Revolutionizing Energy Technologies with Proton Conductors
Innovative energy solutions, such as fuel cells, electrolyzers, and cutting-edge low-power electronics, rely heavily on protons as their primary charge carriers. The widespread adoption of these technologies depends significantly on the efficiency of proton movement within them.
Challenges in Proton Conductivity
Metal oxides have emerged as promising materials for conducting protons at temperatures exceeding 400 degrees Celsius. However, enhancing proton conductivity at lower temperatures remains a challenge for researchers aiming to boost efficiency.
MIT’s Breakthrough in Proton Mobility Prediction
MIT researchers have developed a groundbreaking model to forecast proton mobility across various metal oxides. Their recent study identifies key features of metal oxides that enhance proton conduction and highlights the role of oxide ion flexibility in improving proton transfer.
This research offers valuable insights for scientists and engineers working on energy technologies that utilize protons, which are lighter and more abundant than traditional charge carriers like lithium ions.
Understanding Proton Conduction Mechanisms
“By comprehending the mechanisms and material traits that govern proton conduction, we can enhance the process’s speed,” explains Bilge Yildiz, a professor at MIT. “This understanding allows us to screen material databases or even use AI tools to create compounds optimized for these traits.”
The study, published in the journal Matter, includes contributions from Heejung W. Chung, Pjotrs Žguns, and Ju Li, alongside Yildiz.
Proton Applications in Modern Technology
Protons are already integral to hydrogen production in electrolyzers and fuel cells. They hold potential for future energy storage solutions like proton batteries, which could be more cost-effective than lithium-ion alternatives. Additionally, protons are being explored for low-energy, brain-inspired computing, mimicking synaptic functions in AI devices.
“Proton conductors are crucial for clean energy conversion technologies,” Yildiz notes. “Inorganic proton conductors that function at room temperature are essential for energy-efficient computing.”
The Science Behind Proton Hopping
Protons, the positively charged form of hydrogen, differ from lithium or sodium ions as they lack electrons, consisting solely of a nucleus. They embed into electron clouds of nearby ions, hopping from one to another. In metal oxides, protons form covalent bonds with oxygen ions and move through hydrogen bonds, rotating to prevent back-and-forth shuttling.
MIT researchers hypothesized that the flexibility of oxide ion sublattices is crucial for proton conduction. Their previous studies confirmed that lattice flexibility significantly impacts proton transport.
Quantifying Lattice Flexibility
The team developed a metric called “O…O fluctuation” to measure lattice flexibility, which assesses the spacing changes between oxygen ions due to phonons at finite temperatures. They also compiled a dataset of material features influencing proton mobility to determine their importance in facilitating conduction.
“Our goal was to understand proton movement in inorganic materials to optimize them for energy and computing applications,” Chung explains.
Key Findings and Future Applications
The study ranked seven features, including structural and chemical traits, to predict proton conduction efficiency. The model identified hydrogen bond length and oxygen sublattice flexibility as the most critical factors. Shorter hydrogen bonds and flexible oxygen ion chains enhance proton transport.
Expanding the Horizon of Proton Conductors
The researchers believe their model can predict proton conduction across a broader range of materials. “While generalizing findings requires caution, our study’s chemistries and structures are diverse enough to apply broadly,” Yildiz states.
Beyond screening materials, the findings could train AI models to create materials optimized for proton transfer, potentially leading to hyper-efficient clean energy technologies.
“Large materials databases, like those from Google and Microsoft, could be screened using our findings,” Yildiz suggests. “If suitable compounds don’t exist, we can generate new ones, enhancing energy efficiency and viability of clean energy and computing devices. Our next steps involve designing materials with flexible oxide ion sublattices.”
This research received support from the U.S. Department of Energy’s Energy Frontier Center and the National Science Foundation’s Graduate Research Fellowship Program.
