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Minimising the ohmic resistance of an alkaline electrolysis cell through effective cell design / Robert Phillips; Adam Edwards; Bertrand Rome; Daniel R. Jones; Charles W. Dunnill
International Journal of Hydrogen Energy, Volume: 42, Issue: 38, Pages: 23986 - 23994
Swansea University Author: Dunnill, Charlie
Accepted Manuscript under embargo until: 14th August 2018
The efficiency of an alkaline electrolysis cell depends strongly on its internal cell resistance, which becomes the dominant efficiency driver at high current densities. This paper uses Electrochemical Impedance Spectroscopy to decouple the ohmic resistance from the cell voltage, and, for the first...
|Published in:||International Journal of Hydrogen Energy|
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The efficiency of an alkaline electrolysis cell depends strongly on its internal cell resistance, which becomes the dominant efficiency driver at high current densities. This paper uses Electrochemical Impedance Spectroscopy to decouple the ohmic resistance from the cell voltage, and, for the first time, quantify the reduction in cell resistance achieved by employing a zero gap cell configuration when compared to the conventional approach. A 30% reduction in ohmic resistance is demonstrated for the zero gap cell when compared to a more conventional design with a 2 mm electrode gap (in 1 M NaOH and at standard conditions). The effect on the ohmic resistance of operating parameters, including current density and temperature, is quantified; the zero gap cell outperforms the standard cell at all current densities, particularly above 500 mA·cm−2 Furthermore, the effect of electrode morphology on the ohmic resistance is investigated, showing that high surface area foam electrodes permit a lower ohmic resistance than coarser mesh electrodes. These results show that zero gap cell design will allow both low cost and highly efficient alkaline electrolysis, which will become a key technology for short term and inter-seasonal energy storage and accelerate the transition towards a decarbonised society.
This holds the key to the successful implementation of intermittent renewable energy storage in the form of hydrogen gas. This is currently one of the biggest challenges for a developed economy in the face of climate change. We show that through selective and intelligent design we can achieve the high efficiency of PEM electrolysis alongside the cost effectiveness of alkaline, thus bringing Hydrogen production as an energy storage concept into the realms of reality. This technology is the core for a outreach project called @TheHydrogenBike where we have travelled the country to science fairs informing thousands of children and adults about the potential use of hydrogen as an energy vector and it's ability to decouple the supply and demand relationship associated with intermittent renewable energy resources. It has generated grant income form the RSC (2.8K), Innovation Acceleration (£5k) and GCRF networks and is the core technology implemented in the £15M GCRF hub project that we are currently applying for. It is also a key reason that we are receiving the £9M RICE funding from WEFO to scale the technology into a commercial unit on Tata steel site in Port Talbot.
Alkaline electrolysis; Electrochemical impedance spectroscopy; Zero gap; Porous electrodes; Renewable energy storage
College of Engineering