Pyrophosphate Na2FeP2O7 as a low-cost and high-performance positive electrode material for sodium secondary batteries utilizing an inorganic ionic liquid

作者：Chen Chih Yao; Matsumoto Kazuhiko; Nohira Toshiyuki^*; Hagiwara Rika; Orikasa Yuki; Uchimoto Yoshiharu

来源：Journal of Power Sources, 2014, 246: 783-787.

DOI：10.1016/j.jpowsour.2013.08.027

• Sodium secondary battery
• Na2FeP2O7
• Positive electrode
• Ionic liquid
• Bis(fluorosulfonyl)amide

The electrochemical performance of a Na2FeP2O7 positive electrode has been evaluated in an inorganic ionic liquid NaFSA-KFSA (FSA = bis(fluorosulfonyl)amide) at 363 K. The electrode delivers a reversible capacity of 91 mAh g(-1) with excellent rate capability (59 mAh g(-1) at 2000 mA g(-1)) and a capacity retention of 91% over 1000 cycles, which facilitates the development of low-cost and high-safety sodium secondary batteries for large-scale energy storage applications. The average oxidation state of iron increases upon sodium extraction, as evidenced by the edge shift of an X-ray absorption spectroscopy analysis. According to an extended X-ray absorption fine structure analysis, the sodium extraction is accompanied by a shortening of Fe-O bonds.

• 出版日期2014-1-15