Lithium cobalt oxides and methods of making same

Abstract

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 Co A O 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 +by ≦c, wherein x ={right arrow over (S)} &Circlesolid;{right arrow over (P)} ; y ={right arrow over (S)} &Circlesolid;{right arrow over (P)} ; the vector {right arrow over (S)} is the x-ray spectrum for the Li Co A O compound; the vectors {right arrow over (P)} and {right arrow over (P)} defining the principal component space are determined by measuring the x-ray powder diffraction values {right arrow over (S)} between 15° and 120° using a 0.02° step size and CuK&agr; rays for a large sample set of lithium cobalt oxides and using the regression of {right arrow over (S)} 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 and y values for Li Co A O compounds in the sample set that have a capacity fade after 50 cycles of less than or equal to 15%.