An azobenzene-modified redox-active ionic liquid electrolyte for supercapacitors

A new redox-active ionic liquid (2-(4-(phenyldiazenyl)phenoxy)ethyl)-1-methyl-imidazolium tetrafluoroborate ([ABEMIM][BF4]) is demonstrated. It is incorporated into another ionic liquid ([EMIM][BF4]) to form a mixed IL electrolyte, which can markedly improve the capacitance performance of carbon-based supercapacitors via extra pseudocapacitance contribution. It opens up a new path to develop high-energy supercapacitors through introducing a redox-active ionic liquid to electrolytes.