CN108400297B

CN108400297B - Silicon-based lithium ion battery cathode material and preparation method thereof

Info

Publication number: CN108400297B
Application number: CN201810119502.4A
Authority: CN
Inventors: 童路攸; 韩彬; 陈丽鲜; 刘雷; 尹佳
Original assignee: Zhejiang Hengyuan New Energy Technology Co Ltd; Shandong Forever New Energy Co Ltd
Current assignee: Zhejiang Hengyuan New Energy Technology Co Ltd; Shandong Forever New Energy Co Ltd
Priority date: 2018-02-06
Filing date: 2018-02-06
Publication date: 2020-08-14
Anticipated expiration: 2038-02-06
Also published as: CN108400297A

Abstract

The invention relates to a silicon-based lithium ion battery cathode material and a preparation method thereof, belongs to the technical field of lithium ion batteries, and solves the problems of poor conductivity and short cycle life of the conventional silicon-based cathode material. The method comprises the steps of firstly, preparing ZnO/SiO with a core-shell structure by hydrolyzing organic silicon by taking nano zinc oxide as a template agent₂(ii) a ZnO/SiO₂Mixing with Zn powder and carrying out high-temperature treatment to obtain ZnO/SiO_x(0≤X<2) (ii) a Then reacting with acid to obtain hollow H-SiO_x(ii) a Then H-SiO_xCoating polyaniline on the surface to obtain H-SiO_x(iii) a/PANI; finally adsorbing graphene oxide on the surface of polyaniline and reducing to obtain H-SiO_xthe/PANI/RGO is the silicon-based lithium ion battery cathode material. The preparation process and equipment requirements are low, the silicon-based negative electrode material is good in structural stability and high in conductivity, and the cycle life is greatly prolonged.

Description

Silicon-based lithium ion battery cathode material and preparation method thereof

Technical Field

The invention relates to a silicon-based lithium ion battery cathode material and a preparation method thereof, belonging to the technical field of lithium ion batteries.

Background

The lithium ion battery has the advantages of high energy density, long cycle life, no pollution in use and the like, becomes the subject of new energy research at present, and is widely applied to notebooks, mobile phones and electric automobiles. At present, graphite is generally used as a negative electrode material of the lithium ion battery, but the energy density of the whole lithium ion battery is limited due to the low theoretical capacity of the graphite. The theoretical capacity of silicon can reach 4200mAhg^-1Far higher than graphite and on earthThe storage capacity is rich, and the lithium ion battery anode material is excellent; however, silicon has poor conductivity, and its volume expansion during charging and discharging is more than 3 times, so that the problems of material particle breakage, material falling off from the current collector, etc. are easily caused, and the battery capacity is rapidly attenuated, the battery life is short, and the rate capability is poor.

In order to improve the activity of silicon and the application in the battery field, in the prior art, a carbon layer or graphene is deposited on the surface of silicon nanoparticles through chemical vapor deposition to increase the electrical conductivity of silicon and improve the performance of the battery. However, the method has high requirements on equipment, high energy consumption and high requirements on deposition conditions. And the silicon nano particles are doped by boric acid, and then etched by silver nitrate solution, so that porous silicon is formed, the volume expansion is relieved, and the service life of the battery is prolonged. In the method, the doping amount of boron is not high, the cost of silver nitrate is high, the obtained holes are small and small, and the performance is not greatly improved. And in addition, the silicon-based material and high-conductivity materials such as graphene, activated carbon, carbon nanotubes and the like are subjected to ball milling and the like by a physical method, so that the conductivity of the silicon-based material is increased, and the performance of the battery is improved. However, the physical method has the disadvantages of poor structural stability of the material and low binding ability between the components.

Disclosure of Invention

The invention provides a silicon-based lithium ion battery cathode material and a preparation method thereof aiming at the defects in the prior art, and solves the problems of poor conductivity, low structural stability and short cycle life of the silicon-based material when the silicon-based material is used as the lithium ion battery cathode material.

One of the purposes of the invention is realized by the following technical scheme, and the preparation method of the silicon-based lithium ion battery cathode material comprises the following steps:

A. adding an organic silicon source and ammonia water into the nano zinc oxide dispersion liquid, reacting, filtering to obtain a precipitate, and heating the precipitate to obtain ZnO/SiO with a core-shell structure₂；

B. Under the protection of inert gas, ZnO/SiO with a core-shell structure₂Mixing with active Zn powder, and performing heat treatment at high temperature to obtain silicon-based material ZnO/SiO with lithium storage activity_xSaid SiO_xWherein the value of X is not less than 0 and not more than X<2；

C. ZnO/SiO_xReacting with dilute acid solution to remove ZnO and excessive zinc powder in the inner layer, centrifuging, and washing to obtain hollow silicon-based material H-SiO_x；

