CN108232165A - A kind of preparation method of carbon-silicon composite material - Google Patents

Abstract

The present invention relates to a kind of preparation methods of carbon-silicon composite material, it includes the following steps：(a) catalyst is dissolved in the first solvent and is configured to catalyst solution；The catalyst is the mixture formed selected from one or more of molysite, nickel salt, cobalt salt and mantoquita；(b) carbon source is dissolved in the second solvent and is configured to carbon source solution；(c) adding in silicon materials in the catalyst solution makes catalyst be supported on the silicon materials surface, then being added into carbon source solution makes carbon source be supported on its surface；Or add in silicon materials in the mixed solution that the catalyst solution and the carbon source solution are formed, catalyst and carbon source is made to be supported on the silicon materials surface；(d) product of step (c) in reducibility gas is calcined, then cleaned.The impurity such as metal salt, oxide and the carbide after catalyst reduction can be effectively removed, effectively keep the capacity of silicium cathode material.

Description

A kind of preparation method of carbon silicon composite material

technical field

The invention belongs to the field of negative electrode materials for lithium ion batteries, and relates to a carbon-silicon composite material, in particular to a preparation method of the carbon-silicon composite material.

Background technique

Due to its large theoretical capacity of 4200mAh/g and mature preparation technology, silicon materials are considered to be very likely to replace graphite materials as anode materials for the next generation of lithium batteries; especially at the current stage when battery capacity has become the bottleneck of the development of various industries , the large capacity of silicon anode materials has attracted more attention. The main technical problem faced by the silicon anode material is that the volume of the silicon material expands violently during the process of lithium ions entering and exiting, resulting in material pulverization; resulting in a significant decrease in the capacity of the stage sheet, and short circuits caused by piercing the film. The widely researched silicon anode material preparation process mainly focuses on nano-silicon simple substance to provide access for lithium ions, improve its charge and discharge performance, and reduce the degree of pulverization. Silicon-carbon composite materials can also be prepared, and the carbon material is coated with the silicon material to tolerate its volume expansion and the like. The preparation of silicon carbon negative electrode materials includes ball milling method, chemical vapor deposition method, pyrolysis method, etc. Among them, chemical vapor deposition requires the use of gases containing carbon sources such as acetylene, methane, etc. The experimental process is complicated and dangerous, and vapor deposition can only Deposited on the surface of the agglomerated material, the carbon material cannot grow uniformly on the surface of the silicon material.

Contents of the invention

The object of the present invention is to provide a method for preparing a carbon-silicon composite material in order to overcome the deficiencies of the prior art.

In order to achieve the above object, the technical scheme adopted in the present invention is: a kind of preparation method of carbon-silicon composite material, it comprises the following steps:

(a) dissolving the catalyst in the first solvent to prepare a catalyst solution; the catalyst is a mixture of one or more selected from iron salts, nickel salts, cobalt salts and copper salts;

(b) dissolving the carbon source in the second solvent to prepare a carbon source solution; the carbon source is selected from quinolinic acid, sodium alginate, polyvinylpyrrolidone, starch, cellulose and polyacrylic acid resin or A mixture of several compositions; the first solvent and the second solvent are independently selected from distilled water, ethanol, methanol, isopropanol, ethylene glycol and glycerol or a mixture of several compositions;

(c) adding silicon material to the catalyst solution to load the catalyst on the surface of the silicon material, and then adding it to the carbon source solution to make the carbon source support on the surface; or adding silicon material to the catalyst solution and the In the mixed solution formed by the carbon source solution, the catalyst and the carbon source are supported on the surface of the silicon material;

(d) Calcining the product of step (c) in a reducing gas, followed by washing.

Another object of the present invention is to provide another preparation method of carbon-silicon composite material, which comprises the following steps:

(a) dissolving the catalyst in the first solvent to prepare a catalyst solution; the catalyst is a mixture of one or more selected from iron salts, nickel salts, cobalt salts and copper salts;

(b) adding a silicon material to the catalyst solution so that the catalyst is supported on the surface of the silicon material;

(c) Calcining the product of step (b) together with the carbon source in a reducing gas, followed by cleaning.

Preferably, the catalyst is selected from Fe(NO ₃ ) ₃ , FeCl ₃ , Fe ₂ (SO ₄ ) ₃ , Ni(CH ₃ COO) ₂ , NiCO ₃ , NiCl ₂ , Ni(NO ₃ ) ₂ , NiSO ₄ , Co(CH ₃ COO) ₂ , CoCO ₃ , Co(NO ₃ ) ₂ , CoSO ₄ , Cu(CH ₃ COO) ₂ , CuCO ₃ , CuCl ₂ , Cu(NO ₃ ) ₂ and CuSO ₄ or A mixture of several compositions.

