Fabrication of PANI-coated honeycomb-like MnO2 nanospheres with enhanced electrochemical performance for energy storage

A new binary composite of MnO2/PANI has been synthesized as electrode material for energy storage. In the composite, the MnO2 nanospheres with a honeycomb-like structure are coated with PANI layers, in which MnO2 serve as a scaffold for PANI layer and PANI act as a protective coating layer to restrain MnO2 nanospheres from dissolution in acidic electrolyte, and causing a synergic effect. The composite, when the mass ratio of MnO2 and aniline is 1:1, exhibits a high specific capacitance of 565 F g(-1) (specific capacity of 126 mAh g(-1)) at a discharge current density of 0.8 A g(-1) and a high specific capacity of 143 mAh g(-1) at the scan rate of 20 mV s(-1) in 0.5 M Na2SO4-0.5 M H2SO4 solution. In addition, the electrode material retains about 77% of the initial capacitance after 1000 cycles of charge-discharge at 8 A g(-1). These results demonstrate that the special morphology and shorter diffusion pathways (SEM and EIS) make the binary composite a promising candidate for future energy storage applications. (C) 2015 Elsevier Ltd. All rights reserved.