Simultaneously enhanced electrochemical performance and air stability of Ni-rich cathode with a modified washing process

Water washing has been regarded as one of the most effective strategies to remove surface residual lithium of nickel-rich layered oxides for lithium-ion batteries (LIBs). However, the loss of lattice lithium during the water washing process deteriorates the electrochemical performances and air stability. Herein, washing the LiNi0.90Co0.08Al0.02O2 (NCA) with ammonium dihydrogen phosphate (NH4H2PO4) solution has been proposed to simultaneously enhance electrochemical performances and air stability, in which in-situ generated Li3PO4 coating layer on surface of NCA can suppress the loss of lattice lithium. Besides, as a fast ionic conductor, Li3PO4 coating layer on NCA can prevent the direct contact with electrolyte/air. As a result, the NH4H2PO4 solution washed NCA cathode can deliver a high capacity of 131.9 mAh·g−1 at 10.0C rate as well as impressive cycle stability with a capacity retention of 83.1