Enhanced rate capability and cycling stability of lithium-rich cathode material Li1.2Ni0.2Mn0.6O2 via H3PO4 pretreating and accompanying Li3PO4 coating

H3PO4 pretreated and Li3PO4 coated Li-rich materials Li1.2Ni0.2Mn0.6O2 have been prepared via hydrothermal followed by a facile modified method. The pretreated process partially extracts Li and O from lattice, results in pre-activation of Li2MnO3 component and the formation of spinel phase. A stable Li3PO4 coating is formed on the surface of the material during the subsequent heat treatment. H3PO4 pretreatment and Li3PO4 coating are skillfully combined using a simple method. Electrochemical studies exhibit that the electrochemical performance of Li1.2Ni0.2Mn0.6O2 is obviously improved after surface modification. The surface treated material with 0.04 mol L-1 H3PO4 shows more excellent electrochemical properties than those of Li1.2Ni0.2Mn0.6O2 cathode, with a high specific discharge capacity of 262.6 mAh g(-1) at 0.1 C, a great capacity retention of 92.2% at 1 C after 100 cycles, and an outstanding rate capability reaching 105.4 mAh g(-1) at 10 C. The enhanced performance is caused by the formation of spinel phase and Li3PO4 coating layer, which can accelerate the migration of Li+ and facilitate the charge transfer reaction. The Li3PO4 coating also inhibits the dissolution of transition metal ions and enhances the stability of electrode/electrolyte interface.