Liquefied gas electrolytes for electrochemical energy storage devices

• Published in: Science (American Association for the Advancement of Science) Vol. 356; no. 6345
• Main Authors: Rustomji, Cyrus S., Yang, Yangyuchen, Kim, Tae Kyoung, Mac, Jimmy, Kim, Young Jin, Caldwell, Elizabeth, Chung, Hyeseung, Meng, Y. Shirley
• Format: Journal Article
• Language: English
• Published: United States AAAS 15.06.2017
• Subjects: Science & Technology - Other Topics
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.aal4263

Electrochemical capacitors and lithium-ion batteries have seen little change in their electrolyte chemistry since their commercialization, which has limited improvements in device performance. Combining superior physical and chemical properties and a high dielectric-fluidity factor, the use of electrolytes based on solvent systems that exclusively use components that are typically gaseous under standard conditions show a wide potential window of stability and excellent performance over an extended temperature range. Electrochemical capacitors using difluoromethane show outstanding performance from –78° to +65°C, with an increased operation voltage. The use of fluoromethane shows a high coulombic efficiency of ~97% for cycling lithium metal anodes, together with good cyclability of a 4-volt lithium cobalt oxide cathode and operation as low as –60°C, with excellent capacity retention.