Facile dip coating processed graphene/MnO2 nanostructured sponges as high performance supercapacitor electrodes

Graphene-MnO2 based supercapacitors with excellent power and energy density make them potentially promising candidates for future energy storage systems. However, it is still a challenge to develop a simple, inexpensive and scalable method to fabricate such capacitors. Here, a low cost “dip and dry” processes were used to fabricate hierarchical graphene/MnO2 nanostructured sponges with high performance as hybrid supercapacitor electrodes. Commercial sponges were chose as skeletons to construct homogeneous three-dimensional interconnected macro-network RGO composite, which can be operated even under a high scan rate of 200V/s and own outstanding cycle performance with ∼10% degradation after 10,000 cycles at a charge–discharge specific current of 10A/g. Sponge@RGO@MnO2 based supercapacitors also retain ∼90% of its capacitance after 10,000 cycles under a scan rate of 10V/s. The maximum E and highest P of sponge@RGO based device are 2.08Wh/kg and 94kW/kg, respectively, at the operate voltage of 0.8V and the maximum E of 8.34Wh/kg and highest P of 47kW/kg are achieved based on the sponge@RGO@MnO2 at the operate voltage of 0.8V. The high specific capacitance, wide operation range, good energy and power density, excellent cycling stability, facile preparation process, and low cost of as-fabricated supercapacitors could make them as promising devices for commercial production.