Inventors:
Yuan Gao - Ocean NJ
Marina Yakovleva - Gastonia NC
John F. Engel - Belmont NC
Assignee:
FMC Corporation - Philadelphia PA
International Classification:
H01B 108
US Classification:
2525212, 2525181, 4292181, 4292313, 42923195, 429223, 429224, 429322, 429209, 423594, 423599, 423617, 423624, 423635, 423641
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. 96w1. 05, 0x0. 05, -0. 02y0. 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)} {right arrow over (P)} ; y ={right arrow over (S)} {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 15Â and 120Â using a 0. 02Â step size and CuK 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%.
