Polyaniline-coated silicon-based composite material and method for preparing the same

Abstract

The application provides a preparation method of a polyaniline-coated silicon-based composite material, and is characterized in that the method comprises the following steps: providing a mixed solution of a silicon-based material, an aniline monomer and an aqueous inorganic acid solution; adding an ammonium persulfate solution dropwise under stirring to perform an in-situ polymerization reaction; performing a filtration treatment after the reaction is completed; collecting polyaniline-coated silicon-based material powder; washing the polyaniline-coated silicon-based material powder to neutrality with deionized water to obtain polyaniline-coated silicon-based material; dispersing the neutral polyaniline-coated silicon-based material in an aqueous ammonia solution, stirring, filtering and washing to neutrality with deionized water to obtain intrinsic polyaniline-coated silicon-based material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium ion batteries, and particularly relates to a polyaniline-coated silicon-based composite material and a preparation method thereof. BACKGROUND

[0002] With higher requirements for the capacity of secondary batteries, silicon, as a high theoretical specific capacity (4200 mAh g -1 ) has been introduced into the negative electrode of lithium ion batteries. However, the volume of silicon as a lithium ion negative electrode material changes greatly during the charging and discharging process, resulting in serious material pulverization. During the charging process, the new interface generated due to the particle rupture continues to react with the electrolyte to generate an SEI film, which causes the thickness of the SEI film to become thicker and thicker, resulting in the loss of negative active material and the continuous consumption of electrolyte, which causes the capacity of the battery to decrease sharply. In addition, the presence of HF in the electrolyte not only corrodes the electrode material, causing the electrolyte to fail, but also affects the quality of the negative SEI film. At present, the carbon-coated method is generally used to solve the problem of material pulverization. However, the actual coated carbon layer is difficult to achieve the purpose of being uniform and continuous, so that the internal silicon is partially exposed. Polyaniline, as a polymer, can be used as a precursor for calcined carbon materials. The usual practice is to calcine the doped polyaniline synthesized by the oxidation method to obtain a carbon material rich in nitrogen atoms. Since the calcined polyaniline loses the characteristics of a polymer, it does not have the ability to reversibly oxidize / reduce and convert between the doped state and the undoped state. The problem of HF corroding the electrode material, causing the electrolyte to fail, and affecting the quality of the negative SEI film still exists. SUMMARY

[0003] The purpose of the present application is to provide a polyaniline-coated silicon-based composite material and a preparation method thereof, which aims to solve the problem that the existing carbon-coated silicon-based negative electrode material uses polyaniline as a coating precursor raw material and forms a carbon-coated material on the surface of the silicon-based material by calcination. Since the calcined polyaniline loses the characteristics of a polymer, the carbon-coated silicon-based negative electrode material does not have the ability to reversibly oxidize / reduce and convert between the doped state and the undoped state. The problem of HF corroding the electrode material, causing the electrolyte to fail, and affecting the quality of the negative SEI film still exists.

[0004] To achieve the above-mentioned purpose of the application, the technical solutions adopted by the present application are as follows:

[0005] In one aspect, the present application provides a preparation method of a polyaniline-coated silicon-based composite material, which comprises the following steps:

[0006] A mixed solution of a silicon-based material, an aniline monomer, and an aqueous inorganic acid solution is provided. An ammonium persulfate solution is added dropwise under stirring conditions to perform an in-situ polymerization reaction. After the reaction is completed, a filtration treatment is performed, and a polyaniline-coated silicon-based material powder is collected. The polyaniline-coated silicon-based material is washed to neutral with deionized water to obtain a polyaniline-coated silicon-based material.

[0007] The neutral polyaniline-wrapped silicon-based material is dispersed in an ammonia solution, stirred, filtered, and washed with deionized water until neutral to obtain the intrinsic polyaniline-wrapped silicon-based material.

[0008] Preferably, the concentration of the inorganic acid is 0.1-2.0 mol / L.

