Crab shells could help power the next generation of rechargeable batteries

Anyone who has tasted fresh crab claws or lobster tails can attest how difficult it is to get through their tough shells. But instead of throwing them away, the researchers are “recycling” these seashells into a porous, carbon-filled material with a variety of uses. Now, a group reports in ACS Omega used this “crab carbon” to create anode material for sodium-ion batteries—an upcoming competitor to lithium-ion chemists.

Lithium-ion batteries have become ubiquitous in recent years, powering phones, cars, and even toothbrushes. But because the amount of lithium metal in the world is limited, some researchers have turned their attention to its “chemical cousin”. Previously, researchers created a biodegradable zinc-ion battery using chitin in crab shells. But these wastes can be replaced by turning into “hard” carbon,” a material that has been discovered as a possible anode for sodium-ion battery.

Although chemically similar to lithium, sodium ions larger and therefore incompatible with the anode of lithium-ion batteries, which are usually made of graphite. When hard carbon is combined with metallic semiconductor materials, such as transition metal dichalcogenide (TMDs), this material could become the anode of a viable battery. So Yun Chen, Yue Zhao, Hongbin Liu and Tingli Ma wanted to explore how two different TMDs—tin sulfide and iron sulfide—can be combined with hard carbon made from crab shells to create a sodium battery anode. -ion ​​feasible.

To create “crab carbon,” the researchers heated crab shells to temperatures in excess of 1000 F. They then added carbon to a solution of tin sulfide (SnS).₂) or iron sulfide (FeS₂), and then dry them to form the anode. The fibrous, porous structure of crab carbon provides a large surface area, which enhances the material’s electrical conductivity and efficient ion transport capacity.

When testing in a battery sample, the team found that both composites have good capacity and can last at least 200 cycles. This work could provide a route to recycling other wastes and help develop more sustainable battery technologies, the researchers say.