AlF3 Surface‐Coated Li[Li0.2Ni0.17Co0.07Mn0.56]O2 Nanoparticles with Superior Electrochemical Performance for Lithium‐Ion Batteries

Li-rich layered cathode materials have already drawn considerable attention owing to their high capacity performance for Li-ion batteries (LIBs). In this work, layered Li-rich Li[Li0.2 Ni0.17 Co0.07 Mn0.56 ]O2 nanoparticles are surface-modified with AlF3 through a facile chemical deposition method. The AlF3 surface layers have little impact on the structure of the material and act as buffers to prevent the direct contact of the electrode with the electrolyte; thus, they enhance the electrochemical performance significantly. The 3 wt % AlF3 -coated Li-rich electrode exhibits the best cycling capability and has a considerably enhanced capacity retention of 83.1 % after 50 cycles. Moreover, the rate performance and thermal stability of the 3 wt % AlF3 -coated electrode are also clearly improved. Surface analysis indicates that the AlF3 coating layer can largely suppress the undesirable growth of solid electrolyte interphase (SEI) film and, therefore, stabilizes the structure upon cycling.