| abstract |
A particulate lithium nickel oxide material comprises particles having the formula LiaNixCoyMgzAlpO2+b, in which 0.95 ≤ a ≤1.05, 0.90 ≤ x < 0.95, 0.040 ≤ y ≤ 0.050, 0.030 ≤ z ≤ 0.045, 0.0055 ≤ p ≤ 0.0075, and -0.1 ≤ b ≤ 0.1. Preferably, 1.00 ≤ a ≤1.05, 0.91 ≤ x < 0.94, 0.043 ≤ y ≤ 0.047, 0.035 ≤ z ≤ 0.040, 0.0058 ≤ p ≤ 0.0065, and -0.05 ≤ b ≤ 0.05. The particles may comprise a core and an enriched surface layer at the surface of the core, the surface layer preferably comprising a higher concentration of aluminium than the core. Substantially all of the Al, and no cobalt, may be present in the enriched surface layer. Further aspects of the invention include a cathode comprising the particulate lithium nickel oxide material, and a lithium secondary cell or battery comprising such a cathode. This material has excellent capacity retention despite its very low cobalt content, which is desirable for cost, environmental and ethical reasons. |