Silicon-carbon composite for secondary battery anode material, and method for manufacturing the same.

Abstract

The present invention relates to a silicon-carbon composite for secondary battery anode material and a method for manufacturing the same, and more specifically, to a silicon-carbon composite for secondary battery anode material and a method for manufacturing the same that can improve the characteristics of a secondary battery when applied as an anode material by minimizing the volume change of silicon particles during the charging and discharging process of the secondary battery.

Claims

1. A silicon-carbon composite comprising silicon particles and a porous carbon structure, The silicon particles exist in an amorphous or crystalline state. The average grain size of the crystalline silicon particles is 10 nm or less. The porous carbon structure includes micropores, mesopores, and macropores. Based on a total pore volume of 100 vol% of the porous carbon structure, the micropores comprise 10 to 30 vol%, the mesopores comprise 20 to 40 vol%, and the macropores comprise 40 to 60 vol%. Silicon-carbon composite.

2. The total porosity of the porous carbon structure is 0.6 to 1.5 cm. ３ / g is The silicon-carbon composite according to claim 1.

3. The specific surface area of ​​the porous carbon structure is 200 to 1,000 m². ２ / g is The silicon-carbon composite according to claim 1.

4. The average particle size of the aforementioned silicon particles is 1 to 100 nm. The average particle size of the silicon-carbon composite particles is 4 to 8 μm. The silicon-carbon composite according to claim 1.

5. The porous carbon structure is formed from carbon black or a mixture of carbon black and a binder. The silicon-carbon composite according to claim 1.

6. The binder comprises one or more of the following: phenolic resin, coal tar pitch, and polyacrylonitrile. The silicon-carbon composite according to claim 5.

7. In the case of a mixture of carbon black and binder, When the total weight of the mixture is 100% by weight, the carbon black is present in an amount of 40 to 70% by weight, and the binder is present in an amount of 30 to 60% by weight. The silicon-carbon composite according to claim 5.

8. The silicon-carbon composite has a coating layer formed on its surface using a carbon-based coating material. The silicon-carbon composite according to claim 1.

9. When the total weight of the silicon-carbon composite is 100% by weight, the content of silicon particles contained in the silicon-carbon composite is 40 to 80% by weight. The silicon-carbon composite according to claim 1.

10. The following equation 1 satisfies the condition that the span value is between 0.8 and 1.

2. The silicon-carbon composite according to claim 1. <Equation 1> Span = (D ９０ -D １０ ) / D ５０

11. A silicon-carbon composite comprising any one of claims 1 to 10, Negative electrode material for secondary batteries.

12. A method for producing a silicon-carbon composite according to any one of claims 1 to 10, (a) The step of placing a porous carbon structure inside a chemical vapor deposition (CVD) reactor; (b) A step of supplying silicon-source gas in a chemical vapor deposition (CVD) reactor and reacting it under atmospheric pressure and a temperature of 400°C to 550°C to chemically vapor-deposit silicon particles onto the porous carbon structure; and, (c) A step of precipitating the result of (b) into a solid to obtain a silicon-carbon composite; including, A method for manufacturing silicon-carbon composites.

13. The above step (a) is carried out under a carrier gas atmosphere. The carrier gas includes one or more of nitrogen gas and argon gas. A method for producing a silicon-carbon composite according to claim 12.

14. In step (a) above, hydrogen (H ２ ) Add more gas, A method for producing a silicon-carbon composite according to claim 12.

15. The silicon source gas is selected from the group consisting of monosilane (SiH ４ ), disilane (Si ２ H ６ ), monochlorosilane (SiHCl ３ ), dichlorosilane (SiHCl ２ Cl ２ ), trichlorosilane (SiHCl ３ ), and trimethylsilane (SiH(CH ３ )) ３ ), and contains one or more selected from the group consisting of A method for producing a silicon-carbon composite according to claim 12.

16. The step after step (c) above further includes the step of forming a coating layer with a carbon-based coating material on the surface of the obtained silicon-carbon composite, A method for producing a silicon-carbon composite according to claim 12.

17. The above step (d) is carried out by one of the following methods: coating by chemical vapor deposition (CVD), coating by solution immersion followed by solvent evaporation, coating by solution immersion followed by solvent evaporation and annealing, sol-gel coating, vapor phase immersion coating, molten immersion coating, or atomic deposition coating. A method for producing a silicon-carbon composite according to claim 16.

18. Step (d) above involves forming a carbon-based coating layer by chemical vapor deposition (CVD) using a carbon source gas containing one or more gases selected from the group consisting of methane, ethane, propane, butane, acetylene, and ethylene. A method for producing a silicon-carbon composite according to claim 17.

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