NEGATIVE ELECTRODE MATERIAL FOR NONAQUEOUS ELECTROLYTE SECONDARY BATTERY, MAKING METHOD AND LITHIUM ION SECONDARY BATTERY

• US 20100288970A1
• Filed: 05/17/2010
• Published: 11/18/2010
• Est. Priority Date: 05/18/2009
• Status: Abandoned Application

• Current Assignee: Shin-Etsu Chemical Company Limited
• Original Assignee: Shin-Etsu Chemical Company Limited
• Inventors: Fukuoka, Hirofumi, Kashida, Meguru, WATANABE, Koichiro
• Application Number:
  US12/781,579
• Publication Number:
  US 20100288970A1
• Time in Patent Office: Days
• US Class Current: 252/182.1
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 4/0428 Chemical vapour deposition
• CPC Class Codes: H01M 4/134 Electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/1395 of electrodes based on metals, Si or alloys
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A negative electrode material for nonaqueous electrolyte secondary batteries comprises composite particles which are prepared by coating surfaces of particles having silicon nano-particles dispersed in silicon oxide with a carbon coating, and etching the coated particles in an acidic atmosphere. The silicon nano-particles have a size of 1-100 nm. The composite particles contain oxygen and silicon in a molar ratio: O<O/Si<1.0. Using the negative electrode material, a lithium ion secondary battery can be fabricated which features a high 1st cycle charge/discharge efficiency, a high capacity, and improved cycle performance.

Claims

1. A negative electrode material for nonaqueous electrolyte secondary batteries, comprising composite particles which are prepared by coating surfaces of particles having silicon nano-particles dispersed in silicon oxide with a carbon coating and etching the coated particles in an acidic atmosphere, wherein the silicon nano-particles have a size of 1 to 100 nm and a molar ratio of oxygen to silicon is from more than 0 to less than 1.0.

2. The negative electrode material of claim 1 wherein the composite particles have an average particle size of 0.1 to 50 μ

m and a BET specific surface area of 0.5 to 100 m²/g.

3. The negative electrode material of claim 1 wherein the carbon coating is formed by chemical vapor deposition.

4. A lithium ion secondary battery comprising the negative electrode material of claim 1.

5. A method of preparing a negative electrode material comprising composite particles, for use in nonaqueous electrolyte secondary batteries, comprising the steps of:

(I) effecting chemical vapor deposition of carbon on silicon oxide particles prior to disproportionation reaction or particles having silicon nano-particles dispersed in silicon oxide to form coated particles which are surface coated with carbon and have silicon nano-particles with a size of 1 to 100 nm dispersed in silicon oxide, and

(II) etching the coated particles in an acidic atmosphere to form the composite particles.