Cathode active material and process for its production

Abstract

To provide a cathode active material having excellent cycle characteristics and a small decrease in the discharge voltage, and a process for its production. A process for producing a cathode active material, which comprises a step of mixing at least one sulfate (A) selected from the group consisting of a sulfate of Ni, a sulfate of Co and a sulfate of Mn with at least one carbonate (B) selected from the group consisting of sodium carbonate and potassium carbonate in an aqueous solution state to obtain a coprecipitated compound, a step of mixing the coprecipitated compound with an aqueous phosphate solution, a step of volatilizing a water content from the mixture of the coprecipitated compound and the aqueous phosphate solution to obtain a precursor compound, and a step of mixing the precursor compound with lithium carbonate and firing the mixture at from 500 to 1000° C.; and a cathode active material obtainable by the production process, which comprises Li, at least one transition metal element (X) selected from the group consisting of Ni, Co and Mn, and P, wherein the average coefficient of variation (CV value) of the calculated peak intensity ratio (Ip/Ix) of P to the transition metal element (X) is from 0 to 20% as determined by a method for measuring coefficient of variation.

Dependencies are inferred from the claim text.