Positive electrode active material for non-aqueous electrolyte secondary battery and method for producing the same, and non-aqueous electrolyte secondary battery using positive electrode active material
An object of the present invention is to provide a positive electrode active material for a non-aqueous electrolyte secondary battery, which can solve the problem that the capacity remarkably decreases with an increase of the number of charging and discharging cycles in a high capacity non-aqueous electrolyte secondary battery using a positive electrode active material for a non-aqueous electrolyte secondary battery made of particles of an alkali metal composite oxide containing nickel. A positive electrode active material for a non-aqueous electrolyte secondary battery, comprising a nickel-alkali metal-containing composite oxide having cracks on the surface of primary particles is used.
1. A positive electrode active material for a non-aqueous electrolyte secondary battery, comprising a nickel-alkali metal-containing composite oxide having cracks on the surface of primary particles, wherein the composition of the nickel-alkali metal-containing composite oxide is represented by the following general formula (I):
Li w-x Na x Ni 1-y-z Mn y Me z O 2 (1)
wherein, in the formula (I), w satisfies the following relation: 0.9≦w≦1.1, x satisfies the following relation: 0<x≦0.05, y satisfies the following relation: 0=y, z satisfies the following relation: 0<z≦0.34, and Me represents Al, and wherein the primary particles have an average particle size of from 1 to 50 μm.
2. The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the nickel-alkali metal-containing composite oxide does not form secondary particles.
3. A non-aqueous electrolyte secondary battery comprising a battery case, and an electrode plate group and a non-aqueous electrolyte, which are sealed into the battery case, the electrode plate group including a positive electrode plate containing the positive electrode active material according to claim 1 and a negative electrode plate, which face each other with a separator being interposed therebetween.