D. Mixing hollow silicon-based material H-SiO_XAnd adding an aniline monomer into a mixed solution of water and ethanol, adjusting the pH value of the system to be 1-2, adding an ammonium persulfate solution, carrying out a polymerization reaction, and after the reaction is finished, centrifuging and washing to obtain the polyaniline PANI coated hollow silicon-based material H-SiO_xBinary composite material H-SiO_x/PANI；

E. Mixing the above binary composite material H-SiO_xAdding the/PANI and graphene oxide dispersion liquid into water, and adsorbing graphene oxide on the binary composite material H-SiO through electrostatic adsorption_xAdding a reducing agent on the surface of the PANI, and controlling the temperature to react at 70-90 ℃ to obtain a ternary composite material H-SiO for adsorbing and reducing graphene oxide RGO on the surface of polyaniline_x/PANI/RGO。

The invention obtains the ZnO/SiO with the core-shell structure by using nano zinc oxide as a template and organic silicon as a silicon source₂The material takes active Zn powder as a reducing agent to reduce silicon dioxide into SiO with lithium storage activity under the condition of high temperature_xMaterial, wherein X has a value in the range of 0. ltoreq.X<2. The silicon dioxide has no lithium storage activity, while the silicon-based material SiO obtained after reduction in the invention_XHas lithium storage activity, can generate intercalation and deintercalation reaction with lithium ions when being used as a negative electrode material of a lithium ion battery, and achieves the effect of providing high capacity. And Zn powder is used as a reducing agent, other irrelevant elements cannot be introduced, the introduction of impurities is avoided, and the influence on the SiO of the active silicon-based material caused by reduction of zinc oxide by an over-active reducing agent is avoided_xIs reduced. Then removing redundant zinc powder and silicon-based material ZnO/SiO under the action of dilute acid_XInternal ZnO template to obtain hollow structureSilicon-based material H-SiO_xThe formed hollow structure is beneficial to relieving the volume expansion of the silicon-based material during lithium embedding, the material structure is stabilized, and the battery service life and the battery capacity are improved. Since the silicon-based materials themselves have a low electrical conductivity, in H-SiO_XThe outer layer is coated with a polyaniline layer, the polyaniline is an excellent conductive high polymer material, the conductivity of the material can be increased, the internal resistance of the material can be reduced, and a formed conductive network can provide a lithium ion transmission channel; meanwhile, polyaniline has elasticity, and when the volume of the silicon-based material on the inner layer expands in the charging and discharging processes, the polyaniline can restrict the silicon-based material, so that the stress caused by the volume expansion is relieved, and the capacity attenuation caused by the breakage of silicon-based particles and the falling off from the current collector is reduced. And finally, adsorbing graphene oxide on the outer layer of the material and reducing the graphene oxide, so that the composite material has higher structural stability and conductivity, and the capacity retention rate of the material is improved. H-SiO in the silicon-based lithium ion battery cathode material_xThe three components of PANI and RGO are cooperated to obtain the ternary composite material H-SiO_xthe/PANI/RGO has the advantages of high conductivity, high structural stability and long cycle life. The preparation process and equipment of the invention have low requirements, the reaction does not need to be carried out under harsh conditions such as high vacuum and the like, and the invention also has the advantages of low cost, no pollution and environmental protection.

In the above method for preparing the silicon-based lithium ion battery negative electrode material, preferably, the organic silicon source in step a is selected from methyl orthosilicate, ethyl orthosilicate or butyl orthosilicate. The organic silicon source is adopted for introducing the silicon source to form ZnO/SiO with a core-shell structure₂Has the advantage of easily available raw materials. Preferably, the mass ratio of the organic silicon source to the zinc oxide in the step a is 3:1 to 1: 3.

In the preparation method of the silicon-based lithium ion battery cathode material, the heating temperature in the step A is preferably 60-120 ℃. The purpose is to form a stable silicon dioxide layer, improve the stability and avoid the phenomena of material particle fracture and the like.

In the preparation method of the silicon-based lithium ion battery cathode material, preferably, in the step A, the shape of the nano zinc oxide is spherical or rod-shaped, and the particle size of the nano zinc oxide is 10-200 nm. By introducing the nano-scale zinc oxide template, the composite materials with different shapes, particle sizes and pore diameters can be obtained by controlling.

In the preparation method of the silicon-based lithium ion battery cathode material, the temperature of the high-temperature treatment in the step B is preferably 400-1000 ℃. The purpose of high-temperature treatment is to reduce silicon dioxide into silicon-based material SiO with lithium storage activity_xAnd provides high capacity. More preferably, the temperature of the high-temperature treatment is 500 to 800 ℃.

In the preparation method of the silicon-based lithium ion battery cathode material, the zinc powder and ZnO/SiO in the step B are preferably selected₂The mass ratio of (A) to (B) is 1: 1-5: 1. Aims to obtain SiO with different oxygen contents by regulating and controlling the amount of zinc powder_xAnd the reducing agent utilizes zinc powder instead of magnesium powder and other more active metals to prevent the reduction of the inner layer zinc oxide from influencing the reduction of the outer layer silicon dioxide. The optimal reaction time is 3-24 h generally, and the silicon dioxide can be reduced sufficiently, so that the active silicon-based material is obtained. In the preparation method of the silicon-based lithium ion battery cathode material, preferably, the dilute acid in the step C is dilute hydrochloric acid or dilute sulfuric acid, and the concentration of the dilute acid is 1-6 mol/L.

