Study of cycle performance of Li-ion capacitors

Li-ion capacitors were assembled with an activated carbon cathode and hard carbon/stabilized lithium metal powder (SLMP) anode. The stabilities of cathode and anode were determined by different methods, including the half-cell and full-cell methods. It was found that the highest potential of the activated carbon electrode should be less than 4.5 V vs. Li/Li⁺ potential; while the lowest potential of hard carbon/SLMP electrode should be greater than 0.1 V vs. Li/Li⁺ potential. Scanning electron microscopy images showed that the growth rate of the solid electrolyte interface (SEI) layer increased rapidly when the lowest potential of hard carbon/SLMP electrode was less than 0.1 V vs. Li/Li⁺ potential.