KAIST researchers develop mechanical nanoscale fasteners for fuel cell membranes; lower cost, higher efficiency, easily manufactured
09 November 2015
Scientists at KAIST have developed a physical interlocking interface that can tightly bind a sulfonated poly(arylene ether sulfone) (SPAES) membrane and a Nafion catalyst layer in PEM fuel cells, paving the way for lower-cost, higher-efficiency and more easily manufactured proton exchange membrane (PEM) fuel cells. They reported on their work in a recent paper in the journal Advanced Materials.
To generate electricity, PEM fuel cells rely on two chemical compartments separated by a permeable catalyst membrane. This membrane acts as an electrolyte; a negative electrode is bonded to one side of the membrane and a positive electrode is bonded to the other. The electrolyte membrane is often based on a polymer of perfluorosulfonic acid. Due to its high cost, however, a less expensive hydrocarbon-based electrolyte membrane has attracted interest in this technology sector.
Up to now, the challenge in adopting such a hydrocarbon membrane has been that the interface between the electrode and hydrocarbon membrane is weak. This causes the membrane to delaminate relatively easily, falling apart and losing efficiency with use.
Professor Hee-Tak Kim of the Department of Chemical and Biomolecular Engineering at the Korea Advanced Institute of Science and Technology (KAIST) and his research team have developed a new fastening system that bonds the two materials—a SPAES membrane and a Nafion catalyst layer—mechanically rather than chemically. This opens the way to the development of fuel cell membranes that are less expensive, easier to manufacture, stronger and more efficient.
|Schematic of the fabrication of the pillar P-SPAES membrane and its working principle of interlocking effects. Source: KAIST. Click to enlarge.|
The researchers achieved this by moulding a pattern of tiny cylindrical pillars on the face of the hydrocarbon membrane. The pillars protrude into a softened skin of the electrode with heat. The mechanical bond sets and strengthens as the material cools and absorbs water. The pillar-patterned hydrocarbon membrane is cast using silicone moulds.
Owing to higher expansion with hydration for the SPAES membrane than for the Nafion layer, a strong normal force is generated at the interface of a SPAES pillar and a Nafion hole, resulting in an 8-fold increase of the interfacial bonding strength at RH 50% and a 4.7-times increase of the wet/dry cycling durability.
The new interlocking method also appears to offer a way to bond many types of hydrocarbon membranes that, until now, have been rejected because they couldn’t be fastened robustly. This would make hydrocarbon membranes practical for a number of applications beyond fuel cells such as rechargeable redox flow batteries.
The research team is now developing a stronger and more scalable interlocking interface for their nanoscale fasteners.
Oh, K.-H., Kang, H. S., Choo, M.-J., Jang, D.-H., Lee, D., Lee, D. G., Kim, T.-H., Hong, Y. T., Park, J.-K. and Kim, H.-T. (2015) “Interlocking Membrane/Catalyst Layer Interface for High Mechanical Robustness of Hydrocarbon-Membrane-Based Polymer Electrolyte Membrane Fuel Cells” Adv. Mater., 27: 2974–2980 doi: 10.1002/adma.201500328
Advances like this make the small, steady, incremental improvements that will make PEMs more affordable and easier to manufacture.
Posted by: SJC | 09 November 2015 at 10:20 AM
PEMs may soon be easier and cheaper to mass produce that ICEs and batteries. They may also be more compact, have higher energy density, be lighter and much more efficient than ICEs and closer to batteries efficiency.
Coupled with lower cost clean H2 and improved H2 on-board storage units; anti-FCEVs may have to change their mind about extended range all weather (all sizes) electrified future vehicles?
Efficient clean H2 production, storage and distribution is not a real challenge. It is a well known technology with many near future improvements to come.
Mixed Home and Vehicle electricity production, usage and security will become a real H2 advantage.
Posted by: HarveyD | 09 November 2015 at 01:37 PM
Having to produce billions of battery cells per year with near perfection is a challenge. If we can use smaller PEMs with PHEV level batteries, we might have a good combination.
Posted by: SJC | 09 November 2015 at 03:13 PM
Posted by: vire | 15 July 2016 at 06:44 PM