A Korean research team has developed a new proton exchange membrane (PEM) that significantly enhances the performance of electrochemical hydrogen storage systems.
This next-generation PEM for LOHC-based electrochemical hydrogen storage was developed using a hydrocarbon-based polymer called SPAES.
It reduces toluene permeability by over 60% compared to the commercially available perfluorinated PEM Nafion and improves the Faradaic efficiency of hydrogenation to 72.8%.
Barriers to efficient electrochemical hydrogen storage
Liquid organic hydrogen carriers (LOHCs), such as toluene, are promising liquid compounds for storing and transporting hydrogen.
Unlike compressed (over 100 bar) or liquefied (-252.9 °C) hydrogen, LOHCs can be handled under milder conditions.
However, in electrochemical hydrogenation systems, a common issue is the undesired crossover of toluene through the membrane, which not only reduces efficiency but also contaminates the oxygen evolution reaction (OER) catalyst on the anode side.
Additionally, the kinetics of hydrogen absorption and desorption in many materials are slow, reducing the system’s overall efficiency and responsiveness.
Moreover, synthesising high-performance materials often involves complex and expensive processes, raising economic concerns. Safety issues, such as the risk of hydrogen leakage and the reactivity of certain materials under operational conditions, also pose significant obstacles to practical implementation.
Together, these technical and economic factors must be addressed to make electrochemical hydrogen storage a viable and scalable solution for energy systems.
Reducing the permeability of toluene molecules
To address these concerns, the research team designed a new hydrocarbon-based SPAES membrane with narrowed hydrophilic domains (approx. 2.1 nm), which serve as proton pathways in the membrane.
These narrow domains drastically reduce the permeability of toluene molecules, decreasing their diffusivity by a factor of 20.
As a result, the toluene crossover was reduced by 60%, and the Faradaic efficiency increased from 68.4% to 72.8%. In long-term operation (48 hours), the voltage degradation rate decreased by 40%, from 1270 mV/h to 728 mV/h. The membrane also showed strong chemical and mechanical stability, with minimal structural changes over extended use in hydrogen storage.
Commercialising the new technology
The researchers expect this technology to pave the way for standalone, high-efficiency electrochemical hydrogen storage systems that can be commercialized around 2030.
Dr Soonyong So of the Korea Research Institute of Chemical Technology (KRICT) stated that this research offers a solution to the performance bottlenecks of membrane technology in electrochemical hydrogen storage.
KRICT President Youngkook Lee added that the technology could be widely applied in eco-friendly energy systems such as hydrogen fuel cell vehicles and hydrogen power generation, thereby contributing to the hydrogen economy.
