阅读说明：本技术 一种高容量高循环效率的硅基/石墨烯纳米带复合材料及其制备方法 (High-capacity high-cycle-efficiency silicon-based/graphene nanoribbon composite material and preparation method thereof ) 是由 李新禄 姚丛 王荣华 于 2020-04-15 设计创作，主要内容包括：本发明公开了一种高容量高循环效率的硅基/石墨烯纳米带复合材料及其制备方法,属于化学电源技术领域。本发明的复合材料包括以下质量百分比的组分：硅基材料10-98％,石墨烯纳米带1-89％,锂元素1-10％；本发明将硅基材料经过表面活性剂处理使之带上正电的静电荷,接着将处理后的硅基材料和石墨烯纳米带通过搅拌混合,经收集干燥高温处理后得到复合材料；再将得到的复合材料直接与锂片机械接触,通过调节外部施加压力和施压时间实现可控预锂化。本发明具有工艺简单,操作方便的特点,并且本发明制备得到的硅基/石墨烯纳米带复合材料比容量高,首次库伦效率高,循环寿命长,倍率性能强,可应用于高比能的锂离子电池。(The invention discloses a silicon-based/graphene nanoribbon composite material with high capacity and high cycle efficiency and a preparation method thereof, and belongs to the technical field of chemical power sources. The composite material comprises the following components in percentage by mass: 10-98% of silicon-based material, 1-89% of graphene nanoribbon and 1-10% of lithium element; according to the invention, a silicon-based material is treated by a surfactant to be charged with positive static charges, then the treated silicon-based material and a graphene nano-belt are stirred and mixed, and a composite material is obtained after collection, drying and high-temperature treatment; and then, the obtained composite material is directly in mechanical contact with a lithium sheet, and controllable pre-lithiation is realized by adjusting external applied pressure and applied pressure time. The method has the characteristics of simple process and convenience in operation, and the silicon-based/graphene nanoribbon composite material prepared by the method has high specific capacity, high first coulombic efficiency, long cycle life and strong rate capability, and can be applied to a lithium ion battery with high specific energy.)

1. A high-capacity high-cycle-efficiency silicon-based/graphene nanoribbon composite material is characterized by comprising the following components in percentage by mass:

10 to 98 percent of silicon-based material

1-89% of graphene nanoribbon

1 to 10 percent of lithium element

Wherein the silicon-based material is micro-nano silicon powder or silicon monoxide or porous silicon, the average particle size of the silicon-based material is 0.01-30 mu m, and the specific surface area is 5-500m²·g^-1Pore volume of 0.01-5cm³·g^-1(ii) a The diameter of the graphene nanoribbon is 5-50nm, the length of the graphene nanoribbon is 1-100 mu m, and the carbon content of the graphene nanoribbon is more than or equal to 95%.

2. The high-capacity high-cycle-efficiency silicon-based/graphene nanoribbon composite material as claimed in claim 1, wherein the composite material comprises the following components in percentage by mass:

87 percent of silicon-based material

10 percent of graphene nanoribbon

3 percent of lithium element

Wherein the silicon-based material is nano silicon powder with the average particle size of 10nm and the specific surface area of 120m²·g^-1Pore volume of 0.81cm³·g^-1(ii) a Diameter of the graphene nanoribbon5nm, 10 μm in length and 95% carbon.

3. The high-capacity high-cycle-efficiency silicon-based/graphene nanoribbon composite material as claimed in claim 1, wherein the composite material comprises the following components in percentage by mass:

silicon-based material 64%

30 percent of graphene nanoribbon

6 percent of lithium element

Wherein the silicon-based material is silicon monoxide, the average particle diameter of the silicon-based material is 30nm, and the specific surface area of the silicon-based material is 50m²·g^-1Pore volume of 0.25cm³·g^-1(ii) a The diameter of the graphene nanoribbon is 10nm, the length of the graphene nanoribbon is 30 microns, and the carbon content of the graphene nanoribbon is 98%.

4. The high-capacity high-cycle-efficiency silicon-based/graphene nanoribbon composite material as claimed in claim 1, wherein the composite material comprises the following components in percentage by mass:

silicon-based material 10%

86 percent of graphene nanoribbon

Lithium element 4%

Wherein the silicon-based material is porous silicon with an average particle size of 30 μm and a specific surface area of 200m²·g^-1Pore volume of 1.5cm³·g^-1(ii) a The diameter of the graphene nanoribbon is 50nm, the length of the graphene nanoribbon is 60 microns, and the carbon content of the graphene nanoribbon is 99%.