In the preparation method of the silicon-based lithium ion battery cathode material, preferably, H-SiO in the step D_XThe mass ratio of the aniline monomer to the ammonium persulfate monomer is 1: 3-3: 1, and the molar ratio of the aniline monomer to the ammonium persulfate is 1: 1. The purpose is to obtain polyaniline coating layers with different thicknesses, so that the material has better conductivity and a lithium ion transmission channel is provided.

In the preparation method of the silicon-based lithium ion battery cathode material, preferably, graphene oxide and H-SiO in the step E_xThe mass ratio of the/PANI is 1: 10-1: 1, and the reducing agent is hydroiodic acid, hydrogen peroxide or vitamin C. Can reduce the graphene oxide under the condition of ensuring that the silicon-based material is not dissolved and the polyaniline is not dedoped,the material has high battery activity.

The second purpose of the invention is realized by the following technical scheme that the silicon-based lithium ion battery cathode material comprises a hollow active silicon-based material H-SiO_xSaid SiO_xWherein the value of X is not less than 0 and not more than X<2; the hollow active silicon-based material is H-SiO_xIs coated with polyaniline PANI; reduced Graphene Oxide (RGO) is adsorbed on the surface of the polyaniline; the negative electrode material is H-SiO_x/PANI/RGO. The hollow active silicon-based material of the inner layer has lithium storage activity, can perform intercalation and deintercalation reaction with lithium ions, provides high capacity, and the formed hollow structure is favorable for relieving the volume expansion of the silicon-based material during lithium intercalation, realizes the effect of stabilizing the material structure and prolongs the service life of the battery; H-SiO_xThe polyaniline coated outside can play a role in increasing conductivity and reducing internal resistance, has elasticity, can play a role in restraining a silicon-based material and relieving stress generated by volume expansion, and avoids capacity attenuation caused by cracking or falling of silicon-based particles; the reduced graphene oxide adsorbed on the surface of the polyaniline can stabilize the material structure and improve the conductivity. The three components have synergistic effect, so that the cathode material has the advantages of good conductivity, high structural stability and long cycle life.

In summary, compared with the prior art, the invention has the following beneficial effects:

1. the preparation process and equipment of the invention have low requirements, the reaction does not need to be carried out under harsh conditions such as high vacuum and the like, and the invention also has the advantages of low cost, no pollution and environmental protection.

2. In the silicon-based lithium ion battery cathode material prepared by the invention, H-SiO_xThe three components of PANI and RGO are cooperated to obtain the ternary composite material H-SiO_xthe/PANI/RGO has the advantages of good conductivity, high structural stability and long cycle life. The silicon-based lithium ion battery cathode material prepared by the invention is 0.5Ag^-1The capacity of the current density of the capacitor still remains 885mAhg after 50 cycles^-1The capacity retention rate is high.

Drawings

FIG. 1 shows H-SiO in example 1 of the present invention_xTransmission electron microscopy of the material.

FIG. 2 is a diagram showing H-SiO in example 2 of the present invention_xTransmission electron microscopy of/PANI/RGO material.

FIG. 3 shows H-SiO in example 3 of the present invention_xCycling performance plots of the/PANI/RGO materials at different current densities.

FIG. 4 shows H-SiO in example 3 of the present invention_xthe/PANI/RGO material is 0.5Ag^-1Current density of (a).

Detailed Description

The technical solutions of the present invention will be further specifically described below with reference to specific examples and drawings, but the present invention is not limited to these examples.

Example 1

(1) 1g of nano spherical zinc oxide particles with the particle size of 200nm are taken and dispersed in 50mL of mixed solution of water and ethanol to form nano zinc oxide dispersion liquid. Then, 1g of tetraethyl orthosilicate was slowly added to the nano zinc oxide dispersion solution while stirring. And after all tetraethyl orthosilicate is added, adding 5mL of concentrated ammonia water, stirring for 30 minutes, centrifuging, washing, and drying the obtained precipitate. Then placing the precipitate in a muffle furnace, heating to 120 ℃ and processing for 1h to obtain ZnO/SiO with a core-shell structure₂；

(2) Taking the ZnO/SiO with the core-shell structure₂And zinc powder according to the mass ratio of 1: 4, and heating the mixture at the temperature of 650 ℃ for reduction reaction for 3 hours in a tube furnace under the protection of nitrogen atmosphere. After the reaction is finished, the silicon-based material ZnO/SiO with lithium storage activity is obtained_x(hereinafter, ZnO/SiO_xIs represented by (a), wherein SiO_xIs a silicon-based material with lithium storage activity, and the numerical range of X is more than or equal to 0 and less than or equal to X<2；

