Crabs could be the unlikely hero the battery industry needs

By On Sep 11, 2022

Has anyone ordered a Krabby battery?

Chitin and its derivative chitosan are natural polymers found in crustaceans and elsewhere in nature. Engineers from the University of Maryland have devised a way to make zinc-based batteries more durable by incorporating chitosan. This could pave the way for alternatives to lithium-ion batteries, which are becoming increasingly expensive, in addition to the environmental issues associated with lithium mining. Crab meat is delicious – that’s an undeniable, garlicky, buttery truth. But here’s something you might not know about your penchant for boiled crab: An estimated six to eight million tons of crab, shrimp, and lobster shell waste are produced worldwide each year, with most of it being dumped straight back into the ocean or into landfills . depending on the country. The problem is not so much the enormous waste thrown at the table as the lost opportunity. The tough exoskeletons of crustaceans and their marine species are rich in useful, versatile chemicals such as calcium carbonate, used in medicine and industry, and chitin, the second most abundant natural polymer on Earth. Over the years, scientists have extracted chitin from crab shells for everything from tissue engineering to making biodegradable plastics. Since this and its sister polymer chitosan are considered environmentally friendly and non-toxic, there has been a lot of interest in incorporating these chemical compounds into batteries of all things. In a paper published earlier this month in the journal Matter, a group of engineers at the University of Maryland did just that, creating an impressive chitin-zinc battery that’s biodegradable but still holds plenty of electricity. As the world moves towards a more sustainable future, there is hope that a rechargeable battery derived from crustaceans may be a viable alternative or even replacement for the ever-increasing demand for lithium-ion batteries (hello electric vehicles!). At the same time, lithium itself is becoming a scarce resource. “It’s really exc using chitin, you take advantage improving its reproducibility and potential for binding to zinc to make new electrode materials,” Mark MacLachlan, professor of supramolecular materials at the University of British Columbia, who was not involved in the study, told Popular Mechanics. email. All you need are electrons (and some conducting metals). The spark that lights up your phone is the result of some chemistry going on deep inside the battery. Chemical reactions called redox reactions produce a steady drumming of electric current in the form of moving electrons. These travel through a circuit made up of the battery’s electrodes (made of two different conductive metals), its chemical electrolyte (a gel or liquid-like material containing charged particles called ions), and whatever device or device the battery is connected to. Different metals and electrolytes are used in the battery. For example, in a common household alkaline battery, the positive electrode (cathode) is made of manganese oxide and the negative electrode (or anode) is made of the trace mineral zinc. The electrolyte in between is potassium hydroxide. In lithium-ion batteries, lithium is usually combined with another metal, such as cobalt at the cathode and carbon at the anode, and also makes up the electrolyte. Lithium-ion batteries are a rising star in the energy world because they’re lightweight yet pack a punch. of energy (and can be recharged). It’s no surprise that these batteries have found their way into nearly every electronic device and electric vehicle over the past few decades, but lithium extraction takes a huge and devastating toll on the environment. Not only that, but lithium-ion batteries are not easily broken down or recycled, making them not entirely compatible with sustainability – at least in their current form. “Storage batteries as green energy sources are essential to reduce our dependence on fossil fuels and reduce greenhouse gas emissions. However, due to the increasing demand for electric vehicles have been producing and consuming huge amounts of batteries in recent years, increasing the potential for environmental problems,” says Meiling Wu, first author of the new study and a postdoctoral fellow at the University of Maryland. in an email to Popular Mechanics. “For example, polypropylene and polycarbonate separators, which are often used in lithium-ion batteries, take hundreds or thousands of years to degrade and further burden the environment.” Crayfish to the rescue Scientists have toyed with chitin over the years, looking for ways to incorporate the organic substance – which is structurally similar to cellulose in plants – into batteries. In 2016, MacLachlan and his lab at the University of British Columbia discovered that when you cook chitin with nitrogen at temperatures up to 1,652 degrees Fahrenheit, it turns former crustacean shells into a carbon-nitrogen material suitable for electrodes. But Wu and her colleagues at the University of Maryland decided to take a different approach. Their focus was on zinc-based batteries, which are common disposable but non-rechargeable batteries. Because the mineral is more readily available than lithium (read: cheaper to produce and supply) and less toxic (zinc batteries use water as an electrolyte), there has been a lot of interest in zinc as our silver-white energy knight. The exchange of lithium for zinc, however, is not smooth. In batteries as an electrode, zinc has a disturbing tendency to form irregularities on its surface. These irregularities occur when electrons move and bubble into small bumps that snowball into larger and larger ones called dendrites, which disrupt the battery’s electrical flow. Because chitosan, a chemically treated derivative of chitin, interacts well with and can retain water, Wu and her colleagues believed it could be used to make an ator battery separator—a semipermeable membrane that keeps oppositely charged electrodes apart—that is also biodegradable. So how do they do it what? The researchers took a coin-sized film of chitosan and bathed it in a zinc-laden solution to get the mineral to adhere to the film. Then, they extruded the chitosan-zinc film and pressed it tightly so that it was densely packed. Unlike previous attempts to thicken chitosan films, this technique allowed for relatively large pores (up to five micrometers in size), allowing ions to move freely, said Jodie Lutkenhaus, a professor of chemical engineering at Texas A&M University who was not involved in the study. Popular Mechanics. “This is crucial because when you think about a cancer shell, you think it’s really hard and dense, which is not good for conducting ions,” says Lutkenhaus, who has done research on organic batteries. a zinc anode was placed on top of a chitosan-zinc separator along with a cathode made of an organic compound called poly(benzoquinonyl sulfide), or PBQS. When Wu and her colleagues ran the Krabby battery in the lab, they didn’t see any dendrite formation on the zinc anode. Surprisingly, for 400 hours (or 1,000 charge cycles) it generated an electric current of 50 milliamps per square centimeter, which is close to what small lithium batteries can handle. They then buried the chitosan-based electrolyte, not the entire battery itself, to see how long it would take to degrade. Wu says they found that it took about five months for microorganisms living in the dirt to consume the electrolyte, which is much faster than conventional electrolytes lying in landfills, and is definitely good for the environment. “It doesn’t mean that the battery device will degrade itself in five months,” he says. “Actually, the electrolyte is packed in a closed cell that is separated from air and organisms. Such a device can work for a much longer time.” The Future of Chitosan-Based Batteries While you won’t be seeing crab-shaped batteries anytime soon, researchers hope that their batteries will become commonplace and will be used in electronic devices such as your mobile phone in dedicated storage for renewable energy that is fed into the commercial grid. . Given that chitosan costs only about $1.70 per gram and that you don’t need a lot of it to make their prototype (only about 20 micrograms for a 20mm coin-sized battery), this may give the chitosan-zinc battery a cost advantage over lithium-ion batteries, which are suffering from climbing demand and accompanying costs. But with high temperatures due to climate change affecting marine life the most, the question is what will happen to costs if batteries made from chitosan take off. It is also worth considering how truly green its use would be in the future – we must take into account the carbon footprint of the activities associated with obtaining chitin and turning it into chitosan. “I think the next important step would be to do a techno-economic analysis to look at what the global production of chitosan is, and if we’re going to use it for, say, grid energy storage, do we have enough access to it?” says Lutkenhaus. “If we start using it, will that change the price because of demand … it’s a life cycle analysis … the carbon footprint of the crab capture, shipping and processing.” Fortunately, Wu says, we have other sources of chitin, such as in insects and fungal cell walls, so it’s not entirely unreasonable for a marine source to fall by the wayside. And while no one has yet attempted to synthesize chitin in the laboratory, who knows what the future might hold. Right now, it seems that our salty marine debris could be the solution to our current energy problems.

