The need for batteries that store generated energy and powered engines is being sparked by increasing demands for renewable energy and electric vehicles. However, the batteries that power these sustainable solutions are not always green enough. Scientists have constructed a zinc battery with a biodegradable electrolyte from an unexpected source—crab shells.
Crab and shrimp shells are an abundant source of chitin. Image Credit: Liangbing Hu
The new study was published in the journal Matter on September 1st, 2022.
Vast quantities of batteries are being produced and consumed, raising the possibility of environmental problems. For example, polypropylene and polycarbonate separators, which are widely used in Lithium-ion batteries, take hundreds or thousands of years to degrade and add to environmental burden.
Liangbing Hu, Study Lead Author and Director, Center for Materials Innovation, University of Maryland
Ions are transported back and forth between positively and negatively charged terminals by an electrolyte in batteries. A battery’s electrolyte, which can be a liquid, paste, or gel, sometimes contains flammable or corrosive compounds. This innovative battery uses a gel electrolyte comprised of a biological substance called chitosan to store energy from large-scale wind and solar sources.
Chitosan is a derivative product of chitin. Chitin has a lot of sources, including the cell walls of fungi, the exoskeletons of crustaceans, and squid pens. The most abundant source of chitosan is the exoskeletons of crustaceans, including crabs, shrimps, and lobsters, which can be easily obtained from seafood waste. You can find it on your table.
Liangbing Hu, Study Lead Author and Director, Center for Materials Innovation, University of Maryland
This chitosan electrolyte totally degraded within five months, making it a biodegradable electrolyte, which indicates that around two-thirds of the battery might be broken down by microorganisms. Instead of the recyclable lead or lithium, the metal component is left behind, in this case, zinc.
Zinc is more abundant in earth’s crust than lithium. Generally speaking, well-developed zinc batteries are cheaper and safer.
Liangbing Hu, Study Lead Author and Director, Center for Materials Innovation, University of Maryland
With an energy efficiency of 99.7% after 1000 battery cycles, this battery made of zinc and chitosan is a good choice for storing energy produced by wind and solar for transfer to power grids.
Hu and his group intend to keep trying to make batteries, including the manufacturing process, even more environmentally friendly.
Hu adds, “In the future, I hope all components in batteries are biodegradable. Not only the material itself but also the fabrication process of biomaterials.”
The study was aided by the Research Corporation for Science Advancement, Facebook Reality Labs Research, the University of Maryland A. James Clark School of Engineering and Maryland Nanocenter, and AIMLab.
Journal Reference
Wu, M., et al. (2022) A sustainable chitosan-zinc electrolyte for high-rate zinc-metal batteries. Matter. doi.org/10.1016/j.matt.2022.07.015.