Surface modification of Na0.44MnO2 via a nonaqueous solution-assisted coating for ultra-Stable and High-Rate sodium-ion batteries

Sodium-ion batteries (SIBs) provide an attractive option for large-scale electrochemical energy storage applications. However, the approach to realize highly reversible cathode materials needs further exploration. Our work adopts a universal nonaqueous solution process in coating functional Al-PO4 layer on cathode material Na0.44MnO2 (NMO) for SIBs. Surface modification of NMO by AlPO4 coating layer facilitates the interfacial charge transfer reactions and enhances pseudocapacitance's contribution. The optimized 0.5 wt% AlPO4-coated Na0.44MnO2 (0.5 wt% AP-NMO) exhibits an enhanced capacity retention ratio of 80.3% after 500 cycles at 5 C (1 C=120 mA g-1) and a higher discharge capacity of 92 mAh g-1 at 10 C (1200 mA g-1). In addition, it can release a reversible capacity of 42 mAh g-1 at an ultra-high current density of 50 C (6000 mA g-1) and maintain 76% of the initial capacity after 2000 cycles. The coated materials also show extraordinary electrochemical stability at 60 degrees C. This research paves a way to apply an effective surface modification technique for enhancing transition metal oxide cathodes for SIBs.