Optimally, the calcination temperature is 500-1200°C, and the calcination time is 0.1-48h.

Optimally, the ratio of the silicon material to the catalyst is 1˜1000:1.

Further, the mass ratio of the silicon material to the carbon source is 1:0.2-100.

Optimally, the cleaning is firstly cleaned with a cleaning solution, and then cleaned to neutrality with deionized water; the cleaning solution is one or a mixture of hydrochloric acid, nitric acid and hydrofluoric acid.

Due to the application of the above-mentioned technical scheme, the present invention has the following advantages compared with the prior art: the preparation method of the carbon-silicon composite material of the present invention, by loading catalyst and carbon source on the surface of the silicon material, and performing calcination and cleaning, it can be used on the surface of the silicon material In-situ growth of carbon nanotubes or carbon fibers is not only simple in process and suitable for large-scale production, but also can grow carbon nanotubes and carbon fibers uniformly on the surface of silicon materials, overcome the inhomogeneity of vapor deposition method growth; and can effectively remove catalysts Impurities such as oxides and carbides produced by the reduced metal salts and silicon materials under high temperature conditions can effectively maintain the capacity of the silicon negative electrode material; while the carbon nanotubes and carbon fibers generated on the silicon surface can provide silicon volume expansion in the cycle. Space, and increase the electrical conductivity and mechanical properties between silicon particles, effectively improving the long-term cycle performance and rate performance of the material.

Description of drawings

Fig. 1 is the SEM figure of the silicon-carbon composite material that makes in embodiment 1;

Fig. 2 is the SEM figure of the silicon-carbon composite material obtained in embodiment 2-3;

Fig. 3 is the first charge-discharge curve of the silicon-carbon composite material prepared in the comparison sample and embodiment 1;

Fig. 4 is the long-term cycle performance of the silicon-carbon composite assembled battery prepared in embodiment 1;

Detailed ways

The preparation method of the carbon-silicon composite material of the present invention comprises the following steps: (a) dissolving the catalyst in the first solvent to prepare a catalyst solution; the catalyst is selected from iron salts, nickel salts, cobalt salts and copper salts One or a mixture of several components; (b) dissolving the carbon source in the second solvent to prepare a carbon source solution; the carbon source is selected from quinolinic acid, sodium alginate, polyvinylpyrrolidone, starch, cellulose and a mixture of one or more of polyacrylic resins; the first solvent and the second solvent are independently selected from distilled water, ethanol, methanol, isopropanol, ethylene glycol and glycerol One or a mixture of several components; (c) adding silicon material to the catalyst solution to make the catalyst support on the surface of the silicon material, and then adding it to the carbon source solution to make the carbon source support on the surface; or silicon The material is added to the mixed solution formed by the catalyst solution and the carbon source solution, so that the catalyst and the carbon source are supported on the surface of the silicon material; (d) the product of step (c) is calcined in a reducing gas, and then Just wash it. Another group of preparation method of carbon-silicon composite material of the present invention, it comprises the following steps: (a) catalyst is dissolved in the first solvent and is mixed with catalyst solution; Described catalyst is selected from iron salt, nickel salt, cobalt salt and copper One or more mixtures of salts; (b) adding silicon material to the catalyst solution to make the catalyst supported on the surface of the silicon material; (c) mixing the product of step (b) with carbon source Calcination in reducing gas, followed by cleaning. The above two methods support catalysts and carbon sources on the surface of silicon materials, and perform calcination and cleaning. Not only are the processes simple and suitable for large-scale production; they can also effectively remove impurities such as metal salts and oxides after catalyst reduction, and effectively maintain silicon negative electrode The capacity of the material.

In the above method, the catalyst is selected from Fe(NO ₃ ) ₃ , FeCl ₃ , Fe ₂ (SO ₄ ) ₃ , Ni(CH ₃ COO) ₂ , NiCO ₃ , NiCl ₂ , Ni(NO ₃ ) ₂ , NiSO _4. One of Co(CH ₃ COO) ₂ , CoCO ₃ , Co(NO ₃ ) ₂ , CoSO ₄ , Cu(CH ₃ COO) ₂ , CuCO ₃ , CuCl ₂ , Cu(NO ₃ ) ₂ and CuSO ₄ or a mixture of several components. The calcination temperature is 500-1200°C, and the calcination time is 0.1-48h. The ratio of the silicon material to the catalyst is preferably 1˜1000:1. The mass ratio of the silicon material to the carbon source is preferably 1:0.2-100. The cleaning is firstly cleaned with a cleaning solution, and then cleaned to neutrality with deionized water; the cleaning solution is one or a mixture of hydrochloric acid, nitric acid and hydrofluoric acid.

