Sodium‐ and Potassium‐Hydrate Melts Containing Asymmetric Imide Anions for High‐Voltage Aqueous Batteries. Issue 40 (30th August 2019)

• Record Type: Journal Article
• Authors: Zheng, Qifeng; Miura, Shota; Miyazaki, Kasumi; Ko, Seongjae; Watanabe, Eriko; Okoshi, Masaki; Chou, Chien‐Pin; Nishimura, Yoshifumi; Nakai, Hiromi; Kamiya, Takeshi; Honda, Tsunetoshi; Akikusa, Jun; Yamada, Yuki; Yamada, Atsuo
• Is Part Of: Angewandte Chemie international edition. Volume 58:Issue 40(2019)
• Page Start: 14202
• Page End: 14207
• Publication Date: 2019-08-30
• Subjects: aqueous batteries -- asymmetric imide anion -- electrochemistry -- hydrates -- potential window expansion; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201908830
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Aqueous Na‐ or K‐ion batteries could virtually eliminate the safety and cost concerns raised from Li‐ion batteries, but their widespread applications have generally suffered from narrow electrochemical potential window (ca. 1.23 V) of aqueous electrolytes that leads to low energy density. Herein, by exploring optimized eutectic systems of Na and K salts with asymmetric imide anions, we discovered, for the first time, room‐temperature hydrate melts for Na and K systems, which are the second and third alkali metal hydrate melts reported since the first discovery of Li hydrate melt by our group in 2016. The newly discovered Na‐ and K‐ hydrate melts could significantly extend the potential window up to 2.7 and 2.5 V (at Pt electrode), respectively, owing to the merit that almost all water molecules participate in the Na + or K + hydration shells. As a proof‐of‐concept, a prototype Na3 V2 (PO4 )2 F3 |NaTi2 (PO4 )3 aqueous Na‐ion full‐cell with the Na‐hydrate‐melt electrolyte delivers an average discharge voltage of 1.75 V, that is among the highest value ever reported for all aqueous Na‐ion batteries. Abstract : For the first time, room‐temperature hydrate melts for Na and K systems were discovered by exploring optimized eutectic systems of Na and K salts with asymmetric imide anions, thereby leading to a significant expansion of the potential window, which will open new frontiers in aqueous electrolytes for high‐voltage and safe batteries.