtained by longitudinally dechaining carbon nanotubes, with a width of 4nm ≤ 300nm and a length of 30nm ≤ 100μm. The active material includes at least one of silicon, tin, boron, phosphorus, or their oxides or lithium compounds.

[0011] Preferably, the average particle size of the active material is 1 nm ≤ D50 ≤ 20 μm; Among them, silicon oxide is SiO x , 1≤x≤2; the silicon lithiation compound is SiLi y , 1.7≤y≤4.4; Tin oxide is SnO z , 1≤z≤2; tin lithium is SnLi m , 2.6≤m≤4.4; The boron oxide is B2O3; the boron lithium compound is B6Li7. Phosphorus oxide is PO n , 1.5≤n≤2.5; the lithium phosphate compound is PLi3.

[0012] Preferably, the solvent in step (1) is at least one of ethanol, propanol, isopropanol, N-methylpyrrolidone, toluene and water, and the mass concentration of graphene nanoribbons in the mixed slurry is 0.1-10%.

[0013] Preferably, the supercritical reaction in step (2) is a supercritical state of CO2, NH3, H2O or NMP, with a reaction pressure of 7.3-23 MPa, a reaction temperature of 31-451℃, and a reaction time of 0.5-2.0 h.

[0014] Preferably, the gas-liquid insoluble phase in step (3) is the gas-liquid insoluble phase; The gas is at least one of air, nitrogen, and argon, with a pressure of 0.1-3.0 MPa and an inlet temperature of 80-200°C; The liquid is at least one of water, ethanol, propanol, isopropanol, N-methylpyrrolidone (NMP), and toluene.

[0015] Preferably, the specific steps of lithium and magnesium plating in step (4) are as follows: First, molten lithium is used to plate the surface of the sphere at a temperature of 80-500℃ and an inert atmosphere at normal pressure. Then, the temperature is switched to 600-1200℃ and an inert atmosphere at normal pressure, and molten magnesium is used to plate the surface of the sphere that has been plated with lithium. The surface is then cooled to room temperature.

[0016] Preferably, the inert atmosphere is at least one of high-purity nitrogen, argon, and helium.

[0017] A lithium-ion battery anode material obtained by the preparation method described above.

[0018] The lithium-ion battery anode material prepared by the above-described method, or the application of the above-described lithium-ion battery anode material in lithium-ion batteries, semi-solid / quasi-solid batteries, and all-solid batteries.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) The method of the present invention is simple and easy to implement, with low production cost and high efficiency. It is green and environmentally friendly, which is conducive to large-scale production and easy to promote and apply. (2) The negative electrode material prepared by the present invention has the advantages of high sphericity, controllable particle size, high tap density and high mechanical strength, which fundamentally overcomes the problems of low volumetric energy density, low power density and unstable cycle and violent volume expansion of negative electrode materials. (3) The graphene nanoribbons used in this invention have a high aspect ratio and an open structure at the edges. They have reactive sites and are easy to electrostatically adhere to and cross-wrap with silicon, tin, boron, phosphorus or their oxides or their lithium compounds, which has a self-toughening effect, enhances structural stability and cycle life, and effectively suppresses severe volume expansion. (4) The negative electrode material obtained by the present invention has the characteristics of high reversible capacity, strong rate performance, strong cycle stability and high volumetric energy / power density, and can be widely used in lithium-ion batteries and all-solid-state batteries. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings in this description are merely embodiments of the present invention.

[0021] Figure 1 This is a SEM image of the lithium-ion battery anode material obtained in Example 1 of the present invention; Figure 2 This is a graph showing the first charge-discharge curve of the lithium-ion battery anode material obtained in Example 1 of the present invention; Figure 3 This is a graph showing the 500-cycle cycling curve of the lithium-ion battery anode material obtained in Example 1 of this invention. Figure 4 This is a SEM image of the product obtained in the comparative example of this invention. Detailed Implementation

[0022] Embodiments of the present invention are described below, examples of which are shown in the accompanying drawings. The embodiments described with reference to the drawings are exemplary and intended to explain the present invention, but are not to be construed as limiting the present invention.

