Enabling Rapid and Stable Sodium Storage via a P2-Type Layered Cathode with High-Voltage Zero-Phase Transition Behavior.

Currently, a major target in the development of Na-ion batteries is the concurrent attainment of high-rate capacity and long cycling stability. Herein, an advanced Na-ion battery with high-rate capability and long cycle stability based on Li/Ti co-doped P2-type NaMnNiO, a host material with high-voltage zero-phase transition behavior and fast Na migration/conductivity during dynamic de-embedding process, is constructed. Experimental results and theoretical calculations reveal that the two-element doping strategy promotes a mutually reinforcing effect, which greatly facilitates the transfer capability of Na. The cation Ti doping is a dominant high voltage, significantly elevating the operation voltage to 4.4 V. Meanwhile, doping Li shows the function in charge transfer, improving the rate performance and prolonging cycling lifespan. Consequently, the designed P2-NaMnNiLiTiO cathode material exhibits discharge capacities of 129, 104, and 85 mAh g under high voltage of 4.4 V at 1, 10, and 20 C, respectively. More importantly, the full-cell delivers a high initial capacity of 198 mAh g at 0.1 C (17.3 mA g) and a capacity retention of 73% at 5 C (865 mA g) after 1000 cycles, which is seldom witnessed in previous reports, emphasizing their potential applications in advanced energy storage.