Nanocomposite Proton Exchange Membranes Based on Sulfonated Poly (2,6-Dimethyl-1,4-Phenylene Oxide) with Enhanced Performance for Fuel Cell Applications

Abstract

A series of composite membranes based on sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO) comprising phosphotungstic acid (PWA) were fabricated and investigated as polymeric electrolytes for hydrogen/oxygen fuel cell (PEMFC) applications. Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) matrices were first sulfonated to different extents to determine the maximum possible sulfonation degree, which ensures the highest proton conductivity as hydrolytic stability was not sacrificed. Subsequently, 20 wt% of PWA as a strong solid super acid was added into sulfonated polymeric matrices. Prepared composite membranes were characterized for their different properties including water uptake capacity, proton conductivity, and hydrolytic stability. The results of conductivity measurements revealed that in the presence of PWA molecules the proton conductivity of SPPO membranes with sulfonation degree of 40% was improved from 1.82 × 10 −2 S cm −1 to 2.57 × 10 −2 S cm −1 at 25 • C. The improved proton conductivity of the SPPO/PWA composite membranes was attributed to the possible interaction of the hydronium molecules with sulfonate groups on SPPO chains as well as the PWA particles. Moreover, it was found that prepared PWA-filled ionomers (SPPO-40) were able to provide high proton conductivity (0.08132 S cm −1 ) even at elevated temperature ranges (120 • C) as well as hydrolytic stability. Fuel cell performance tests showed that SPPO-40/PWA-20 nanocomposite membranes were able to provide 64% higher power output compared to corresponding pristine SPPO at 80 • C. Owing to the favorable properties of high proton conductivity, high power density, ease of preparation, and low cost, SPPO/PWA composite membrane could be considered as a promising polyelectrolyte for moderate temperature PEMFC applications.

Molecular dynamics simulation analysis of hydration effects on microstructure and transport dynamics in sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) fuel cell membranes

“…Hasani-Sadrabadi et al reported that the observed methanol permeation in nanocomposite PEMs based on SPPO and organically modified montmorillonite clay was decreased compared to Nafion membranes [15]. In a similar work, Aliabadi et al demonstrated that nanocomposite membranes consisting of SPPO with 40% sulfonation level and 20 wt% phosphotungstic acid resulted in higher conductivity than pure SPPO membranes [16]. More recent investigations revealed that various blended acidebase membranes including SPPO/poly(ether imide) (PEI), SPPO/brominated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) and SPPO/poly(benzimidazole) (PBI) offer desirable properties like good morphological strength, acceptable proton conductivity and reduced methanol crossover through the membrane indicating their potential for PEMFC and DMFC applications [17,18].…”

Synthesis and characterization of copolysulfonate of 1,1′-bis(3-methyl-4-hydroxyphenyl)cyclohexane, bisphenol-A, and 4,4′-diphenyl disulfonyl chloride

“…are promising high performance engineering thermoplastics owing to their excellent chemical, thermal, mechanical, thermooxidative, and hydrolytic stability [1][2][3][4][5][6][7][8]. They find their industrial applications in fuel cells, membrane, and other industries.…”

Preparation and performance of sulfonated poly(ether ether ketone) membranes enhanced with ammonium ionic liquid and graphene oxide

“…1,2 The proton exchange membrane (PEM) is the key performance-defining component of PEMFCs and has been the focus of intense research by researchers. 3,4 At present, most PEMs are based on perfluorosulfonic acid (PFSA), which is composed of an electrically neutral unit and an ionized unit covalently bonded to the main chain of a hydrophobic polymer as a pendant group. [5][6][7][8][9] Nafion ® membranes have good proton conductivity and mechanical and chemical stability, though with shortcomings, such as low operating temperature and high cost, which need to be addressed.…”