In 2022, Maryland engineers turned crab-shell chitosan into a zinc-battery electrolyte; after more than 1,000 cycles, the zinc anode still delivered 99.7% coulombic efficiency

People often throw crab and prawn shells straight in the trash without thinking about them. But these shells may have more uses than many people realize. A 2022 study published in Matter, titled A sustainable chitosan-zinc electrolyte for high-rate zinc-metal batteries, developed a zinc-metal battery using a biodegradable chitosan electrolyte derived from crustacean shells. The battery recorded 99.7% energy efficiency after 1,000 cycles.

A battery that could power the future

Crab, prawn and lobster shells contain chitin, which can be processed into chitosan. The researchers used chitosan to create a biodegradable gel electrolyte for their zinc battery. In a separate biodegradation test, they found that about two-thirds of the battery's components could be broken down by microbes, while the chitosan portion decomposed completely in about five months. The finding does not mean the entire battery would disappear after five months in normal conditions, but it does show the potential for making some battery materials more biodegradable.


Once the chitosan breaks down, the remaining metal component is zinc rather than lithium or lead. Zinc is more abundant in the Earth's crust than lithium, although their crustal abundances are relatively similar. Zinc-based batteries are also being explored because of their potential cost and safety advantages over some lithium-ion systems. Pairing a biodegradable electrolyte with a zinc-based battery could therefore offer one possible route towards reducing the environmental burden of some battery materials.

Why this battery is easier on the planet

This research came from the University of Maryland, whose feature on the project explained the researchers' concerns about the growing number of batteries being produced and used worldwide. The study offers an unusual example of turning a food-industry by-product into a material for energy storage. Rather than treating discarded crustacean shells simply as waste, researchers explored whether their chitosan content could be put to work in a battery electrolyte.

That storage role is important. Wind and solar power generate electricity intermittently, so energy-storage systems can help supply power when generation does not match demand. The strong cycling performance of the zinc-chitosan battery suggests that the approach merits further investigation, although considerably more testing would be needed before it could be considered for commercial applications.

That does not mean crab-shell batteries will appear in phones or cars anytime soon. Turning a laboratory breakthrough into a commercial product takes time, money and extensive testing. But the research points to a broader possibility: future batteries could be designed with their environmental impact in mind from the beginning, including what happens to individual components when their useful life ends.