Surface-functionalized graphene-based quasi-solid-state Na-ion hybrid capacitors with excellent performance

A novel energy storage device called quasi-solid-state symmetric Na-ion capacitor (QSS-NIC) has been developed by using oxygen-functionalized crumpled graphene as both anode and cathode and Na-ion conducting gel polymer as electrolyte. Benefiting from the elaborate design of electrode material and configuration, the QSS-NIC achieves a high energy density, high power density and prominent cycling stability.160