Electrolyte Highway Breakthrough Unlocks Affordable Low-Temperature Hydrogen Fuel

Researchers at Kyushu University have developed a solid-oxide fuel cell that operates at just 300C, less than half the usual operating temperature. The team was able to do this by engineering a 'ScO6 highway' in the electrolyte, allowing protons to move quickly without losing performance. 'The team expects that their new findings will lead to the development of low-cost, low-temperature SOFCs and greatly accelerate the practical application of these devices,' said the researchers in a press release. Interesting Engineering reports: 'While SOFCs are promising due to their high efficiency and long lifespan, one major drawback is that they require operation at high temperatures of around 700-800C (1292F-1472F),' added the researchers in a press release. Such heat requires costly, specialized heat-resistant materials, making the technology expensive for many applications. A lower operating temperature is expected to reduce these manufacturing costs.

The team's success comes from re-engineering the fuel cell's electrolyte, the ceramic layer that transports protons (hydrogen ions) to generate electricity. Previously, scientists faced a trade-off. Adding chemical dopants to an electrolyte increases the number of available protons but also tends to clog the material's crystal lattice, slowing proton movement and reducing performance. The Kyushu team worked to resolve this issue. 'We looked for oxide crystals that could host many protons and let them move freely -- a balance that our new study finally struck,' stated Yamazaki.

They found that by doping two compounds, barium stannate (BaSnO3) and barium titanate (BaTiO3), with high concentrations of scandium (Sc), they could create an efficient structure. Their analysis showed that the scandium atoms form what the researchers call a 'ScO6 highway.' This structure creates a wide and softly vibrating pathway through the material. 'This pathway is both wide and softly vibrating, which prevents the proton-trapping that normally plagues heavily doped oxides,' explained Yamazaki. The resulting material achieves a proton conductivity of more than 0.01 S/cm at 300C, a performance level comparable to conventional SOFC electrolytes that run at more than double the temperature. The research has been published in the journal Nature Materials.

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