(3) The obtained ZnO/SiO_xThe mixture was put into a dilute hydrochloric acid solution and stirred for 1 hour to react, the concentration of the dilute hydrochloric acid being 1 mol/L. After the reaction is finished, carrying out centrifugation and washing treatment to obtain a hollow active silicon-based substance H-SiO_x；

(4) Taking 1g of hollow silicon-based substance H-SiO_xDispersing in 200mL of mixed solution of water and ethanol, and stirring uniformly to form uniformly dispersed H-SiO_xAnd (3) dispersing the mixture. Then 1mL of aniline monomer is added, after the mixture is fully stirred, 2.45g of ammonium persulfate is added, hydrochloric acid is added to adjust the pH value of the system to be 2, and polymerization reaction is carried out for 6h under the ice bath condition. After the polymerization reaction is finished, centrifuging, washing for 3 times by using ethanol to obtain the binary composite material H-SiO with Polyaniline (PANI) substance coated on the surface of the hollow active silicon-based substance_x/PANI；

(5) Taking 0.3g of the binary composite material H-SiO_xthe/PANI substance is dispersed in 30mL of water, then 30mL of 2mg/mL graphene oxide dispersion liquid is added, and the mixture is fully stirred for 1 h. Then, 0.5g of vitamin C is added into the dispersion liquid, the dispersion liquid is heated to 80 ℃ in a water bath, the temperature is kept, the reaction is carried out for 10 minutes, centrifugation, washing and drying are carried out, the Polyaniline (PANI) surface adsorption reduction graphene oxide RGO ternary composite material is obtained, and the final product H-SiO is the final product_xThe negative electrode material is a hollow silicon-based substance (H-SiO) with lithium storage activity from inside to outside in sequence_x) Polyaniline (PANI), and Reduced Graphene Oxide (RGO).

FIG. 1 is a schematic view showing a hollow Si-based material H-SiO in the present example_xTransmission electron micrograph (D). As can be seen from the figure, the resulting H-SiO_xThe coating is a hollow silicon-based material, the thickness of the silicon-based layer is about 50nm, the pore size is about 200nm, and the particle size of the coating accords with the particle size of nano zinc oxide.

The obtained final product H-SiO_xThe electrochemical performance test is carried out on the/PANI/RGO, and the test process is as follows: H-SiO prepared in this example_xthe/PANI/RGO negative electrode material is used as a working electrode, a lithium sheet is used as a counter electrode, and 1mol/L LiPF is adopted₆The electrolyte (wherein, the solvent is ethylene carbonate: dimethyl carbonate with the volume ratio of 1: 2) and the diaphragm is 2400 type polypropylene film produced by Celgard company, and the CR2032 type button cell is assembled. The test is carried out at room temperature within the voltage range of 0.001-2V. The multiplying power test is firstly carried out by 0.1Ag in sequence^-1,0.3Ag^-1,0.5Ag^-1,1Ag^-1Current density ofCirculating for 10 circles and returning to 0.1Ag^-1The current density of (a) was cycled for 10 cycles, and the test results are shown in table 1; the current density of the charge-discharge cycle test is 0.5Ag^-1The test results are shown in Table 2.

Example 2

(1) 1g of spherical nano zinc oxide particles with the particle size of 10nm are taken and dispersed in 50mL of mixed solution of water and ethanol to form nano zinc oxide dispersion liquid. Then, 3g of tetramethyl orthosilicate was slowly added to the nano zinc oxide dispersion while stirring. After the tetramethylorthosilicate is completely added, 5mL of strong ammonia water is added, the mixture is stirred for 30 minutes, and then the mixture is centrifuged and washed, and the obtained precipitate is dried. Then placing the precipitate in a muffle furnace, heating to 100 ℃ and processing for 1.5h to obtain ZnO/SiO with a core-shell structure₂；

(2) Taking the ZnO/SiO with the core-shell structure₂And zinc powder according to the mass ratio of 1:3, and heating the mixture in a tube furnace under the protection of nitrogen atmosphere at the temperature of 750 ℃ for 6 hours to perform reduction reaction. After the reaction is finished, the silicon-based material ZnO/SiO with lithium storage activity is obtained_x(hereinafter, ZnO/SiO_xIs represented by (a), wherein SiO_xIs a silicon-based material with lithium storage activity, and the numerical value of X is more than or equal to 0 and less than or equal to X<2；

(3) The obtained ZnO/SiO_xThe mixture is put into a dilute sulfuric acid solution and stirred for reaction for 1 hour, wherein the concentration of the dilute sulfuric acid is 2 mol/L. After the reaction is finished, carrying out centrifugation and washing treatment to obtain a hollow active silicon-based substance H-SiO_x；

