Negative Electrode Active Material For Nonaqueous Electrolyte Secondary Batteries

Abstract

Provided is a novel method of preparing a negative electrode for nonaqueous electrolyte secondary batteries, which contains silicon and is capable of improving cycle characteristics and is also capable of suppressing aggregation of active material particles in a slurry. After formation of a molten liquid by any one of methods (i) to described in the specification, the molten liquid is micronized by atomization or liquid quenching, thereby forming a micronized active material in the form of powder, and the micronized active material is pulverized and classified in a nitrogen atmosphere in which air is present in an amount of less than 1%, and the balance is composed of nitrogen, to thereby adjust the particle size of the micronized active material.

1 - 11 . (canceled) 
     
     
         12 . A production method of a negative electrode active material for nonaqueous electrolyte secondary batteries, wherein after a molten liquid is formed by any one of the following methods (i) to (iii), the molten liquid is micronized by atomization or liquid quenching, thereby forming a micronized active material in the form of powder, and the micronized active material is pulverized and classified in a nitrogen atmosphere in which air is in an amount of less than 1%, and the balance is composed of nitrogen to thereby adjust the particle size of the micronized active material:
 (i) heating a silicon-containing material to obtain the molten liquid, or   (ii) mixing an additive element with the silicon-containing material and heating the mixture to obtain the molten liquid, or   (iii) heating the silicon-containing material to obtain an intermediate molten liquid, and adding the additive element to the intermediate molten liquid, thereby forming the molten liquid.   
     
     
         13 . The production method of a negative electrode active material for nonaqueous electrolyte secondary batteries according to  claim 12 , wherein the additive element is any one or two or more elements selected from a group consisting of transition metal elements, semi-metal elements, or metal elements of Group 3, semi-metal elements or metal elements of Group 4, and non-metal or semi-metal elements of Group 5. 
     
     
         14 . The production method of a negative electrode active material for nonaqueous electrolyte secondary batteries according to  claim 12 , wherein the additive element is any one or two or more elements selected from a group consisting of Ni, B, Cu, Co, Ti, Fe, In, Nb, and Ag. 
     
     
         15 . The production method of a negative electrode active material for nonaqueous electrolyte secondary batteries according to  claim 12 , wherein the additive element is boron.