Distinct Self-Discharge Processes via Manipulating Electrode Pore Size of Carbon-Based Electrochemical Capacitors

Controlling self-discharge has become imperative for developing advanced electrochemical capacitors for periodic energy storage and integrated circuit design with superior cyclability and long lifespan. Carbons with various pore size distributions exhibit distinct self-discharge performances where the voltage decay rate evolves differently as self-discharge proceeds. A "three-stage" self-discharge model and the concept of two self-discharge drags are proposed, depicting the evolution of driving forces in different carbons. The trajectory of ion migrating out of the double-layer structure can be broken down section-wise and correlated to specific impedance parameters by analyzing the diffusion kinetics data collected throughout the process, which can be further traced back to the structure-dependent drags. The findings deepen the understanding of self-discharge behavior and the effects of pore size on ionic diffusion kinetics, which will inspire exploring the underlying mechanism from a structural characteristics perspective. Rapid and unpredictable self-discharge has significantly limited the use of electrochemical capacitors as a dependable power source. Acquiring a comprehensive understanding of self-discharge has become essential to regulate this phenomenon. A correlation between pore size and the rate of self-discharge are established, highlighting distinct variations of the self-discharge rate based on the ion diffusion kinetics associated with pore size changes.image