Crab meat is delicious – that’s an undeniable, garlicky, buttery truth. But here’s something you might not know about your penchant for boiled crab: An estimated six to eight million tons of crab, shrimp, and lobster shell waste are produced worldwide each year, with most of it being dumped straight back into the ocean or into landfills . depending on the country.

The problem isn’t so much the massive waste thrown away for dinner as it is the lost opportunity. The tough exoskeletons of crustaceans and their marine species are rich in useful, versatile chemicals such as calcium carbonate, used in medicine and industry, and chitin, the second most abundant natural polymer on Earth.

Over the years, scientists have extracted chitin from crab shells for everything from tissue engineering to making biodegradable plastics. Since this and its sister polymer chitosan are considered environmentally friendly and non-toxic, there has been a lot of interest in incorporating these chemical compounds into batteries of all things.

In a paper published earlier this month in the journal Matter, one team of engineers at the University of Maryland did just that, creating an impressive chitin-zinc battery that’s biodegradable but still holds plenty of electricity. As the world moves towards a more sustainable future, there is hope that a rechargeable battery derived from crustaceans may be a viable alternative or even replacement for the ever-increasing demand for lithium-ion batteries (hello electric vehicles!). At the same time, lithium itself is becoming a scarce resource.

“This is a really exciting use of chitin that takes advantage of its renewability and zinc-binding potential to make new electrode materials,” Mark MacLachlan, a professor of supramolecular materials at the University of British Columbia who was not involved in the study, told Popular Mechanics in an email. .

All You Need Is Electrons (And Some Conductive Metals)

The spark that lights up your phone is the result of some chemistry going on deep inside the battery.

Chemical reactions called redox reactions produce a steady drumming of electric current in the form of moving electrons. These travel through a circuit made up of the battery’s electrodes (made of two different conductive metals), its chemical electrolyte (a gel or liquid-like material containing charged particles called ions), and whatever device or device the battery is connected to.

Different metals and electrolytes are used in the battery. For example, in a common household alkaline battery, the positive electrode (cathode) is made of manganese oxide and the negative electrode (or anode) is made of the trace mineral zinc. The electrolyte in between is potassium hydroxide. In lithium-ion batteries, lithium is usually combined with another metal, such as cobalt at the cathode and carbon at the anode, to form an electrolyte as well.

