Dual function Li-reactive coating from residual lithium on Ni-rich NCM cathode material for Lithium-ion batteries

Abstract

In this study, lithium phosphate (Li3PO4) is coated on the surface of Ni-rich LiNi0.91Co0.06Mn0.03O2 cathode material to enhance its cyclability and rate performance. The process is carried-out by achieving dual benefits, reduction of residual lithium compounds by converting them into Li3PO4 coating material. The 0.1 mol.% Li3PO4 (LiP) sample exhibits a capacity retention of 82% while the pristine NCM shows only 68.1% after 100 cycles. In addition, the LiP-0.1 NCM delivers high discharge capacities (161.9 mAh g−1 at 3C, 144.3 mAh g−1 at 4C and 94.6 mAh g−1 at 5C) as compared to the pristine NCM (129.3 mAh g−1 at 3C, 67.4 mAh g−1 at 4C and 33.4 mAh g−1 at 5C) in the voltage range of 3.0–4.3 V. In addition, the irreversible phase transition has also suppressed in the coated sample which is confirmed by cyclic voltammetry. Our study suggests that Li3PO4 coating reduces the polarization and acts as protecting layer between the electrode and electrolyte that results in the superior electrochemical performance.