[0009] Preferably, in the step of preparing the polyaniline-wrapped silicon-based material, the amount of the added ammonium persulfate solution satisfies that the molar ratio of the ammonium persulfate to the aniline monomer is 2-3:1.

[0010] Preferably, the concentration of the ammonia solution is 0.1-2.0 mol / L.

[0011] Preferably, the reaction temperature of the in-situ polymerization reaction is 15-35℃, and the reaction time is not less than half an hour.

[0012] Preferably, the inorganic acid is at least one selected from sulfuric acid, hydrochloric acid, and nitric acid.

[0013] Preferably, the silicon-based material is at least one selected from silicon-carbon composite material, silicon-oxygen composite material, and carbon-coated silicon-oxygen material.

[0014] Preferably, the adding ratio of the silicon-based material and the aniline monomer satisfies that the weight percentage content of the intrinsic polyaniline is 0.1%-10% based on 100% of the total weight of the intrinsic polyaniline-wrapped silicon-based material.

[0015] Another aspect of the present application provides a polyaniline-coated silicon-based composite material, which is the intrinsic polyaniline-wrapped silicon-based material, and includes a core and a coating layer coated on the surface of the core, the core is a silicon-based material, and the coating layer is intrinsic polyaniline.

[0016] Preferably, the weight percentage content of the intrinsic polyaniline is 0.1%-10% based on 100% of the total weight of the intrinsic polyaniline-wrapped silicon-based material.

[0017] Still another aspect of the present application provides a lithium ion battery including the polyaniline-coated silicon-based composite material prepared by the method of the present application or the above-mentioned polyaniline-coated silicon-based composite material of the present application.

[0018] The present invention provides a method for preparing a polyaniline-coated silicon-based composite material. This involves coating the silicon-based material surface with polyaniline via in-situ polymerization, followed by dedoping the doped polyaniline (Emeraldine Salt, ES) through reduction to obtain intrinsic polyaniline (Leucoemeradine Base, LB). This results in an intrinsic polyaniline-coated silicon-based material with the intrinsic polyaniline coating on its surface. On one hand, the intrinsic polyaniline, as a polymer material with a loose structure, can form a continuous and complete coating layer on the silicon-based material surface, reducing the pulverization of the negative electrode material. Specifically, when the silicon-based material is carbon-coated, the intrinsic polyaniline can repair the carbon coating layer, ensuring its continuity and integrity. On the other hand, since the main chain segments of the intrinsic polyaniline contain quinones, it can be acid-doped in an acidic environment to obtain doped polyaniline. Therefore, when the intrinsic polyaniline-coated silicon-based material described in this invention is used as a negative electrode material for lithium-ion batteries, the intrinsic polyaniline can absorb HF in the electrolyte, reducing the HF concentration, thereby reducing the damage of HF to the electrode material and electrolyte and improving battery performance. The reaction of intrinsic polyaniline to doped polyaniline under acidic conditions is shown in the following equation (from right to left), where HA represents an inorganic acid, A - Representing inorganic acid anions, the left side of the reaction equation represents doped polyaniline, and the right side represents intrinsic polyaniline. Furthermore, the intrinsic polyaniline reacts with acid to transform into doped polyaniline, thus enabling the material to change from non-conductive to conductive.

[0019]

[0020] This invention provides a polyaniline-coated silicon-based composite material, in which intrinsic polyaniline is coated onto the surface of a silicon-based material. On one hand, the intrinsic polyaniline, as a polymer material with a loose structure, can form a continuous and complete coating layer on the surface of the silicon-based material, reducing the pulverization of the negative electrode material. Specifically, when the silicon-based material is carbon-coated, the intrinsic polyaniline can repair the carbon coating layer, ensuring its continuity and integrity. On the other hand, since the main chain segments of the intrinsic polyaniline contain quinones, it can be doped with acid in an acidic environment to obtain doped polyaniline. Therefore, when the intrinsic polyaniline-coated silicon-based material of this invention is used as a negative electrode material for lithium-ion batteries, the intrinsic polyaniline can absorb HF in the electrolyte, reducing the HF concentration and thus reducing the damage of HF to the electrode material and electrolyte, improving battery performance. Furthermore, the intrinsic polyaniline can react with acid to transform into doped polyaniline, enabling the material to change from non-conductive to conductive.

