Electrochemical and structural investigation of NaCrO2 as a positive electrode for sodium secondary battery using inorganic ionic liquid NaFSA–KFSA

• Published in: Journal of power sources Vol. 237; pp. 52 - 57
• Main Authors: Chen, Chih-Yao, Matsumoto, Kazuhiko, Nohira, Toshiyuki, Hagiwara, Rika, Fukunaga, Atsushi, Sakai, Shoichiro, Nitta, Koji, Inazawa, Shinji
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.09.2013; Elsevier
• Subjects: Applied sciences; Bis(fluorosulfonyl)amide; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Exact sciences and technology; Ionic liquid; Materials; NaCrO2; Positive electrode; Sodium secondary battery; Structural analysis; Bis(fluorosulfonyl)amide; Positive electrode; Sodium secondary battery; NaCrO2; Structural analysis; Ionic liquid; Ternary compound; Structural design; Cathode; Secondary cell; Electrode material; Inorganic compound; Chromium Oxides; Sodium; NaCrO; Battery; Sodium Oxides
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2013.03.006

The electrochemical performance of NaCrO2 as a positive electrode material for an intermediate-temperature sodium secondary battery was evaluated in an inorganic ionic liquid, NaFSA–KFSA (FSA = bis(fluorosulfonyl)amide), at 363 K. The positive electrode using NaCrO2, acetylene black, and polytetrafluoroethylene exhibited a stable discharge capacity of 113 mA h g−1 at a current density of 125 mA g−1. The Coulombic efficiency and the capacity retention at the 100th cycle were 99.6% and 98.5%, respectively. Even at the very high current density of 2000 mA g−1, the discharge capacity was maintained at 63 mA h g−1. X-ray diffraction analyses revealed that the deintercalation of Na+ ion from NaCrO2 was associated with several phase transitions in the following sequence: rhombohedral O3, monoclinic O′3, and monoclinic P′3. ► The performance of NaCrO2 positive electrode was evaluated at 363 K. ► NaFSA–KFSA was used as an intermediate temperature inorganic electrolyte. ► The phase transition behavior of NaCrO2 during desodiation was clarified. ► The phase transition occurred more readily at 363 K compared to room temperature. ► The reaction kinetics was enhanced at 363 K, giving the improved rate capability.