Experimental Study on Calendar Aging of Commercial Lithium-ion Capacitors

As an attractive new-type energy storage device, lithium-ion capacitor (LIC) has widespread commercial value and prospects for development in renewable energy and transportation. Aging behavior is an important indicator for evaluating application value for LIC. However, the research on aging characteristics is currently lacking. In the paper, we conduct floating aging tests on commercial LICs under high or low terminal voltages, which are accelerated by high temperature. We select periodic electrochemical impedance spectroscopy measurements to characterize lifetime. The frequency-domain model is introduced to describe the features and separate the reaction process. The variation rule of model parameters during the whole aging process is calculated. Finally, voltage, as a major factor, is deeply analyzed for its influence on calendar life, which provides a reference for the floating aging mechanism.