Mitigating the voltage fading and air sensitivity of O3-type NaNi0.4Mn0.4Cu0.1Ti0.1O2 cathode material via La doping

The practical application of O3-type layered oxides cathode materials for sodium ion batteries (SIBs) is hindered by two major difficulties, including capacity decay rooted in multiphase transitions and storage issue originated from sensitivity to moisture. Herein, we report a series of O3-type layered oxides Na(Ni0.4Cu0.1Mn0.4Ti0.1)1-xLaxO2 (x = 0, 0.001, 0.003, 0.005, termed as NMCT, NMCT-Lax, respectively) cathode materials synthesized via spray pyrolysis followed by high-temperature sintering method, which manifest enhanced electrochemical performance and air stability as compared to the NaNi0.5Mn0.5O2 (termed as NM) material. Optimum performance is achieved in the NMCT-La0.001 material that delivers a high initial discharge capacity of 170.1 mAh g−1 in the voltage range of 2.0–4.4 V at 0.1C (1C = 150 mA g−1). NMCT-La0.001 exhibits a highly reversible structural transformation during charging/discharging as demonstrated by in-situ XRD, and it keeps the original crystal structure after being exposed to the air for 30 days. The capacity decay of NMCT is effectively decelerated at high voltage (>4.2 V) after La doping, as which can stabilize the structure of the material by reducing the Mn3+ content through suppressing the Jahn-Teller effect. The research with respect to La doping provides a facile and instructive way for the design of high-performance cathode materials for SIBs.