Mixed bi-material electrodes based on LiMn_2O_4 and activated carbon for hybrid electrochemical energy storage devices

摘要

The performance of mixed bi-material electrodes composed of the battery material, LiMn_2O_4, and the electrochemical capacitor material, activated carbon, for hybrid electrochemical energy storage devices is investigated by galvanostatic charge/discharge and pulsed discharge experiments. Both, a high and a low conductivity lithium-containing electrolyte are used. The specific charge of the bi-material electrode is the linear combination of the specific charges of LiMn_2O_4 and activated carbon according to the electrode composition at low discharge rates. Thus, the specific charge of the bi-material electrode falls between the specific charge of the activated carbon electrode and the LiMn_2O_4 battery electrode. The bi-material electrodes have better rate capability than the LiMn_2O_4 battery electrode. For high current pulsed applications the bi-material electrodes typically outperform both the battery and the capacitor electrode.