Corny Lithium-Ion Batteries Could Hold Quadruple the Charge

Photo credit: Getty Images
Photo credit: Getty Images

From Popular Mechanics

Could a simple materials change make electric car batteries able to four times more energy? Scientists in South Korea think so. In a new paper in the American Chemical Society’s Nano Letters, a research team details using silicon and repurposed corn starch to make better anodes for lithium ion batteries.

This team is based primarily in the Korea Institute of Science and Technology (KIST), where they’ve experimented with microemulsifying silicon, carbon, and corn starch into a new microstructured composite material for use as a battery anode. This is done by mixing silicon nanoparticles and corn starch with propylene gas and heating it all to combine.

Using biowaste corn starch is already pretty popular, with products like biodegradeable “corn plastic” cutlery, packaging, and the infamous nontoxic packing peanut. The same qualities that make corn starch attractive in these applications apply to the silicon anode project. Existing lithium-ion batteries use carbon anodes, and scientists know silicon would work better in many ways but have struggled to stabilize the silicon enough for this use to be practical. “To enhance the stability of silicon, Dr. Jung and his team focused on using materials that are common in our everyday lives, such as water, oil, and starch,” KIST wrote in a statement about the paper.

The heating was just as inspired by everyday life: “A simple thermal process used for frying food was employed to firmly fix the carbon and silicon, preventing the silicon anode materials from expanding during charge and discharge cycles,” the statement says. The starch and heat work together to make a new kind of anode that is both temperature and structurally stable.

Inside, the material uses the strongest attributes of all three of its component parts, the scientists say: “silicon nanoparticles embedded in micron-sized amorphous carbon balls derived from corn starch that is capsuled by thin graphitic carbon layer.” In other words, the silicon bits are the peanuts, coated in corn starch chocolate and a carbon candy shell. The “dual carbon matrix” cushioning the silicon makes it both conductive and stable.

The researchers say the simple approach and accessible materials mean their new anode is more ready for a mass market than some other research might be. And their results are astonishing: their statement says the silicon-carbon anode showed four times more capacity than existing graphite anodes and held up well over 500 charge cycles.

In this paper, the research team describes their corn starch as biowaste, which is an umbrella term that refers to anything from byproducts of manufacturing to human biological waste products like sewage. Intentionally manufactured corn starch is a huge industry around the world because of corn starch’s many uses in powder form.

Biowaste corn starch is likely an agricultural byproduct that would otherwise be discarded, so turning them back into batteries would be a huge boon for the environment.

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