Charging electric-vehicle batteries in Ithaca’s frigid winter can be tough, and freezing temperatures also decrease the driving range. Hot weather can be just as challenging, leading to decomposition of battery materials and, possibly, catastrophic failure.

For electric vehicles (EVs) to be widely accepted, safe and fast-charging lithium-ion batteries need to be able to operate in extreme temperatures. But to achieve this, scientists need to understand how materials used in EVs change during temperature-related chemical reactions, a so-far elusive goal.

Now, Cornell chemists led by Yao Yang, Ph.D. ’21, assistant professor of chemistry and chemical biology in the College of Arts and Sciences, have developed a way to diagnose the mechanisms behind battery failure in extreme climates using electron microscopy. Their first-of-its-kind operando (“operating”) electrochemical transmission electron microscopy (TEM) enables them to watch chemistry in action and collect real-time movies showing what happens to energy materials during temperature changes.

The work was done in close collaboration with Erik Thiede, assistant professor of chemistry and chemical biology (A&S). Thiede’s group developed new data analysis algorithms to analyze the movies generated by the TEM. Their paper, “Operando Heating and Cooling Electrochemical 4D-STEM Probing Nanoscale Dynamics at Solid-Liquid Interfaces,” was published May 23 in the Journal of the American Chemical Society.

“We now have an opportunity to investigate battery operation down to minus 50 degrees Celsius (minus 58 degrees Fahrenheit), as in extremely cold Arctic climates, and catalyst activation and degradation up to 300 degrees Celsius (572 degrees Fahrenheit) as in many industrial catalysts and every car’s catalytic converter,” Yang said.

The researchers used a three-electrode electrochemical circuit and a two-electrode heating and cooling circuit to achieve quantitative electrochemistry with access to this full temperature range.

Yang’s group has been working on the TEM instrument development for three years, in collaboration with industry partner Protochips Inc. in North Carolina. His work advances development of electrochemical methods to study energy materials for powering safer and faster-charging lithium batteries, as well as for splitting water for green hydrogen production.

“We’ve also been designing nanocatalysts for carbon emissions reduction to sustainable liquid fuels, efforts which help address the global problem of climate change,” said Yang. That project is being co-led by co-authors Sungin Kim, a Korean Sejong Science Fellow, and Valentin Briega-Martos, both chemistry postdoctoral researchers.

Thiede’s research originally focused on developing new machine-learning and artificial-intelligence algorithms for analyzing cryogenic electron microscopy images of protein structures.

“Then I realized that our group’s algorithms are also incredibly helpful in the automated analysis of gigabyte-to-terabyte microscopic images and movies from the Yang group,” Thiede said.

“The data the Yang group collects is every computational scientist’s dream. It allows us to see new scientific phenomena but is complicated enough that analyzing it requires new algorithms, which makes us feel the power of the joint experiment-theory approach.”

Other co-authors include Kwanghwi Je, a Cornell Schmidt AI Fellow who leads the Thiede group’s AI and machine-learning efforts for energy materials; Yafet Negash ’27; chemistry postdoctoral researchers Shikai Liu and Juhyung Choi; chemistry first-year Ph.D. students Zhijing (Zora) Zhang, Rafael Guzman-Soriano, Wenqi Li and Jiahong Jiang; and Yimo Han, Ph.D. ’17, an assistant professor at Rice University.