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 Al2Cl7− to free Al3+. Al2Cl6Br− was used instead of Al2Cl7− as the dissociation reaction reagent. A 15‐fold faster reaction rate of Al2Cl6Br− dissociation than that of Al2Cl7− 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 Al2Cl6Br− instead of Al2Cl7−, 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.