5. The high-capacity high-cycle-efficiency silicon-based/graphene nanoribbon composite material as claimed in claim 1, wherein the composite material comprises the following components in percentage by mass:

silicon-based material 70%

Graphene nanoribbon 25%

5 percent of lithium element

Wherein the silicon-based material is silicon monoxide, the average particle diameter of the silicon-based material is 10 mu m, and the specific surface area of the silicon-based material is 5m²·g^-1Pore volume of 0.01cm³·g^-1(ii) a The diameter of the graphene nanoribbon is 40nm, the length of the graphene nanoribbon is 100 microns, and the carbon content of the graphene nanoribbon is 99.9%.

6. The high-capacity high-cycle-efficiency silicon-based/graphene nanoribbon composite material as claimed in claim 1, wherein the composite material comprises the following components in percentage by mass:

silicon-based material 40%

58 percent of graphene nanoribbon

2 percent of lithium element

Wherein the silicon-based material is micron silicon powder, the average particle size of the silicon-based material is 5 microns, and the specific surface area of the silicon-based material is 16m²·g^-1Pore volume of 0.08cm³·g^-1(ii) a The diameter of the graphene nanoribbon is 20nm, the length of the graphene nanoribbon is 5 microns, and the carbon content of the graphene nanoribbon is 99.9%.

7. The high-capacity high-cycle-efficiency silicon-based/graphene nanoribbon composite material as claimed in claim 1, wherein the composite material comprises the following components in percentage by mass:

silicon-based material 50%

Graphene nanoribbon 44%

6 percent of lithium element

Wherein the silicon-based material is porous silicon, the average particle diameter of the silicon-based material is 90nm, and the specific surface area of the silicon-based material is 500m²·g^-1Pore volume of 5cm³·g^-1(ii) a The diameter of the graphene nanoribbon is 30nm, the length of the graphene nanoribbon is 20 microns, and the carbon content of the graphene nanoribbon is 99.9%.

8. A method for preparing the high-capacity high-cycle-efficiency silicon-based/graphene nanoribbon composite material as claimed in any one of claims 1 to 7, wherein the method comprises the following steps:

(1) preparation of silicon-based Material Mixed solution

Dissolving a silicon-based material and a surfactant in deionized water, and mixing and stirring for 30-240min to obtain a mixed solution in which the silicon-based material with positive charges is suspended;

wherein the proportion of the silicon-based material, the surfactant and the deionized water is 1 g: (0.05-0.5) g: (100-1000) mL;

(2) preparation of silicon-based/graphene nanoribbon composite

Ultrasonically dispersing the graphene nanoribbon in deionized water for 1-12h to obtain 0.1-10mol/L dispersion liquid, then adding the dispersion liquid into the silicon-based material mixed liquid, ultrasonically oscillating for 5-240min under the frequency condition of 50-1000Hz, collecting precipitates through solid-liquid separation, drying, and sintering in an inert atmosphere to obtain the silicon-based/graphene nanoribbon composite material;

wherein the mass ratio of the graphene nanoribbon to the silicon-based material is 1: 0.1 to 100;

(3) pre-lithiated silicon-based/graphene nanoribbon composites

The silicon-based/graphene nanoribbon composite material is directly and mechanically pressed with a metal lithium sheet soaked by lithium ion battery electrolyte under the protection of inert gas, and the applied pressure is 0.1-10 kg-cm^-1And (3) applying pressure for 5-600min to obtain the final silicon-based/graphene nanoribbon composite material with high capacity and high cycle efficiency.

9. The method for preparing the high-capacity high-cycle-efficiency silicon-based/graphene nanoribbon composite material according to claim 8, wherein the surfactant in the step (1) is a positively charged agent or polymer, including but not limited to cetyl trimethyl ammonium bromide, polydiallyldimethyl ammonium chloride, and octadecyl dimethyl benzyl quaternary ammonium chloride.

10. The method for preparing the silicon-based/graphene nanoribbon composite material with high capacity and high cycle efficiency according to claim 8, wherein the drying temperature in the step (2) is 60-150 ℃, and the drying time is 6-24 h; the sintering is carried out by heating to 200-800 ℃ at the speed of 1-10 ℃/min and sintering for 0.5-10 h.

