LiTa2PO8 coated nickel-rich cathode material for improved electrochemical performance at high voltage

Abstract

LiNi0.8Co0.1Mn0.1O2 (NCM) will have higher energy density at high voltage, but severe electrochemical polarization and capacity decay are likely to occur because of structural degradation. In this paper, LiTa2PO8 is used as a coating layer to modify the NCM. Covered with a 2–4 nm coating layer, the material structure does not change significantly, and the structure is more stable. More importantly, LiTa2PO8 has an ordered channel with three-dimensional Li+ ion transport, which plays a key role in improving Li+ transmission efficiency. The results show that the electrochemical properties of the material are significantly improved after coating at high voltage. After 100 cycles, the capacity retention increases from 71.58% to 84.85%, voltage stability also notably improved, the polarization is weaker, and the reversible charge and discharge capacity at high rate (3C) is significantly higher than that of raw materials. The change in morphology after 100 cycles proves that the LiTa2PO8 coating prevents direct contact between the cathode materials and the electrolyte, inhibits the side reaction and enhance the surface structure stability of the cathode materials.