Improving the electrochemical cycle stability of LiNi0.8Co0.1Mn0.1O2 via Al (H2PO4)3 treatment on its precursor

Ni-rich layered transition -metal oxides are important cathodes for lithium -ion batteries (LIBs). Unfortunately, they still suffer from capacity fading arising from structure transformation and side reactions. Cation doping and surface coating with a protective layer can alleviate the problem. Herein, a synergistic strategy of Al3+ doping near the surface and Li3PO4-LiAlO2 coating is adopted to modify LiNi0.8Co0.1Mn0.1O2 (NCM811), and it is carried out by using a simple Al(H2PO4)3 wet deposition method on its precursor. Structure and surface analysis show that Li3PO4-LiAlO2 is formed on the NCM surface and some Al3+ ions enter the near -surface lattice of cathode particles. Compared to NCM811, the modified-NCM811 exhibits slower impedance growth and better capacity retention (from 55.55 % to 75.09 % after 100 cycles) during cycling, which shows the strategy can effectively stabilize the interface and crystal structure.