Lithium-ion batteries are rising stars in the energy world because they’re lightweight yet pack a ton of energy (and they’re rechargeable). It’s no surprise that these batteries have found their way into nearly every electronic device and electric vehicle over the past few decades, but lithium extraction takes a huge and devastating toll on the environment. Not only that, but lithium-ion batteries are not easily broken down or recycled, making them not entirely compatible with sustainability – at least in their current form.

“Storage batteries as green energy sources are essential to reduce our dependence on fossil fuels and reduce greenhouse gas emissions. However, due to the increasing demand for electric vehicles in recent years, huge amounts of batteries have been produced and consumed, increasing the potential for environmental problems,” says Meiling Wu, first author of the new study and a postdoctoral fellow at the University of Maryland. in an email to Popular Mechanics. “For example, polypropylene and polycarbonate separators, which are often used in lithium-ion batteries, take hundreds or thousands of years to degrade and further burden the environment.”

Crabs to the Rescue

Scientists have toyed with chitin over the years, looking for ways to incorporate the organic substance — which is structurally similar to cellulose in plants — into batteries. In 2016, MacLachlan and his lab at the University of British Columbia discovered that when you cook chitin with nitrogen at temperatures up to 1,652 degrees Fahrenheit, it turns former crustacean shells into a carbon-nitrogen material suitable for electrodes.

But Wu and her colleagues at the University of Maryland decided to take a different approach. Their focus was on zinc-based batteries, which are common disposable but non-rechargeable batteries. Because the mineral is more readily available than lithium (read: cheaper to produce and supply) and less toxic (zinc batteries use water as an electrolyte), there has been a lot of interest in zinc as our silver-white energy knight.

The exchange of lithium for zinc, however, is not smooth. In batteries as an electrode, zinc has a disturbing tendency to form irregularities on its surface. These irregularities occur when electrons move through and bubble up into small bumps that snowball into larger and larger ones called dendrites, which disrupt the battery’s electrical flow.

Because chitosan, a chemically treated derivative of chitin, works well with water and can keep it from floating willy-nilly, Wu and her colleagues believed it could be used to make a battery separator—a semipermeable membrane that keeps oppositely charged electrodes apart—also it is biodegradable.

So how did they do it? The researchers took a coin-sized film of chitosan and bathed it in a zinc-laden solution to get the mineral to adhere to the film. Then, they extruded the chitosan-zinc film and pressed it tightly so that it was densely packed. Unlike previous attempts to thicken chitosan films, this technique allowed for relatively large pores (up to five micrometers in size), allowing ions to move freely, said Jodie Lutkenhaus, a professor of chemical engineering at Texas A&M University who was not involved in the study. Popular Mechanics.

“This is key because when you think about a crab’s shell, you think it’s really hard and dense, which is not good for conducting ions,” says Lutkenhaus, who has done research on organic batteries.

To complete the build, a zinc anode was placed on top of the chitosan-zinc separator along with a cathode made of an organic compound called poly(benzoquinonyl sulfide), or PBQS. When Wu and her colleagues ran the Krabby battery in the lab, they didn’t see any dendrite formation on the zinc anode. Surprisingly, for 400 hours (or 1,000 charge cycles) it generated an electric current of 50 milliamps per square centimeter, which is close to what small lithium batteries can handle.

They then buried the chitosan-based electrolyte, not the entire battery itself, to see how long it would take to degrade. Wu says they found that it took about five months for microorganisms living in the dirt to consume the electrolyte, which is much faster than conventional electrolytes lying in landfills, and is definitely good for the environment.

“It doesn’t mean that the battery device will degrade itself in five months,” he says. “Actually, the electrolyte is packed in a closed cell that is separated from air and organisms. Such a device can work for a much longer time.”

The Future of Chitosan-Based Batteries

While you won’t see crab-shaped batteries anytime soon, the researchers hope that their batteries will become mainstream and used in electronic devices like your cell phone, in dedicated storage for renewable energy fed into the commercial grid.

Given that chitosan costs only about $1.70 per gram and that you don’t need a lot of it to make their prototype (only about 20 micrograms for a 20mm coin-sized battery), this may give the chitosan-zinc battery a cost advantage over lithium-ion batteries, which are suffering from climbing demand and accompanying costs.

But with high temperatures due to climate change affecting marine life the most, the question is what will happen to costs if batteries made from chitosan take off. It is also worth considering how truly green its use would be in the future – we must take into account the carbon footprint of the activities associated with obtaining chitin and turning it into chitosan.

“I think the next important step would be to do a techno-economic analysis to look at what the global production of chitosan is, and if we’re going to, say, use it for grid energy storage, do we have enough access to that?” Lutkenhaus says. “If we start using it, will that change the price because of demand … [Also] there’s a life cycle analysis involved … the carbon footprint of the crab capture, shipping and processing.”

Fortunately, Wu says, we have other sources of chitin, such as in insects and fungal cell walls, so it’s not entirely silly if a marine source falls by the wayside. And while no one has yet attempted to synthesize chitin in the laboratory, who knows what the future might bring. Right now, it seems that our salty marine debris could be the solution to our current energy problems.