[0021] The lithium ion battery provided by the application can effectively reduce the damage of HF to electrode materials and electrolyte and improve the performance of the battery due to the use of the polyaniline-coated silicon-based composite material prepared by the method of the application or the polyaniline-coated silicon-based composite material described above. DETAILED DESCRIPTION

[0022] In order to make the technical problems to be solved by the application, the technical solutions and the beneficial effects clearer, the application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and not used to limit the application.

[0023] In the description of the application, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0024] The polyaniline-coated silicon-based composite material provided by the embodiment of the application is an intrinsic state polyaniline-coated silicon-based material, which comprises a core and a coating layer coated on the surface of the core. The core is a silicon-based material, and the coating layer is intrinsic state polyaniline.

[0025] The polyaniline-coated silicon-based composite material provided by the embodiment of the application is an intrinsic state polyaniline-coated silicon-based material, which comprises a core and a coating layer coated on the surface of the core. The core is a silicon-based material, and the coating layer is intrinsic state polyaniline. On the one hand, the intrinsic state polyaniline, as a kind of high polymer material, has loose structure, and can form a continuous and complete coating layer when coated on the surface of the silicon-based material, thereby reducing the pulverization of the negative electrode material. In particular, when the silicon-based material is a carbon-coated silicon-based material, the intrinsic state polyaniline can repair the carbon coating layer, so that the carbon coating layer is continuous and complete. On the other hand, since the main chain segment of the intrinsic state polyaniline contains quinone structure, it can be doped with acid to obtain doped state polyaniline in an acidic environment. Therefore, when the intrinsic state polyaniline-coated silicon-based material is used as a negative electrode material of a lithium ion battery, the intrinsic state polyaniline can absorb HF in the electrolyte to reduce the concentration of HF, so as to achieve the purpose of reducing the damage of HF to electrode materials and electrolyte and improving the performance of the battery. In addition, the reaction of the intrinsic state polyaniline with acid to convert into doped state polyaniline can also realize the change of the material from non-conductive to conductive. The reaction of the intrinsic state polyaniline converting into doped state polyaniline under acidic conditions is shown in the following formula (from right to left), wherein HA represents inorganic acid, and A -The left side of the reaction formula represents the doped state polyaniline, and the right side represents the intrinsic state polyaniline. In addition, the intrinsic state polyaniline can be converted into the doped state polyaniline by reacting with the acid, and the change from non-conductive to conductive can also be realized.

[0026]

[0027] In the embodiment of the present application, preferably, the weight percentage of the intrinsic state polyaniline is 0.1%-10% based on the total weight of the silicon-based material coated with the intrinsic state polyaniline, so as to obtain a suitable thickness of the intrinsic state polyaniline coating layer, thereby ensuring that the silicon-based material coated with the intrinsic state polyaniline has a suitable gram capacity when used as a negative electrode material of a lithium ion battery. If the content of the intrinsic state polyaniline is too high, the thickness of the coating layer is too thick, which will reduce the gram capacity of the material, and even cannot be used as a preferred negative electrode material of a lithium ion battery; if the content of the intrinsic state polyaniline is too low, it is difficult to achieve complete and continuous coating, and it is also difficult to achieve the effect of avoiding the influence of HF.

[0028] In the embodiment of the present application, the silicon-based material is a conventional silicon-based material, including but not limited to at least one of a silicon-carbon composite material, a silicon-oxygen composite material, and a carbon-coated silicon-oxygen material. In particular, when the silicon-based material itself is a core-shell structure, and the outer layer is a carbon material layer, the intrinsic state polyaniline can repair the carbon coating layer, so that the carbon coating layer is continuous and complete.

[0029] The polyaniline-coated silicon-based composite material in the embodiment of the present application can be prepared by the following method.

