South SFV Today

The longevity of electric vehicle (EV) batteries may be greater than previously estimated, according to a study conducted by scientists at the SLAC-Stanford Battery Center. This research suggests that EV owners might not need to replace battery packs or purchase new vehicles as soon as once thought.

Typically, battery tests have been performed under controlled lab conditions, with constant discharge and recharge cycles. However, the study published in Nature Energy on December 9 indicates that real-world driving conditions could result in longer battery life. "We’ve not been testing EV batteries the right way," stated Simona Onori, senior author and associate professor of energy science and engineering at Stanford University.

Researchers tested 92 commercial lithium-ion batteries over two years using different discharge profiles. They found that profiles mimicking actual driving behavior led to increased battery life expectancy. The use of a machine learning algorithm allowed researchers to assess the effects of dynamic discharge profiles on battery degradation.

Contrary to previous beliefs, the study found that sharp accelerations did not harm but rather slowed down battery aging. "Pressing the pedal with your foot hard does not speed up aging," explained Alexis Geslin, one of the lead authors and a PhD student at Stanford's School of Engineering.

The study also explored differences between cycle-induced aging and time-induced aging of batteries. Geslin noted that for consumers who use their EVs sporadically, time plays a more significant role in battery aging compared to frequent cycling seen in commercial vehicles like buses.

The research suggests an optimal discharge rate for balancing time and cycle aging for consumer EVs. It proposes updates to EV battery management software based on these findings to enhance battery longevity under real-world conditions.

Le Xu, a postdoctoral scholar involved in the study, emphasized the importance of evaluating new battery chemistries with realistic demand profiles. The implications extend beyond EVs; they could influence other energy storage applications and materials where aging is critical.

"This work highlights the power of integrating multiple areas of expertise," said Onori.

This research was supported by various fellowships and included contributions from William Chueh, Devi Ganapathi, Kevin Moy, among others from Stanford University.

For further information, media contact is available through Mark Golden at Stanford's Precourt Institute for Energy.