[0023] Example 1 This invention provides a method for preparing a lithium-ion battery anode material, specifically including the following steps: (1) Graphene nanoribbons were dissolved in water according to a certain mass ratio and mixed and stirred to obtain a graphene nanoribbon slurry with a mass concentration of 1.0 wt% and uniform dispersion. Then, silicon was mixed into the graphene nanoribbon slurry according to a mass ratio of 80:20 of graphene nanoribbons to silicon and uniformly dispersed to obtain mixed slurry A. The width of the graphene nanoribbons was 40 nm and the length was 30 μm. The average particle size of silicon was 100 nm. (2) Mixed slurry A was reacted at a constant temperature of 11.4 MPa and 133 °C for 0.5 h to obtain mixed slurry B; (3) The mixed slurry B is spheroidized and granulated by gas-liquid two-phase insolubility, and spherical bodies are obtained by solid-liquid separation; wherein the gas used is air, the gas pressure is 0.5MPa and the air inlet temperature is 120℃; (4) The spherical body is coated with lithium at 500°C and argon atmosphere at normal pressure for 2.0 h. Then, the spherical body is coated with magnesium at 800°C and argon atmosphere at normal pressure for 2.0 h. After cooling to room temperature, the final product is a lithium-ion battery anode material, wherein the lithium-ion battery anode material contains 70 wt% graphene nanoribbons and 30 wt% silicon.

[0024] The SEM image of the lithium-ion battery anode material obtained in this embodiment is derived from... Figure 1 It can be seen that graphene nanoribbons intertwine silicon particles into a spherical composite, which is tightly bound and has a controllable particle size.

[0025] Example 2 This invention provides a method for preparing a lithium-ion battery anode material, specifically including the following steps: (1) Graphene nanoribbons were dissolved in N-methylpyrrolidone according to a certain mass ratio. After mixing and stirring, a graphene nanoribbon slurry with a mass concentration of 3.0 wt% and uniform dispersion was obtained. Then, Si3Li7 was mixed into the graphene nanoribbon slurry according to a mass ratio of 60:40 between graphene nanoribbons and Si3Li7. After uniform dispersion, a mixed slurry A was obtained. The width of the graphene nanoribbons was 20 nm and the length was 50 μm. The average particle size of Si3Li7 was 30 nm. (2) Mixed slurry A was reacted at a constant temperature of 4.8 MPa and 451 °C for 1.0 h to obtain mixed slurry B; (3) The mixed slurry B is spheroidized and granulated using a gas-liquid two-phase insoluble interface, and spherical bodies are obtained after solid-liquid separation; the gas used is nitrogen, the gas pressure is 1.0 MPa, and the inlet temperature is 100℃. (4) The spherical body is coated with lithium at 150°C and argon atmosphere at normal pressure for 0.5 h. Then, the spherical body is coated with magnesium at 600°C and argon atmosphere at normal pressure for 0.5 h. After cooling to room temperature, the final product is a lithium-ion battery anode material, wherein the lithium-ion battery anode material contains 60 wt% graphene nanoribbons and 740 wt% Si3Li.

