Phytic acid modified manganese dioxide/graphene composite aerogel as high-performance electrode materials for supercapacitors

Abstract

Incorporating manganese dioxide (MnO2) with reduced oxide graphene (RGO) holds great potential as favourable supercapacitor electrodes for energy storage applications. In order to improve the adhesive strength and stability, we synthesized a phytic acid (PA)-linked MnO2/RGO aerogel (MnO2/P-RGO) through a simple self-assembled hydrothermal and freeze-drying method. Herein, PA as a bridge could accelerate the firm immobilization of MnO2 on RGO sheets to synthesize the composite aerogel with a three-dimensional (3D) layered porous structure. The 3D MnO2/P-RGO composite aerogel as a supercapacitor electrode could achieve the high specific capacitance of 645 F g−1 under the current density of 1 A g−1 and 410 F g−1 at 40 A g−1. Furthermore, the composite aerogel exhibits remarkable long-term stability, 94.9% of the initial capacitance after 10,000 cycles under the high current density of 20 A g−1. Moreover, the assembled MnO2/P-RGO//RGO asymmetric supercapacitor (ASc) shows the maximum energy density of 59.2 W h kg−1at 1.48 kW kg−1 and could remain 28.8 W h kg−1 at the maximum power density of 57.6 kW kg−1. Additionally, the MnO2/P-RGO//RGO ASc also exhibits excellent long cycling stability with 91.6% of the initial capacitance after 10,000 cycles at 20 A g−1, indicating its promising practical application for high-efficiency supercapacitors.