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 200 V/s and own outstanding cycle performance with similar to 10% degradation after 10,000 cycles at a charge-discharge specific current of 10 A/g. Sponge@RGO@MnO2 based supercapacitors also retain similar to 90% of its capacitance after 10,000 cycles under a scan rate of 10 V/s. The maximum E and highest P of sponge@RGO based device are 2.08 Wh/kg and 94 kW/kg, respectively, at the operate voltage of 0.8 V and the maximum E of 8.34 Wh/kg and highest P of 47 kW/kg are achieved based on the sponge@RGO@MnO2 at the operate voltage of 0.8 V. 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. (C) 2013 Elsevier Ltd. All rights reserved.