Rechargeable Zinc-Aqueous Polysulfide Battery with a Mediator-Ion Solid Electrolyte

Large scale energy storage for the electric grid will need low cost and high energy density solutions. We demonstrate in this letter a rechargeable zinc-aqueous polysulfide battery in which a metallic zinc anode is separated from a liquid aqueous polysulfide catholyte by an alkali-metal-ion solid-state electrolyte, wherein the alkali metal ion is Na⁺ or Li⁺. The solid-state electrolyte effectively separates the anode from the reactive polysulfide catholyte, preventing the crossover of the polysulfide species and maintaining good electrochemical performance with a reversible discharge capacity of 822 mA h g^-1 with nearly 100% Coulombic efficiency.