Technical Field

The invention relates to the technical field of chemical power lithium ion batteries, in particular to a pre-lithiation high-capacity high-cycle-efficiency silicon-based/graphene nanoribbon composite material and a preparation method thereof.

Background

The rapid development of electric automobiles puts higher requirements on the energy density of lithium ion batteries, but the energy density of the batteries is low due to the low specific capacity of electrode materials of the conventional commercial power batteries, so that the endurance mileage of the electric automobiles is limited. Particularly, the theoretical specific capacity of the graphite negative electrode of the lithium ion battery is only 372mAh/g, which greatly limits the energy density of the battery, and therefore, a new negative electrode material needs to be developed to improve the energy density of the battery.

The silicon negative electrode material has obvious advantages due to high theoretical specific capacity (4200mAh/g), is rich in earth crust elements, low in cost and environment-friendly, and is the next generation of lithium ion battery negative electrode material with the most potential; but at the same time, the disadvantages of the prior art are prominent, the large volume expansion effect, poor conductivity and easy occurrence of pulverization in charge and discharge cycles limit the commercial application of silicon-based materials. Therefore, solving the defects of the silicon-based material has great significance for the development of new energy industries.

The graphene nanoribbon is used as quasi-one-dimensional ribbon graphene, has good electrical conductivity, large specific surface area, thinness and other excellent performances, has good flexibility and water solubility due to the quasi-one-dimensional structure, can be flexibly and mutually wound into a three-dimensional network structure and form a self-supporting porous film, and is more favorable for transmission and storage of electrons or ions.

At present, the preparation method of the silicon-carbon composite material is generally to carry out multi-step high-temperature carbonization treatment on carbon-containing precursors such as single-substance silicon, natural graphite or artificial graphite, high molecular polymers and the like. The existing silicon-carbon cathode material of a lithium ion battery and a preparation method thereof are disclosed as the preparation method of the high-performance silicon-carbon-graphite composite cathode material for the lithium ion battery with the application number of 201911176477.4, and the preparation method comprises the following steps: dissolving an organic carbon source in a solvent, adding nano silicon particles, uniformly mixing, adding crystalline flake graphite into the mixture, and carrying out continuous vacuum-high pressure impregnation reaction and vacuum drying to obtain a silicon-carbon composite material precursor; and spheroidizing the precursor of the silicon-carbon composite material, then coating the precursor with a surface solid phase, and finally sintering and screening to obtain the target product. However, the main disadvantages of this technical route are: firstly, the process is complex, the equipment is various, the actual operation is difficult, the large-scale production is not facilitated, the energy consumption is large in multiple high-temperature sintering, and part of organic solvents are not environment-friendly; the first coulombic efficiency of the composite material is low; the specific capacity of the composite material is improved compared with that of graphite, but is still lower; fourthly, the bonding force between the carbon material and the silicon material is poor, and the carbon material and the silicon-based material generate gaps in the charge-discharge cycle process, so that the capacity is quickly attenuated.

Therefore, the problem to be solved by those skilled in the art is how to provide a silicon-based/graphene nanoribbon composite material with simple process, excellent operation and excellent electrochemical performance and a preparation method thereof.

Disclosure of Invention

The invention aims to provide a silicon-based/graphene nanoribbon composite material with high capacity and high cycle efficiency and a preparation method thereof aiming at the phenomena of complex preparation process, high cost and insufficient charge and discharge performance of the existing silicon-carbon composite material, and the silicon-based/graphene nanoribbon composite material has the advantages of simple process, convenience in operation, low production cost, good production safety and the like, is convenient for popularization and application, and is beneficial to realizing large-scale production; in addition, the pre-lithiated silicon-based/graphene nanoribbon composite material prepared by the method has the characteristics of high specific capacity, high first coulombic efficiency, long cycle life, high rate capability and the like, can form a self-supporting porous film without adding a binder, and is suitable for a high-specific energy lithium ion battery cathode material.