[0030] Correspondingly, another aspect of the embodiment of the present application provides a preparation method of a polyaniline-coated silicon-based composite material, including the following steps:

[0031] S01. A mixed solution of a silicon-based material, an aniline monomer, and an aqueous inorganic acid solution is provided; an ammonium persulfate solution is added dropwise under stirring conditions to perform an in-situ polymerization reaction; after the reaction is completed, a filtration treatment is performed, and a polyaniline-coated silicon-based material powder is collected; the polyaniline-coated silicon-based material is washed to neutral with deionized water to obtain a polyaniline-coated silicon-based material.

[0032] S02. The neutral polyaniline-coated silicon-based material is dispersed in an aqueous ammonia solution, stirred, filtered, and washed to neutral with deionized water to obtain an intrinsic state polyaniline-coated silicon-based material.

[0033] The method for preparing polyaniline-coated silicon-based composite materials provided in this invention involves coating the surface of a silicon-based material with polyaniline through in-situ polymerization, followed by dedoping the doped polyaniline (Emeraldine Salt, ES) through reduction to obtain intrinsic polyaniline (Leucoemeradine Base, LB). This results in an intrinsic polyaniline-coated silicon-based material with the intrinsic polyaniline coating on its surface. On one hand, the intrinsic polyaniline, as a polymer material with a loose structure, can form a continuous and complete coating layer on the surface of the silicon-based material, reducing the pulverization of the negative electrode material. Specifically, when the silicon-based material is carbon-coated silicon-based, the intrinsic polyaniline can repair the carbon coating layer, ensuring its continuity and integrity. On the other hand, since the main chain segments of the intrinsic polyaniline contain quinones, it can be acid-doped in an acidic environment to obtain doped polyaniline. Therefore, when the intrinsic polyaniline-coated silicon-based material described in this embodiment of the invention is used as a negative electrode material for lithium-ion batteries, the intrinsic polyaniline can absorb HF in the electrolyte, reducing the HF concentration, thereby reducing the damage of HF to the electrode material and electrolyte and improving battery performance. The reaction of intrinsic polyaniline to doped polyaniline under acidic conditions is shown in the following formula (from right to left), where HA represents an inorganic acid, A - Representing inorganic acid anions, the left side of the reaction equation represents doped polyaniline, and the right side represents intrinsic polyaniline. Furthermore, the intrinsic polyaniline reacts with acid to transform into doped polyaniline, thus enabling the material to change from non-conductive to conductive.

[0034]

[0035] Specifically, in step S01 above, a mixed solution of silicon-based material, aniline monomer, and inorganic acid aqueous solution is provided. The silicon-based material is selected from at least one of silicon-carbon composite materials, silicon-oxygen composite materials, and carbon-coated silicon-oxygen materials. The aniline monomer serves as the reactive monomer for polyaniline. Preferably, the addition ratio of the silicon-based material and the aniline monomer satisfies the following: based on the total weight of the intrinsic polyaniline-coated silicon-based material as 100%, the weight percentage of intrinsic polyaniline is 0.1%-10%, thereby obtaining an intrinsic polyaniline coating layer of suitable thickness, thus ensuring that the intrinsic polyaniline-coated silicon-based material has a suitable specific capacity when used as a lithium-ion battery anode material. If the content of the aniline monomer is too high, the resulting coating layer will be too thick, reducing the specific capacity of the material and potentially rendering it unsuitable as a preferred anode material for lithium-ion batteries. If the content of the aniline monomer is too low, it will be difficult to achieve complete and continuous coating, and the effect of avoiding the influence of HF cannot be effectively achieved.

[0036] The inorganic acid in the inorganic acid aqueous solution is doped into the in-situ polymerization reaction of the aniline monomer as a doping molecule on one hand, and the doping is carried out during the polymerization to form the doped polyaniline; on the other hand, the acidic environment provided by the inorganic acid can also promote the in-situ polymerization reaction and improve the doping rate. It should be understood here that, due to the large molecular weight of the organic acid, the corresponding steric hindrance is large, and when the organic acid is close to the polyaniline formed during the polymerization, the combination of the two is difficult, which also reduces the doping effect and even cannot be doped. Therefore, the inorganic acid is used to provide the doping element and the acidic reaction environment in the application. Preferably, the concentration of the inorganic acid is 0.1-2.0 mol / L, so as to obtain a suitable doping amount and doping effect.

