| 摘要 |
It is to provide a cathode active material powder for a positive electrode for a lithium secondary battery, which has a large volume capacity density, high safety and excellent durability for charge and discharge cycles. A cathode active material powder for a lithium secondary battery characterized by comprising a first composite oxide powder represented by the formula (1) Li<SUB>p</SUB>Q<SUB>x</SUB>M<SUB>y</SUB>O<SUB>z</SUB>F<SUB>a </SUB>(wherein Q is Co or Mn, M is aluminum or an alkaline earth metal element or a transition metal element other than Q, provided that when Q is Co, 0.9<=p<=1.1, 0.980<=x<=1.000, 0<=y<=0.02, 1.9<=z<=2.1, x+y=1, and 0<=a<=0.02, and when Q is Mn, 1<=p<=1.3, x=2-y, 0<=y<=0.05, z=4, and a=0), having an average particle size D50 of from 5 to 30 mum, and having a compression breaking strength of at least 40 MPa; and a second composite oxide powder represented by the formula (2) Li<SUB>p</SUB>Ni<SUB>x</SUB>Co<SUB>y</SUB>Mn<SUB>z</SUB>N<SUB>q</SUB>O<SUB>r</SUB>F<SUB>a </SUB>(wherein N is aluminum or 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<=z<=0.5, 0<=q<=0.05, 1.9<=r<=2.1, x+y+z+q=1, and 0<=a<=0.02), having an average particle size D50 of from 2 to 30 mum, and having a compression breaking strength less than 40 MPa; in a ratio (weight ratio) of the first composite oxide powder/the second composite oxide powder being from 95/5 to 30/70.
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