Hole Polaron Diffusion in the Final Discharge Product of LithiumSulfur Batteries
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2017 American Chemical Society. Poor electronic conductivity of bulk lithium sulfide (Li 2 S) is a critical challenge for the debilitating performance of the lithium-sulfur battery. This study focuses on investigating the thermodynamic and kinetic properties of native defects in Li 2 S based on a first-principles approach. It is found that the hole polaron p + can form in Li 2 S by removing a 3p electron from an S 2- anion. The p + diffusion barrier is only 90 meV, which is much lower than the Li vacancy (V Li- ) diffusion barrier. Hence p + has the potential to serve as a charge carrier in the discharge product. Once the vacancy-polaron complex (V Li- -2p + ) forms, the charge transport will be hindered due to the relatively higher diffusion barrier of the complex. Heteroatom dopants, which can decrease the p + formation energy and increase V Li- formation energy, are expected to be introduced to the discharge product to improve the electronic conductivity. (Figure Presented).