Asymmetric Charge Storage Characteristic of Carbon Electrodes in Electric Double Layer Capacitors

Electrochemical capacitors (EC)., also known as supercapacitors (SC)., are widely utilized in energy storage technology., manifesting their superiority of high power density., long cycle life., and maintenance-free throughout entire life cycle. However., a certain degree of asymmetry has been found in the charge storage behavior of the same carbon material when being used as the positive and negative electrodes of electric double layer capacitors (EDLCs). Such a capacitive mismatch between positive and negative electrodes might have adverse effects on the performance of EDLC devices., resulting in the decrease in energy density and power density of the devices. In this work., a self-built EDLC was constructed to conduct cyclic voltammetry measurements for both positive and negative electrodes in various types of electrolytes. Then the influences of scan rate., ion species., and solvent on the asymmetry of carbon electrodes were investigated. These insights will provide rational directions for developing electrochemical capacitors with improved energy storage performance.