Crab shells can be used to make new battery materials

Anyone who has tasted fresh crab legs knows how tough the shell can be. But rather than simply throw them away, researchers from Shandong First Medical University and Kyushu University of Technology in Japan have "upgraded" them into porous, carbon-filled materials with a wide range of uses. As they report in the latest issue of 《ACS Omega》, they have used this "crab carbon" to make anode material for sodium-ion batteries, which would be a very competitive competitor in lithium electrochemistry.

Lithium-ion batteries have become ubiquitous in most everyday mobile devices in recent years, powering cellphones, cars and even toothbrushes. But because the amount of lithium 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 from crab shells. But these discarded casings can also be converted into "hard carbon," a material that has been explored as a possible anode for sodium-ion batteries. When hard carbon is combined with a metal semiconductor material such as transition metal disulfide (TMD), the material can be used as a battery anode.

Although sodium ions are chemically similar to lithium, sodium ions are larger and incompatible with the anodes of lithium-ion batteries. The researchers explored how to combine two different TMDS -- tin sulfide and iron sulfide -- with hard carbon made from crab shells to make a viable sodium-ion battery anode.

To make the "crab carbon", the researchers heated crab shells to more than 540 ° C, added the carbon to a solution of tin sulfide or iron sulfide, and dried them to form an anode. Crab Carbon's porous fiber structure provides a large surface area, enhancing the material's electrical conductivity and ability to efficiently transport ions.

When tested in a model battery, the team found that both composites had good capacity, lasting at least 200 cycles.

Article from Science and Technology Daily