Lithium manganate particles for non-aqueous electrolyte secondary battery, process for producing the same, and nonaqueous electrolyte secondary battery

Abstract

The present invention provides lithium manganate which has a high output and is excellent in high-temperature stability. The present invention relates to lithium manganate particles which are produced by mixing a lithium compound, a manganese compound, a Y compound and an A compound with each other and then calcining the resulting mixture, and have a composition represented by the following chemical formula 1 and an average secondary particle diameter (D 50 ) of 1 to 15 μm, Li 1+x Mn 2−x−y Y y O 4 +z A  (Chemical Formula) in which Y is at least one element selected from the group consisting of Al and Mg; A is a sintering aid element having a melting point of not higher than 850° C.; x and y satisfy 0.03≦x≦0.15 and 0≦y≦0.20, respectively; z is in the range of 0 to 2.5 mol % based on Mn, wherein the lithium manganate particles have a sulfur content of not more than 100 ppm.

1 . Lithium manganate particles having a composition represented by the following chemical formula 1:
   Li 1+x Mn 2−x−y Y y O 4   +z A  (Chemical Formula 1)
   
       in which Y is at least one element selected from the group consisting of Al and Mg; A is a sintering aid element having a melting point of not higher than 850° C.; x and y satisfy 0.03≦x≦0.15 and 0≦y≦0.20, respectively; z is in the range of 0 to 2.5 mol % based on Mn,
 which lithium manganate particles have a sulfur content of 1 to 100 ppm and an average secondary particle diameter (D 50 ) of 1 to 15 μm, and have such properties that when measuring characteristics of a secondary battery produced by using the lithium manganate particles as a positive electrode active material, a high temperature cycle retention rate of the secondary battery is not less than 92%, and a capacity recovery rate of the secondary battery is not less than 95%. 
 
     
     
         2 . Lithium manganate particles according to  claim 1 , wherein the lithium manganate particles have a lattice constant of 0.818 to 0.822 nm. 
     
     
         3 . Lithium manganate particles according to  claim 1 , wherein when measuring charge/discharge capacities of the secondary battery produced by using the lithium manganate particles as a positive electrode active material, an initial discharge capacity of the secondary battery is not less than 80 mAh/g and not more than 120 mAh/g. 
     
     
         4 . A process for producing the lithium manganate particles as defined in  claim 1 , comprising the steps of:
 mixing manganese oxide formed of Mn 3 O 4 , a Y element compound and a lithium compound with each other; and   calcining the resulting mixture at a temperature of 800° C. to 1050° C.   
     
     
         5 . A process for producing the lithium manganate particles according to  claim 4 , wherein the manganese oxide has a sulfur content of 1 to 60 ppm. 
     
     
         6 . A process for producing the lithium manganate particles according to  claim 4 , wherein the manganese oxide has an average primary particle diameter of not less than 0.5 μm. 
     
     
         7 . A non-aqueous electrolyte secondary battery comprising a positive electrode active material a part or whole of which is formed from the lithium manganese particles as defined in  claim 1 .