[0026] Example 3 This invention provides a method for preparing a lithium-ion battery anode material, specifically including the following steps: (1) Graphene nanoribbons were dissolved in toluene according to a certain mass ratio. After mixing and stirring, a graphene nanoribbon slurry with a mass concentration of 0.4 wt% and uniform dispersion was obtained. Then, the graphene nanoribbons were mixed with Si5Li... 22 Si5Li was mixed in a mass ratio of 80:20 22 A mixed slurry A was obtained by uniformly dispersing a graphene nanoribbon mixture; wherein the graphene nanoribbons had a width of 50 nm and a length of 30 μm; and Si5Li... 22 The average particle size is 50 nm; (2) Mixed slurry A was reacted at a constant temperature of 22.1 MPa and 374 °C for 0.5 h under supercritical H2O conditions to obtain mixed slurry B; (3) The mixed slurry B is spheroidized and granulated using a gas-liquid two-phase insoluble interface, and spherical bodies are obtained after solid-liquid separation; the gas used is argon, the gas pressure is 0.1MPa, and the inlet temperature is 80℃. (4) Molten lithium was used to deposit lithium on the surface of the spherical body at 250°C and argon atmosphere under normal pressure for 0.1 h. Then, the temperature was switched to 800°C and argon atmosphere under normal pressure, and molten magnesium was used to deposit magnesium on the surface of the lithium-deposited spherical body for 0.1 h. After cooling to room temperature, the final product, a lithium-ion battery anode material, was obtained. The lithium-ion battery anode material contains 80 wt% graphene nanoribbons and Si5Li. 22 20wt%.

[0027] Example 4 This invention provides a method for preparing a lithium-ion battery anode material, specifically including the following steps: (1) Graphene nanoribbons were dissolved in ethanol according to a certain mass ratio. After mixing and stirring, a graphene nanoribbon slurry with a mass concentration of 0.1wt% and uniform dispersion was obtained. Then, Sn was mixed into the graphene nanoribbon slurry according to a mass ratio of 50:50 between graphene nanoribbons and Sn. After uniform dispersion, mixed slurry A was obtained. The width of the graphene nanoribbons was 300nm and the length was 100μm. The average particle size of Sn was 10μm. (2) Mixed slurry A was reacted at a constant temperature of 7.3 MPa and 31 °C for 2.0 h to obtain mixed slurry B; (3) The mixed slurry B is spheroidized and granulated using a gas-liquid two-phase insoluble interface, and spherical bodies are obtained after solid-liquid separation; the gas used is air, the gas pressure is 2.0 MPa, and the air inlet temperature is 130℃. (4) The spherical body is coated with lithium at 600°C and argon atmosphere at normal pressure for 2.0 h. Then, the spherical body is coated with magnesium at 1200°C and argon atmosphere at normal pressure for 2.0 h. After cooling to room temperature, the final product is a lithium-ion battery anode material, wherein the lithium-ion battery anode material contains 50 wt% graphene nanoribbons and 50 wt% Sn.

[0028] Example 5 This invention provides a method for preparing a lithium-ion battery anode material, specifically including the following steps: (1) Graphene nanoribbons were dissolved in isopropanol according to a certain mass ratio. After mixing and stirring, a graphene nanoribbon slurry with a mass concentration of 10.0 wt% and uniform dispersion was obtained. Then, the graphene nanoribbons were mixed with Sn5Li 13 Sn5Li was subjected to a mass ratio of 90:10 13 Mixed with graphene nanoribbon slurry and uniformly dispersed, a mixed slurry A is obtained; wherein the graphene nanoribbons have a width of 4 nm and a length of 30 nm; Sn5Li 13 The average particle size is 1 nm; (2) Mixed slurry A was reacted at a constant temperature of 1.0 h in an NH3 atmosphere with a pressure of 11.4 MPa and a temperature of 133 °C to obtain mixed slurry B; (3) The mixed slurry B is spheroidized and granulated using a gas-liquid two-phase insoluble interface, and spherical bodies are obtained after solid-liquid separation; the gas used is argon, the gas pressure is 1.5MPa, and the inlet temperature is 200℃. (4) Molten lithium was used to deposit lithium on the surface of the spherical body at 600℃ and argon atmosphere at normal pressure for 0.2h. Then, the temperature was switched to 1200℃ and argon atmosphere at normal pressure, and molten magnesium was used to deposit magnesium on the surface of the lithium-deposited spherical body for 0.2h. After cooling to room temperature, the final product, a lithium-ion battery anode material, was obtained. The lithium-ion battery anode material contains 90wt% graphene nanoribbons and Sn5Li 13 10wt%.