The present invention will be further described below in conjunction with examples.

Example 1

The invention provides a kind of preparation method of carbon-silicon composite material, it comprises the following steps:

(a) use distilled water to prepare 0.1M Ni(CH ₃ COO) ₂ solution (ie catalyst solution);

(b) use distilled water to prepare 3%wt sodium alginate solution (i.e. carbon source solution);

(c) Add silicon material (100nm, Shenzhen Kejing Zhida Technology Co., Ltd.) into Ni(CH ₃ COO) ₂ solution (the mass ratio of Ni(CH ₃ COO) ₂ to silicon is 1:20, stir for 2 hours, and heated and dried at 100°C to obtain a catalyst-supported silicon material; then add the catalyst-supported silicon material to the carbon source solution so that the mass ratio of the catalyst-supported silicon material to the carbon source is 1:10, stir for 2 hours, and dry to obtain catalyst-supported silicon material coated with carbon source;

(d) The product of step (c) is placed in a crucible, then loaded into a tube furnace, filled with a mixed gas of hydrogen and argon (the volume ratio of hydrogen to argon is 5:95), and then heated at 5 ° C / The speed of hour is warming up to 700 DEG C of temperature; After rising to target temperature, keep warm for 2 hours and carry out high-temperature calcining, naturally cool to room temperature; Wash with deionized water until neutral, the resulting product is shown in Figure 1, the first charge and discharge curve of the battery made of silicon-carbon composite materials is shown in Figure 3 (right figure), and the long-term cycle and efficiency are shown in Figure 4.

Example 2

The invention provides a kind of preparation method of carbon-silicon composite material, it comprises the following steps:

(a) use distilled water to prepare 0.1M Ni(CH ₃ COO) ₂ solution (ie catalyst solution);

(b) Add the silicon material (100nm, Shenzhen Kejing Zhida Technology Co., Ltd.) as the matrix material into the catalyst solution (the mass ratio of catalyst to silicon is 1:20), stir for 2 hours, and heat and dry to obtain the catalyst loading silicon material;

(c) the product of step (b) is placed in the crucible, and then packed into a tube furnace (put into quinolinic acid at the front end of the tube furnace or mix with the aforementioned product), the mixture of quinolinic acid and catalyst-loaded silicon material The mass ratio is 20:1, filled with a mixture of hydrogen and argon (5/95), and then heated up to 700°C at a rate of 5°C/hour; after rising to the target temperature, keep it warm for 2 hours for high-temperature reduction , naturally cooled to room temperature; the obtained material was added to a concentration of 10wt% hydrochloric acid solution for cleaning (about 10 minutes), and then cleaned to neutrality with deionized water, the resulting product is shown in Figure 2 (SEM figure on the left) shown.

Example 3

The invention provides a kind of preparation method of carbon-silicon composite material, it comprises the following steps:

(a) use distilled water to prepare 0.1M Ni(CH ₃ COO) ₂ solution (ie catalyst solution);

(b) use distilled water to prepare 3%wt sodium alginate solution (i.e. carbon source solution);

(c) mixing the catalyst solution and the carbon source solution so that the mass ratio of the silicon material to the carbon source and the catalyst is 1:10:0.05, stirring for 2 hours, and heating and drying to obtain a silicon material supported by the catalyst and the carbon source;

(d) the product of step (c) is placed in a crucible, then packed into a tube furnace, filled with a mixed gas of hydrogen and argon (same as above), and then heated to a temperature of 700° C. at a rate of 5° C./hour; After reaching the target temperature, heat preservation for 2 hours and carry out high-temperature calcination, and naturally cool to room temperature; the product obtained is added to a concentration of 10wt% hydrochloric acid solution for cleaning (about 10 minutes), and then cleaned to neutral with deionized water, the obtained The product is shown in Figure 2 (SEM image on the right).

Example 4

The present invention provides a method for preparing a carbon-silicon composite material, the steps of which are basically the same as those in Example 1, except that the catalyst used in step (a) is Cu(CH ₃ COO) ₂ .

Example 5

The present invention provides a method for preparing a carbon-silicon composite material, the steps of which are basically the same as those in Example 1, except that the catalyst used in step (a) is Fe(NO ₃ ) ₃ .

Example 6

The present invention provides a method for preparing a carbon-silicon composite material, the steps of which are basically the same as those in Example 1, except that the carbon source used in step (b) is sodium alginate.

Example 7

The present invention provides a method for preparing a carbon-silicon composite material, the steps of which are basically the same as those in Example 1, except that the carbon source used in step (b) is polyvinylpyrrolidone.

