Self-discharge of lithium-ion capacitors

In this work we report a detailed investigation about the self-discharge of lithium-ion capacitors (LICs). To date, this process has been only marginally investigated. However,the understanding of the dynamics of the self-discharge taking place in LICs appear of importance in view of the optimization of their performance. We showed that LIC display a rather high self-discharge, comparable to that of electrochemical capacitor, and that the main responsible for this process is the positive electrode. Furthermore, we demonstrated that the use of repeated float tests is affecting the self-discharge of LICs, and that after 50–100 h at high voltage their self-discharge is significantly reduced.