Electroreflectance imaging of gold-H₃PO₄ supercapacitors. Part II: microsupercapacitor ageing characterization

Abstract

This microsupercapacitor ageing study demonstrates the usefulness of the electroreflectance technique by quantifying local charge accumulation. Two separate devices with interdigitated electrodes were evaulated over a period of 4.1 million charge/discharge cycles. The key results are spatial mapping of charge accumulation in the gold electrodes derived from variation in the observed electrode reflectance. The nominal device exhibited little change in spatial distribution throughout the ageing cycle and serves as a comparison for the test device, which exhibited some nonuniform charge accumulation behavior. Further, an accelerated ageing test was completed by applying increasing voltage pulses up to 1.46 V to the device. Visual evidence of electrode ageing emerged in the reflectance distribution. An equivalent circuit model was developed to assess the evolution of individual circuit elements that correlate to the physical causes of ageing.

Symmetric All-Solid-State Supercapacitor Operating at 1.5 V Using a Redox-Active Gel Electrolyte

“…In recent years, supercapacitors have emerged to be promising energy storage devices for their fast power delivery, excellent cyclic stability, and low maintenance costs. , The general approach to boost energy density by using pseudocapacitive electrode materials such as transition metal oxides and conducting polymers involves complicated fabrication processes and leads to poor cycle life . Recently, several groups have investigated the possibility of enhancing energy density by introducing redox-active species into the electrolyte.…”