V2O5 Polysulfide Anion Barrier for Long-Lived Li–S Batteries

We describe a V 2 O 5 polysulfide anion barrier for a Li–S battery containing a Li metal anode, an organic solvent-based electrolyte, and a nanostructured carbon–sulfur composite cathode that cycles without degradation from dissolution of soluble polysulfide anions. Degradation is prevented by the micrometer-scale V 2 O 5 layer that physically isolates the anode and cathode electrolytes, thus blocking diffusion of dissolved polysulfide anions while permitting solid-state transport of Li + cations. This divided cell architecture eliminates the interaction of soluble polysulfide with the Li anode. Mechanical integrity of the thin V 2 O 5 layer is achieved by depositing the layer on a commercial polymeric battery separator. In addition, the isolated cathode electrolyte is optimized by the intentional addition of Li 2 S 8, which suppresses redistribution of sulfur within the nanostructured carbon–sulfur composite cathode. A 5 mA h pouch cell of this design has been cycled >300 times over ∼1 year without noticeable degradation at capacities of 800 mA h g-sulfur –1 .