Improved EV battery technology will outmatch degradation from climate change

(Press-News.org) Climate change was poised to create an interesting catch-22 for electric vehicles. Electrifying transportation can go a long way to reducing carbon emissions that are driving up global temperatures. But warmer temperatures also accelerate the degradation of batteries, whose performance can be a make-or-break factor for people considering an EV purchase.

In a new study led by the University of Michigan, however, researchers have shown that batteries have gotten a lot better over the past several years. So much so, in fact, that their gains will more than offset their expected heat-related degradation on a warming planet. The research was supported by federal funding from the U.S. National Science Foundation and the National Natural Science Foundation of China.

"Thanks to technological improvements, consumers should have more confidence in their EV batteries, even in a warmer future," said Haochi Wu, lead author of the study published in the journal Nature Climate Change. Wu performed the work as a visiting doctoral student at the U-M School for Environment and Sustainability, or SEAS.

The team's study combined EV simulations with models of battery degradation and climate change to compare the endurance of old batteries made between 2010 and 2018 with new batteries made between 2019 and 2023. In a scenario where the planet warms by 2 degrees Celsius, old batteries would see their lifetimes drop by an average of 8% up to a maximum of 30%. For new batteries, the average lifetime drop is just 3% and the maximum is only 10%.

"I think these improvements are well-known to experts in the field. But, when I started this project, I was looking at web forums and reading how people were deciding on cars," Wu said. "There are still a lot of durability concerns about EV batteries."

Those concerns were driven, in part, by a rash of incidents about a decade ago where EV drivers in warmer climates saw their battery capacities evaporate, Wu said. But those should be problems of the past, according to the team's analysis. 

Hot takes

The researchers looked at battery lifetimes across 300 cities around the world in a variety of warming scenarios and found that the improvements held up globally. In fact, the warmest cities, like those nearest the equator, actually stand to see the biggest gains.

The team's methodology also stood out to experts in the field, as well as to editors at the journal that published the work. Their framework coupled climate projections with experimentally calibrated models of battery degradation and simulations of EV driving behavior to create high-fidelity battery profiles at granular temporal scales, Wu said.

"The authors find an interesting way to model the important role of technological advance in mitigating the negative effect of climate change," wrote the editorial team at Nature Climate Change. The journal also invited Wu and Craig to submit a research briefing about their work, making it more visible and accessible to the research community.

There are some important caveats associated with the study's results, however, pointed out senior author, Michael Craig, associate professor at SEAS and the Department of Industrial and Operations Engineering, or IOE. Importantly, the team used two representative EVs for their work, the Tesla Model 3 and the Volkswagen ID.3.

"In regions like Europe and the United States, we feel like we've got a good handle on the battery technology that's available in those regions," Craig said. "But when we're looking at cities in India or sub-Saharan Africa, for example, they may have very different vehicle fleets—and they almost certainly do. So our results may be optimistic for those regions."

In these regions, the impacts of warming are also going to be worse and felt more acutely, which highlights another dimension of how inequalities are exacerbated by climate change. This theme also came through in another recent study from Craig and Wu. 

Road maps to resilience

Published in the journal Joule, the researchers' related project was inspired by a similar question about how global warming would impact rooftop solar cell performance. In particular, they examined where climate change would push solar panels into high-temperature risks and extreme high-temperature risks, which are technical thresholds defined by the International Electrochemical Commission, or IEC. These high-temperature risks can accelerate the degradation of conventional solar panels, which can reduce their reliability and prompt sooner-than-expected replacement.

They found that, under the current IEC standards, those risks are underestimated for more than half of our existing and future rooftop photovoltaic installation capacity. Again, these risks will be most acute where warming will be the greatest, which are often low- and middle-income areas.

"On the solar side, we're saying we know the risk is coming, so we need to prepare for it and update our standards. But if you update the standards, there's a whole menu of options available to panel developers, manufacturers and installers that can deal with that risk," Craig said. "Just like EV technology is mitigating that risk, we can mitigate the risk in solar. We just need to have some foresight."

Although that by itself doesn't solve the issues of inequity, it does mean that groups looking for answers can focus on how the technology is deployed rather than whether it exists.

"More vulnerable regions are going to suffer a larger negative impact from climate change, but we're finding technological improvements can mitigate that," Wu said. "That is good news." 

Parth Vaishnav and Jiahui Chen of U-M also contributed to the Nature Climate Change study. Qinqin Kong and Matthew Huber of Purdue University were co-authors of the Joule report. Mingyan Sun of Peking University was a collaborator on both projects. 

Funding for the Joule study came from the NSF, NSFC, NASA and the Smart Grid-National Science and Technology Major Project. Both studies were supported by Advanced Research Computing at U-M.

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