MIT News July 23, 2024
A quantitative understanding of the physical traits of a material that regulates proton diffusion is necessary for accelerating the discovery of fast proton conductors which is key for advancing many electrochemical technologies. A team of researchers in the US (MIT, Auburn University, Northwestern University) mapped the structural, chemical and dynamic properties of solid acids to the elementary steps of the Grotthuss mechanism of proton diffusion by combining ab initio molecular dynamics simulations, analysis of phonon spectra and atomic structure calculations. They identified the donor–hydrogen bond lengths and the acidity of polyanion groups as key descriptors of local proton transfer and the vibrational frequencies of the cation framework as the key descriptor of lattice flexibility. The latter facilitates rotations of polyanion groups and long-range proton migration in solid acid proton conductors. The calculated lattice flexibility also correlated with the experimentally reported superprotonic transition temperatures. They screened the Materials Project database and identified potential solid acid proton conductors with monovalent, divalent and trivalent cations, including Ag+, Sr2+, Ba2+ and Er3+ cations, which go beyond the traditionally considered monovalent alkali cations (Cs+, Rb+, K+, and NH4+) in solid acids… read more. Open Access TECHNICAL ARTICLE
… proton diffusion via the Grotthuss
mechanism in a solid acid… Credit:
Energy Environ. Sci., Advance Article, 19 June 2024Â