Improved Energy Capacity of Aprotic Li-O2 Batteries by Forming Cl-Incorporated Li2O2 as the Discharge Product

Aprotic lithium oxygen (Li-O-2) batteries are promising devices for use in sustainable energy management systems as they have the potential to achieve significantly higher energy densities than current state-of-the-art Li-ion batteries. However, the low electrical conductivity of the main discharge product, lithium peroxide (Li2O2), which forms on the positive electrode, gradually suppresses the electrochemical reactions involved in the discharge process, thereby lowering the energy capacity of these systems. Herein, we demonstrate that the energy capacity of Li-O-2 batteries can be significantly improved by simply adding chloride ions to the electrolyte. Scanning electron microscopy analysis revealed that thick chloride (Cl)-incorporated Li2O2 films formed on the positive electrode as the discharge product. Using conductive atomic force microscopy, the Cl-incorporated Li2O2 films were shown to exhibit much higher electric conductivity than pristine Li2O2.. Taken together, the present findings suggest that modulation of the electrical conductivity of the discharge product by the incorporation of heteroatoms is an effective approach for constructing Li-O-2 batteries with high volumetric energy density.