Electric vehicle batteries have improved considerably in recent years, but their limited ability to store energy still keeps many people from giving up their gas-burning cars. That may be about to change, though, as a new anode material is said to offer a whopping four-fold increase in capacity.
Batteries incorporate two electrodes – an anode and a cathode – which ions travel between through an electrolyte. Among other things, the capacity of a battery is affected by the amount of electrons that are able to build up in the anode.
Typically, those anodes are made of graphite. According to scientists at the Korea Institute of Science and Technology (KIST), silicon offers 10 times the energy storage capacity of graphite, but it has one major disadvantage as an anode material – it swells up during the charge/discharge cycle, causing its surface to crack and its capacity to thus drop drastically.
Attempts have been made to produce stabilized silicon anodes, but the cost and complexity of the techniques involved have generally made them commercially unviable. That's where KIST's new technology is claimed to come in.
Dr. Hun-Gi Jung and colleagues started by dissolving sweet potato-derived starch in water, dissolving silicon in corn-derived oil, and then mixing and heating the two solutions. What resulted was a carbon-silicon composite material, in which tiny carbon spheres kept the silicon from swelling.
When tested, anodes made from the composite were reportedly found to have four times the storage capacity as similar graphite anodes, yet they also remained stable over 500 charge/discharge cycles. Additionally, batteries utilizing the new anodes could be charged to 80 percent their full capacity in just five minutes.
"The simple processes we adopted and the composites with excellent properties that we developed are highly likely to be commercialized and mass-produced," says Jung. "The composites could be applied to lithium-ion batteries for electric vehicles and energy storage systems."
The research is described in a paper that was recently published in the journal Nano Letters.
Source: National Research Council of Science & Technology via EurekAlert
