Abstract
Ion-conducting membranes are essential components in many electrochemical devices, but they often add substantial cost, limit performance, and are susceptible to degradation. This work investigates membraneless electrochemical flow cells for hydrogen production from water electrolysis that are based on angled mesh flow-through electrodes. These devices can be fabricated with as few as three parts (anode, cathode, and cell body), reflecting their simplicity and potential for low-cost manufacture. 3D printing was used to fabricate prototype electrolyzers that were demonstrated to be electrolyte agnostic, modular, and capable of operating with minimal product crossover. Prototype electrolyzers operating in acidic and alkaline solutions achieved electrolysis efficiencies of 61.9% and 72.5%, respectively, (based on the higher heating value of H2) when operated at 100 mA cm−2. Product crossover was investigated using in situ electrochemical sensors, in situ imaging, and by gas chromatography (GC). GC analysis found that 2.8% of the H2 crossed over from the cathode to the anode stream under electrolysis at 100 mA cm−2 and fluid velocity of 26.5 cm s−1. Additionally, modularity was demonstrated with a three-cell stack, and high-speed video measurements tracking bubble evolution from electrode surfaces provide valuable insight for the further optimization of electrolyzer design and performance.
Highlights
Solar and wind energy have the potential to power the planet without the environmental impact of fossil fuels, but encounter significant challenges to widespread adoption due to their low capacity factors and inherent intermittency.[1]
In order to overcome this challenge, affordable grid-scale energy storage technology is needed that can make electricity generation from these technologies more widespread.[2]. One solution to this issue is to convert excess renewable electricity into stored chemical energy in the form of hydrogen gas (H2),[3] which represents a promising candidate for grid scale energy storage and as a carbon-free replacement of fossil fuels in the transportation and industry sectors.[4]
Much of the cost of producing H2 by water electrolysis comes from the price of electricity,[6,8] but as the price of electricity from wind and solar continues to decrease and time-of-use pricing schemes become more prevalent, decreasing the cost of electrolyzer technology will be of great importance to making a renewable hydrogen future a reality
Summary
Solar and wind energy have the potential to power the planet without the environmental impact of fossil fuels, but encounter significant challenges to widespread adoption due to their low capacity factors and inherent intermittency.[1]. Operating the device under a flow rate of 6.6 cm s−1 results in a significant increase in current and a disappearance of the saw-tooth pattern, consistent with the visual observation that the generated bubbles are continuously removed from electrode surface (Fig. 3c).
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