Researchers learn how to better predict battery degradation

Lithium-ion battery cells

Some electric-car owners go to great lengths to preserve the battery life in their electric cars. Others just plug them in every time they’re finished driving and charge them up to full.

Maybe, according to new research announced earlier this week, the durability of batteries can be determined after only the first few charge cycles, and may have as much to do with the formation of the cells than their use.

The research from MIT, Stanford, and the Toyota Research Institute shows how automakers and other lithium-ion battery consumers can use artificial intelligence, along with comprehensive test data, to predict which battery cells will last the longest.

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The scientists trained their computers on collecting a few hundred million data points from the tested battery cells and measured voltage declines along with a few other factors in the first five charge cycles of a battery cell’s life, and were able to predict the cells’ actual life-cycles within 9 percent 95 percent of the time.

The lifespan of the batteries in the study varied dramatically, from 150 to 2,300 charge cycles. Researchers assumed the end of life for the battery cells was after they lost 20 percent of their capacity.

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The work could have dramatic implications for fast charging for electric cars, as well as potentially for such simple, everyday things as range and capacity meters. Researchers found that different methods of fast charging had an effect on battery life, but that natural variances in battery formation had an equivalent effect. The study points to how batteries can be developed to accept a fast charge in as little as 10 minutes.

The research is also expected to dramatically speed up the development of new battery technologies. “For all of the time and money that gets spent on battery development, progress is still measured in decades,” said Toyota Research Institute researcher Patrick Herring, one of the co-authors of the study. “In this work, we are reducing one of the most time-consuming steps—battery testing—by an order of magnitude.”

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“The standard way to test new battery designs is to charge and discharge the cells until they die,” said co-lead author Peter Attia, a Stanford doctoral candidate in Materials Science and Engineering. “Since batteries have a long lifetime, this process can take many months and even years. It’s an expensive bottleneck in battery research.”

The methodology could also allow battery manufacturers for example to sort batteries by their expected lifespans and direct longer-lasting batteries toward electric cars, those with somewhat shorter spans to electronics, and others to less critical applications.

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