A reversible water electrolyser with porous PTFE based OH− conductive membrane as energy storage cells

• A reversible water electrolyser was prepared with porous PTFE based OH− membrane.
• Current density was improved by adopting the PFTE composite OH− membrane.
• The peak power density in fuel cell mode achieved 0.163 W cm−2 at 45 °C.
• In the water electrolyser mode, degradation rate was only 0.0379 mV h−1.

An OH− conductive anion exchange membrane was prepared by a pore-filling method with porous polytetrafluoroethylene and a quaternary ammonium polymethacrylate ionomer. The composite membrane exhibited less swelling ratios of thickness and area variation and stronger tensile strength than the pristine polymethacrylate membrane. The ionic conductivity of the composite membrane was not as good as the pristine polymethacrylate ionomer membrane. However, the composite membrane was ultra-thin therefore it leaded to a smaller ionic resistance of the MEA and improved current densities. In fuel cell mode, the peak power densities were respectively 0.114 and 0.163 W cm−2 at 20 and 45 °C. In water electrolyser mode, at a current density of 100 mA cm−2 the cell voltages were about 1.61 V and 1.52 V respectively at 22 °C and 50 °C. In the water electrolyser mode, the degradation rate was only 0.0379 mV h−1 after 120 h at a current density of 100 mA cm−2 at 22 °C.