[0029] Example 6 This invention provides a method for preparing a lithium-ion battery anode material, specifically including the following steps: (1) Graphene nanoribbons were dissolved in propanol according to a certain mass ratio. After mixing and stirring, a graphene nanoribbon slurry with a mass concentration of 5.0 wt% and uniform dispersion was obtained. Then, the graphene nanoribbons were mixed with Sn5Li 22 Sn5Li was mixed in a mass ratio of 60:40 22 Mixed with graphene nanoribbon slurry and uniformly dispersed, a mixed slurry A is obtained; wherein the graphene nanoribbons have a width of 4 nm and a length of 80 μm; Sn5Li 13 The average particle size is 10 μm; (2) Mixed slurry A was reacted at a constant temperature of 10 MPa and 31 °C for 1.8 h to obtain mixed slurry B; (3) The mixed slurry B is spheroidized and granulated using a gas-liquid two-phase insoluble interface, and spherical bodies are obtained after solid-liquid separation; the gas used is argon, the gas pressure is 0.5MPa, and the inlet temperature is 150℃. (4) Molten lithium was deposited on the surface of the spherical body at 150°C and argon atmosphere under normal pressure for 0.1 h. Then, the temperature was switched to 600°C and argon atmosphere under normal pressure, and molten magnesium was deposited on the surface of the lithium-plated spherical body for 0.2 h. After cooling to room temperature, the final product, a lithium-ion battery anode material, was obtained. The lithium-ion battery anode material contains 60 wt% graphene nanoribbons and Sn5Li. 22 40wt%.

[0030] Example 7 This invention provides a method for preparing a lithium-ion battery anode material, specifically including the following steps: (1) Graphene nanoribbons were dissolved in water according to a certain mass ratio and mixed and stirred to obtain a graphene nanoribbon slurry with a mass concentration of 2.0 wt% and uniform dispersion. Then, B was mixed into the graphene nanoribbon slurry according to a mass ratio of 95:5 between graphene nanoribbons and B. After uniform dispersion, mixed slurry A was obtained. The graphene nanoribbons had a width of 10 nm and a length of 20 μm. The average particle size of B was 0.1 μm. (2) Mixed slurry A was reacted at a constant temperature of 23 MPa and 374 °C under supercritical H2O conditions for 2.0 h to obtain mixed slurry B; (3) The mixed slurry B is spheroidized and granulated using a gas-liquid two-phase insoluble interface, and spherical bodies are obtained after solid-liquid separation; the gas used is argon, the gas pressure is 1.5MPa, and the inlet temperature is 160℃. (4) The spherical body is coated with lithium at 600°C and argon atmosphere at normal pressure for 1.5 h. Then, the spherical body is coated with magnesium at 1000°C and argon atmosphere at normal pressure for 1.5 h. After cooling to room temperature, the final product is a lithium-ion battery anode material, wherein the lithium-ion battery anode material contains 95 wt% graphene nanoribbons and 5 wt% B.

[0031] Example 8 This invention provides a method for preparing a lithium-ion battery anode material, specifically including the following steps: (1) Graphene nanoribbons were dissolved in N-methylpyrrolidone according to a certain mass ratio. After mixing and stirring, a graphene nanoribbon slurry with a mass concentration of 5.0 wt% and uniform dispersion was obtained. Then, B6Li7 was mixed into the graphene nanoribbon slurry according to a mass ratio of graphene nanoribbons to B6Li7 of 85:15. After uniform dispersion, mixed slurry A was obtained. The width of the graphene nanoribbons was 50 nm and the length was 50 μm. The average particle size of B6Li7 was 5 μm. (2) Mixed slurry A was reacted at a constant temperature of 7.5 MPa and 451 °C for 1.0 h to obtain mixed slurry B; (3) The mixed slurry B is spheroidized and granulated using a gas-liquid two-phase insoluble interface, and spherical bodies are obtained after solid-liquid separation; the gas used is argon, the gas pressure is 1.2MPa, and the inlet temperature is 180℃; (4) The spherical body is coated with lithium on the surface at 200°C and argon atmosphere at normal pressure for 0.5h. Then, the surface is coated with magnesium on the lithium-coated spherical body at 800°C and argon atmosphere at normal pressure for 0.5h. After cooling to room temperature, the final product is a lithium-ion battery anode material, wherein the lithium-ion battery anode material contains 85wt% graphene nanoribbons and 15wt% B6Li.

