A new battery that’s completely biodegradable and recyclable is just around the corner. The secret? Crab shells and a little zinc. Safe and eco-friendly, the new breed of battery can be recharged at least 1,000 times, which makes it ideal for storing either wind or solar energy.
Today, lithium-ion is the most widely used battery for grid energy storage. Needless to say, the near geometric rise in renewables and electric vehicles has severely burdened the availability of materials needed to make lithium batteries. What’s more, recycling these batteries when they’re used up is complicated and expensive. It’s disconcerting that the bulk of the estimated 15 million metric tons of discarded batteries will end up in landfills by 2030.
Taking on the challenge of creating a biodegradable and recyclable battery, researchers at the University of Maryland and the University of Houston rolled up their sleeves and went to work. They began with Zinc, which is cheaper and far more plentiful than lithium. The problem they faced was that ordinary batteries are made of metal oxide cathodes, zinc anodes, and water-based electrolytes. All of these are placed as irregular zinc deposits on surface electrodes. That made them not only unsafe but electrically empty in a short time.
The solution? A new biodegradable gel electrolyte found in chitosan, a compound produced from chitin. Chitin it so happens is the protein that exists in the tough shells of crabs, lobsters, and shrimp. In fact, Chitin is typically just tossed out as a food industry byproduct. So by uniting chitin and zinc, you get a resilient gel membrane, ideal for a battery’s electrolyte. The new battery uses zinc for the anode but simply replaces the regular cathode with a biodegradable organic substance.
The resultant battery boasts some pretty impressive specs: an efficiency of 99.7% over 1,000 cycles when running at a high current density. These ‘crab’ batteries are very environmentally friendly. That’s because the chitosan electrolyte and cathode material biodegrade when buried in the soil after only a few months. As for the zinc, it can be recycled.