Patent ID: 6579475
Filing Date: 2003-06-17
Classification: C01G,C01P,H01M,Y02E

Abstract:
A lithium cobalt oxide compound (LiwCo1âˆ’xAxO2+y) having a hexagonal layered crystal structure and wherein 0.96&lE;w&lE;1.05, 0&lE;x&lE;0.05, âˆ’0.02&lE;y&lE;0.02 and A is one or more dopants, said lithium cobalt oxide having a position within the principal component space defined by the following relationship:axi+byi&lE;c wherein xi={right arrow over (S)}i&Circlesolid;{right arrow over (P)}c1; yi={right arrow over (S)}i&Circlesolid;{right arrow over (P)}c2; the vector {right arrow over (S)}i is the x-ray spectrum for the LiwCo1âˆ’xAxO2+y compound; the vectors {right arrow over (P)}c1 and {right arrow over (P)}c2 are determined by measuring the x-ray powder diffraction values {right arrow over (S)}i between 15Â° and 120Â° using a 0.02Â° step size and CuK&agr; 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 xi and yi values for LiwCo1âˆ’xAxO2+y compounds in the sample set that have a capacity fade after 50 cycles of less than or equal to 15%.