Particulate mixture, active material aggregate, cathode active material, cathode, secondary battery, and methods for producing the same

Abstract

A particulate mixture etc., which can be used as a precursor of lithium transition metal silicate-type compound of small particle size and low crystallinity, is provided. Further, a cathode active material that can undergo charge-and-discharge reaction in room temperature, and comprises lithium transition metal silicate-type compound, is provided. It is a mixture of silicon oxide particulates, transition metal oxide particulates, and lithium transition metal silicate particulates, and its powder X-ray diffraction measurement shows diffraction peaks near 2θ=33.1° and near 2θ=35.7°, and said silicon oxide particulates and said transition metal oxide particulates are amorphous, and said lithium transition metal silicate particulates are in a microcrystalline or amorphous state. Furthermore, a cathode active material obtained by grinding the active material aggregate obtained by heat-treating this particulate mixture is provided.

1 .- 11 . (canceled) 
     
     
         12 . A method for producing a particulate mixture, which comprises:
 supplying a lithium source, a transition metal source, and a silicon source into a flame in a reaction vessel, and synthesizing a particulate mixture.   
     
     
         13 . The method for producing a particulate mixture according to  claim 12 , wherein said flame is an oxyhydrogen flame, and the inside of said reaction vessel is under inert gas-filled atmosphere. 
     
     
         14 . The method for producing a particulate mixture according to  claim 12 , wherein said flame is a hydrocarbon flame containing oxygen, and the inside of said reaction vessel is under inert gas-filled atmosphere. 
     
     
         15 . The method for producing a particulate mixture according to  claim 12 , wherein said lithium source, said transition metal source, and said silicon source are chlorides, and raw materials of said flame contain at least hydrogen gas and oxygen gas. 
     
     
         16 . The method for producing a particulate mixture according to  claim 12 , wherein said lithium source, said transition metal source, and said silicon source are supplied to said flame as gases, or supplied after passing through a carburetor as liquids or solutions. 
     
     
         17 . A method for producing an active material aggregate, which comprises heat-treating a particulate mixture produced by the method for producing a particulate mixture of  claim 12  at 300-900° C. for 0.5 to 10 hours. 
     
     
         18 . The method for producing an active material aggregate according to  claim 17 , wherein said heat-treating is performed by adding a carbon source. 
     
     
         19 . A method for producing a cathode active material, which comprises grinding the active material aggregate produced by the method for producing an active material aggregate of  claim 17 .