Ionic liquid incorporated SPEEK/Chitosan solid polymer electrolytes: ionic conductivity and dielectric study

In this study, polymeric membranes composed of ionic liquid (IL), 1-ethyl-3-methylimidazolium tetrafluoroborate supported sulfonated poly(ether ether ketone) (SPEEK), and chitosan (CS) were prepared as novel promising solid polymer electrolytes (SPEs). First, the SPEEK polymer matrix was obtained by sulfonation of the PEEK polymer backbone. A composite membrane series (SPEEK/CS/IL-(1-4)) was created by adding CS at varying weight ratios according to the SPEEK. Structural, thermal, mechanical, and morphological characterizations were performed by FTIR, TGA, DMA, and SEM, respectively. Proton conductivity and dielectric measurements were performed over a wide temperature range to evaluate electrochemical properties. Composite membranes were stable for electrochemical processes at average temperatures. Storage modules have also improved with the addition of CS. All composite membranes showed ionic conductivities greater than 1 x 10(-4) S.cm(-1), and the maximum conductivity was measured for SPEEK/CS/IL-4 as 9.87 x 10(-3) S.cm(-1). Proton conductivity and dielectric tests showed that the SPEEK/CS/IL membrane series was presented as a novel SPE candidate.