Chitin/zinc battery showed nearly 100% efficiency
A newly published academic study has found chitin to be a plausible sustainable energy source for electric vehicles.
Chitin is the major structural component of crustaceans found in the outer casings of crabs, lobsters and shrimps, and the exoskeletons of most insects.
The paper, “A sustainable chitosan-zinc electrolyte for high-rate zinc-metal batteries,” was authored by University of Maryland Professor Liangbing Hu, and published in September 2022 in the scientific journal Matter.
Hu told Newsweek the battery can be used for internal combustion engines or to store energy generated by large-scale wind and solar arrays for transfer to power grids. But the key improvement the batteries could bring to the commercial space is greater affordability and sustainability, Hu said.
“Vast quantities of batteries are being produced and consumed, raising the possibility of environmental problems,” Hu said. “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.”
Chitin has already found commercial use in medicines, pesticides, fertilizers, and as an edible film on foods.
Chitin holds the key to demands for renewable energy
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It holds the key to satisfying the motor industry’s growing demand for renewable energy, says the U.S. team. The zinc battery has a biodegradable electrolyte containing chitin extracted from crab shells. Chitin is a natural compound known as a biopolymer. It is already used in medicines, pesticides, fertilizers and as an edible film on foods. Batteries use an electrolyte to shuttle ions back and forth between positively and negatively charged terminals.
It can be a liquid, paste or gel, and include flammable or corrosive chemicals. The new electrolyte is a gel comprising chitosan, a derivative of chitin.
Hu said: “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.”
About two-thirds of the battery could be broken down by microbes. The chitosan electrolyte crumbled completely within five months. It left behind the metal component zinc, rather than lead or lithium, which could be recycled.
Hu said: “Zinc is more abundant in earth’s crust than lithium. Generally speaking, well-developed zinc batteries are cheaper and safer.”
The battery has an energy efficiency of 99.7 percent after 1,000 battery cycles. It could even store energy generated by large-scale wind and solar sources for transfer to power grids. The researchers plan to work on making batteries even more environmentally friendly from the manufacturing process onward.
Hu added: “In the future, I hope all components in batteries are biodegradable. Not only the material itself but also the fabrication process of biomaterials.”
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By Prachi Patel September 8, 2022
A new battery made from crab shells and zinc promises to be fully biodegradable and recyclable. The safe, eco-friendly battery can be recharged at least 1,000 times, making it suitable for storing wind and solar energy for the power grid.
Lithium-ion is today the most widely used battery technology for grid energy storage. But the explosion of renewables and electric vehicles has put strain on the already tenuous supply chain of materials that go into lithium batteries.
Mining battery metals harms the environment. Plus, it is not easy or economical to recycle lithium batteries at the end of their lives, so most of the 15 million metric tons of discarded batteries the world is expected to produce by 2030 will likely end up in landfills.
Researchers at the University of Maryland and University of Houston wanted to make a more sustainable battery. They started with zinc-metal battery chemistry, which scientists have been developing for grid storage for several years. Zinc is much more abundant than lithium in the earth’s crust, so zinc-ion batteries are cheaper. But traditional batteries—made of zinc anodes, metal oxide cathodes, and water-based electrolytes—suffer from uneven deposition of zinc on the electrode surface, which makes them unsafe and short-lived.
So the researchers made a new biodegradable gel electrolyte from chitosan, a compound derived from chitin, the protein that makes up the tough shells of crustaceans such as crabs, lobsters, and shrimps. Chitin is usually thrown away as a byproduct of the food industry.
By combining chitin and zinc, they made a strong gel membrane that served as the electrolyte for the battery. They used zinc for the anode as usual, but replaced the conventional cathode with one made of a biodegradable organic material. The battery, reported in the journal Matter, maintained an efficiency of 99.7% over 1,000 cycles when operating at a high current density.
Two-thirds of the battery is biodegradable, making it very environmentally friendly. Both the chitosan electrolyte and cathode material biodegrade in soil in a few months, and the zinc left behind can be recycled. “In the future, I hope all components in batteries are biodegradable,” said UMD materials scientist and engineer Liangbing Hu in a press release. “Not only the material itself but also the fabrication process of biomaterials.”
Source: Meiling Wu et al. A sustainable chitosan-zinc electrolyte for high-rate zinc-metal batteries. Matter, 2022.