Ti/Co co-doped O3-Na(Ni0.3Fe0.2Mn0.5)0.85Ti0.1Co0.05O2 with high rate and durable cathode material for sodium-ion batteries

Abstract

O3-type layered oxides are widely investigated as cathodes for Na-ion batteries (SIBs) due to their high theoretical capacities and splendid initial Coulombic efficiency. However, they suffer from fast capacity fading owing to the complicated phase transformations, especially in high cut-off voltage (>4 V). Herein, Ti and Co elements were simultaneously introduced to O3-Na(Ni0.3Fe0.2Mn0.5)0.85Ti0.1Co0.05O2 (NFMTC) cathode material, and the effects of Ti/Co co-doping on phase structure and electrochemical properties were analyzed in detail. The results reveal that Ti/Co co-doping can enhance the {010} plane, interlayer space and Na-ion diffusion kinetics, resulting in the improved electrochemical performance. Therefore, the NFMTC cathode delivers a high reversible capacity of 174.7 mAh g−1 at 0.1 C in the voltage range of 2.0–4.3 V and a good rate capability (53% of the initial capacity at 5 C) as well as an excellent capacity retention of 78% after 300 cycles at 1 C. This work maybe provides a guidance to explore high-performance cathode materials for sodium ion batteries.