Engineering Redox Potential of Lithium Clusters for Electrode Material in Lithium-Ion Batteries

Low negative electrode potential and high reactivity makes lithium (Li) ideal candidate for obtaining highest possible energy density among other materials. In this work we show a novel route with which the overall electrode potential could significantly be enhanced through selection of cluster size. Using first principles density functional theory and continuum dielectric model, we studied free energy and redox potential as well as investigated relative stability of Li-n (n <= 8) clusters in both gas phase and solution. We found that Li-3 has the lowest negative redox potential (thereby highest overall electrode potential) suggesting that cluster based approach could provide a novel way of engineering the next generation battery technology. The microscopic origin of Li-3 cluster's superior performance is related to two major factors: gas phase ionization and difference between solvation free energy for neutral and positive ion. Taken together, the present study provides insight into the engineering of redox potential in battery and could stimulate further work in this direction.