Operando monitoring of local current density distributions in anion exchange membrane water electrolysis

Kurzfassung

The integration of renewable energy sources in the electricity grid raises new challenges regarding intermediate storage of energy to cover the energy demand at any time and to overcome the gap between temporal availability of renewable energy and the actual needs. Electrochemically generated hydrogen represents one of the most promising options for solving this issue. Due to its high efficiency, compactness, simple and robust system design, high hydrogen purity, and low cost components, anion exchange membrane water electrolysis (AEMWE) can be beneficially used to convert this surplus energy into hydrogen. Nevertheless, technological challenges have to be overcome for a wide spread commercialization of this technology, including stack performance and lifetime as well as suitable operation strategies. The joint R&D project INSIDE - In-situ Diagnostics in Water Electrolysers developed in-situ diagnostics tools for monitoring of the locally resolved current densities in different water electrolysis technologies. The investigated tools are based on the segmented printed circuit board (PCB) technology patented by DLR and widely used already in the fuel cell community. For the adaption to the new application of AEMWE, new requirements regarding the layout and the used materials had to be taken into account. Thereby, the electrochemical and thermal conditions should not be influenced by the applied monitoring tool. The developed PCB prototype for AEMWE was integrated into short stacks using 3 and 19 cells. Significant challenges for this integration were the modification of the sealing concept and the avoidance of cross talk between segments caused by lateral conductivity. The presented work will highlight the successful validation of the prototype under real operating conditions applying self-pressurizing mode for hydrogen up to 30 bar. The impact of the prototype on the stack performance as well as identified optimization potentials for the stack design will be presented. This undertaking received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) for Fuel Cell and Hydrogen Joint Technology Initiative under Grant No. 621237 (INSIDE).