Asymmetric aqueous electrochemical capacitors with energy densities as high as 22 Wh kg-1, power densities of 11 kW kg-1 and a cell voltage of 2 V were fabricated using cost effective, high surface carbon derived from coal tar pitch and manganese dioxide. The narrow pore size distribution of the activated carbon (mean pore size ∼0.8 nm) resulted in strong electroadsorption of protons making them suitable for use as negative electrodes. Amorphous manganese dioxide anodes were synthesized by chemical precipitation method with high specific capacitance (300 F g-1) in aqueous electrolytes containing bivalent cations. The fabricated capacitors demonstrated excellent cyclability with no signs of capacitance fading even after 1000 cycles.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Energy Engineering and Power Technology
- Physical and Theoretical Chemistry
- Electrical and Electronic Engineering