February 26th, 2020 by Tina Casey
No, really. They literally cooked this new electric vehicle battery up out of corn starch. A team of researchers at the Korea Institute of Science and Technology set themselves to the task of replacing graphite in an EV battery, and the answer was as simple (almost) as turning on the backyard grill. For bonus points, the new battery also introduces more sustainable, bio-based material into the EV supply chain.
Solving the EV Battery Supply Chain Puzzle
To be crystal clear, electric vehicles beat conventional cars hands-down for lifecycle carbon emissions. However, as the EV market heats up, auto manufacturers are paying closer attention to supply chain issues involving the materials used in batteries.
Developing a more environmentally friendly EV battery has been on the US Energy Department’s to-do list since at least 1995. For both economic and national defense reasons, the agency also has an interest in promoting battery materials that can be produced domestically.
The new KIST research could mark a big step forward on both counts. The study involves developing a bio-based substitute for graphite, which is currently the material of choice for the anodes of lithium-ion batteries.
As a bio-based alternative, the new material works around environmental issues related to graphite mining.
It also solves the domestic sourcing issue. The US has plenty of corn, but graphite mining in this country stopped after 1990 (though our neighbor Canada is one of the world’s leading suppliers, behind Brazil and of course, China).
Biobased Materials For A Better EV Battery
Aside from sustainability issues, graphite has been nailed as one of the factors limiting the range of EV batteries.
Researchers have been zeroing in on silicon as a replacement for graphite, based on its superior energy storage capacity. However, silicon alone does not stand up to the cycling demands of rechargeable batteries. It expands upon charge and shrinks upon discharge, making for a short, unstable lifespan.
One emerging strategy is to combine silicon with other materials, and that’s where the new KIST research comes in.
Deploying a “simple thermal process used for frying food,” the team dissolved corn starch in water, mixed in oil and silicon, and heated up the concoction.
The process fixed micron-sized carbon spheres firmly around the silicon, with a bonus layer of graphitic carbon. The spheres prevent the silicon from expanding during charging cycles, and they also provide for more efficient conductivity.
That is reflected in the performance of the new battery, as described by KIST:
The composite materials developed by the research team demonstrated a capacity four-times greater than that of graphite anode materials (360mAh/g ? 1,530mAh/g) and stable capacity retention over 500 cycles. It was also found that the materials enable batteries to charge to more than 80% capacity in only five minutes.
Kids, Do Not Try This At Home
The full KIST study is available in the journal Nano Letters. If you’ve seen it mentioned on other websites and can’t find the link, now worries. CleanTechnica spent many long minutes tracking it down for you.
Here it is under the title, “Nano/Microstructured Silicon–Carbon Hybrid Composite Particles Fabricated with Corn Starch Biowaste as Anode Materials for Li-Ion Batteries.“
If you spotted that thing about C3H6 gas, that’s the fuel they used to fry up their EV battery batter.
If you’re trying this at home, don’t mistake C3H6 for C3H8. C3H6 is the chemical formula for cyclopropane, not propane. Cyclopropane is a bit different from regular old grill-friendly gas:
It is easily ignited. The vapors are heavier than air. Contact with the liquid may cause frostbite. It can asphyxiate by the displacement of air and has a narcotic effect in high concentration (formerly used as an anesthetic gas). Under prolonged exposure to fire or intense heat the containers may rupture violently and rocket.
Anyways, if it all pans out you can add corn starch to the growing list of bio-based materials appearing in the automobile supply chain, along with dandelion rubber and cow bones, among others.
Meanwhile, over here in the US the Energy Department is pursuing silicon for lithium-ion batteries through the — you guessed it — Silicon Anode Consortium.