Pulse-Assisted Low-Temperature Sintering to Enhance the Fast-Charging Capability for P2-Layered Na-Based Cathodes

Utilizing an anionic redox reaction for charge compensation is a promising breakthrough in boosting the energy density of P2-layered Na-based cathodes. However, sluggish kinetics and irreversible surface oxygen loss cause poor rate performance and severe capacity degradation, plaguing the practical fast-charging cathode application for sodium-ion batteries. Herein, a pulse-assisted low-temperature sintering strategy is first proposed to alleviate the above obstacles successfully. First, the primary particles are optimized with minor size and less agglomeration. Further analysis via a series of in situ and ex situ characterizations reveals the generation of surface oxygen vacancies, which facilitate the electrochemical kinetics and induce a robust spinel-like protective film. The synergistic effect suppresses the irreversible oxygen release and unfavorable interfacial reactions and improves the structural integrity and electrochemical kinetics in prolonged cycling. Consequently, the optimized cathode of P2-type Na0.72Li0.24Mn0.76O2 shows a splendid cycle life of 130.5 mA h g(-1) after 100 cycles at 200 mA g(-1) and excellent rate capacity of 107.9 mA h g(-1) at 1000 mA g(-1) in the voltage range of 1.5-4.5 V. The full cell is assembled with a presodiation anode, which delivers a promising energy density (similar to 485.2 W h kg(-1), 1.0-4.4 V). Another practical asset stems from its low-energy consumption through a low-temperature sintering process. Overall, this work offers a guiding significance to enhance the electrochemical kinetics and fast-charging capability for sodium-Mn-based oxide cathodes with anionic redox.