Facile formation of a Li3PO4 coating layer during the synthesis of a lithium-rich layered oxide for high-capacity lithium-ion batteries

The facile surface modification of transition-metal hydroxide precursors with ammonium dihydrogen phosphate was performed by ball-milling before the calcination process. The prepared precursors were mixed with the required amount of lithium hydroxide and then simply calcined to obtain lithium-phosphate-coated lithium transition metal oxide cathodes during the one-pot calcination process. A thin, homogeneous Li3PO4 coating is firstly formed on the surface of the precursor owing to the abundance of lithium at a lower-temperature range, and subsequent formation of lithium transition metal oxide is achieved at a higher-temperature range during the calcination process. The Li3PO4-coated cathode electrode with the high loading level over 12 mg cm−1 exhibits a discharge capacity of 106 mAh g−1 at 5C at ambient temperature. Furthermore, it delivers 90% capacity retention after 50 cycles at 60 °C.