Crab and Shrimp Shells Could Be Used to Make Battery Parts of the Future

Scientists building new materials are looking to nature for inspiration.

|
Aug 24 2016, 11:00am

Iridescent film of cellulose nanocrystals in a Petri dish. Image: Michael Giese

Scientist Mark MacLachlan's lab at the University of British Columbia is stacked with the empty shells of various crustaceans, like shrimp, crab, and lobster. It sounds like the aftermath of a seafood banquet, but MacLachlan is trying to transform these shells into something usable: materials to make coffee cups and battery parts.

Many researchers are looking to nature for inspiration when designing new materials. Some have suggested, as my colleague Sarah Emerson pointed out, that we could make cities out of synthetic bone, for example. "There's a big drive to make new materials from nature, to get away from using oil products," MacLachlan told me. And nature has spent millions of years perfecting its design.

A film of chitin extracted from a crab shell, and a quarter for size. Image: Thanh-Dinh Nguyen

MacLachlan is interested in chitin, a biomaterial found in the shells of iridescent beetles and crustaceans. (He typically works with shrimp and crab, he told me. Lobster is harder to get on the West coast.)

"If you take a crab shell, and you remove the mineral and protein, you get left with a sheet of chitin organized into a spiral structure," he explained. That structure not only provides support, but also iridescence. Chitin is biodegradable and renewable, he said—and shells are an abundant and easily available source of it, because they're currently thrown away as food waste.

Iridescent chitin membranes from crab shells Image: Thanh-Dinh Nguyen

Chitin can be used to make biodegradable plastics (MacLachlan has suggested we could be drinking from shrimp-based coffee cups one day), or electrodes for batteries. "In a rechargeable battery, the electrode is a porous carbon material," he said. When chitin is heated up to 900℃ in the presence of nitrogen, it creates a nitrogen-doped carbon that could function as a battery's electrode, he explained.

We probably won't see any crab-based batteries powering our devices, at least not anytime soon. The technology is still too expensive to implement commercially. "Right now, it's quite a bit cheaper to produce from natural gas or oil," he said. Chitin-based plastics, on the other hand, are a little more realistic. He's working on various healthcare and dental applications, too.

Still, the equation could change as the technology improves, and if and when oil and gas become less widely available, or more expensive. "One of the biggest attractions is that it's from a natural resource, rather than from oil," he said. "It could theoretically be done from shrimp."