While setting up their new lab, Purdue University researchers ended up with piles of packing peanuts. Professor Vilas Pol suggested an environmentally friendly way to reuse the waste.
The team converted their lab's extra packing peanuts into high-performance carbon electrodes for rechargeable lithium-ion batteries. The batteries outperform conventional graphite electrodes. Carbon-nanoparticle and microsheet anodes were built from polystyrene and starch-based packing peanuts, respectively.
Packing peanuts, though valuable for shipping, are difficult to break down and often end up in landfills. The polystyrene peanuts also contain chemicals and detergents that can contaminate soil and aquatic ecosystems.
With the Purdue method, the peanuts are heated between 500 and 900 degrees Celsius in a furnace under inert atmosphere, and in the presence or absence of a transition metal salt catalyst. The resulting material is then processed into the anodes.
Commercial anode particles are about 10 times thicker than the new anodes and have higher electrical resistance, which increase charging time. The Purdue method is potentially practical for large-scale manufacturing.
"In our case, if we are lithiating this material during the charging of a battery it has to travel only 1 micrometer distance, so you can charge and discharge a battery faster than your commercially available material," Pol said.
Future work will include steps to potentially improve performance by increasing the surface area and pore size to improve the electrochemical performance.
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