High-energy and long-life aluminum−sulfur battery: Employment of electrocatalytic function into continuous multiple reactions within quasi-solid-state electrolyte

Abstract Aluminum−sulfur (Al−S) batteries of ultrahigh energy-to-price ratios are promising for next-generation energy storage, while they suffer from large charge/discharge voltage hysteresis and short lifespan. Herein, an electrocatalyst-boosting quasi-solid-state Al−S battery is proposed, in which sulfur is anchored on the cobalt/nitrogen co-doped graphene (S@CoNG, as the positive electrode) and chloroaluminate-based ionic liquid (IL) is encapsulated into metal-organic frameworks (IL@MOF, as the quasi-solid-state electrolyte). Mechanistically, the Co−N bonds in CoNG act as electrocatalytic center to continuous induce breaking of Al−Cl bonds and S−S bonds and accelerate the kinetics of sulfur conversion, endowing the Al−S battery with much shortened voltage gap of 0.32 V and 0.98 V in the discharge voltage plateau. Within quasi-solid-state IL@MOF electrolytes, shuttle effect of polysulfides has been inhibited, which stabilizes the process of reversible sulfur conversion. Consequently, the assembled Al−S battery presents high specific capacity of 820 mAh g−1 and 78% capacity retention after 300 cycles. This concept here offers novel insights to design practical Al−S batteries for stable energy storage.