Rational design strategy for optimization of clamping pressure to minimize contact resistance between electrode and current collector while preserving porosity of electrodes in water electrolyzers

Abstract

The compressive clamping pressure at the interface of gas‐diffusion‐layer (GDL) and current collector decreases the contact resistance between them though it reduces the porosity and surface roughness of electrocatalysts, which would in turn decrease the efficiency of an electrolyzer. We explore these issues of trade‐off between porosity versus contact resistance and provide a design heuristic for optimum clamping pressure. The present work provides an estimate of the optimal value of clamping pressure for an alkaline water electrolyzer having membrane electrode assembly (MEA), taking account of the variation in porosity of catalyst layers and contact resistance obtained via half‐cell studies performed at different pressures. Towards this, we define the performance‐index (Φ) which is the ratio of Faradaic current density and resistances resulting from contact‐interfaces in electrolyzers and we suggest that the maxima in Φ corresponds to optimum clamping pressure.

Electrochemical Cycling‐Induced Amorphization of Cobalt(II,III) Oxide for Stable High Surface Area Oxygen Evolution Electrocatalysts

“…[4] The excellent chemical and mechanical stability, tuneable porosity and surface chemistry, high specific surface area, and excellent diversity in structure makes these MOFs derived suitable for electrocatalysis. [5] This demands further improvement of electrocatalytic properties which can be achieved in following ways: 1) enhancing surface roughness of electrode which can increase the number of electrocatalytically active sites with formation of edges, steps and exposure of high-Miller indexed surfaces, [6] 2) use of highly porous three dimensional electrode, [2c,3b,e,6e,7] however, during assembling the electrode into device, the imposed clamping pressure has to be optimized so that porosity of three dimensional (3D) electrocatalyst is not significantly decreased while increasing contact with the current collector, [8] (3) enhancing the conductivity of either electrocatalyst or support thereby reducing overall charge transport through electrode, [3g,9] (4) enhancing surface electrocatalytic activity either through doping [6e,10] or (5) support-electrocatalyst interaction, [3g,6e,11] (6) the specific activity of OER can also be increased either by altering the crystal structure (through polymorphic engineering) or through microstructure modification by introducing crystal defects, dislocations and grain boundaries. [12] Apart from these modifications an approach to improve electrocatalytic activity is to synthesize amorphous material with a greater number of under-saturated active sites near the surface and promote the adsorption of reaction intermediates and reduction in charge-transfer resistance through the electrocatalyst.…”

Controlling Mass Transport in Direct Carbon Dioxide Zero-Gap Electrolyzers via Cell Compression

“…To better control and understand CO 2 mass transport, this work leverages the zero-gap membrane electrode assembly (MEA) electrochemical architecture, which consists of two electrodes on either side of the membrane that are compressed inside a cell housing. − The advantages of using zero-gap MEAs have recently been demonstrated for CO 2 reduction with improved product formation rates, CO 2 utilization, and cell voltages. − This study, in particular, introduces a methodology to directly control the CO 2 mass transport by varying the applied cell compression to the MEA through the modification of gasket thickness, inspired by device optimizations performed for hydrogen fuel cells, water electrolyzers, and redox flow batteries. − The changes in CO 2 mass transport ultimately dictate the voltage and current density at which the electrolyzer operates, which provides insights into operating conditions that lead to high energy efficiencies for more sustainable energy use. Specifically, controlling the mass transport in the GDEs coated with a Ag catalyst leads to diverging CO 2 -to-CO conversion activity and selectivity trends, which are explained based on the characterization of the electrode thickness and porosity, and the computational modeling of the MEA.…”

Dissolution Induced Self-Selective Zn- and Ru-Doped TiO2Structure for Electrochemical Generation of KClO3

“…As the enhanced selectivity was achieved without increasing overall cost, the explored strategy is potentially worthy enough for consideration towards producing large area electrodes on an industrial scale. However, during preparation of the electrode, the clamping pressure has to be optimized so that generated porosity does not reduce due to the destruction of microstructure under the influence of clamping pressure (34).…”