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Highlights

A novel composite membrane incorporated glass microfiber (GMF) and polytetrafluoroethylene (PTFE) nanoporous film is applied to phosphoric acid fuel cell for performance enhancement.

From room temperature to phosphoric acid fuel cell maximum operating temperature 220 °C, GMF and PTFE have almost no loss on weight.

To meet high conductivity and long-term durability at the same time, this study proposes a new composite membrane by stacking two membranes with different porosities and functions together.

From AC impedance analysis, the proton conductivity (0.71 S/cm at 150 °C) of the composite membrane is much higher than those of reported phosphoric acid porous membranes (∼10−2 S/cm at 150 °C).

A fuel cell using the composite membrane with Pt/C catalyst exhibits a high performance with a peak current density of 1761 A/cm2 and power density of 614 mW/cm2 at 140 °C with H2 and pure O2 supply.

Abstract

A novel composite membrane consisting glass microfiber (GMF) and polytetrafluoroethylene (PTFE) nanoporous film is applied to phosphoric acid fuel cell (PAFC) for performance enhancement and reducing electrolyte leakage. With 93% high porosity, the GMF can fully load phosphoric acid to maintain high proton conductivity. However, the large opening of the GMF membrane cannot effectively prevent the leakage of phosphoric acid. Therefore, in this study, a 25 μm thick PTFE thin film with pore size 50–400 nm is employed to cover the surface of GMF for preventing phosphoric acid leakage. This composite proton exchange membrane possesses both thermal and chemical stability at the working temperature of phosphoric acid fuel cell, while providing high proton conductivity. The proton conductivity of the composite membrane (0.71 S/cm at 150 °C) is much higher than those of reported phosphoric acid porous membranes (∼10−2 S/cm at 150 °C). The fuel cell using the composite membrane with Pt/C catalyst exhibits excellent performance with peak power density of 614 mW/cm2 and current density of 1761 mA/cm2 at 140 °C under pure H2 and O2 supply, while proton conductivity is maintained 2.6 times higher than that of the pure GMF membrane due to the less phosphoric acid leakage by using PTFE film.

Keywords

Phosphoric acid

Composite membrane

High temperature fuel cell

Hygrogen energy

Fuel cell

© 2018 Published by Elsevier Ltd.