Researchers at the Shandong Academy of Medical Sciences, China, and Kyushu Institute of Technology, Japan, are “upcycling” crab shells into porous, carbon-filled materials with a wide variety of uses, including using the crab carbon to create anode materials for sodium-ion batteries.

The researchers said they had already created a biodegradable zinc-ion battery by using crab shells.

The sodium-ion batteries are considered an upcoming competitor to lithium-ion chemistries, which have become ubiquitous in recent years. However, because of the limited amount of lithium metal available globally, researchers have turned their attention to its “chemical cousins” instead.

It was found that these could be turned into “hard carbon,” a material explored as a possible anode for sodium-ion batteries.

While sodium ions are chemically almost similar to lithium, they are larger and therefore incompatible with a lithium-ion battery’s anode, which is typically made of graphite.

When hard carbon is combined with metallic semiconductor materials, such as the transition metal dichalcogenides (TMD), the material can become a feasible battery anode.

The researchers wanted to explore how two different TMDs — tin sulfide and iron sulfide — could be combined with hard carbon made from crab shells to create a viable sodium-ion battery anode.

Making “Crab Carbon” 

The researchers heated crab shells to temperatures exceeding 1,000 degrees F. They then added the carbon to a solution of either tin sulfide (SnS₂) or iron sulfide (FeS₂) and 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 said this work could provide a route to upcycle other wastes and help develop more sustainable battery technologies.

Recently, researchers at the Dresden University of Technology transformed single-cell algae into functional perovskite materials by converting mineral shells into lead halide perovskites with tunable physical properties.

In January, researchers at the Daegu Gyeongbuk Institute of Science & Technology said they developed a new electrolyte technology through magnetic nanoparticles that can improve both the stability and lifespan of next-generation lithium batteries.