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

1. A process for producing a lithium-containing composite oxide for a positive electrode for a lithium secondary battery, the lithium-containing composite oxide being represented by the formula Li p Q q N x M y O 2 (wherein Q is at least one element selected from the group consisting of titanium and zirconium, N is Co, M is at least one element selected from the group consisting of Al, alkaline earth metal elements and transition metal elements other than Q, Co, Mn and Ni,0.9≦p≦1.1, 0<q≦0.03, 0.97≦x<1.00, 0≦y<0.03 and q+x+y=1), which comprises firing a mixture of a lithium source, an Q element source and an N element source, in an oxygen-containing atmosphere, wherein the Q element source is a Q element compound aqueous solution having a pH of from 0.5 to 11, wherein the Q element compound aqueous solution is selected from the group consisting of an aqueous solution of titanium lactate chelate, an aqueous solution of triethanolamine titanium chelate, an aqueous solution of zirconium ammonium carbonate and an aqueous solution of a halogenated zirconium ammonium, and said mixture is fired at from 950 to 1,080° C.

2. The process according to claim 1 , wherein the Q element compound aqueous solution is at least one aqueous solution selected from the group consisting of an aqueous solution of titanium lactate chelate and an aqueous solution of triethanolamine titanium chelate, and having a pH of from 1.0 to 9.5.

3. The process according to claim 1 , wherein the Q element compound aqueous solution is at least one aqueous solution selected from the group consisting of an aqueous solution of zirconium ammonium carbonate and an aqueous solution of a halogenated zirconium ammonium, and having a pH of from 2 to 11.

4. The process according to claim 1 , wherein the lithium source, the Q element compound aqueous solution and the N element source, are mixed, the water medium is removed from the obtained mixture, and the mixture is fired at from 950 to 1,080° C. in an oxygen-containing atmosphere.

5. The process according to claim 1 , wherein the Q element compound aqueous solution and the N element source, are mixed, the water medium is removed from the obtained mixture, and the mixture is mixed with the lithium source, and the obtained mixture is fired at from 950 to 1,080° C. in an oxygen-containing atmosphere.

6. The process according to claim 1 , wherein a lithium composite oxide powder containing the N element source, is preliminarily prepared, the lithium composite oxide powder and the Q element compound aqueous solution, the water medium is removed from the obtained mixture, and the mixture is fired at from 950 to 1,080° C. in an oxygen-containing atmosphere.

7. The process according to claim 1 , wherein the M element is present and the M element source is an M element compound aqueous solution.

8. The process according to claim 1 , wherein the M element is present and the M element is at least one member selected from the group consisting of Hf, Mg, Cu, Sn, Zn and Al.

9. The process according to claim 1 , wherein the M element is present and the M element is Al and Mg, the Al/Mg atomic ratio is from 1/3 to 3/1, and 0.005≦y≦0.025.

10. The process according to claim 1 , wherein the M element is present and the M element is Mg, the Q element/Mg atomic ratio is from 1/40 to 2/1, and 0.005≦y≦0.025.

11. The process according to claim 1 , wherein the integral breadth of the diffraction peak on (110) plane at 2θ=66.5±1° of the lithium-containing composite oxide is from 0.08 to 0.14° as measured by means of X-ray diffraction in which CuKα is used as a radiation source, and the specific surface area is from 0.2 to 0.7 m 2 /g.

12. The process according to claim 1 , wherein the lithium-containing composite oxide has an average particle size of from 3 to 20 μm.