Bifunctional TiN@N-doped-graphene catalyst based high sulfur content cathode for reversible Aluminum-Sulfur batteries

Aluminum-sulfur (Al-S) batteries are drawing extensive attentions for the development of economical battery systems owing to the high theoretical capacity of 1672 mAh g(-1) and low-cost naturally abundant electrode materials, Al and S. However, Al-S batteries are beset by poor reversibility and low actual capacity, only few reversible Al-S cells have been reported until now. In this work, factors affecting Al-S batteries performance are explored and explained, such as the inactive discharge product(Al2S3), polysulfides diffusion and the self discharge reaction on the surface of SEI-layer-free aluminum anode. And we demonstrate an improved Al-S battery by effectively adjust the voltage window and develop TiN@N-doped-graphene catalyst materials to modify the sulfur cathode. This catalyst is for the first time applied in Al-S batteries and explored its positive effects during the reversible Al-S reactions. Comprehensive electrochemical testing and ex-situ characterization certificates that, in the discharging process, the shuttle effect of polysulfides is suppressed based on the strong adsorption of catalyst; in the charging process, sulfide redox kinetics are promoted and the decomposition reaction barrier is reduced by the catalyst. The Al-S cell delivers an initial capacity of ~& nbsp;993 mAh g(-1) and maintains a capacity of ~& nbsp;500 mAh g(-1) after 200 cycles.