Role of alloying in Cu2O conversion anode for Li-ion batteries

Abstract

The successful use of metal oxides as conversion anodes in Li-ion batteries invokes the formation and subsequent reductive decomposition of Li2O. Given the standard reduction potential of Li/Li+ couple, the reduction of Li2O to Li is a thermodynamic challenge. This work investigates the interaction of Li+ ions with a Cu2O matrix computationally using the first principles-based DFT + U methodology. Alloying of Cu and Li takes place more readily than Li2O formation in the early part of the charge cycle. Li2O formation is predicted in the later part of the charge cycle. We attribute the capacity fading observed in oxide conversion anodes to the irreversible accumulation of Li2O and the reversible charge storage capacity delivered by the conversion anodes to alloying. This work indicates that reversible alloying plays a far greater role in the charge–discharge process than is generally acknowledged.