Pseudocapacitive and battery-type organic polymer electrodes for a 1.9 V hybrid supercapacitor with a record concentration of ammonium acetate

Abstract Aqueous all-organic battery-supercapacitor hybrid (BSH) devices are emerging as promising alternative energy storage systems to conventional metal-ion batteries/supercapacitors in terms of their easy processability, high tunability, cost-effectiveness, and recyclability. In this study, we demonstrate an all-organic BSH device using a record concentration of ammonium acetate (30 m NH4Ac) as a cheap and green electrolyte. This novel water-in-salt system possesses an electrochemical stability window up to 2.1 V. In addition, organic polymers comprising of perylenetetracarboxy diimide core and the mixed aromatic amine groups are employed as negative and positive electrodes, respectively. The polymers show low water solubility, good crystallinity, and nano-morphology, which make them decent candidates for the all-organic aqueous BSH device. More importantly, electrochemical kinetic analysis of polymer electrodes reveals that the negative and positive electrodes display pseudocapacitive and battery-type behaviors, respectively. For the first time, an all-organic BSH device with 30 m NH4Ac is fabricated, which delivers a specific capacity of 42 mA h g−1 at 200 mA g−1 and capacity retention of ca. 63% after 5000 cycles. It further shows the maximum energy density of 16.5 Wh kg−1 and power density of 719 Wh kg−1, depicting great potential in energy storage applications.