(4) Taking 1g of hollow silicon-based substance H-SiO_xDispersing the mixture into 200mL of mixed solution of water and ethanol, stirring the mixture evenly, adding 1.5mL of aniline monomer, stirring the mixture fully, adding 3.68g of ammonium persulfate, adding hydrochloric acid to adjust the pH value of the system to be 1.5, and carrying out polymerization reaction for 6 hours under the ice bath condition. After the polymerization reaction is finished, centrifuging, and washing for 3 times by using ethanol to obtain the binary composite material H-SiO with Polyaniline (PANI) substance coated on the surface of the hollow silicon-based substance_x/PANI；

(5) Taking 0.3g of the binary composite material H-SiO_xthe/PANI material was dispersed in 30mL water,then 30mL of 1mg/mL graphene oxide dispersion was added, and the mixture was stirred well for 1 hour. Then adding 0.5mL of hydroiodic acid into the dispersion, heating the dispersion in a water bath to 90 ℃, keeping the temperature for reaction for 10 minutes, centrifuging and washing, drying the obtained solid product, and obtaining the Polyaniline (PANI) surface adsorption Reduction Graphene Oxide (RGO) ternary composite material, namely the final product H-SiO_xThe negative electrode material is a hollow silicon-based substance (H-SiO) with lithium storage activity from inside to outside in sequence_x) Polyaniline (PANI), and Reduced Graphene Oxide (RGO).

FIG. 2 shows H-SiO in this example_xTransmission electron micrograph of/PANI/RGO composite material, from which it can be seen that the resulting H-SiO_xReduced graphene oxide in/PANI/RGO composite material is adsorbed on H-SiO_xa/PANI surface; polyaniline is coated on H-SiO_xOn the surface, a coating layer is formed. The components are tightly combined to form a stable structure.

The obtained final product H-SiO_xThe electrochemical performance test is carried out on the/PANI/RGO, and the test process is as follows: H-SiO prepared in this example_xthe/PANI/RGO negative electrode material is used as a working electrode, a lithium sheet is used as a counter electrode, and 1mol/L LiPF is adopted₆The electrolyte (wherein, the solvent is ethylene carbonate: dimethyl carbonate with the volume ratio of 1: 2) and the diaphragm is 2400 type polypropylene film produced by Celgard company, and the CR2032 type button cell is assembled. The test is carried out at room temperature within the voltage range of 0.001-2V. The multiplying power test is firstly carried out by 0.1Ag in sequence^-1,0.3Ag^-1,0.5Ag^-1,1Ag^-1Current density of 10 cycles, then returning to 0.1Ag^-1The current density of (a) was cycled for 10 cycles, and the test results are shown in table 1; the current density of the charge-discharge cycle test is 0.5Ag^-1The test results are shown in Table 2.

Example 3

(1) 1g of spherical nano zinc oxide particles with the particle size of 30nm are taken and dispersed in 50mL of mixed solution of water and ethanol to form nano zinc oxide dispersion liquid. Then, 1.5g of tetrabutyl orthosilicate was slowly added to the nano zinc oxide dispersion while stirring. Adding tetrabutyl orthosilicate after the tetrabutyl orthosilicate is completely added5mL of strong ammonia water, stirring for 30 minutes, centrifuging, washing, and drying the obtained precipitate. Then placing the precipitate in a muffle furnace, heating to 60 ℃ and processing for 1h to obtain ZnO/SiO with a core-shell structure₂；

(2) Taking the ZnO/SiO with the core-shell structure₂And zinc powder according to the mass ratio of 1:3, and heating the mixture in a tube furnace under the protection of nitrogen at the temperature of 850 ℃ for 3 hours to perform reduction reaction. After the reaction is finished, the silicon-based material ZnO/SiO with lithium storage activity is obtained_x(hereinafter, ZnO/SiO_xIs represented by (a), wherein SiO_xIs a silicon-based material with lithium storage activity, and the numerical range of X is more than or equal to 0 and less than or equal to X<2；

(3) The obtained ZnO/SiO_xThe mixture was put into a dilute hydrochloric acid solution and stirred for 1 hour, the concentration of the dilute hydrochloric acid being 3 mol/L. After the reaction is finished, carrying out centrifugation and washing treatment to obtain a hollow active silicon-based substance H-SiO_x；

(4) Taking 1g of hollow silicon-based substance H-SiO_xDispersing the mixture into 200mL of mixed solution of water and ethanol, adding 3mL of aniline monomer after stirring uniformly, adding 7.35g of ammonium persulfate after fully stirring, adding hydrochloric acid to adjust the pH value of the system to 1, and carrying out polymerization reaction for 8h under the ice bath condition. After the polymerization reaction is finished, centrifuging, washing the precipitate for 3 times by using ethanol to obtain a binary composite material H-SiO of which the surface of the hollow active silicon-based substance is coated with Polyaniline (PANI) substance_x/PANI；

(5) Taking 0.3g of the binary composite material H-SiO_xthe/PANI substance is dispersed in 30mL of water, then 30mL of 3mg/mL graphene oxide dispersion liquid is added, and the mixture is fully stirred for 1 h. Then adding 0.5mL of hydrogen peroxide into the dispersion, heating the dispersion in a water bath to 80 ℃, keeping the temperature for reaction for 10 minutes, centrifuging, washing and drying to obtain a Polyaniline (PANI) surface adsorption-reduction graphene oxide RGO ternary composite material, namely the final product H-SiO_xThe negative electrode material is a hollow silicon-based substance (H-SiO) with lithium storage activity from inside to outside in sequence_x) Polyaniline (PANI), and Reduced Graphene Oxide (RGO).

