An all-in-one flexible supercapacitor based on redox ionogel electrolyte with high cycle performance

Abstract In this study, we prepare a kind of supercapacitor (SC) through all-in-one assembled method with redox-active ionogel electrolyte and carbon paper electrodes. The ionogel is compounded with poly (vinyl alcohol) (PVA), polyacrylamide (PAAM), lithium sulfate (Li2SO4), and 1-butyl-3-methylimidazolium bromide ionic liquid (BMIMBr IL). The device reveals outstanding long-term stability of 99.6% percent after 5000 times charge/discharge test in high current density, which is largely owed to the all-in-one method and low loss rate of ionogel that provides confined space, stable structure and good contact between electrodes and electrolytes interfaces. Due to the existence of double cross-link structure, ionogels exhibit excellent mechanical properties, which are proved by bending tests of flexible devices. Additionally, wide potential window of 1.6 V and pseudocapacitance provided by bromide ions redox reaction (Br- /Br3-) make the device have a relatively high area capacitance of 284.8 mF cm−2 in the activated carbon field. Moreover, the device also possesses a high energy density of 25.3 Wh kg−1 with the power density of 99.8 W kg−1 at 0.5 mA cm−2 current density.