| abstract |
Provided is a positive electrode active substance for lithium ion batteries which has high capacitance and good rate characteristics. The disclosed positive electrode active substance for lithium ion batteries has a structure represented by the compositional formula Lix(NiyM1-y)Oz (therein, M represents at least one element selected from among Mn, Co, Al, Mg, Cr, Ti, Fe, Nb, Cu and Zr, x is 0.9-1.2, y is 0.80-0.89 and z is 1.9 or higher), wherein the lattice constant (a) and the composition ratio of Li and M (Li/M) are such that when plotted in a graph having the lattice constant (a) as the X axis and the composition ratio of Li and M (Li/M) as the Y axis, the plot of the lattice constant (a) and the composition ratio (Li/M) falls within the area delimited by the four straight lines represented by the formulae y=1.01, y=1.10, x=2.8748, and x=2.87731, and the lattice constant (c) is 14.2-14.25. |