Will getTo the final product H-SiO_xThe electrochemical performance test is carried out on the/PANI/RGO, and the test process is as follows: H-SiO prepared in this example_xthe/PANI/RGO negative electrode material is used as a working electrode, a lithium sheet is used as a counter electrode, and 1mol/L LiPF is adopted₆The electrolyte (wherein, the solvent is ethylene carbonate: dimethyl carbonate with the volume ratio of 1: 2) and the diaphragm is 2400 type polypropylene film produced by Celgard company, and the CR2032 type button cell is assembled. The test is carried out at room temperature within the voltage range of 0.001-2V. The multiplying power test is firstly carried out by 0.1Ag in sequence^-1,0.3Ag^-1,0.5Ag^-1,1Ag^-1Current density of 10 cycles, then returning to 0.1Ag^-1Current density of (a) was cycled for 10 cycles, and the results are shown in fig. 3 and table 1; the current density of the charge-discharge cycle test is 0.5Ag^-1The results are shown in FIG. 4 and Table 2.

Wherein FIG. 3 is a diagram of H-SiO in the present example_xCycling profile of the/PANI/RGO composite at different current densities. As can be seen from FIG. 3, the ternary composite material H-SiO_xthe/PANI/RGO negative electrode material is 0.1Ag^-1,0.3Ag^-1,0.5Ag^-1,1Ag^-1At a current density of 1188mAhg in capacity^-1,1102mAhg^-1,887mAhg^-1,732mAhg^-1(ii) a When the current density is from 1Ag^-1Back to 0.1Ag^-1When the material is used, the capacity of the material can be recovered to 1152mAhg^-1The excellent rate capability and good cycle performance of the material are demonstrated.

Wherein FIG. 4 shows H-SiO in this example_xthe/PANI/RGO composite material is 0.5Ag^-1The first capacity of the material is up to 987mAhg^-1The capacity of the second circle is 947mAhg^-1The capacity is still 885mAhg after 50 cycles of circulation^-1The theoretical capacity of the graphite is greatly improved, and the capacity retention rate is 89.6 percent, which shows that the silicon-based material has high cycle stability.

Example 4

(1) 1g of nano-rod-shaped zinc oxide particles with the particle size of 100nm are taken and dispersed in 50mL of mixed solution of water and ethanol to form nano-zinc oxide dispersion liquid. Then 2g of tetra-ortho-silicic acidEthyl ester is slowly added into the nano zinc oxide dispersion liquid while stirring. And after all tetraethyl orthosilicate is added, adding 5mL of concentrated ammonia water, stirring for 30 minutes, centrifuging, washing, and drying the obtained precipitate. Then placing the precipitate in a muffle furnace, heating to 110 ℃ and processing for 2h to obtain ZnO/SiO with a core-shell structure₂；

(2) Taking the ZnO/SiO with the core-shell structure₂And zinc powder according to the mass ratio of 1:5, and heating the mixture in a tube furnace under the protection of nitrogen atmosphere at the temperature of 700 ℃ for 6 hours to perform reduction reaction. After the reaction is finished, the silicon-based material ZnO/SiO with lithium storage activity is obtained_x(hereinafter, ZnO/SiO_xIs represented by (a), wherein SiO_xIs a silicon-based material with lithium storage activity, and the numerical range of X is more than or equal to 0 and less than or equal to X<2；

(3) The obtained ZnO/SiO_xThe mixture was put into a dilute hydrochloric acid solution and stirred for 1 hour, and the concentration of the dilute hydrochloric acid was 6 mol/L. After the reaction is finished, centrifuging and washing are carried out to obtain a hollow active silicon-based substance H-SiO_x；

(4) Taking 1g of hollow silicon-based substance H-SiO_xDispersing in 200mL of mixed solution of water and ethanol, and stirring uniformly to form uniformly dispersed H-SiO_xAnd (3) dispersing the mixture. Then 1mL of aniline monomer is added, after the mixture is fully stirred, 2.45g of ammonium persulfate is added, hydrochloric acid is added to adjust the pH value of the system to be 1.0, and the polymerization reaction is carried out for 6h under the ice bath condition. After the polymerization reaction is finished, centrifuging, and washing for 3 times by using ethanol to obtain the binary composite material H-SiO with Polyaniline (PANI) substance coated on the surface of the hollow active silicon-based substance_x/PANI；

(5) Taking 0.3g of the binary composite material H-SiO_xthe/PANI substance is dispersed in 30mL of water, then 30mL of 1.5mg/mL graphene oxide dispersion liquid is added, and the mixture is stirred for 1 hour. Then adding 0.5g hydriodic acid into the dispersion, heating the dispersion in a water bath to 80 ℃, keeping the temperature for reaction for 10 minutes, centrifuging, washing and drying to obtain a Polyaniline (PANI) surface adsorption Reduced Graphene Oxide (RGO) ternary composite material, namely the final product H-SiO_xa/PANI/RGO negative electrode material, the negative electrode material is from inside to outsideHollow silicon-based substance (H-SiO) with lithium storage activity_x) Polyaniline (PANI), and Reduced Graphene Oxide (RGO).

