Faradaic and Non-Faradaic Self-Discharge Mechanisms in Carbon-Based Electrochemical Capacitors

Electrochemical capacitors (ECs) play a crucial role in electrical energy storage, offering great potential for efficient energy storage and power management. However, they face challenges such as moderate energy densities and rapid self-discharge. Addressing self-discharge necessitates a fundamental understanding of the underlying processes. This review sets itself apart from other reviews by focusing on the basic principles of self-discharge processes in carbon-based ECs, particularly examining the nature of the process and the involvement of redox reactions. This study delineates the potential conditions for various self-discharge processes and proposes plausible criteria for differentiation, complemented by mathematical modeling. Additionally, the model selection, curve fitting, and effective tuning methods are explored to control self-discharge processes. This perspective introduces self-discharge origins with respect to their diagnostic models. By categorizing them into Faradaic and non-Faradaic processes, the perspective helps researchers identify self-discharge mechanisms with possible suppression tactics highlighted and the necessity of developing characterization guidelines and techniques complementing diagnostic models to establish the self-discharge science. image