[0037] The mixing solution of the silicon-based material, the aniline monomer and the inorganic acid aqueous solution is obtained by dispersing the silicon-based negative electrode material in the inorganic acid aqueous solution and then adding the aniline monomer.

[0038] In the embodiment of the application, the in-situ polymerization reaction is carried out under stirring by adding the ammonium persulfate solution dropwise. The ammonium persulfate in the ammonium persulfate solution is used as an oxidant to oxidize the aniline monomer and then initiate the in-situ polymerization reaction. Preferably, the addition amount of the ammonium persulfate solution satisfies that the molar ratio of the ammonium persulfate to the aniline monomer is 2-3:1, for example, the addition amount of the aniline is 1 mol, and the addition amount of the ammonium persulfate is 2-3 mol, so as to facilitate the stable and orderly occurrence of the in-situ polymerization reaction.

[0039] In the embodiment of the application, the reaction temperature of the in-situ polymerization reaction can be below 60℃, and preferably, the reaction temperature of the in-situ polymerization reaction is 15-35℃, and the reaction time is not less than half an hour. If the reaction temperature is too low, such as lower than 5℃, the in-situ polymerization reaction is not facilitated. The reaction can be carried out normally under the room temperature of 35℃, and on the other hand, the energy can be saved, and the heating operation can be avoided to simplify the reaction process.

[0040] After the in-situ polymerization reaction is completed, the polyaniline-coated silicon-based material powder is collected by filtering treatment, and the polyaniline-coated silicon-based material powder is washed with deionized water until neutral, so as to remove the residual inorganic acid and avoid the influence of the residual inorganic acid on the de-doping by the ammonia water in the following step. After the washing until neutral, the polyaniline-coated silicon-based material is obtained.

[0041] In the step S02, the neutral polyaniline-coated silicon-based material is dispersed in an aqueous ammonia solution to remove the doped polyaniline in the polyaniline-coated silicon-based material, so as to obtain the intrinsic polyaniline with a main chain segment containing a quinone structure. When the intrinsic polyaniline-coated silicon-based material is used as a negative electrode material of a lithium ion battery, the intrinsic polyaniline can absorb HF in the electrolyte to reduce the concentration of HF, so as to reduce the damage of HF to the electrode material and the electrolyte and improve the performance of the battery.

[0042] Preferably, the concentration of the aqueous ammonia solution is 0.1-2.0 mol / L, so as to provide a suitable pH environment, remove the inorganic anions originally doped in the polyaniline by a reduction reaction, and obtain the intrinsic polyaniline-coated silicon-based material. Meanwhile, the obtained intrinsic polyaniline is protected from side reactions. If the concentration of the aqueous ammonia solution is too low, the de-doping effect cannot be effectively achieved. If the concentration of the aqueous ammonia solution is too high, the intrinsic polyaniline cannot be doped again due to excessive reduction of the aqueous ammonia itself, and loses the ability to combine with acid. When the intrinsic polyaniline-coated silicon-based material is used as a negative electrode material of a lithium ion battery, the excessively reduced polyaniline cannot absorb HF in the electrolyte, so as to fail to solve the influence of HF.

[0043] The reduction reaction of the embodiment of the present application is achieved by stirring. The reaction time should be no less than half an hour, preferably 2-16 hours, and more preferably 12 hours, so as to avoid excessive reduction of the obtained intrinsic polyaniline by the aqueous ammonia.

[0044] In addition, the embodiment of the present application further provides a lithium ion battery comprising the polyaniline-coated silicon-based composite material prepared by the method of the present application or the above-mentioned polyaniline-coated silicon-based composite material.