And carrying out related performance tests on the obtained product, wherein the specific tests comprise: the test is carried out at room temperature within the voltage range of 0.001-2V. The multiplying power test is firstly carried out by 0.1Ag in sequence^-1,0.3Ag^-1,0.5Ag^-1,1Ag^-1Current density of 10 cycles, then returning to 0.1Ag^-1The current density of (a) was cycled for 10 cycles, and the test results are shown in table 1; the current density of the charge-discharge cycle test is 0.5Ag^-1The test results are shown in Table 2.

Example 5

(1) 3g of nano rod-shaped zinc oxide particles with the particle size of 120nm are taken and dispersed in 50mL of mixed solution of water and ethanol to form nano zinc oxide dispersion liquid. Then 1g of tetramethyl orthosilicate was slowly added to the nano zinc oxide dispersion while stirring. After the tetramethylorthosilicate is completely added, 5mL of concentrated ammonia water is added, the mixture is stirred for 30 minutes, then centrifugation and washing are carried out, and the obtained precipitate is dried. Then placing the precipitate in a muffle furnace, heating to 60 ℃ and processing for 3h to obtain ZnO/SiO with a core-shell structure₂；

(2) Taking the ZnO/SiO with the core-shell structure₂And the zinc powder according to the mass ratio of 5:1, and heating the mixture in a tubular furnace under the protection of nitrogen atmosphere at the temperature of 1000 ℃ for carrying out reduction reaction for 3 hours. After the reaction is finished, the silicon-based material ZnO/SiO with lithium storage activity is obtained_x(hereinafter, ZnO/SiO_xIs represented by (a), wherein SiO_xIs a silicon-based material with lithium storage activity, and the numerical range of X is more than or equal to 0 and less than or equal to X<2；

(3) The obtained ZnO/SiO_xThe mixture was put into a dilute hydrochloric acid solution and stirred for 1 hour, and the concentration of the dilute hydrochloric acid was 4.0 mol/L. After the reaction is finished, centrifuging and washing are carried out to obtain a hollow active silicon-based substance H-SiO_x；

(4) Taking 1g of hollow silicon-based substance H-SiO_xDispersing in 200mL of mixed solution of water and ethanol, and stirring uniformly to form uniformly dispersed H-SiO_xAnd (3) dispersing the mixture. Then 0.5mL of aniline monomer is added,after stirring sufficiently, 1.23g of ammonium persulfate was added, and hydrochloric acid was added to adjust the pH of the system to 1.5, and polymerization was carried out for 6 hours under ice bath conditions. After the polymerization reaction is finished, centrifuging, and washing for 3 times by using ethanol to obtain the binary composite material H-SiO with Polyaniline (PANI) substance coated on the surface of the hollow active silicon-based substance_x/PANI；

(5) Taking 0.3g of the binary composite material H-SiO_xthe/PANI substance is dispersed in 30mL of water, 200mL of 1.5mg/mL graphene oxide dispersion is added, and the mixture is fully stirred for 1 h. Then adding 0.5g hydriodic acid into the dispersion, heating the dispersion in a water bath to 80 ℃, keeping the temperature for reaction for 20 minutes, centrifuging, washing and drying to obtain a Polyaniline (PANI) surface adsorption Reduced Graphene Oxide (RGO) ternary composite material, namely the final product H-SiO_xThe negative electrode material is a hollow silicon-based substance (H-SiO) with lithium storage activity from inside to outside in sequence_x) Polyaniline (PANI), and Reduced Graphene Oxide (RGO).

And carrying out related performance tests on the obtained product, wherein the specific tests comprise: the test is carried out at room temperature in the voltage range of 0.001-2V. The multiplying power test is firstly carried out by 0.1Ag in sequence^-1,0.3Ag^-1,0.5Ag^-1,1Ag^-1Current density of 10 cycles, then returning to 0.1Ag^-1The current density of (a) was cycled for 10 cycles, and the test results are shown in table 1; the current density of the charge-discharge cycle test is 0.5Ag^-1The test results are shown in Table 2.

