Patent ID: 7381498

Claim:
A positive electrode active material powder for a lithium secondary battery characterized by comprising a first granular powder having a compression breaking strength of at least 50 MPa and a second granular powder having a compression breaking strength of less than 40 MPa, formed by agglomeration of many fine particles of a lithium composite oxide represented by the formula Li p Ni x Co y Mn z M q O 2-a F a (wherein M is Al, an alkaline earth metal element or a transition metal element other than Ni, Co and Mn, 0.9≦p≦1.1, 0.2≦x≦0.8, 0≦y≦0.4 0.10≦z≦0.42,y+z>0, 0≦q≦0.05, 1.9≦2-a≦2.1, x+y+z+q=1, and 0≦a≦0.02) to have an average particle size D50 of from 3 to 15 μm, in a weight ratio of the first granular powder/the second granular powder being from 50/50 to 90/10; wherein the ratio of the compression strength of the first granular powder/the compression strength of the second granular powder is from 65/30 to 200/10.