Example 8

The present invention provides a method for preparing a carbon-silicon composite material, the steps of which are basically the same as those in Example 1, except that the carbon source used in step (b) is starch.

Example 9

The present invention provides a method for preparing a carbon-silicon composite material, the steps of which are basically the same as those in Example 1, except that the carbon source used in step (b) is polyacrylic acid resin.

Disperse the carbon-silicon composite material prepared in each of the above examples with sodium alginate and acetylene black in water according to the mass ratio of 70:15:15 and fully stir for 30 minutes to obtain a uniformly mixed slurry, and coat it on the current collector On copper foil, dried and sliced. Move the dry pole piece to the glove box, use the lithium piece as the counter electrode, assemble the 2032 button cell (electrolyte is 1MLiPF ₆ is the EC/DMC/DEC solution that the volume ratio of conductive salt is 1:1:1, and VC with a mass fraction of 2% and FEC with a mass fraction of 10% are added as additives); the assembled battery is sealed and left to stand for 10 h. Test the electrochemical performance of the static battery on a charge-discharge tester with a constant current (the charge-discharge rate is 0.2C, and the voltage range is 0.01-1V).

Electrochemical properties of batteries assembled from silicon-carbon composites prepared in Examples 1-5 in Table 1

It can be seen that the decomposition temperature of different carbon sources is very different, and the carbon materials formed are also different. Among them, the polyacrylic resin produces hard carbon materials at high temperature, which has the advantages of high capacity and good cycle performance, and also has first-week efficiency. Low and low potential lithium storage rate performance is poor.

The above-mentioned embodiments are only to illustrate the technical concept and characteristics of the present invention. Equivalent changes or modifications made in the spirit shall fall within the protection scope of the present invention.

Claims (7)

1. a preparation method of carbon-silicon composite material, is characterized in that, it comprises the following steps: (a) dissolving the catalyst in the first solvent to prepare a catalyst solution; the catalyst is a mixture of one or more selected from iron salts, nickel salts, cobalt salts and copper salts; (b) dissolving the carbon source in the second solvent to prepare a carbon source solution; the carbon source is selected from quinolinic acid, sodium alginate, polyvinylpyrrolidone, starch, cellulose and polyacrylic acid resin or A mixture of several compositions; the first solvent and the second solvent are independently selected from distilled water, ethanol, methanol, isopropanol, ethylene glycol and glycerol or a mixture of several compositions; (c) adding silicon material to the catalyst solution to load the catalyst on the surface of the silicon material, and then adding it to the carbon source solution to make the carbon source support on the surface; or adding silicon material to the catalyst solution and the In the mixed solution formed by the carbon source solution, the catalyst and the carbon source are supported on the surface of the silicon material; (d) Calcining the product of step (c) in a reducing gas, followed by washing. 2. A preparation method for a carbon-silicon composite material, characterized in that it comprises the following steps: (a) dissolving the catalyst in the first solvent to prepare a catalyst solution; the catalyst is a mixture of one or more selected from iron salts, nickel salts, cobalt salts and copper salts; (b) adding a silicon material to the catalyst solution so that the catalyst is supported on the surface of the silicon material; (c) Calcining the product of step (b) together with the carbon source in a reducing gas, followed by cleaning. 3. The preparation method of the carbon-silicon composite material according to claim 1 or 2, characterized in that: the catalyst is selected from Fe(NO ₃ ) ₃ , FeCl ₃ , Fe ₂ (SO ₄ ) ₃ , Ni(CH ₃ COO) ₂ , NiCO ₃ , NiCl ₂ , Ni(NO ₃ ) ₂ , NiSO ₄ , Co(CH ₃ COO) ₂ , CoCO ₃ , Co(NO ₃ ) ₂ , CoSO ₄ , Cu(CH ₃ COO) ₂ , CuCO _3. A mixture of one or more of CuCl ₂ , Cu(NO ₃ ) ₂ and CuSO ₄ . 4. The method for preparing the carbon-silicon composite material according to claim 1 or 2, characterized in that: the calcination temperature is 500-1200° C., and the calcination time is 0.1-48 hours. 5. The method for preparing the carbon-silicon composite material according to claim 1 or 2, characterized in that the ratio of the silicon material to the catalyst is 1-1000:1. 6 . The method for preparing a carbon-silicon composite material according to claim 5 , wherein the mass ratio of the silicon material to the carbon source is 1:0.2-100. 7. according to the preparation method of the described carbon-silicon composite material of claim 1 or 2, it is characterized in that: described cleaning is to adopt cleaning solution to clean first, then clean to neutrality with deionized water; Described cleaning solution is hydrochloric acid, One or more mixtures of nitric acid and hydrofluoric acid.