Comparative example 1

And (3) taking the spherical nano silicon powder with the particle size of 200nm on the market, and carrying out related performance tests. The specific test is as follows: the test is carried out at room temperature in the voltage range of 0.001-2V. The multiplying power test is firstly carried out by 0.1Ag in sequence^-1,0.3Ag^-1,0.5Ag^-1,1Ag^-1Current density of 10 cycles, then returning to 0.1Ag^-1Current density of (d) was cycled for 10 cycles. The test results of the corresponding spherical nano-silicon powder are shown in table 1; and a current density of 0.5Ag for performing corresponding charge-discharge cycle test^-1The specific test results are shown in table 2.

Table 1 below is for the corresponding examplesThe final product H-SiO is obtained_xThe results of the rate test of the commercial nano-silicon powder in the comparative examples and/PANI/RGO. The specific test results are shown in table 1 below:

TABLE 1

Table 2 below shows the final products H-SiO obtained in the corresponding examples_xThe results of charge-discharge cycle tests were carried out on the commercial nano-silicon powders of the/PANI/RGO and comparative examples. The specific test results are shown in table 2 below:

TABLE 2

As can be seen from the test results in Table 1 above, the current density of the commercial nano-silicon powder used was 0.1Ag^-1The specific capacity is up to 3210mAhg^-1When the current density is 1Ag^-1The time capacity is only 124mAhg^-1When the current density returns to 0.1Ag^-1The time capacity is only recovered to 345mAhg^-1The rate capability is poor. The silicon-based material prepared by the method of the invention is 1Ag^-1Still has 760mAhg at all times^-1Above capacity, when the current density returns to 0.1Ag^-1The hourly capacity can be recovered to 930mAhg^-1Above, the high-power-factor optical fiber has better power performance.

From the test results in table 2, it can be seen that the capacity retention rate is only 6.5% after 50 cycles of the cycle by using the commercially available nano silicon powder; the capacity retention rate of the silicon-based material prepared by the method is more than 80%. Therefore, compared with the commercial nano silicon, the silicon-based material prepared by the method has obviously improved rate capability and cycle performance.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

Claims

1. A preparation method of a silicon-based lithium ion battery cathode material is characterized by comprising the following steps:

E. Mixing the above binary composite material H-SiO_xAdding the/PANI and graphene oxide dispersion liquid into water to enable the graphene oxide to be adsorbed on the binary composite material H-SiO_xAdding a reducing agent into the PANI surface, and controlling the temperature to react at 70-90 ℃ to obtain polyaniline surface adsorbed reduced oxygenTernary composite material H-SiO of graphene RGO_x/PANI/RGO。

2. The method for preparing the silicon-based lithium ion battery anode material according to claim 1, wherein the organic silicon source in the step A is one selected from methyl orthosilicate, ethyl orthosilicate and butyl orthosilicate.

3. The preparation method of the silicon-based lithium ion battery cathode material according to claim 1, wherein the mass ratio of the organic silicon source to the zinc oxide in the step A is 3: 1-1: 3.

4. The preparation method of the silicon-based lithium ion battery anode material according to claim 1, 2 or 3, wherein the heating temperature in the step A is 60-120 ℃.

5. The preparation method of the silicon-based lithium ion battery anode material according to claim 1, 2 or 3, wherein the shape of the nano zinc oxide in the step A is spherical or rod-shaped, and the particle size of the nano zinc oxide is 10-200 nm.

6. The preparation method of the silicon-based lithium ion battery negative electrode material as claimed in claim 1, 2 or 3, wherein the zinc powder and ZnO/SiO in the step B₂The mass ratio of (A) to (B) is 1: 5-5: 1; and the temperature of the high-temperature treatment in the step B is 400-1000 ℃.

7. The preparation method of the silicon-based lithium ion battery anode material according to claim 1, 2 or 3, wherein the dilute acid in the step C is dilute hydrochloric acid or dilute sulfuric acid, and the concentration of the dilute acid is 1-6 mol/L.

8. The preparation method of the silicon-based lithium ion battery anode material according to claim 1, 2 or 3, wherein in the step D, H-SiO is adopted_XThe mass ratio of the aniline monomer to the ammonium persulfate monomer is 1: 3-3: 1, and the molar ratio of the aniline monomer to the ammonium persulfate is 1: 1.

9. The preparation method of the silicon-based lithium ion battery anode material according to claim 1, 2 or 3, wherein the graphene oxide and H-SiO in the step E_xThe mass ratio of the/PANI is 1: 10-1: 1, and the reducing agent is hydroiodic acid, hydrogen peroxide or vitamin C.

10. A silicon-based lithium ion battery cathode material is characterized in that the cathode material adopts the ternary composite material H-SiO obtained by the method of any one of claims 1 to 9_xThe negative electrode material comprises a hollow active silicon-based material H-SiO_xSaid SiO_xWherein the value of X is not less than 0 and not more than X<2; the hollow active silicon-based material is H-SiO_xThe polyaniline-coated polyaniline composite material is coated with polyaniline PANI, and Reduced Graphene Oxide (RGO) is adsorbed on the surface of the polyaniline.