Supercapacitors, as promising electrochemical energy storage devices, are spurring great interests for energy storage due to their excellent cyclability, high power density, fast charging rate, high efficiency and easy fabrication. Supercapacitors can complement batteries in many cases where high power and extensive cycling are required. Organic electrolytes used in current EDLC supercapacitors are flammable, toxic, expensive, not environmentally friendly, and may cause fire and other safety concerns. On the other hand, aqueous electrolyte with better ionic conductivity and low cost could be used for next-generation large scale supercapacitors with enhance safety and low environmental impact. However, thermodynamic voltage window of aqueous electrolyte (~1.2V) in symmetric capacitors could significantly limit energy density. This issue could be addressed by introduction of asymmetric design, where high overpotentials for H2 and O2 evolution at the EDLC negative and pseudocapacitive positive electrode could extend the effective voltage window of aqueous electrolyte to above 2V. In this presentation, our recent efforts on one-pot synthesis of composites at nanoscale for pseudocapacitive positive electrode in asymmetric aqueous supercapacitors will be discussed. Various experiments are carried out to elucidate the formation mechanism, optimize the formation conditions, and enhance electrode conductivity and stability. The improved electrochemical performance in terms of specific energy, specific power, cycling performance are elucidated by electrochemical characterization.

One-pot synthesis of composites for aqueous supercapacitors

244th National Meeting (2012)

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