2D amorphous iron phosphate nanosheets with high rate capability and ultra-long cycle life for sodium ion batteries

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2016-01, Vol.4 (12), p.4479-4484
• Main Authors: Liu, Tongchao, Duan, Yandong, Zhang, Guangxing, Li, Maofan, Feng, Yancong, Hu, Jiangtao, Zheng, Jiaxin, Chen, Jitao, Pan, Feng
• Format: Article
• Language: English
• Subjects: Amorphous materials; Cathodes; Discharge; Electric batteries; Nanostructure; Sodium; Transmission electron microscopy; Two dimensional
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c6ta00454g

In our previous work, we reported the formation and mechanism of mono/bi-layer phosphate-based materials and their high performance as cathode materials for Li-ion batteries. In this work, we report that 2D amorphous nanosheets can be used as cathode materials to achieve outstanding performance for sodium ion batteries (SIBs) e.g. a high initial discharge capacity of 168.9 mA h g −1 at 0.1C, ultra-long life (92.3% capacity retention over 1000 cycles), and high rate capability (77 mA h g −1 at 10C) for Na-ion storage, whose electrochemical performance is also much superior to the reported amorphous FePO 4 or olivine NaFePO 4 with advantages of short paths and larger implantation surface areas for fast Na-ion diffusion and large specific surfaces with more interfacial capacitance. Interestingly, NaFePO 4 nano-crystals with about 10 nm sizes are self-nucleated from amorphous 2D nanosheets in the charge/discharge process, which was verified by transmission electron microscopy (TEM) and in situ electrochemical impedance spectroscopy (EIS). 2D amorphous iron phosphate nanosheet coated carbon exhibits high rate capability and ultra-long cycle life for sodium ion batteries.