Fast surface proton conduction on acid-doped polymer nanofibers in polymer electrolyte composite membranes

• Published in: Electrochimica acta 2019-02, Vol.296, p.1042-1048
• Main Authors: Ibaraki, Taku, Tanaka, Manabu, Kawakami, Hiroyoshi
• Format: Article
• Language: English
• Subjects: Acids; Electrolytes; Electrolytic cells; Fuel cell; Fuel cells; Humidity; Membranes; Nanofiber; Nanofibers; Nanoionics; Phosphoric acid; Phytic acid; Polymer electrolyte; Polymers; Proton conduction; Relative humidity; Sulfonic acid; Ultra-thin membrane
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2018.11.157

Fast surface proton conduction on the acid-doped nanofibers was demonstrated to achieve low membrane resistance under low relative humidity or unfumidified conditions for future fuel cell applications. Polymer electrolyte composite membranes composed of phytic acid-doped polybenzimidazole nanofibers embedded in sulfonated polyimide were designed and fabricated. Scanning transmission electron microscopic observation and proton conductivity measurements of uniaxially-aligned nanofiber composite membranes revealed that the phosphoric acid groups in the doped acid and sulfonic acid groups of the polymer electrolyte matrix were aggregated at the surface of the nanofibers to construct effective proton conductive pathway. In addition to low membrane resistance based on fast surface proton conduction on the acid-doped nanofibers, distinguished gas barrier property and improved membrane stability of the acid-doped nanofiber composite membrane will promise high-performing fuel cells, especially by fabricating ultra-thin polymer electrolyte membrane that can be efficiently operated at low relative humidity. [Display omitted] •Fast surface proton conduction on the acid-doped nanofibers was demonstrated.•Acid groups on the nanofibers constructed effective proton conductive pathways.•An ultra-thin polymer electrolyte membrane with low resistance was obtained.