AsianScientist (Nov. 17, 2015) – Scientists have developed a new way of making fuel cell membranes using nanoscale fasteners, paving the way for lower-cost, higher-efficiency and more easily manufactured fuel cells. Their results have been published in Advanced Materials.
The internal workings of fuel cells vary, but all types mix hydrogen and oxygen to produce a chemical reaction that delivers usable electricity and exhausts ordinary water as a by-product. One of the most efficient types is the proton exchange membrane (PEM) fuel cell, which operates at low enough temperatures to be used in homes and vehicles.
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.
Until 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.
Now, a team led by Professor Kim Hee-Tak of the Department of Chemical and Biomolecular Engineering at the Korea Advanced Institute of Science and Technology (KAIST) has developed a new fastening system that bonds the two materials 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.
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 molds.
“This physically fastened bond is almost five times stronger and harder to separate than current bonds between the same layers,” Kim said.
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.
The article can be found at: Oh et al. (2015) Fuel Cells: Interlocking Membrane/Catalyst Layer Interface for High Mechanical Robustness of Hydrocarbon-Membrane-Based Polymer Electrolyte Membrane Fuel Cells.
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Source: KAIST.
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