[0032] Example 9 This invention provides a method for preparing a lithium-ion battery anode material, specifically including the following steps: (1) Graphene nanoribbons were dissolved in ethanol according to a certain mass ratio. After mixing and stirring, a graphene nanoribbon slurry with a mass concentration of 3.0 wt% and uniform dispersion was obtained. Then, P and PLi3 were mixed in the graphene nanoribbon slurry according to a mass ratio of 50:25:25. After uniform dispersion, mixed slurry A was obtained. The width of the graphene nanoribbons was 200 nm and the length was 90 μm. The average particle size of P was 10 μm. The average particle size of PLi3 was 1 μm. (2) Mixed slurry A was reacted at a constant temperature of 23 MPa and 400 °C under supercritical H2O conditions for 2.0 h to obtain mixed slurry B; (3) The mixed slurry B is spheroidized and granulated using a gas-liquid two-phase insoluble interface, and spherical bodies are obtained after solid-liquid separation; the gas used is nitrogen, the gas pressure is 0.5MPa, and the inlet temperature is 200℃. (4) The spherical body is coated with lithium at 300°C and argon atmosphere at normal pressure for 1.5 h. Then, the spherical body is coated with magnesium at 900°C and argon atmosphere at normal pressure for 1.5 h. After cooling to room temperature, the final product is a lithium-ion battery anode material, wherein the lithium-ion battery anode material contains 50 wt% graphene nanoribbons, 25 wt% P, and 25 wt% PLi.

[0033] Example 10 This invention provides a method for preparing a lithium-ion battery anode material, specifically including the following steps: (1) Graphene nanoribbons were dissolved in water according to a certain mass ratio and mixed and stirred to obtain a mixed slurry A with a mass concentration of 1.0wt% and uniform dispersion; wherein the width of the graphene nanoribbons was 30nm and the length was 10μm. (2) Mixed slurry A was reacted at a constant temperature of 22.1 MPa and 374 °C for 2.0 h under supercritical H2O conditions to obtain mixed slurry B; (3) The mixed slurry B is spheroidized and granulated using a gas-liquid two-phase insoluble interface, and spherical bodies are obtained after solid-liquid separation; the gas used is air, the gas pressure is 0.4MPa, and the air inlet temperature is 120℃. (4) The spherical body is coated with lithium at 400°C and argon atmosphere at normal pressure for 1.0 h. Then, the spherical body is coated with magnesium at 600°C and argon atmosphere at normal pressure for 1.0 h. After cooling to room temperature, the final product is a lithium-ion battery anode material, wherein the lithium-ion battery anode material contains 100 wt% graphene nanoribbons.

