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Fang Liu

Focus on new faculty: Fang Liu is designing batteries tough enough for big trucks

Written By: Jason Daley

According to the U.S. Environmental Protection Agency, transportation is the source of more than a quarter of all greenhouse gas emissions in the country.

However, even if every passenger car swapped its combustion engine for a battery overnight, that still wouldn’t solve the problem: A substantial amount of the emissions come from heavy trucks and aviation. Currently, commercial lithium-ion batteries are not energy-dense enough to keep those power-hungry vehicles moving and achieve a similar driving range.

But Fang Liu, who began as an assistant professor in materials science and engineering at the University of Wisconsin-Madison in August 2022, hopes her research will help put heavy-duty batteries under the hoods of trucks and make renewable energy more reliable.

“I think this is a very promising and important topic to study, especially considering that we are trying to achieve carbon neutrality by 2050,” Liu says. “This can have a huge impact on the overall carbon-emission reduction process.”

Liu completed her bachelor’s degree in polymer engineering at Jilin University in China before pursuing her PhD in chemical engineering at the University of California, Los Angeles. Since 2019, she has worked as a postdoctoral researcher at Stanford, studying lithium-metal and lithium-ion batteries with Professor Yi Cui in materials science and engineering.

At Madison, Liu hopes to continue that research, and is looking at new materials to develop more energy dense rechargeable batteries. In particular, she is looking at changing the electrochemistry of lithium-ion batteries by using lithium metal, rather than graphite, as the anode, and using sulfur as the cathode instead of expensive transition metals like cobalt, manganese and nickel.

While changing those materials amps up the batteries’ energy capacity, it also comes with problems since lithium metal tends to form small branches, or dendrites, that can damage batteries. The sulfur also produces a soluble product that degrades battery performance. Liu is looking for new cell structures, catalysts and electrolytes to help stabilize these materials so they can be used in long-lasting, rechargeable Li-S batteries.

At UW-Madison, Liu says she would also like to begin exploring long-duration batteries for grid-scale storage. These batteries would store energy produced by wind and solar during the day and discharge electricity at night or when the wind isn’t blowing to keep the flow of renewable energy stable.

While these types of batteries are technically feasible, Liu says currently available battery systems are still prohibitively expensive. “The extremely low-price target dramatically limits the kind of materials we can use for these batteries,” she says. “Then the question comes down to, how can we use low-cost materials to provide electricity at a large scale?”

The answer, Liu believes, lies in finding the right materials to enable groundbreaking new chemistry. “My background is in chemical engineering. But my research has mainly focused on materials science design,” Liu says. “I hope to bring the perspective of a chemical engineer to solve materials science problems.”

Liu, who is an experimentalist, says one of the advantages of working at UW-Madison is the deep bench of computational theorists and growing cohort of battery experts at the university. “We have a lot of great scientists and engineers working on theory and modelling in our university,” she says. “I can imagine a lot of collaborations.”

As for moving to Madison after a decade in California, Liu says she grew up in an area with four distinct seasons, so it she’s looking forward to Wisconsin’s vastly varying weather. “A lot of colleagues have recommended ice fishing,” she says. “I would love to try that in winter.”