JPWO2020235748A5 - - Google Patents

Claims (19)

A silicon-graphite composite electrode active material that can be used in secondary batteries,
A silicon-graphite composite in which silicon is mixed with a graphite material is formed as a unit powder body,
The silicon-graphite composite is formed in a form in which silicon is located inside a graphite material,
A silicon-graphite composite electrode active material for a secondary battery, wherein silicon is not exposed on the outer surface of the graphite material. 2. The silicon-graphite composite according to claim 1, wherein the silicon contained in the silicon-graphite composite is configured such that 90% or more of the total weight of silicon is located at a depth of 200 nm or more from the outer surface of the silicon-graphite composite. silicon-graphite composite electrode active material for secondary batteries. The silicon-graphite for a secondary battery according to claim 1, wherein all silicon contained in the silicon-graphite composite is positioned at a depth of 200 nm or more from an outer surface of the silicon-graphite composite. Composite electrode active material. The silicon-graphite composite for a secondary battery according to claim 1, wherein the silicon contained in the silicon-graphite composite is positioned at a depth of 1 μm or more from the outer surface of the silicon-graphite composite. electrode active material. The silicon-graphite composite for a secondary battery according to claim 1, wherein the silicon contained in the silicon-graphite composite is positioned at a depth of 3 μm or more from the outer surface of the silicon-graphite composite. electrode active material. The silicon-graphite composite electrode active material for a secondary battery according to claim 2, wherein silicon contained in the silicon-graphite composite exceeds 10 wt% with respect to the total weight of the silicon-graphite composite. The silicon is graphite using a source gas containing at _{least one} of _{SiH4 , Si2H6} , _Si3H8 , _SiCl4 , _{SiHCl3 , Si2Cl6} , _SiH2Cl2 , and _SiH3Cl . The silicon-graphite composite electrode active material for secondary batteries according to claim 6 , which is deposited on a material. The silicon includes at least one of SiH ₄ , Si ₂ H ₆ , Si ₃ H ₈ , SiCl ₄ , SiHCl ₃ , Si ₂ Cl ₆ , SiH ₂ Cl ₂ and SiH ₃ Cl. The silicon-graphite composite electrode active material for a secondary battery according to claim 7 , wherein the silicon-graphite composite electrode active material for a secondary battery is deposited on the graphite material while supplied with an auxiliary gas containing at least one of germanium. The silicon-graphite composite electrode active material for a secondary battery according to claim 8 , wherein the silicon thin film layer formed on the silicon-graphite composite is formed of amorphous or semi-crystalline silicon particles. The silicon-graphite composite electrode active material for a secondary battery according to claim 9 , further comprising a surface coating layer formed on an outer peripheral surface of the silicon-graphite composite. A method for producing a silicon-graphite composite electrode active material that can be used in a secondary battery, comprising:
A graphite base material preparation stage for preparing a graphite material as a base material,
a silicon layer forming step of forming a silicon layer on the graphite matrix;
A method of manufacturing a silicon-graphite composite electrode active material, comprising a reassembling step of mechanically assembling the graphite with the silicon layer formed thereon into spheroids so that the silicon is located only inside the graphite. 12. The method of claim 11 , wherein the silicon layer is formed by depositing the silicon layer in the form of a thin film on the plate-like graphite through chemical vapor deposition in the step of forming the silicon layer. At least one of SiH ₄ , Si ₂ H ₆ , Si ₃ H ₈ , SiCl ₄ , SiHCl ₃ , Si ₂ Cl ₆ , SiH ₂ Cl ₂ and SiH ₃ Cl is used as a source gas in the step of forming the silicon layer. 13. The method for producing a silicon-graphite composite electrode active material according to claim 12 , wherein a silicon layer is formed. 13. The method of manufacturing a silicon-graphite composite electrode active material according to claim 12 , wherein the silicon layer forming step forms a silicon layer with a thickness of 2 nm to 500 nm on the graphite base material . 15. The method of manufacturing a silicon-graphite composite electrode active material according to claim 14 , wherein the silicon layer is deposited on the graphite base material while the raw material gas is supplied together with an auxiliary gas in the silicon layer forming step. 16. The method of claim 15 , wherein the auxiliary gas contains one or more of carbon, nitrogen, and germanium. The reassembly step includes:
After the graphite base material with the silicon layer formed thereon is put into a spheroidizing device, it is rotated at high speed to mechanically reassemble the silicon-graphite composite.
or,
The graphite base material on which the silicon layer is formed is put into a spheroidizing device and rotated at a high speed, and then an additional graphite material is put in and rotated at a high speed to regenerate the silicon-graphite composite mechanically. configured to assemble
The method for producing the silicon-graphite composite electrode active material according to claim 16 . The method of claim 17 , further comprising a surface coating step of forming an outer coating layer on the surface after the reassembling step. 19. The method of claim 18 , further comprising a surface modification step of modifying the surface of the graphite base material between the graphite base material preparation step and the silicon layer forming step. .

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