[0034] Example 11 This invention provides a method for preparing a lithium-ion battery anode material, specifically including the following steps: (1) Graphene nanoribbons were dissolved in water according to a certain mass ratio and mixed and stirred to obtain a graphene nanoribbon slurry with a mass concentration of 0.5wt% and uniform dispersion. Then, SiO and SnO were mixed in the graphene nanoribbon slurry according to the mass ratio of graphene nanoribbons, SiO and SnO of 10:40:50 and uniformly dispersed to obtain mixed slurry A. The width of the graphene nanoribbons was 60nm and the length was 50μm. The average particle size of SiO and SnO was 5μm. (2) Mixed slurry A was reacted at a constant temperature of 12 MPa and 150 °C for 2.0 h under the supercritical reaction pressure of NH3 to obtain mixed slurry B; (3) The mixed slurry B is spheroidized and granulated using a gas-liquid two-phase insoluble interface, and spherical bodies are obtained after solid-liquid separation; the gas used is air, the gas pressure is 3.0 MPa, and the air inlet temperature is 200℃; (4) The spherical body is coated with lithium at 200°C and argon atmosphere at normal pressure for 2.0 h. Then, the spherical body is coated with magnesium at 1200°C and argon atmosphere at normal pressure for 2.0 h. After cooling to room temperature, the final product is a lithium-ion battery anode material, wherein the lithium-ion battery anode material contains 10 wt% graphene nanoribbons, 40 wt% SiO, and 50 wt% SnO.

[0035] Example 12 This invention provides a method for preparing a lithium-ion battery anode material, specifically including the following steps: (1) Graphene nanoribbons were dissolved in toluene according to a certain mass ratio. After mixing and stirring, a graphene nanoribbon slurry with a mass concentration of 3.0 wt% and uniform dispersion was obtained. Then, according to the ratio of graphene nanoribbons and Si4Li 13 Si4Li and B6Li7 were mixed in a mass ratio of 1:50:49.13 Si4Li was mixed with B6Li7 in a graphene nanoribbon slurry and uniformly dispersed to obtain mixed slurry A; wherein the graphene nanoribbons have a width of 60 nm and a length of 50 μm; and Si4Li7 was mixed with B6Li7 in a graphene nanoribbon slurry. 13 The average particle size of B6Li7 is 5 μm, and the average particle size of B6Li7 is 6 μm. (2) Mixed slurry A was reacted at a constant temperature of 8 MPa and 235 °C for 1.0 h to obtain mixed slurry B; (3) The mixed slurry B is spheroidized and granulated using a gas-liquid two-phase insoluble interface, and spherical bodies are obtained after solid-liquid separation; the gas used is argon, the gas pressure is 1.0 MPa, and the inlet temperature is 100℃. (4) Molten lithium was used to deposit lithium on the surface of the spherical body at 150°C and argon atmosphere under normal pressure for 0.5 h. Then, the temperature was switched to 600°C and argon atmosphere under normal pressure, and molten magnesium was used to deposit magnesium on the surface of the lithium-deposited spherical body for 0.5 h. After cooling to room temperature, the final product, a lithium-ion battery anode material, was obtained. The lithium-ion battery anode material contains 1 wt% graphene nanoribbons and Si4Li 13 50wt%, B6Li 749wt%.

[0036] Example 13 This invention provides a method for preparing a lithium-ion battery anode material, specifically including the following steps: (1) Graphene nanoribbons were dissolved in water according to a certain mass ratio, and after mixing and stirring, a graphene nanoribbon slurry with a mass concentration of 2.0 wt% and uniform dispersion was obtained. Then, according to the ratio of graphene nanoribbons and Si4Li 13 Si4Li was prepared with a mass ratio of B6Li7 and PLi3 of 1:30:40:29. 13 B6Li7 and PLi3 were mixed in a graphene nanoribbon slurry and uniformly dispersed to obtain mixed slurry A; wherein the graphene nanoribbons had a width of 50 nm and a length of 60 μm; Si4Li 13 The average particle size is 5 μm, the average particle size of B6Li7 is 6 μm, and the average particle size of PLi3 is 4 μm; (2) Mixed slurry A was reacted at a constant temperature of 7.5 MPa and 240 °C for 1.5 h to obtain mixed slurry B; (3) The mixed slurry B is spheroidized and granulated using a gas-liquid two-phase insoluble interface, and spherical bodies are obtained after solid-liquid separation; the gas used is argon, the gas pressure is 1.2MPa, and the inlet temperature is 120℃. (4) Molten lithium was used to deposit lithium on the surface of the spherical body at 350°C and argon atmosphere under normal pressure for 0.5 h. Then, the temperature was switched to 700°C and argon atmosphere under normal pressure, and molten magnesium was used to deposit magnesium on the surface of the lithium-plated spherical body for 0.5 h. After cooling to room temperature, the final product, a lithium-ion battery anode material, was obtained. The lithium-ion battery anode material contains 1 wt% graphene nanoribbons and Si4Li 13 30wt%, B6Li740wt%, PLi329wt%.

