Graphene/MnO2 aerogel with both high compression-tolerance ability and high capacitance, for compressible all-solid-state supercapacitors

Abstract

Foam-like graphene with attractive characteristics has been proposed as a promising electrode configuration for compressible supercapacitors. However, current foam-like graphene electrodes are limited by either low compressibility or low capacity. Herein, we used a superelastic graphene aerogel as a conductive backbone and deposited pseudocapacitive materials (MnO₂) into it to obtain a novel compressible electrode with both high compression-tolerance ability and high capacitance. The as-prepared graphene/MnO₂ aerogel withstands 90% repeated compression cycling without any structural collapse and peel-off of MnO₂ spheres from the graphene cell walls. All-solid-state supercapacitors based on graphene/MnO₂ aerogel electrode were assembled to evaluate the electrochemical performances. The gravimetric capacitance of graphene/MnO₂ aerogel reaches 320 F g⁻¹ and can retain 94% even under 90% compressive strain. Moreover, a volumetric capacitance of 66.1 F cm⁻³ is achieved, which is much higher than that of other carbon-based compressible electrodes. Furthermore, several compressible all-solid-state supercapacitors can be integrated and connected in series to enhance the overall output voltage, which offers the potential to meet the needs of practical applications.