Versatility of sulfonated poly (vinylidene fluoride‐co‐hexafluoropropylene) membranes incorporated with sulfonated octaphenyl polyhedral oligomeric silsesquioxane for vanadium redox flow battery applications

Abstract

Hybrid membranes are fabricated using the blends of sulfonated poly (vinylidene fluoride‐co‐hexafluoropropylene) (SPVDF‐co‐HFP) and sulfonated octaphenyl polyhedral oligomeric silsesquioxane (SOPS) as an alternate for expensive Nafion in vanadium redox flow battery (VRFB) applications. The FT‐IR and TEM investigation indicates the successful sulfonation of OPS and uniform distribution of SOPS. The morphological study of hybrid membranes by SEM–EDX and FESEM revealed the excellent dispersing ability of SOPS on a SPVDF‐co‐HFP matrix. The physicochemical analysis of SPVDF‐co‐HFP/SOPS membranes demonstrated an increase in hydrophilic ion‐exchangeable sites. The SPVDF‐co‐HFP/SOPS (0.5 wt.%) membrane displayed a maximum proton conductivity of 6.27 × 10−3 Scm−1 at 80°C because of strong hydrogen bond formation between SPVDF‐co‐HFP and SOPS facilitates proton migration. Besides, the cage‐like structure of SOPS effectively shields vanadium‐ion permeation to 1.21 × 10−8 cm2 min−1 and thus, showed a maximum membrane selectivity of 43.05 × 104 Scm−3 min. Overall, the hybrid membranes of SPVDF‐co‐HFP/SOPS were considered to be a better substitute for Nafion in VRFBs.

Poly(biphenyl piperidinium) Amphiphilic Membranes Functionalized with Propyl Sulfonic Acid and Octadecyl Side Chains for Vanadium Redox Flow Batteries

“…7−9 Therefore, the design of membranes with good ionic conductivity, low vanadium ion permeability, and excellent chemical stability is crucial for VRFB applications. 10,11 The widely used membranes in VRFBs are Nafion proton exchange membranes (PEMs), which generally have high ionic conductivity but suffer from high cost and severe vanadium ion cross-contamination. 7,12−14 Sulfonated aromatic proton exchange membranes based on poly(aryl ether sulfone), 15−19 poly(aryl ether ketone), 20−22 and poly(phenylene ether) 23−26 classes have attracted much attention owing to their lower cost and ease of modification.…”