Researchers harvest carbon from crab shells to form anodes for sodium-ion batteries

In Japan, anybody who has ever enjoyed fresh crab legs or lobster tails can attest to how difficult it is to get through their tough shells. But instead of just throwing them away, researchers are “upcycling” these shells into porous, carbon-filled materials with a wide variety of uses. Now, a team reporting in ACS Omega has used this “crab carbon” to create anode materials for sodium-ion batteries — an up-and-coming competitor to lithium-ion chemistries.

To make their “crab carbon,” the researchers heated crab shells to temperatures exceeding 1000 F. They then added the carbon to a solution of either tin sulfide (SnS2) or iron sulfide (FeS2), then dried them to form anodes. The porous, fibrous structure of the crab carbon provided a large surface area, which enhanced the material’s conductivity and ability to transport ions efficiently. When tested in a model battery, the team found that both composites had good capacities and could last for at least 200 cycles. The researchers say that this work could provide a route to upcycle other wastes and help develop more sustainable battery technologies.