A redox-active electrolyte supercapacitor (RAES) is a promising system that increases the energy density of supercapacitors by adding pseudocapacitance from a redox couple in the electrolyte. However, the energy density of RAESs is still too low for practical use. Enhancing both the operating voltage window and the capacitance of RAESs is essential. In this study, a nonaqueous redox-active electrolyte was designed based on the relative position of the electrochemical stability window of the supporting electrolyte and the redox potential of a redox couple. The combination of decamethylcobaltocene/decamethylcobaltocenium and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide in adiponitrile not only provides additional capacitance from a faradaic redox reaction (21.3 → 57.1 F g–1) but also extends the operating voltage window to nearly the full electrochemical stability window of the supporting electrolyte (3.1 V). A carbon-nanotube-based RAES shows outstanding performance, including improved energy density (75.6 Wh kg–1), compared to previously reported nonaqueous RAESs. This systematic approach could significantly advance the development of high-performance nonaqueous RAESs.-Scientific Journal cover design by scapiens
[Scientific Journal cover design] Low-Thermal-Budget Fluorite-Structure Ferroelectrics for Future Electronic Device Applications
In article number 2100028, Jiyoung Kim, Si Joon Kim, and their team review key factors involved in developing fluorite-structure ferroelectrics
