Protective Coatings for Low-Cost Bipolar Plates and Current Collectors of Proton Exchange Membrane Electrolyzers for Large Scale Energy Storage from Renewables

Hydrogen produced by proton exchange membrane (PEM) electrolysis technology is a promising solution for energy storage, integration of renewables, and power grid stabilization for a cross-sectoral green energy chain. The most expensive components of the PEM electrolyzer stack are the bipolar plates (BPPs) and porous transport layers (PTLs), depending on the design. The high cost is due to the fact that the employed materials need to withstand corrosion at 2 V in acidic environment. Currently, only titanium is the material of choice for the anode side. We use vacuum plasma spraying (VPS) technology to apply highly stable coatings of titanium and niobium to protect stainless steel BPPs from the oxidative conditions on the anode side. The latter is able to decrease the interfacial contact resistance and improves the long-term stability of the electrolyzer. Furthermore, porous transport layers (PTL) can be realized by VPS as well. These coatings can be produced on existing titanium current collectors acting as macro porous layers (MPL). Lastly, free standing multifunctional structures with optimized tortuosity, capillary pressure and gradient porosity are used as current collectors. The coatings and porous structures developed by VPS enable the reduction of the required material and costs without performance losses

Electrochemical Analysis of Synthetized Iridium Nanoparticles for Oxygen Evolution Reaction in Acid Medium

The anode side catalyst is one of the key parts for sustainable hydrogen production via proton exchange membrane (PEM) electrolysis. An optimized synthesis of the oxygen evolution reaction (OER) catalysts may lead to a cost efficient production, promoting the commercialization of new catalyst materials. This work compares the electrochemical characteristics of Ir nanoparticles synthetized in different purities of ethanol and deionized (DI) water as solvents. The use of cetyltrimethyl ammonium bromide (CTAB) as a surfactant is discussed as well. In general, the absence of the surfactant and use of either low ethanol purity or water is detrimental for electrocatalytic properties of the materials. Changes in the Tafel slope are observed, while the analysis of the specific exchange current can be misleading. The active sites from the IrIII/IrIV oxidation peak do not correlate exactly with the OER activities, while the capacitive current provides more meaningful information

Towards developing a backing layer for proton exchange Membrane electrolyzers

Current energy policies require the urgent replacement of fossil energy carriers by carbon neutral ones, such as hydrogen. The backing or micro-porous layer plays an important role in the performance of hydrogen Proton exchange membrane (PEM) fuel cells, reducing contact resistance and improving eactant/product management. Such carbon-based coating cannot be used in PEM electrolysis since it oxidizes to CO2 at high voltages. A functional titanium acro-porous layer (MPL) on the current collectors of a PEM electrolyzer is developed by thermal spraying. It improves the contact with the catalyst layers by ca. 20 mU cm2, increasing significantly the efficiency of the device when operating at high current densities