COLLEGE PARK, Md – In a paper published earlier this month in the journal Matter, one group of engineers at the University of Maryland crafted an impressive chitin-zinc battery made from crab shells that’s biodegradable, but still holds considerable electrical juice.
As the world moves toward a more sustainable future, the hope is that a rechargeable, crab-derived battery may be a viable alternative to, or even a replacement for, lithium-ion batteries, which are increasing in demand. At the same time, lithium itself is becoming a scarce resource.
Chemical reactions called redox reactions produce a steady drumbeat of electrical current in the form of moving electrons. These travel through a circuit consisting 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 appliance or device the battery is hooked up to.
There’s a sundry of metals and electrolytes used in a battery. For instance, in your common household alkaline battery, the positive electrode (the 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 typically ponies up with another metal like cobalt at the cathode and carbon at the anode, and also makes up the electrolyte.
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