First-principles Study of Novel Conversion Reactions for High-capacity Li-ion Battery Anodes

Anodes for Li-ion batteries are primarily carbon-based due to their low cost and long cycle life. However, improvements to the Li capacity of carbon anodes, LiC6 in particular, are necessary to obtain a larger energy density. Stateof-the-art light-metal hydrides for hydrogen storage applications often contain Li and involve reactions requiring Li transport, and light-metal ionic hydrides are candidates for novel conversion materials. Given a set of known solid-state and gas-phase reactants, we have determined the phase diagram in the Li-Mg-B-N-H system in the grand canonical ensemble, as a function of lithium chemical potential. Our model includes vibrational contributions to the total free energy to obtain finite temperature results. We present computational results for four new conversion reactions that are thermodynamically favorable that do not involve gas evolution.