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

Abstract

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 Na0.67 Mn0.67 Ni0.33 O2 , 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 Ti4+ doping is a dominant high voltage, significantly elevating the operation voltage to 4.4V. Meanwhile, doping Li+ shows the function in charge transfer, improving the rate performance and prolonging cycling lifespan. Consequently, the designed P2-Na0.75 Mn0.54 Ni0.27 Li0.14 Ti0.05 O2 cathode material exhibits discharge capacities of 129, 104, and 85mAhg- 1 under high voltage of 4.4V at 1, 10, and 20C, respectively. More importantly, the full-cell delivers a high initial capacity of 198mAhg-1 at 0.1C (17.3mAg-1 ) and a capacity retention of 73% at 5C (865mAg-1 ) after 1000 cycles, which is seldom witnessed in previous reports, emphasizing their potential applications in advanced energy storage.