Selective Doping of Li-rich Layered Oxide Cathode Materials for High-stability Li-ion Rechargeable Batteries

Abstract: We report the discovery of Li-rich Li1+x[(Ni0.225Co0.15Mn0.625)1-yVy]O2 as a cathode material for lithium-ion rechargeable 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 (> 275 mA h g-1), capacity retention (~91.9％ after 50 cycles at 1C), and voltage decay characteristics of the Li-rich layered oxides are improved significantly in comparison with those of the conventional undoped counterpart.