Investigation into the morphological implications on electron transfer dynamics of lithium peroxides by scanning electrochemical microscopy

Lithium–air batteries are highlighted as one of promising next generation battery technology with high gravimetric energy density. To date, however, cyclability of lithium–air batteries has been low, insufficient for commercial use. Many recent research accounts focused on understanding the mechanism of the discharge reaction in attempts to improve the cyclability, and revealed that two structurally distinct lithium peroxide species form during discharge, thin films and toroids, among which toroids formation results in beneficial effects in both cyclability and overall discharge capacity. In this work, scanning electrochemical microscopy was applied to investigate electron transfer dynamics of the two lithium peroxide species, from which a much faster surface electron transfer was observed from lithium peroxide toroids compared to that of thin films. The difference is postulated to stem from the difference in the formation mechanism of the two species.