Improving Li$_2$O$_2$ conductance via polaron preemption: an \textit{ab initio} study of Si doping

Abstract

We report on \textit{ab initio} electronic structure simulations of Li$_2$O$_2$, where 1.6% of lithium atoms are substituted by silicon. It is demonstrated that this leads to the formation of conducting impurity states in the band gap of Li$_2$O$_2$. We show that these states originate from the antibonding orbitals of the oxygen pairs and are remarkably stable against possible polaron formation (upon electron injection). Through this polaron preemption mechanism, the proposed compound is expected to show significantly higher electronic mobility than stoichiometric Li$_2$O$_2$, which could have significant applications in lithium-air batteries.