Process for producing lithium-containing composite oxide for positive electrode for lithium secondary battery

A process for producing a lithium composite oxide, represented by the formula LipLqNxMyOzFa wherein L is at least one element selected from the group consisting of B and P, N is at least one element selected from the group consisting of Co, Mn and Ni, M is at least one element selected from the group consisting of Al, alkaline earth metal elements and transition metal elements other than N, 0.9≦p≦1.1, 0.0<q≦0.03, 0.97≦x<1.00, 0≦y≦0.03, 1.9≦z≦2.1, q+x+y=1 and 0≦a≦0.02, which comprises

• preparing a lithium composite oxide powder comprising an N element and, optionally an M element and fluorine,
• mixing the lithium composite oxide powder with an aqueous solution containing an L element source to obtain a first mixture, wherein the aqueous solution comprising an L element source is an aqueous solution comprising boric acid and/or phosphoric acid and a compound having at least two carboxylic acid groups, or carboxylic acid groups and hydroxyl groups, or mixtures thereof;
• removing an aqueous medium from the first mixture to obtain a second mixture and
• firing said second mixture in an oxygen-containing atmosphere at from 300 to 1,050° C.