In order to achieve the purpose, the invention adopts the following technical scheme:

a high-capacity high-cycle-efficiency silicon-based/graphene nanoribbon composite material comprises the following components in percentage by mass:

10 to 98 percent of silicon-based material

1-89% of graphene nanoribbon

1 to 10 percent of lithium element

Wherein the silicon-based material is nano silicon or silicon monoxide or porous silicon, the average particle diameter of the silicon-based material is 0.01-30, and the specific surface area is 5-500m²·g^-1Pore volume of 0.01-5cm³·g^-1(ii) a The diameter of the graphene nanoribbon is 5-50nm, the length of the graphene nanoribbon is 1-100 mu m, and the carbon content of the graphene nanoribbon is more than or equal to 95%.

The mass percentages of the silicon-based material, the graphene nanoribbon and the lithium element have important influence on the properties of the final composite material. The average grain size span of the silicon-based material is from 10nm to 30 mu m, and the graphene nanoribbon is quasi-one-dimensional strip-structured graphene. When the silicon-based material is nano silicon with small particle size, the graphene nanoribbon with the mass percentage of 1% can be better flexibly and electrostatically adhered and cross-wound to wrap the nano silicon; the silicon-based material is porous silicon with larger particle size, when the mass percentage of the graphene nanoribbon is lower, the graphene nanoribbon with the quasi-one-dimensional strip structure cannot be completely wound and wrapped on the porous silicon in a crossed mode, the mass percentage of the graphene nanoribbon needs to be increased to achieve a better wrapping effect, and the flexible self-supporting porous film can be formed by the graphene nanoribbon and the graphene nanoribbon under the condition that no binder is added.

In order to finally realize high capacity and high cycle efficiency of the composite material and ensure the flexible electrostatic adhesion and cross winding coating effects of the graphene nanoribbon, the silicon-based material is a main contributor of the lithium storage capacity of the composite material, and repeated tests prove that the mass percentage of the silicon-based material is required to be higher than 10%, the mass percentage of the graphene nanoribbon is required to be lower than 89%, the mass percentage of lithium element is required to be kept in a reasonable interval, the pre-lithiation effect is poor due to the low content of the lithium element, and the first coulombic efficiency cannot be improved; on the contrary, the excessive pre-lithiation of the composite material can be caused by the excessively high content of the lithium element, the separation of lithium dendrite can be caused in the charging and discharging processes, and the potential safety hazard of the battery exists.

Preferably, in the silicon-based/graphene nanoribbon composite material with high capacity and high cycle efficiency, the composite material comprises the following components in percentage by mass:

87 percent of silicon-based material

10 percent of graphene nanoribbon

3 percent of lithium element

Wherein the silicon-based material is nano silicon powder with the average particle size of 10nm and the specific surface area of 120m²·g^-1Pore volume of 0.81cm³·g^-1(ii) a The diameter of the graphene nanoribbon is 5nm, the length of the graphene nanoribbon is 10 microns, and the carbon content of the graphene nanoribbon is 95%.

Preferably, in the silicon-based/graphene nanoribbon composite material with high capacity and high cycle efficiency, the composite material comprises the following components in percentage by mass:

silicon-based material 64%

30 percent of graphene nanoribbon

6 percent of lithium element

Wherein the silicon-based material is silicon monoxide, the average particle diameter of the silicon-based material is 30nm, and the specific surface area of the silicon-based material is 50m²·g^-1Pore volume of 0.25cm³·g^-1(ii) a The diameter of the graphene nanoribbon is 10nm, the length of the graphene nanoribbon is 30 microns, and the carbon content of the graphene nanoribbon is 98%.

Preferably, in the silicon-based/graphene nanoribbon composite material with high capacity and high cycle efficiency, the composite material comprises the following components in percentage by mass:

silicon-based material 10%

86 percent of graphene nanoribbon

Lithium element 4%

Wherein the silicon-based material is porous silicon with an average particle size of 30 μm and a specific surface area of 200m²·g^-1Pore volume of 1.5cm³·g^-1(ii) a The diameter of the graphene nanoribbon is 50nm, the length of the graphene nanoribbon is 60 microns, and the carbon content of the graphene nanoribbon is 99%.

Preferably, in the silicon-based/graphene nanoribbon composite material with high capacity and high cycle efficiency, the composite material comprises the following components in percentage by mass:

silicon-based material 70%

Graphene nanoribbon 25%

5 percent of lithium element

Wherein the silicon-based material is silicon monoxide, the average particle diameter of the silicon-based material is 10 mu m, and the specific surface area of the silicon-based material is 5m²·g^-1Pore volume of 0.01cm³·g^-1(ii) a The diameter of the graphene nanoribbon is 40nm, the length of the graphene nanoribbon is 100 microns, and the carbon content of the graphene nanoribbon is 99.9%.

