MULTI-ELECTRON ELECTROCHEMICAL CHARGE STORAGE IN TWO-DIMENSIONAL TRANSITION METAL COMPOUNDS

摘要

Next generation batteries needed for numerous consumer and vehicular applications require improved electrochemical charge storage materials that have higher capacities and longer cycle lives. Rather than using typical single-electron per molecule electrochemical charge storage processes, multi-electron charge storage processes can provide materials with significantly higher capacities. Various multi-electron charge storage transition metal compounds (based on transition metals such as V, W, Mb, Fe, etc.) have been evaluated as intercalation cathodes including V2O5 (V oxidation state: 3+ to 5+) and K2FeO4 (Fe oxidation state: 3+ and 6+). However, obtaining high capacity and high reversibility is a significant challenge with current multi-electron materials. As compounds change oxidation states during intercalation, two specific issues that affect reversibility are (i) the significant structural changes that result in loss of electrical contact, and (ii) different compound solubilities that cause material dissolution.