H-S Cho, M. Kim, C. Lee, S. Lee
Korea Institute of Energy Research (KIER),
Keywords: green hydrogen, alkaline water electrolysis, stack
Summary:The great merits on alkaline electrolyzer regarding maturity, large capacity, and cost-effective features have drawn much attention as one of the applications for energy storage systems connected to the renewable energy sources such as the wind and solar. These may provide economic advantages for the management of peaks and valleys in electrical loads as storing to hydrogen as second energy carrier sources, especially in long-term and large-scale(>MW) storage systems. However, the variable loads arise from the renewable power sources can affect the performance on electrolysis and influence the apparent durability. Here, we will discuss improvements on the alkaline water electrolyzer (AWE) by the significant interaction between engineering and material science disciplines. By applying porous durable and efficient electrode and a reinforced composite inorganic separator with improved cell and stack designs, the AWE can overcome few drawbacks such as low current operation and slow response to variable loads. We believe that the improvements of poor kinetic efficiency and mitigation of components degradation would increase the system lifetime, and thus improve the economics of alkaline water electrolysis. On/off durability in alkaline solutions of the screened electrodes also evaluated using accelerated durability tests and resulted in less than 20 mV degradation over 500 times of on/off cycles. Furthermore, to correlate ex-situ electrode activity results and in-situ performance of AWE, the in-situ single cell of AWE was also evaluated with the mesoporous Nix-Fe1-x LDH(x=0.5~0.7) anodes as oxygen evolution electrode that were directly grown on various forms of metal substrates such as sandblasted plates, mesh, and foam, porous Ni-Zn alloy as hydrogen evolution electrode.