High load, long cycle and flexible zinc-ion hybrid supercapacitors

Zinc-ion hybrid supercapacitor (ZIHS) combines the advantages of both batteries and capacitors to achieve high operating voltage, high energy and high power density. It is considered as a novel sustainable electrochemical energy storage device, but the problems of poor cycling stability and low energy density in most ZIHS still need to be solved. In this work, MnO2@ carbon cloth cathode with high load of 17.2 mg cm−2 was fabricated by in-situ deposition and hydrothermal treatment, and the active carbon extracted from banana peel was used as the anode. The assembled flexible ZIHS device exhibits a remarkable combination of high energy density and high specific capacity, attributed to the synergistic effect achieved by employing two distinct morphologies of MnO2 composites. Notably, the energy density of 674 μWh cm−2 can be maintained at a power density of 999 μW cm−2 In addition, the aqueous ZIHS retention rate was 94.56 % in 80,000 cycles. Therefore, the research results are of great significance to develop a safe, reliable and high electrochemical performance storage device.