[0045] The lithium ion battery provided by the embodiment of the present application can effectively reduce the damage of HF to the electrode material and the electrolyte and improve the performance of the battery, because it comprises the polyaniline-coated silicon-based composite material prepared by the method of the present application or the above-mentioned polyaniline-coated silicon-based composite material.

[0046] The following will be described in combination with specific embodiments.

[0047] Embodiment 1

[0048] A preparation method of a polyaniline-coated silicon-based composite material, comprising the following steps:

[0049] Disperse 5 g of silicon-carbon material in 500 mL of 1 mol / L aqueous sulfuric acid solution, and then add 0.1 g of aniline monomer. Continue stirring for 2 h to fully disperse the aniline. Under vigorous stirring, drop 200 mL of aqueous ammonium persulfate solution containing 11.4 g of ammonium persulfate. Continue stirring for 6 h until the reaction is complete. Filter to obtain polyaniline-coated silicon-based negative electrode material powder, and then wash with deionized water until neutral. Redisperse the obtained neutral polyaniline-coated silicon-based negative electrode material powder in 500 mL of 0.5 mol / L aqueous ammonia solution, and then stir for 12 h. Filter, and then wash with deionized water until neutral to obtain intrinsic polyaniline-coated silicon-based negative electrode material.

[0050] Example 2

[0051] A method for preparing a polyaniline-coated silicon-based composite material, comprising the following steps:

[0052] Disperse 2 g of carbon-coated silicon-oxygen negative electrode composite material in 300 mL of 0.8 mol / L aqueous hydrochloric acid solution, and then add 0.01 g of aniline monomer. Continue stirring for 2 h to fully disperse the aniline. Under vigorous stirring, drop 100 mL of aqueous ammonium persulfate solution containing 4.564 g of ammonium persulfate. Continue stirring for 6 h until the reaction is complete. Filter to obtain polyaniline-coated silicon-based negative electrode material powder, and then wash with deionized water until neutral. Redisperse the obtained neutral polyaniline-coated silicon-based negative electrode material powder in 100 mL of 1.0 mol / L aqueous ammonia solution, and then stir for 12 h. Filter, and then wash with deionized water until neutral to obtain intrinsic polyaniline-coated silicon-based negative electrode material.

[0053] Example 3

[0054] A method for preparing a polyaniline-coated silicon-based composite material, comprising the following steps:

[0055] Disperse 4 g of carbon-coated silicon-oxygen negative electrode composite material in 500 mL of 0.8 mol / L aqueous nitric acid solution, and then add 0.02 g of aniline monomer. Continue stirring for 2 h to fully disperse the aniline. Under vigorous stirring, drop 250 mL of aqueous ammonium persulfate solution containing 9.128 g of ammonium persulfate. Continue stirring for 6 h until the reaction is complete. Filter to obtain polyaniline-coated silicon-based negative electrode material powder, and then wash with deionized water until neutral. Redisperse the obtained neutral polyaniline-coated silicon-based negative electrode material powder in 300 mL of 0.8 mol / L aqueous ammonia solution, and then stir for 12 h. Filter, and then wash with deionized water until neutral to obtain intrinsic polyaniline-coated silicon-based negative electrode material.

[0056] The samples obtained in the above-mentioned Examples 1, 2 and 3 are named S1, S2 and S3 respectively, and the silicon-based materials without polyaniline coating used in the examples are named D1, D2 and D3 respectively. 2 g of each sample is dispersed in 100 mL of ethylene carbonate (EC) solution containing 0.01 mol / L HF, stirred for 1 h, and filtered. The filter cake after filtration is again dispersed in 100 mL of ethylene carbonate (EC), stirred for 1 h, and filtered. The filter cake is repeatedly washed with ethylene carbonate (EC) for 10 times during filtration, and the obtained product is dried in an oven at 60°C. The fluorine element content in the dried sample is semi-quantitatively tested by a scanning electron microscope energy spectrometer, and the percentage of fluorine atoms in S1, S2 and S3 is 1.84%, 1.39% and 1.27% respectively, while the percentage of fluorine atoms in D1, D2 and D3 is 0.01%, 0.02% and 0.01% respectively. The results show that the fluorine content in the polyaniline-coated composite material is much higher than that in the silicon-based material without coating, and the polyaniline coating can effectively absorb HF acid.

