High temperature operation of a composite membrane-based solid polymer electrolyte water electrolyser

The high temperature behaviour of a solid polymer electrolyte (SPE) water electrolyser based on a composite Nafion-SiO2 membranewas investigated and compared to that of a commercial Nafion membrane. The SPEwater electrolyser performancewas studied from80 to 120 oC with an operating pressure varying
between 1 and 3 bar abs. IrO2 and Pt were used as oxygen and hydrogen evolution catalysts, respectively. The assemblies were manufactured by using a catalyst-coated membrane (CCM) technique. The performance was significantly better for the composite Nafion-SiO2 membrane than commercial Nafion 115.
Furthermore, the composite membrane allowed suitable water electrolysis at high temperature under atmospheric pressure. The current densities were 2 and 1.2Acm-2 at a terminal voltage of 1.9V for Nafion-SiO2 and Nafion 115, respectively, at 100 oC and atmospheric pressure. By increasing the temperature
up to 120 oC, the performance of Nafion 115 drastically decreased; whereas, the cell based on Nafion-SiO2 membrane showed a further increase of performance, especially when the pressure was increased to 3 bar abs (2.1Acm-2 at 1.9 V).