Preferably, in the silicon-based/graphene nanoribbon composite material with high capacity and high cycle efficiency, the composite material comprises the following components in percentage by mass:

silicon-based material 40%

58 percent of graphene nanoribbon

2 percent of lithium element

Wherein the silicon-based material is micron silicon powder, the average particle size of the silicon-based material is 5 microns, and the specific surface area of the silicon-based material is 16m²·g^-1Pore volume of 0.08cm³·g^-1(ii) a The diameter of the graphene nanoribbon is 20nm, the length of the graphene nanoribbon is 5 microns, and the carbon content of the graphene nanoribbon is 99.9%.

Preferably, in the silicon-based/graphene nanoribbon composite material with high capacity and high cycle efficiency, the composite material comprises the following components in percentage by mass:

silicon-based material 50%

Graphene nanoribbon 44%

6 percent of lithium element

Wherein the silicon-based material is porous silicon with an average particle size of 50nm and a specific surface area of 500m²·g^-1Pore volume of 5cm³·g^-1(ii) a The diameter of the graphene nanoribbon is 30nm, the length of the graphene nanoribbon is 20 microns, and the carbon content of the graphene nanoribbon is 99.9%.

The invention also discloses a preparation method of the silicon-based/graphene nanoribbon composite material with high capacity and high cycle efficiency, which comprises the following steps:

(1) preparation of silicon-based Material Mixed solution

Dissolving a silicon-based material and a surfactant in deionized water, mixing and stirring for 30-240min to obtain a silicon-based material suspension with positive charges on the surface;

after the silicon-based material is treated by the surfactant, the surface of the silicon-based material is provided with positive charges, the graphene nanoribbon is dispersed in water, the Zeta potential is tested to be a negative value, the graphene nanoribbon can be flexibly and electrostatically adhered to the silicon-based material under the electrostatic action and is wound and wrapped in a cross mode, the graphene nanoribbon and the silicon-based material can be tightly combined without the action of a binder, and the step has important influence on the preparation of the composite material.

In subsequent example 1, nanosilicon/polydiallyldimethylammonium chloride/deionized water was mixed in a ratio of 1 g: 0.1 g: 1000mL for 240min to obtain the nanometer silicon suspension with positive charge, and testing the Zeta potential value to be +19.8 mV.

(2) Preparation of silicon-based/graphene nanoribbon composite

Ultrasonically dispersing the graphene nanoribbon for 1-12h to obtain 0.1-10mol/L dispersion liquid, then adding the dispersion liquid into the silicon-based material suspension, ultrasonically oscillating for 5-240min under the frequency condition of 50-1000Hz, collecting precipitate through solid-liquid separation, drying, and sintering under the inert atmosphere to obtain the silicon-based/graphene nanoribbon composite material;

(3) pre-lithiated silicon-based/graphene nanoribbon composites

The silicon-based/graphene nanoribbon composite material is in direct mechanical contact with a metal lithium sheet soaked by lithium ion battery electrolyte under the protection of inert gas, and 0.1-10kg cm is externally applied^-1And (3) mechanically pressing and contacting for 5-600min to obtain the final silicon-based/graphene nanoribbon composite material with high capacity and high cycle efficiency.

After the silicon-based material is treated by the surfactant, the surface of the silicon-based material is positively charged, the Zeta potential is tested to be a positive value (+19.8mV) in a water system dispersion liquid, the Zeta potential is tested to be a negative value (-4.6mV) in a water system dispersion liquid, the graphene nanoribbon can generate flexible electrostatic adhesion and cross winding wrapping with the silicon-based material under the electrostatic action, a self-supporting flexible porous film can be formed without the action of a binder, and the interaction is incomparable to the existing surface coating carbon and the doped carbon nanomaterial.

Preferably, in the above preparation method of a silicon-based/graphene nanoribbon composite material with high capacity and high cycle efficiency, the ratio of the silicon-based material, the surfactant and the deionized water in step (1) is 1 g: (0.05-0.5) g: (100-1000) mL.

Preferably, in the above method for preparing a high-capacity high-cycle-efficiency silicon-based/graphene nanoribbon composite, the surfactant in step (1) is a positively charged reagent or polymer, including but not limited to cetyltrimethylammonium bromide, polydiallyldimethylammonium chloride, and octadecyldimethylbenzyl quaternary ammonium chloride.

