Lithium-ion batteries are at the heart of so many industries, endemic to modern life, and the demand for them is only set to grow. Yet continued production of new batteries leads to a host of concerns—for one, establishing new mines is an expensive and time-consuming prospect. On top of the expense to the industry, mining is also damaging to the environment, depleting local water resources and polluting the region with run-off debris.
With all these barriers to sustainable production, recycling existing batteries becomes crucial. Manufacturers, however, have long hesitated to invest in recycling over concerns of lower quality, shorter battery life, or damage. These are not unfounded concerns; in applications such as electric vehicles, battery failure could be catastrophic.
This all makes new research published in Joule all the more timely and necessary. Yan Wang, a materials science professor at Worcester Polytechnic Institute, has been studying recycling techniques for eleven years and, with his team, has determined a cathode-recycling technique that produces batteries that perform just as well those made from scratch, and perhaps even better. Their research demonstrates that batteries with the recycled cathode have the best cycle life result yet reported for recycled materials and enable 4200 and 11600 cycles at 80% and 70% capacity retention—which is 33% and 53% better than commercial batteries.
The recycling process Wang and his colleagues developed is similar to currently common methods—dismantling the battery, then melting it down or dissolving it to salvage chemical elements or simple compounds—except the new method foregoes completely breaking the battery down in favor of keeping some of the old cathode’s crucial components intact. Less expensive parts are recycled separately, while the cathode material is dissolved in acid to remove impurities. Then small amounts of the fresh element components are added to ensure correct ratios—another distinction from common methods—and a refreshed cathode powder is produced that can be stuck onto a metal strip and placed in a battery.
The increase in performance can be attributed to increased porosity in the recycled powder vs. commercially produced cathode powder. The recycled powder particles contain particularly large voids in their centers, providing room for the cathode crystal to swell and so making them less likely to crack—a major cause of degradation over time. More pores also mean more exposed surface area, meaning the recycled batteries also charge faster.
While future ambitions could impart this superior structure to all produced batteries, for now, it proves that these recycled cathodes can be as good as or better than imported commercial materials, largely coming from the world leader in battery recycling, China. The approach could cut out a significant chunk of the international trade and transport required for LiPo batteries, creating a path for countries to bolster domestic battery recycling and further increase sustainability. Ascend Elements, a recycling company founded by Wang, is currently in the process of scaling up recycling efforts with this method to make all these ambitions possible as LiPo battery demand continues to grow.
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