Large lithium batteries might be helpful for grid-scale renewable energy storage, as demonstrated by the enormous Tesla battery in South Australia. However, they come with the risk of catching fire and can be very expensive. Zinc-based batteries, also known as zinc-ion batteries, are one of the more affordable and perhaps safer options. A recent development adds yet another reason zinc-ion batteries are the way to go; it reveals how using crab shells could make them far more sustainable.
The Increasing Energy Demand Issue
As we rely more on renewable energy and electric vehicles for transportation, the need for energy storage is only projected to increase. While lithium-ion batteries, which are already used extensively, serve us well, other architectures have more significant long-term promise. Unfortunately, lithium mining is costly, has adverse environmental effects, and the batteries that contain it are usually not recyclable.
Liangbing Hu, the study’s lead author and director of the University of Maryland’s Center for Materials Innovation, said:
“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 the environmental burden.”
Safer, Eco-Friendlier Alternatives
A team of researchers from the University of Maryland and the University of Houston have created a sustainable zinc-ion battery with a biodegradable electrolyte made from crab shells. In addition to its biodegradable properties, the chitosan electrolyte is also non-flammable, which is an important safety factor for batteries.
Zinc-based batteries are one of several potential substitutes being researched by scientists for the tried-and-trusted lithium-ion architecture; this alternative may be safer, more economical, and environmentally friendly. “Zinc is more abundant in Earth’s crust than lithium. So, generally speaking, well-developed zinc batteries are cheaper and safer,” added Hu.
One of the benefits of zinc-ion batteries is their high energy density, which allows them to store a large amount of energy in a small space. This makes them particularly suitable for use in portable electronic devices and electric vehicles, where space is often at a premium. Additionally, because they use an aqueous electrolyte, they are safer than other types of batteries that use flammable or corrosive electrolytes. They are also rechargeable batteries, meaning they can be used over and over again, reducing the need for disposable batteries. Overall, zinc-ion batteries offer a combination of high energy density, safety, and rechargeability, making them an attractive alternative to traditional lithium-ion batteries.
Overcoming Hurdles
Zinc-ion batteries have a short lifespan, a significant barrier in this industry; hence researchers have focused on creating reliable rechargeable versions. This might involve chemical changes that avoid water damage or new electrocatalysts that help preserve their efficiency across repeated discharge cycles. Hu and his team have proposed a different approach that could solve the rechargeability problem and simultaneously increase the devices’ sustainability.
Making Gel Electrolyte with Crab Shells
When a zinc battery cycles, ions move back and forth between the anode and cathode of the metal in an electrolyte solution – many traditional lithium battery electrolyte solutions contain corrosive and flammable chemicals. With this in mind, the team developed a gel electrolyte for use with a zinc anode made from a natural substance called chitosan.
Hu explained:
“Chitosan is a derivative product of chitin. Chitin [the world’s second-most common biopolymer behind cellulose] has a lot of sources, including the cell walls of fungi, the exoskeletons of crustaceans, and squid pens. The most abundant chitosan source is crustaceans’ exoskeletons, including crabs, shrimps and lobsters, which can be easily obtained from seafood waste. You can find it on your table.”
The food industry generates a whopping six to eight million metric tons of shrimp, crab, and lobster shell waste every year. Those shells usually get dumped back into the ocean or landfills, depending on the region. So it will be good to see some of that waste being used!
Chitin and chitosan have recently been used to create compostable food wraps, garden pots, nanoparticles that kill mosquitoes, stronger concrete, and an antibacterial covering, among other things.
Successful Results
The team tested the performance of the zinc-metal battery with the chitosan electrolyte, and found that it was able to operate for 400 hours with an energy efficiency of 99.7% after 1,000 cycles. This offers the potential for storing energy generated by wind and solar for transfer to power grids, as well as for use in portable electronic devices and electric vehicles. The battery also displayed excellent cycling stability and did not develop tentacle-like growths that might impair its performance when running at a high current density of 50 mAh per square centimeter.
One important aspect of any battery is the active material or the substance that stores and releases energy. In zinc-ion batteries, the active material is typically a combination of zinc and other materials, such as carbon. The properties of the active material play a key role in the performance of the battery, including the energy density, charge and discharge rates, and overall performance. By carefully selecting and optimizing the active material, researchers can improve the efficiency and effectiveness of zinc-ion batteries for a variety of applications.
Eco-Friendly Design for a Healthy Planet
Additionally, due to its environmentally friendly design, the chitosan electrolyte can fully degrade in about five months, while hungry microbes can break down two-thirds of the battery. Afterward, any excess zinc can be recycled. “In the future, I hope all components in batteries are biodegradable,” said Hu. The research was published on September 01, 2022, in the journal Matter.
The use of crab shells as a source of chitosan also has the potential to reduce waste in the seafood industry. The food industry generates a whopping six to eight million metric tons of shrimp, crab, and lobster shell waste every year. These shells are often discarded into the ocean or landfills, but using them as a source of chitosan could help repurpose this waste and reduce pollution.
Other Fire-Resistant Batteries
MIT engineers have recently created a new battery design using rock salt, sulfur, and aluminum. It’s cheap, resistant to fires, and charges quickly, making it potentially helpful in powering buildings or electric cars.
Meanwhile, in 2020, the Canadian company Zinc8 developed a zinc-air battery that can store several days’ worth of energy, is up to five times cheaper than lithium-ion, doesn’t degrade, and can’t possibly explode.
Additionally, quinone electrodes were used in aqueous zinc batteries in 2018 as redox-active materials. Quinones are common biological pigments found in various living things (fungi, bacteria, higher plants, and some animals). They can be found in multiple forms, including polycyclic quinones, benzoquinones, naphthoquinones, and anthraquinones.
In conclusion, the development of a sustainable and eco-friendly zinc-ion battery using crab shells as a source of chitosan electrolyte could have significant implications for the renewable energy and battery industries. It offers the potential for safer, more affordable, and more sustainable energy storage solutions that can help reduce our reliance on fossil fuels and protect the environment.
