High‐temperature operation of PEMFC using pore‐filling PTFE/Nafion composite membrane treated with electric field

Summary A pore‐filling polytetrafluoroethylene (PTFE)/Nafion composite membrane was developed for the high‐temperature operation of proton‐exchange membrane fuel cell (PEMFC). Porous PTFE substrate was filled with Nafion solution and cast under an electric field to align ion channel in the through‐plane direction, in which thermal stability and proton conductivity were improved simultaneously. The membranes keep their ion‐exchange ability at high temperatures above 110°C, whereas the casting membranes do not. Enhanced proton conductivity of 158 mS cm−2 at 80°C was observed in the developed membrane; the conductivity is maintained up to 130°C. The operation of PEMFC with the electrically treated membrane at 120°C showed a performance improvement of 40% compare to the non‐treated pore‐filling membrane as indicated by enhanced proton conductivity. In this study, we demonstrate that the electrical alignment of the ion channel in the through‐plane direction improves the proton conductivity and fuel cell performance at a high temperature for a pore‐filling composite membrane. In this article, we developed a new membrane using electric field and pore‐filling technology. Through structural control using an electric field, we improved the proton conductivity of the pore‐filling membrane and manufactured a thermally stable membrane for a fuel cell simultaneously. The study has novelty in that it has simply produced an improved ion exchange membrane by combining two technologies at once.