Batteries age as they recharge. We know this.
We’ve also known for some time that oxygen plays a role, and we’ve blamed a reactive form of oxygen called superoxide. But that explanation was only half the story. While batteries age most when they recharge, superoxide forms mainly during energy release. Something didn't add up. We looked to living cells and how they handle their own aging for inspiration.
In both batteries and cells, reactive oxygen species are at the heart of the problem. Among them is a particularly aggressive form called singlet oxygen. Unlike the oxygen we breathe, singlet oxygen is highly reactive, attacking molecules and causing damage. In plants, for example, it’s produced during photosynthesis and triggers what’s known as oxidative stress. To survive, plants have developed defenses like antioxidants, including carotenoids (Vitamin A) and tocopherols (Vitamin E).
Inspired by these natural defenses, we began to explore whether singlet oxygen might also be the culprit behind battery aging. The challenge was that no one had ever detected singlet oxygen in batteries before. Developing the right tools to find it was like creating a magnifying glass to spot something previously invisible. But once we did, the pieces of the puzzle finally fell into place: singlet oxygen is a major driver of battery aging, particularly during charging. Having the right tools also allowed us ever deeper understanding of formation mechanisms.
This discovery has exciting implications. If we can manage singlet oxygen, we could dramatically extend the lifespan of batteries. That means fewer discarded batteries, better recyclability, and more sustainable energy storage—an urgent need as we transition to sustainable batteries in the future.
The next question is how to protect batteries from this reactive species. Again, we look to nature for inspiration. Just as plants and animals rely on antioxidants and enzymes like superoxide dismutase to combat oxidative damage, we’re exploring ways to incorporate similar protective strategies into batteries.
We’ve opened the door to a better understanding of oxygen chemistry in batteries, but there is still work ahead. How do we refine these protective strategies? Can they be cost-effective?
Despite the challenges, I’m optimistic. Singlet oxygen and other so-called excited species were unknown players in battery aging just a short while ago, and now we know not only that it exists but also the mechanisms by which they form, how to detect, and counteract it.
With continued effort, we’re closer to a future where batteries are longer-lasting, greener, and more efficient.
