Lithium cobalt oxides and methods of making same

摘要

The present invention includes lithium cobalt oxides having hexagonal layered crystal structures and methods of making same. The lithium cobalt oxides of the invention have the formula Li_wCo_1-xA_xO_2+y wherein 0.96<=w<=1.05, 0<=x<=0.05, -0.02<=y<=0.02 and A is one or more dopants. The lithium cobalt oxides of the invention preferably have a position within the principal component space defined by the relationship ax_i+by_i<=C, WHEREIN X_i={right arrow over (S_i.{right arrow over (P_c1; y_i={right arrow over (S_i.{right arrow over (P_c2; the vector {right arrow over (S_i is the x-ray spectrum for the Li_wCo_1-xA_xO_2+y compound; the vectors {right arrow over (P_c1 and {right arrow over (P_c2 defining the principal component space are determined by measuring the x-ray powder diffraction values {right arrow over (S_i between 15° and 120° using a 0.02° step size and CuKalpha rays for a large sample set of lithium cobalt oxides and using the regression of {right arrow over (S_i of the sample set against the capacity fade after 50 cycles of a lithium coin cell that includes a lithium negative electrode and the lithium cobalt oxide as the positive electrode material and that is cycled between 3.0 and 4.3V at a constant current of C/3 during both charge and discharge cycles; and the values a, b and c are determined by using only the x_i and y_i values for Li_wCo_1-xA_xO_2+y compounds in the sample set that have a capacity fade after 50 cycles of less than or equal to 15%.