Flexible low-temperature zinc ion supercapacitor based on gel electrolyte with α-MnO2@rGO electrode

Zinc ion supercapacitors (ZSCs) are considered to be a new generation of energy storage device because of their low cost and battery-like performance. However, the uncontrollable structural deformation and poor cyclic stability make them a great challenge in practical applications. Herein, we developed a flexible quasi-solid-state ZSC assembled with gel electrolytes, porous α-MnO2@reduced graphene oxide(α-MnO2@rGO) cathode, and activated carbon/carbon cloth (AC/CC) anode. The gel electrolytes containing polyvinyl alcohol (PVA), carboxymethylcellulose (CMC), and ethylene glycol (EG) shows great mechanical properties, good electrical conductivity, and can afford a wide electrochemical potential window. The flexible ZSC exhibited an excellent specific capacitance of 575.5 mF cm−2 at a current density of 6 mA cm−2 and good stability during bending test. More important, the device can achieve stable electrochemical properties at low temperature of −20 °C, cycle retention can maintain 89.189 % even after 5000 cycles. This work has successfully proposed an energy storage system with excellent performance, which provides possibilities for multi-scene applications of flexible devices.