Single-atom electrocatalyst and gel polymer electrolyte boost the energy density and life of aluminum-sulfur batteries

Abstract

Aluminum-sulfur (Al-S) batteries are regarded as a desirable candidate for large-scale energy storage because of their high energy density and abundant natural resources of electrode materials. To address the critical issues of low discharge voltage and rapid capacity decay in Al-S batteries, here an electrocatalyst-assisted gel-polymer electrolyte (GPE)-based Al-S battery is fabricated using platinum nanoparticles decorated platinum/nitrogen co-doped graphene (PtNG) as sulfur host for positive electrode and metal-organic frameworks (MOF) filled GPE (MOF@GPE) as solid electrolyte. Pt-based active sites derived from Pt nanoclusters’ surface and atomically dispersed Pt-N2 chemical bonds in PtNG can catalyze the decomposition of sulfur and polysulfides in the electrochemical process, greatly accelerating the sulfur redox kinetics. Furthermore, the MOF fillers in MOF@GPE electrolyte significantly inhibit the shuttle effect of polysulfides, efficiently improving the utilization of sulfur. Consequently, the established Al-S battery delivers a specific capacity of 1009 mAh g−1 with a discharge plateau of ∼0.95 V, along with a capacity retention of 65% after 300 cycles, revealing ultrahigh energy density and long cycle life. Such a strategy of combining electrocatalyst and MOF-based gel electrolyte affords a fresh plateau for promoting the rechargeable ability of Al-S batteries, advancing remarkable routes for achieving efficient and stable energy storage devices.