Na[FSA]-[C3C1pyrr][FSA] ionic liquids as electrolytes for sodium secondary batteries: Effects of Na ion concentration and operation temperature

• Published in: Journal of power sources Vol. 269; pp. 124 - 128
• Main Authors: Ding, Changsheng, Nohira, Toshiyuki, Hagiwara, Rika, Matsumoto, Kazuhiko, Okamoto, Yu, Fukunaga, Atsushi, Sakai, Shoichiro, Nitta, Koji, Inazawa, Shinji
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 10.12.2014
• Subjects: Applied sciences; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Electrolytes; Electrolytic cells; Exact sciences and technology; Ion concentration; Ionic conductivity; Ionic liquids; Optimization; Sodium; Storage batteries; Viscosity; Temperature; Sodium-ion battery; Electrical properties; Sodium secondary batteries; Na ion concentration; Operation temperature; Ionic conductivity; Ions; Secondary cell; Concentration; Ionic liquid; Electrolyte; Ionic liquids; Rheological properties
• ISSN: 0378-7753
• DOI: 10.1016/j.jpowsour.2014.06.033

As electrolytes for sodium secondary batteries operating over a wide temperature range, Na[FSA]-[C sub(3)C sub(1)pyrr][FSA] (FSA = bis(fluorosulfonyl)amide, C sub(3)C sub(1)pyrr = N-methyl-N-propylpyrrolidinium) ionic liquids have been investigated. The effects of Na ion concentration (0-60 mol% Na[FSA]) and operation temperature (253-363 K) on the viscosity and ionic conductivity and charge-discharge performance of Na/Na[FSA]-[C sub(3)C sub(1)pyrr] [FSA]/NaCrO sub(2) cells are studied. Results show that Na ion concentration strongly affects the rate capability of the cells, and that the best rate capability at 363 K is obtained at 40 mol% Na [FSA]. The operation temperature also significantly influences the charge-discharge performance, especially at low temperatures. At operation temperatures below 273 K, 25 mol% Na[FSA] is found to be the optimum Na ion concentration. There exist different optimum ranges of Na ion concentration depending on the operation temperatures.