[0037] Example 14 This invention provides a method for preparing a lithium-ion battery anode material, specifically including the following steps: (1) Graphene nanoribbons were dissolved in ethanol according to a certain mass ratio. After mixing and stirring, a graphene nanoribbon slurry with a mass concentration of 1.0 wt% and uniform dispersion was obtained. Then, SiO, SnO, B2O3 and P2O5 were mixed in the graphene nanoribbon slurry according to the mass ratio of graphene nanoribbons, SiO, SnO, B2O3 and P2O5 of 1:25:20:30:24. After uniform dispersion, mixed slurry A was obtained. The width of the graphene nanoribbons was 100 nm and the length was 60 μm. The average particle size of SiO was 1 μm, the average particle size of SnO was 3 μm, the average particle size of B2O3 was 5 μm and the average particle size of P2O5 was 4 μm. (2) Mixed slurry A was reacted at a constant temperature of 12 MPa and 135℃ for 1.5 h under the supercritical reaction pressure of NH3 to obtain mixed slurry B; (3) The mixed slurry B is spheroidized and granulated using a gas-liquid two-phase insoluble interface, and spherical bodies are obtained after solid-liquid separation; the gas used is air, the gas pressure is 0.5MPa, and the air inlet temperature is 150℃. (4) Molten lithium was used to plate the surface of the spherical body for 1.5 h at a temperature of 500 °C and an argon atmosphere under normal pressure. Then, the temperature was switched to 1200 °C and an argon atmosphere under normal pressure. Molten magnesium was used to plate the surface of the lithium-plated spherical body for 1.5 h. After cooling to room temperature, the final product, a lithium-ion battery anode material, was obtained. The lithium-ion battery anode material contains 1 wt% graphene nanoribbons, 25 wt% SiO, 20 wt% SnO, 30 wt% B2O3, and 24 wt% P2O5.

[0038] The product obtained in Example 1 was used as a negative electrode according to the method of the present invention, with a lithium sheet as the counter electrode, and assembled into a CR2032 coin cell. The liquid electrolyte used was 1 mol·L⁻¹. -1The LiPF6 in EC:DEC (1:1, V / V) battery was tested with a voltage range of 0.005-2.000V. Its constant current charge-discharge performance was tested using the Landian CT2001A battery testing system. The results are as follows: Figure 2-3 , Figure 2 The first charge-discharge curves of the graphene nanoribbon / silicon anode material at a 0.1C rate are shown. The discharge specific capacity and charge specific capacity are 1061 mAh / g and 963 mAh / g, respectively, and the first coulombic efficiency reaches 90.7%, which is significantly higher than the first cycle efficiency of current silicon-based materials. Figure 3 The results showed that after 500 cycles at 0.1C, the graphene nanoribbon / silicon anode material maintained a high specific capacity of 961 mAh / g and achieved a cycle stability of 99.8%, demonstrating excellent cycle stability.

[0039] The comparative example involved the direct physical mixing of graphene nanoribbons and silicon at a mass ratio of 80:20, without the application of the technology of this invention. The morphology of the product was as follows. Figure 4 As shown, the particles are non-spherical and random, with random particle size distribution that is difficult to control. The preparation of the electrode sheets and the manufacturing and testing methods of the coin cells are the same as in Example 1. The relevant data of the comparative example and Example 1 are shown in Table 1. This proves that the negative electrode material obtained by the present invention has advantages such as high discharge capacity, high cycle efficiency, and long service life. The comparative example products are out of touch with actual needs in terms of application and performance.

