Characterization of lithium ion supercapacitors

A hybrid Li-ion supercapacitor combines a traditional supercapacitor electrode with a Li-ion electrode and thus is expected to offer a high performance in terms of both power density and energy density. In this paper, lithium ion supercapacitors with three sizes, 40 F, 100 F and 270 F, are investigated. Different test methods including cycling at different C-rates and temperatures, pulse tests and electrochemical impedance spectroscopy are used to evaluate the energy and power performance. It is found that this new approach reaches a higher energy density without losing much power density compared with traditional supercapacitors. However a power optimized lithium ion battery shows a strong competitiveness over a lithium ion supercapacitor.