Electrochemical double layer capacitor using a microemulsion electrolyte

TL;DR

This paper introduces a microemulsion electrolyte enabling aqueous supercapacitors to operate at voltages up to 5 V, significantly enhancing energy density and cycle life while maintaining safety and cost benefits.

Contribution

It presents a novel microemulsion electrolyte that extends the voltage window of aqueous supercapacitors to 5 V, improving performance and longevity.

Findings

Achieved ~40 F/g capacitance in supercapacitors.

Reached ~40 Wh/kg energy density.

Maintained 99% Coulombic efficiency over 10,000 cycles.

Abstract

The use of aqueous electrolytes in energy storage devices is traditionally limited by the voltage stability window of water at 1.23 V. We present the use of a microemulsion based electrolyte which, although mostly water by mass, has a voltage stability window of up to 5 V. This allows the cost and safety benefits of aqueous electrolytes to finally be realised in high-voltage systems. Supercapacitors constructed using this electrolyte were able to achieve and maintain a capacitance of ~40 F/g and an energy density ~40 Wh/kg of with a Coulombic efficiency of 99\% for over 10,000 cycles on activated carbon.