Conversion of residual lithium into fast ionic conductor coating to achieve one-step double modification strategy in LiNi0.8Co0.15Al0.05O2

The application of Ni-rich ternary cathode materials is restricted by the irreversible phase transition and interfacial side reactions during long-term cycling. Herein, a LiTaO3 coating and Ta5+ doping strategy are simultaneously achieved by a simple solid-phase synthesis. The surface side-reaction and undesired phase transition of LiNi0.8Co0.15Al0.05O2 (NCA) are effectively restrained by this approach, which utilizes residual lithium to afford the coating. The NCA-LTO 3 (The modified NCA with a LiTaO3 coating content of 3 wt%) delivers a high reversible capacity of 168.04 at 5 C (140.56 mAh g−1 for NCA), revealing the enhanced rate capability. More importantly, the cycling life could be greatly maintained after 200 cycles with a significant capacity retention of 94.1% (61.2% for NCA) at 1 C. Mechanism analysis indicates that such improvement is ascribed to the coating of conductor LiTaO3 and doping Ta5+ greatly promoting the Li-ion diffusion and stabilizing the interface of NCA. The study proposes a highly convenient strategy for interfacial optimization of cathode materials toward assisting the large-scale production of high-performance NCA.