An Aluminum-Sulfur Battery with a Fast Kinetic Response.

The electrochemical performance of the aluminum-sulfur (Al-S) battery has very poor reversibility and a low charge/discharge current density owing to slow kinetic processes determined by an inevitable dissociation reaction from Al2 Cl7- to free Al3+ . Al2 Cl6 Br- was used instead of Al2 Cl7- as the dissociation reaction reagent. A 15-fold faster reaction rate of Al2 Cl6 Br- dissociation than that of Al2 Cl7- was confirmed by density function theory calculations and the Arrhenius equation. This accelerated dissociation reaction was experimentally verified by the increase of exchange current density during Al electro-deposition. Using Al2 Cl6 Br- instead of Al2 Cl7- , a kinetically accelerated Al-S battery has a sulfur utilization of more than 80 %, with at least four times the sulfur content and five times the current density than that of previous work.