A team led by Professor Won Yong Lee of the School of Mechanical Engineering at Sungkyunkwan University (Republic of Korea) has created a technology that removes a key limitation of protonic ceramic electrochemical cells (PCECs), a new generation of clean-energy devices. The results were published in the journal Nature Communications.
PCECs can operate in two modes: as fuel cells that generate electricity from hydrogen without polluting emissions, and as electrolyzers that split water to produce hydrogen. They are efficient at lower temperatures than traditional counterparts and are considered promising for the hydrogen economy.
However, inside such cells the dense, smooth electrolyte and the porous electrode do not fully touch. This creates interfacial contact resistance, the resistance to electric current at the boundary between the materials, because of which their potential is not fully used.
To study how contact area affects resistance, the researchers fabricated experimental model cells with different degrees of contact. The analysis showed that the higher the "contact coverage" (the share of the surface where the electrode and electrolyte actually touch), the lower the resistance. The scientists called this parameter key to performance.
To test this on real cells, the team used electrostatic spraying (ESD), a method in which charged liquid droplets are uniformly applied to a surface. In this way a thin, dense nanometer-scale layer was applied to the electrolyte, increasing the contact area.
Cells with the new coating showed better results than conventional ones both in the power-generation mode and in the hydrogen-production mode. They also operated stably under sharp temperature changes thanks to the strong bonding of the electrode and electrolyte.
In addition to pure hydrogen, the cells retained operability and stability when directly using methane or ammonia, promising types of fuel. Moreover, the method made it possible to treat large substrates uniformly, which points to the possibility of scaling for industry.
"No matter how perfect a new material is, it will not reveal its properties if the interfaces between the components are poorly connected," Lee noted. "Our work quantitatively describes microscopic contact behavior and at the same time maximizes performance and durability with the help of a scalable precision nanoscale process."
According to the researcher, the technology could find application in large clean-energy power plants, hydrogen vehicles and environmentally friendly energy storage systems. However, these are still laboratory results, and no timeline for commercial adoption has been reported.