The beneficial effects of the above technical scheme are: the selected surfactants are strong cationic polyelectrolyte or cationic surfactants, and aim to bring positive charges on the surface of the silicon-based material and generate electrostatic adhesion with the graphene nanoribbon.

Preferably, in the above method for preparing a silicon-based/graphene nanoribbon composite material with high capacity and high cycle efficiency, the mass ratio of the graphene nanoribbon to the silicon-based material in step (2) is 1: 0.1-100.

Preferably, in the preparation method of the silicon-based/graphene nanoribbon composite material with high capacity and high cycle efficiency, the drying temperature in the step (2) is 60-150 ℃, and the drying time is 6-24 h; the sintering is carried out by heating to 200-800 ℃ at the speed of 1-10 ℃/min and sintering for 0.5-10 h.

The silicon negative electrode material has high specific capacity, and simultaneously, because the material has large volume expansion effect and poor conductivity, the material is easy to pulverize in the charging and discharging process, so that the capacity of the material is quickly attenuated. The graphene nanoribbon is good in conductivity, large in specific surface area, thin and good in flexibility, can be easily adhered to a silicon-based material in a flexible electrostatic manner and wrapped in a crossed manner, can form a self-supporting flexible porous film without the action of a binder, and can exert the advantages of the two materials to the maximum extent. In addition, the silicon-based composite material generally has the bottleneck problem of low first coulombic efficiency, and the popularization and application of the silicon-based composite material in a full battery are hindered. The stable prelithiation film ensures that the composite material maintains a high coulombic efficiency during the first and subsequent cycles.

According to the technical scheme, compared with the prior art, the invention discloses a silicon-based/graphene nanoribbon composite material with high capacity and high cycle efficiency and a preparation method thereof, and the silicon-based/graphene nanoribbon composite material has the following advantages:

(1) the method has the advantages of few working procedures, low energy consumption, no toxic raw material, good production safety, low production cost, environmental protection and the like in the production process;

(2) the method adopts the procedures of chemical oxidation, mechanical stirring, ultrasonic dispersion mixing and the like, has simple process and convenient operation, is beneficial to realizing large-scale production and is convenient to popularize and apply;

(3) according to the method, a large amount of chemical metallurgy product silicon-based alloy can be directly adopted as a silicon raw material, the cost is low, and the method is favorable for direct large-scale production;

(4) the pre-lithiated silicon-based/graphene nanoribbon composite material prepared by the method obviously improves the initial coulombic efficiency (larger than or equal to 96%) of the material, fundamentally overcomes the bottleneck problem of low initial cycle efficiency of the silicon-based material in the lithium ion charging and discharging process, and can be widely used as a high-end negative electrode material for lithium ion batteries with high energy density and long cycle service life;

(5) the graphene nanoribbon is used as quasi-one-dimensional ribbon graphene, has the excellent performances of good conductivity, large specific surface area, thinness and the like, has good flexibility, can generate flexible electrostatic adhesion with a silicon-based material and cross-wrap and wrap a multiple three-dimensional network structure, obviously increases the conductivity of the composite material, can form a self-supporting flexible porous film without adding a binder, can inhibit the expansion of a silicon material, fundamentally overcomes the pulverization and the falling off of the silicon-based material in the lithium ion charge-discharge cycle process, and ensures the cycle stability and the long service life of the silicon-based negative electrode material;

(6) the graphene nanoribbon adopted by the invention has high length-diameter ratio, the periphery of the graphene nanoribbon is in an open structure, the graphene nanoribbon has the characteristics of high lithium storage capacity and strong rate capability, and the composite material is effectively ensured to have the advantages of high capacity and high rate capability after being compounded with a silicon-based material with high theoretical capacity.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 is an SEM image of a nano-silicon/graphene nanoribbon composite material with high capacity and high cycle efficiency prepared in example 1 of the present invention.

Fig. 2 is a Zeta potential test chart of nano-silicon treated by graphene nanoribbons and poly diallyl dimethyl ammonium chloride in example 1 of the present invention.

Fig. 3 is a first charge-discharge curve diagram and a cycle performance diagram of a high-capacity high-cycle-efficiency silica/graphene nanoribbon composite prepared in example 2 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.