Study of Accelerated Aging Effects on Hybrid Supercapacitors Under Different Fast-Charging Strategies

Hybrid supercapacitors (HSCs) combine the high power density and long cycle life of electrochemical double-layer capacitors (EDLCs) with the energy density of batteries, offering a promising alternative for various applications, including electric vehicles (EVs) and energy management in power grids. However, aging mechanisms can affect HSCs’ performance significantly during high-stress charge phases. This article investigates the effects of accelerated aging on HSCs under different fast-charge profiles. Eight HSCs were subjected to an extensive test campaign involving electrochemical impedance spectroscopy (EIS) and fast-charge/discharge cycles to analyze the impact that accelerated wear-out has on the capacity fading and the internal resistance (IR) of the HSCs. A customized experimental setup was employed to monitor degradation trends, providing a comprehensive dataset over a wide frequency range (100 mHz–100 kHz) at a constant temperature of 20 °C. Additionally, this work evaluates the performance of two capacity degradation models to predict the remaining useful life (RUL) of the HSCs. The results provide insights into the degradation mode of HSCs under different stress conditions in terms of rates and overheating and highlight the role of fast-charge strategies in influencing cycle life and device health. Significantly reduced lifetimes were observed, limited to a few hundred cycles, along with sensible differences in IR trends, with increments above 90% under constant-current constant-voltage (CCCV) profiles.