Positive electrode materials combining high safety and high power in a li rechargeable battery

Abstract

The invention relates to a LiNiCoMnM'Ocomposite oxide for use as a cathode material in a rechargeable battery, with a non-homogenous Ni/M′ ratio in the particles, allowing excellent power and safety properties when used as positive electrode material in Li battery. More particularly, in the formula 0.9<a<1.1, 0.3≦x≦0.9, 0<y≦0.4, 0<y′≦0.4, 0<z≦0.35, e<0.02, 0≦f≦0.05 and 0.9<(x+y+y′+z+f)<1.1; M′ consists of either one or more elements from the group Al, Mg, Ti, Cr, V, Fe, Mn and Ga; N consists of either one or more elements from the group F, Cl, S, Zr, Ba, Y, Ca, B, Sn, Sb, Na and Zn. The powder has a particle size distribution defining a D10, D50 and D90; and the x and z parameters varying with the particles size of the powder, and is characterized in that either one or both of:1−2≧0.005and2−1≧0.005;x1 and z1 being the parameters corresponding to particles having a particle size D90; and x2 and z2 being the parameters corresponding to particles having a particle size D10.