Charge Transport in Al₂S₃ and Its Relevance in Secondary Al–S Batteries

In the past 5 years, we have witnessed an increased interest in developing secondary aluminum–sulfur (Al–S) batteries. One of main obstacles to further advance this technology is large overpotentials observed during recharge battery, which a extent are related insulating nature discharge product, namely Al2S3. The present work aims elucidate mechanisms responsible for ionic and electronic transport Al2S3 their eventual connection with experimentally overpotentials. We use density functional theory at hybrid level determine concentrations mobilities set potential charge carriers system. found that despite decent mobilities, all exhibit negligible equilibrium thus cannot contribute conductivity. Nevertheless, estimate 1 V overpotential (a value very close experimentally) exponentially raises presence negatively charged interstitial sulfur ions point practical conductivity reached. Our study points out importance designing strategies increase reduce Al–S