Face-lifting the surface of LiNi0.8Co0.15Al0.05O2 cathode via Y(PO3)3 to form an in situ triple composite Li-ion conductor coating layer with the enhanced electrochemical performance

Abstract

Abstract Due to the assets such as adequate discharge capacity and rational cost, LiNi0.8Co0.15Al0.05O2 (NCA), a high-nickel ternary layered oxide, is regarded to be a favorable cathode contender for lithium-ion batteries. However, the superior commercial application is restricted by the surface residual alkaline lithium salt (LiOH or/and Li2CO3) of nickel-rich cathode materials, which will expedite the disintegration of the structure and the engendering of gas (CO2). Therefore, in this paper, we devise and fabricate a Y(PO3)3 modified LiNi0.8Co0.15Al0.05O2 (NCA), intending to optimize the surface residual alkaline lithium salt (antecedent deportation of H2O and CO2) while forming an in situ triple composite Li-ion conductor coating (Y(PO3)3-Li3PO4-YPO4) to enhance the electrochemical behavior. Under this method, the 2 mol% Y(PO3)3 modified NCA electrode reveals exceptional rate capability (5 C/156.3 mAh g−1) and extraordinary cycle stability after 200 cycles (2 C/88.3%), whereas the original sample is only 5 C/123.1 mAh g−1 and 2 C/71.2% after 200 cycles. Conspicuously, even under the draconian circumstances of the high temperature and the high rate at 55 °C/1 C, the 2 mol% Y(PO3)3 modified NCA electrode sustains a high reversible capacity, with an admirable capacity retention rate of 89.4% after 100 cycles. These contented results signify that the surface remodeling tactic presents a viable scheme for ameliorating high-nickel materials’ performance and appropriateness.