High-Modulus Single-Ion-Conducting Electrolytes Based on a Rigid-Rod Polyanion

Single-ion-conducting electrolytes enable easy processingand canblock Li dendritic growth, showing potential for use in solid-statebatteries. We report solid electrolytes that combine a rigid-rod polyanion,poly(2,2 & PRIME;-disulfonyl-4,4 & PRIME;-benzidine terephthalamide)(PBDT), with Na+ or Li+ counterions, and poly(ethyleneglycol) (PEG, M (n) = 400 g mol(-1)). PBDT-PEG membranes show Young's modulus from 90 to 2110MPa that increases with the PBDT content and is >4x higherforLi-based vs Na-based electrolytes. We attribute this dramaticallyhigher modulus in LiPBDT-PEG to poorer ion dissociation betweenLi(+) and PBDT sulfonate groups and stronger interactionsbetween LiPBDT and PEG. These membranes show an increase in ionicconductivity with increasing PEG concentration (0.1-7 & mu;Scm(-1) at 30 & DEG;C), reaching 0.13 mS cm(-1) at 120 & DEG;C. These materials use highly rigid and charged PBDTdouble helices to "solidify" low-molecular-weight PEGinto mechanically strong and highly single-ion-conductive solid polymerelectrolytes with high thermal stability. Their combination of highcation conductivity and high modulus exceeds those of competing single-ionconductors at 30 & DEG;C.