[0057] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a polyaniline-coated silicon-based composite material, characterized in that, The method comprises the following steps: providing a mixed solution of a silicon-based material, an aniline monomer and an aqueous inorganic acid solution; adding an ammonium persulfate solution dropwise under stirring to perform an in-situ polymerization reaction, performing a filtration treatment after the reaction is completed, collecting a polyaniline-coated silicon-based material powder, washing with deionized water until neutral, and obtaining a polyaniline-coated silicon-based material; wherein the polyaniline is covered on the surface of the silicon-based material by in-situ polymerization; dispersing the neutral polyaniline-coated silicon-based material in an aqueous ammonia solution, performing stirring treatment, performing filtration, washing with deionized water until neutral, and obtaining an intrinsic state polyaniline-coated silicon-based material; wherein the intrinsic state polyaniline-coated silicon-based material is used as a lithium ion battery negative electrode material, and the intrinsic state polyaniline is used to absorb HF in an electrolyte; wherein the adding ratio of the silicon-based material and the aniline monomer satisfies that the weight percentage of the intrinsic state polyaniline is 0.1%-10% based on 100% of the total weight of the intrinsic state polyaniline-coated silicon-based material; wherein the silicon-based material is selected from at least one of a silicon-carbon composite material and a carbon-coated silicon-oxygen material; when the silicon-based material itself is a core-shell structure and the outer layer is a carbon material layer, the intrinsic state polyaniline can repair the carbon coating layer to make the carbon coating layer continuous and complete.

2. The method for preparing polyaniline-coated silicon-based composite material as described in claim 1, characterized in that, The concentration of the inorganic acid is 0.1-2.0 mol / L.

3. The method for preparing polyaniline-coated silicon-based composite material as described in claim 1, characterized in that, In the step of preparing the polyaniline-coated silicon-based material, the adding amount of the ammonium persulfate solution satisfies that the molar ratio of the ammonium persulfate to the aniline monomer is 2-3:

1.

4. The method for preparing polyaniline-coated silicon-based composite material as described in claim 1, characterized in that, The concentration of the aqueous ammonia solution is 0.1-2.0 mol / L.

5. The method for preparing the polyaniline-coated silicon-based composite material according to any one of claims 1-4, characterized in that, The reaction temperature of the in-situ polymerization reaction is 15-35 ℃, and the reaction time is not less than half an hour.

6. The method of claim 1-4, wherein the polyaniline-coated silicon-based composite is prepared by the steps of: The inorganic acid is selected from at least one of sulfuric acid, hydrochloric acid and nitric acid.

7. A polyaniline-coated silicon-based composite material, characterized in that, The polyaniline-coated silicon-based composite material is an intrinsic state polyaniline-coated silicon-based material, comprising a core and a coating layer covering the surface of the core, the core is a silicon-based material, and the coating layer is intrinsic state polyaniline; wherein the polyaniline is covered on the surface of the silicon-based material by in-situ polymerization, the intrinsic state polyaniline-coated silicon-based material is used as a lithium ion battery negative electrode material, and the intrinsic state polyaniline is used to absorb HF in an electrolyte; The weight percentage of the intrinsic state polyaniline is 0.1%-10% based on 100% of the total weight of the intrinsic state polyaniline-coated silicon-based material; wherein the silicon-based material is selected from at least one of a silicon-carbon composite material and a carbon-coated silicon-oxygen material; when the silicon-based material itself is a core-shell structure and the outer layer is a carbon material layer, the intrinsic state polyaniline can repair the carbon coating layer to make the carbon coating layer continuous and complete.

8. A lithium-ion battery, characterized by, The polyaniline-coated silicon-based composite material prepared by the method according to any one of claims 1-6 or the polyaniline-coated silicon-based composite material according to claim 7.