Ex-situ analysis of interlayer membranes for metal-sulfur batteries with solid polymer electrolytes

Metal-sulfur batteries with solid polymer electrolytes are advantageous from both an energy density and a safety standpoint. However, the polysulfide shuttle effect is one challenge that plagues these batteries from being commercially viable for most applications. Polymeric interlayer membranes can be employed in metal-sulfur batteries to mitigate polysulfide transport out of the cathode and into the bulk electrolyte. These interlayers have commonly been studied for use in metal-sulfur batteries with liquid electrolytes via ex-situ analyses. Here, we report on methodology for ex-situ analysis of species transport across polymer interlayers to be used in lithium-sulfur batteries containing solid polymer electrolyte. Visual and elemental analyses were conducted to determine the interlayers’ abilities to reject polysulfides as a result of varying polysulfide contact time, repelling ion content, and applied potential to the system. As color change in polymer films correlates to polysulfide uptake, a visual analysis was done to quantitatively assess polysulfide uptake in the interlayers. Elemental analysis on lithium and sulfur concentration in the interlayers revealed movement of lithium, polysulfides, and electrolyte anions. Furthermore, it was shown that an increase in ion content for ionomeric interlayers composed of crosslinked copolymers based on polyethers and tethered anions leads to better polysulfide rejection. • Ex-situ testing polysulfide-rejecting interlayers for solid metal-sulfur batteries. • Both diffusion and migration setups were demonstrated. • Rejection capability determined with colorimetric analysis and elemental analysis.