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

Abstract

We report the discovery of Li-rich Li1+x[(Ni0.225Co0.15Mn0.625)1−yVy]O2 as a cathode material for rechargeable lithium-ion batteries in which a small amount of tetravalent vanadium (V4+) is selectively and completely incorporated into the manganese sites in the lattice structure. The unwanted oxidation of vanadium to form a V2O5-like secondary phase during high-temperature crystallization is prevented by uniformly dispersing the vanadium ions in coprecipitated [(Ni0.225Co0.15Mn0.625)1−yVy](OH)2 particles. Upon doping with V4+ ions, the initial discharge capacity (>275mAhg−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.