New analysis shows ion slowdown in fuel cell material
Dislocations in oxides such as cerium dioxide, a solid electrolyte for fuel cells, turn out to have a property that is the opposite of what researchers had expected, according to a new analysis at MIT. Researchers had thought that a certain kind of strain — specifically, strain caused by dislocations in the material’s atomic lattice — would speed the transport of oxygen ions through the material, potentially leading to the much faster diffusion that is necessary in high-performance solid oxide fuel cells, water-splitting, or oxygen-separation membranes. But the new atomic-level simulation of oxide ion transport has revealed that while these dislocations do greatly accelerate atom transport in metals, they can have the opposite effect in this metal-oxide material, and possibly in many others. Instead of easing ion mobility, it turns out that dislocations in cerium dioxide cause a kind of “traffic jam” for the flowing ions, slowing them to a crawl, says...