Patent ID: 8153297
Filing Date: 2012-04-10
Classification: H01M,Y02E,Y02P

Abstract:
1. A positive electrode active material comprising a lithium-containing composite oxide containing nickel and manganese elements and not containing cobalt element, said positive electrode active material comprising primary particles of said composite oxide having a twinning portion, the nickel and manganese elements being uniformly dispersed at the atomic level, said primary particles having a particle size of 0.1 to 2 μm, said primary particles forming secondary particles with a particle size of 2 to 20 μm, and the lithium-composite oxide is formed by: (a) coprecipitating nickel and manganese in an aqueous solution to form a composite hydroxide to form a composite hydroxide containing nickel and manganese, (b) heating the composite hydroxide to form a dry precursor, (c) mixing the dry precursor with a lithium compound to form a mixture, (d) rapidly heating the mixture at a rising temperature rate of not less than 7° C./min to a baking temperature in a range of 1000° C. to 1200° C., and (e) subsequently quenching the mixture at a cooling rate of not less than 5° C./min from the baking temperature to a temperature in a range of 700° C. to room temperature.