What are polydisulfide polymers?
Disulfide batteries use a redox shuttle between disulfide bonds ($\ce{R-SS-R}$) and two thiolates ($\ce{R-S-}$), e.g.:



Often the counter-ions are $\ce{Li+}$ but this is hardly a requirement. Since two electrons can be transferred in the charging / discharging cycle, the theoretical energy density is very high.

One downside (e.g., in my past research) is that you're breaking the polymer bonds during discharge, creating oligomers and monomers that might be more soluble in the electrolyte than the original polymer. This might cause problems with cyclability, since your electroactive material might leave the electrode.