[0040] Table 1. Test data of the materials obtained from the comparative example and Example 1 in coin cells.

[0041] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a lithium-ion battery anode material, characterized in that, Specifically, the following steps are included: (1) Graphene nanoribbons and active materials are dispersed in a solvent and mixed evenly to obtain a mixed slurry A; (2) The mixed slurry A is subjected to a supercritical reaction to obtain mixed slurry B; (3) The mixed slurry B is granulated by gas-liquid insoluble phase to obtain spherical bodies C; (4) A lithium-ion battery anode material is obtained by sequentially plating lithium and magnesium onto the surface of the spherical body C.

2. The method for preparing a lithium-ion battery negative electrode material according to claim 1, characterized in that, The mass ratio of graphene nanoribbons to active material in step (1) is (1-100):(0-99).

3. The method for preparing a lithium-ion battery negative electrode material according to claim 2, characterized in that, The graphene nanoribbons are obtained by longitudinally dechaining carbon nanotubes, with a width of 4nm ≤ width ≤ 300nm and a length of 30nm ≤ length ≤ 100μm. The active material includes at least one of silicon, tin, boron, phosphorus, or their oxides or lithium compounds.

4. The method for preparing a lithium-ion battery anode material according to claim 3, characterized in that, The average particle size of the active material is 1 nm ≤ D 50 ≤20μm; Among them, silicon oxide is SiO x , 1≤x≤2; the silicon lithiation compound is SiLi y , 1.7≤y≤4.4; Tin oxide is SnO z , 1≤z≤2; tin lithium is SnLi m , 2.6≤m≤4.4; The boron oxide is B2O3; the boron lithium compound is B6Li7. Phosphorus oxide is PO n , 1.5≤n≤2.5; the lithium phosphate compound is PLi3.

5. The method for preparing a lithium-ion battery negative electrode material according to claim 1, characterized in that, The solvent in step (1) is at least one of ethanol, propanol, isopropanol, N-methylpyrrolidone, toluene and water, and the mass concentration of graphene nanoribbons in the mixed slurry is 0.1-10%.

6. The method for preparing a lithium-ion battery negative electrode material according to claim 1, characterized in that, The supercritical reaction in step (2) is a supercritical state of CO2, NH3, H2O or NMP, with a reaction pressure of 7.3-23 MPa, a reaction temperature of 31-451℃ and a reaction time of 0.5-2.0 h.

7. The method for preparing a lithium-ion battery negative electrode material according to claim 1, characterized in that, The gas-liquid insoluble phase mentioned in step (3) is the gas and liquid insoluble phase; The gas is at least one of air, nitrogen, and argon, with a pressure of 0.1-3.0 MPa and an inlet temperature of 80-200°C; The liquid is at least one of water, ethanol, propanol, isopropanol, N-methylpyrrolidone, and toluene.

8. The method for preparing a lithium-ion battery negative electrode material according to claim 1, characterized in that, The specific steps of lithium and magnesium plating in step (4) are as follows: First, molten lithium is used to plate the surface of the sphere at a temperature of 80-500℃ and an inert atmosphere at normal pressure. Then, the temperature is switched to 600-1200℃ and an inert atmosphere at normal pressure, and molten magnesium is used to plate the surface of the sphere that has been plated with lithium. The surface is then cooled to room temperature.

9. A lithium-ion battery anode material obtained by the preparation method according to any one of claims 1-8.

10. The application of a lithium-ion battery anode material obtained by the preparation method according to any one of claims 1-8 or the lithium-ion battery anode material according to claim 9 in lithium-ion batteries, semi-solid / quasi-solid batteries and all-solid batteries.

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