Li-ni-based composite oxide particles for non-aqueous electrolyte secondary battery, process for producing the same, and non-aqueous electrolyte secondary battery

Abstract

The present invention relates to Li—Ni-based composite oxide particles comprising Mn, and Co and/or Al, wherein Co and Al are uniformly dispersed within the particles, and Mn is present with a gradient of its concentration in a radial direction of the respective particles such that a concentration of Mn on a surface of the respective particles is higher than that at a central portion thereof. The Li—Ni-based composite oxide particles can be produced by allowing an oxide and a hydroxide comprising Mn to mechanically adhere to Li—Ni-based oxide comprising Co and/or Al; and then heat-treating the obtained material at a temperature of not lower than 400° C. and not higher than 1,000° C. The Li—Ni-based composite oxide particles of the present invention are improved in thermal stability and alkalinity.

1 . Li—Ni-based composite oxide particles comprising Mn, and Co and/or Al, Co and Al being present within the particles,
 Mn being present with a gradient of its concentration in a radial direction of the respective particles, and 
 a concentration of Mn on a surface of the respective particles being higher than that at a central portion thereof. 
 
     
     
         2 . (canceled) 
     
     
         3 . (canceled) 
     
     
         4 . (canceled) 
     
     
         5 . Li—Ni-based composite oxide particles according to  claim 1 , wherein a suspension prepared by suspending the Li—Ni-based composite oxide particles in distilled water has a pH value of not more than 11.5 as measured after allowing the suspension to stand at room temperature. 
     
     
         6 . A process for producing the Li—Ni-based composite oxide particles as defined in  claim 1 , comprising the steps of allowing an oxide and/or a hydroxide which comprise Mn to mechanically adhere to an Li—Ni-based oxide comprising Co and/or Al; and then heat-treating the obtained material at a temperature of not lower than 400° C. and not higher than 1,000° C. 
     
     
         7 . A process for producing the Li—Ni-based composite oxide particles as defined in  claim 1 , comprising the steps of allowing an oxide and/or a hydroxide which comprise Mn to mechanically adhere to an Ni-based hydroxide comprising Co and/or Al; mixing the obtained material with a lithium compound; and then heat-treating the obtained mixture at a temperature of not lower than 700° C. and not higher than 1,000° C. in an oxygen-containing atmosphere. 
     
     
         8 . A process for producing the Li—Ni-based composite oxide particles as defined in  claim 1 , comprising the steps of dropping a manganese-containing solution and an alkali solution to a suspension of Ni-based hydroxide particles comprising Co and/or Al to produce a manganese-containing hydroxide, a manganese-containing oxide hydroxide or a manganese-containing oxide on a surface of a nickel oxide; subjecting the obtained material to washing with water and drying; mixing the dried material with a lithium compound; and then heat-treating the obtained mixture at a temperature of not lower than 700° C. and not higher than 1,000° C. in an oxygen-containing atmosphere. 
     
     
         9 . A non-aqueous electrolyte secondary battery comprising the Li—Ni-based composite oxide particles as defined in  claim 1 , as a positive electrode active substance. 
     
     
         10 . A non-aqueous electrolyte secondary battery according to  claim 9 , wherein when using a negative electrode comprising a material capable of absorbing and desorbing a metallic lithium or a lithium ion, an exothermic peak temperature as measured by differential thermal analysis at a positive electrode under the condition that the cell is charged to 4.5 V is not lower than 240° C.