MIT engineers have identified key traits for fast proton conduction and found six promising candidates which showed superior performance and provided deeper atomic insights.
Materials that conduct protons could revolutionize climate technologies but require high temperatures. Developing alternatives for lower-temperature operation could enhance fuel cells, clean fuel electrolyzers, proton batteries, and iono-electronic devices.
MIT engineers have enhanced proton conductor development by identifying key material traits for fast proton conduction. They pinpointed six promising new candidates through quantitative analysis and simulations, which suggest superior performance over existing materials, pending experimental confirmation. The study also offers deeper atomic insights into how these materials function.
Current hydrogen production methods, like steam methane reforming, release significant carbon dioxide. Similarly, effective electrochemical systems dependent on good proton conductors could benefit the production of key industrial chemicals and potential fuels like ammonia.
However, most inorganic materials that conduct protons only function at high temperatures ranging from 200 to 600 degrees Celsius. These temperatures are energy-intensive to maintain and can lead to material degradation. The team first aimed to develop a fundamental and quantitative understanding of proton conduction by studying a class of inorganic proton conductors known as solid acids to address the issue.
The researchers employed computer simulations to explore solid acids, a material class that excels as proton conductors at temperatures above 200 degrees Celsius. These materials feature a substructure known as the polyanion group sublattice, which must rotate and relocate the proton for effective transfer. By identifying key phonons that enhance this sublattice’s flexibility—crucial for proton conduction—the team could sift through extensive databases for superior proton-conducting materials.
They discovered solid acid compounds, previously used in various applications but not as proton conductors, that possessed optimal lattice flexibility. Further simulations of the selected materials under relevant temperatures verified their potential as efficient proton conductors for fuel cells and other uses. This led to the identification of six promising materials with faster-predicted proton conduction rates than existing top performers.
It may take several years to transform these theoretical discoveries into practical devices. The initial applications will likely be electrochemical cells producing fuels and chemical feedstocks like hydrogen and ammonia.
