A Ca‐Ion Electrochromic Battery via a Water‐in‐Salt Electrolyte. (14th July 2021)

• Record Type: Journal Article
• Authors: Tong, Zhongqiu; Kang, Tianxing; Wan, Yingpeng; Yang, Rui; Wu, Yan; Shen, Dong; Liu, Shihao; Tang, Yongbing; Lee, Chun‐Sing
• Is Part Of: Advanced functional materials. Volume 31:Number 41(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-07-14
• Subjects: aqueous batteries -- Ca‐ion redox -- electrochromic batteries -- multivalent‐ion charge carrier -- water‐in‐salt electrolytes; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202104639
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Multivalent‐ion batteries with electrochromic functionality are an emerging green technology for development of low‐carbon society. Compared to Mg 2+, Zn 2+ and Al 3+, Ca 2+ has a low polarization strength similar to that of Li +, therefore Ca 2+ for electrochromism and battery can avoid kinetic issues caused by other multivalent‐ions with high polarization strength. Here, by exploiting Ca‐ion carriers for electrochromism and a water‐in‐salt (WIS) Ca(OTF)2 electrolyte for the first time, a new and safe aqueous Ca‐ion electrochromic battery (CIEB) has been demonstrated. The WIS Ca(OTF)2 electrolyte demonstrates enhanced anion‐cation interactions and decreased water activity. Vanadium oxide (VO x ) and indium hexacyanoferrate (InHCF) films are respectively developed as anode and cathode because of their stable and high‐rate Ca 2+ insertion/extraction, as well as matched electrochromism. The CIEB demonstrates a stable and high‐rate capability, a high energy density of 51.4 mWh m −2 at a power density of 1737.3 mW m −2, and a greenish yellow‐to‐black electrochromism. The presented results are beneficial for understanding redox kinetics in WIS electrolytes, and inspire researches on batteries and electrochromism with multivalent‐ions. Abstract : An aqueous calcium‐ion electrochromic battery is built by exploiting Ca‐ion carriers for electrochromism and a novel water‐in‐salt Ca(OTF)2 electrolyte for the first time. This device demonstrates an excellent rate capability, high cycling stability, a good energy density of 51.4 mWh m −2 at a power density of 1737.3 mW m −2, and an attractive greenish yellow‐to‐black electrochromism during the charge/discharge processes.