Gradient catalyst layer design towards current density homogenization in PEM water electrolyzer with serpentine flow field

Abstract

The inhomogeneous current density distribution might cause irreversible damage to the membrane electrode assemblies of proton exchange membrane water electrolyzers. Herein, the impact of gradient catalyst distribution on the current density uniformity inside the electrolyzer with serpentine flow field is investigated using a three-dimensional model. The gradient catalyst distribution in parallel and vertical flow directions is considered. It is found that, at low working voltage (1.8 V), gradient catalyst loading in the vertical flow direction would enhance the current density distribution uniformity by 77.6 %, and at the same time improve the electrolyzer performance by up to 4.0 %, whereas in parallel flow direction the corresponding improvement is by 34.5 % and 4.17 %, respectively. At high working voltage of 2.4 V, due to the pronounced impact of mass transportation process, similar and limited improvement in the current density uniformity (11.47–11.87 %) and electrolyzer performance (1.3–1.45 %) is found under the gradient catalyst loading design in both flow directions. This study provides important guidance for the design of proton exchange membrane water electrolyzer using serpentine flow field.