Layered lithium nickel manganese cobalt composite oxide powder for material of positive electrode of lithium secondary battery, process for producing the same, positive electrode of lithium secondary battery therefrom, and lithium secondary battery

摘要

A powder of a layered lithium-nickel-manganese-cobalt composite oxide for use as a positive-electrode material for lithium secondary battery is provided which, when used as a positive-electrode material for lithium secondary battery, enables a cost reduction and higher safety to be reconciled with improved battery performances.;The powder of a layered lithium-nickel-manganese-cobalt composite oxide for use as a positive-electrode material for lithium secondary battery is composed of secondary particles formed by the aggregation of primary particles. It has a composition represented by the following formula (I), has a volume resistivity of 5×10⁵ Ω·cm or lower in the state of being compacted at a pressure of 40 MPa, and has a value of C/S, wherein C is the concentration of carbon contained therein (% by weight) and S is the BET specific surface area thereof (m²/g), of 0.025 or smaller. The powder has been regulated so as to have a volume resistivity not higher than the specified value and a considerably reduced carbon content while having a composition in a limited range, whereby a cost reduction and higher safety can be reconciled with improved battery performances.Li_1+zNi_xMn_yCo_1−x−yO_δ  (I)(0z≦0.91, 0.1≦x≦0.55, 0.20≦y≦0.90, 0.50≦x+y≦1, 1.9≦δ≦3).