Selective doping of Li-rich layered oxide cathode materials for high-stability rechargeable Li-ion batteries

Abstract We report the discovery of Li-rich Li 1+x [(Ni 0.225 Co 0.15 Mn 0.625 ) 1−y V y ]O 2 as a cathode material for rechargeable lithium-ion batteries in which a small amount of tetravalent vanadium (V 4+ ) is selectively and completely incorporated into the manganese sites in the lattice structure. The unwanted oxidation of vanadium to form a V 2 O 5 -like secondary phase during high-temperature crystallization is prevented by uniformly dispersing the vanadium ions in coprecipitated [(Ni 0.225 Co 0.15 Mn 0.625 ) 1−y V y ](OH) 2 particles. Upon doping with V 4+ ions, the initial discharge capacity (>275 mA h g −1 ), capacity retention, and voltage decay characteristics of the Li-rich layered oxides are improved significantly in comparison with those of the conventional undoped counterpart.