Plastic membrane offers super-fast electric vehicle charging

A thin plastic membrane that stops rechargeable batteries from discharging when not in use and allows for rapid recharging has been developed by Ohio State University (OSU) researchers.

The technology controls the way charge flows inside a battery and was inspired by how living cell membranes transport proteins in the body.

It could find applications in high powered ‘supercapacitors’ for electric cars and even help prevent battery fires, the likes of which have affected Tesla’s vehicles in the past. 

The ‘smart’ membrane could enable the development of a new category of fast-charging and powerful batteries called ‘redox transistor batteries’ for automobiles that will travel farther on a single charge.

Today’s best eco-friendly cars can only travel around 200 miles after an eight-hour charge, while gas-powered cars can cover the same distance after only one minute spent at the pump. The researchers hope their new technology can boost electric car batteries to provide up to tens of miles per minute of charge.

“That’s still an order of magnitude away from the equivalent measure in gasoline, but it’s a place to start,” said Vishnu-Baba Sundaresan, assistant professor at OSU.

Sundaresan said that today’s hybrid and electric cars are hitting the performance limit because of how charge is stored in conventional batteries. He also believes that his new membrane technology might be the only way to push past that limit until an entirely new category of battery electrodes are developed.

“Research over the last 50-plus years has focused on advancing the chemistry of battery electrodes to increase capacity,” Sundaresan said.

“We’ve done that, but the increase in capacity has come at the cost of robustness and the ability to rapidly charge and discharge batteries. Electric vehicle design is mature enough now that we know the limit they’re reaching is because of the chemistry of lithium-ion batteries.”

Sundaresan and doctoral student Travis Hery call their invention an ‘ionic redox transistor’, and they’re using it to develop a new kind of battery in which energy is stored in a liquid electrolyte which people can recharge or empty out and refill as they would refill a gas tank.

“For everyday commuting, the electrolyte can be simply regenerated by plugging it into a power outlet overnight or while parked at the garage. For long road trips, you could empty out the used electrolyte and refill the battery to get the kind of long driving range we are accustomed to with internal combustion engines,” Sundaresan said.

“We believe that this flexibility presents a convincing case for weaning our dependence on internal combustion engines for transportation.”

In laboratory tests, the engineers found that their membrane also reliably controlled charging and discharging in batteries powered by ions of lithium, sodium and potassium. It allowed the batteries to function normally, but reduced charge loss to zero when the batteries were not in use.

Tesla recently unveiled an upgraded version of its Model S that features a 100 kilowatt-hour (kWh) battery, a slight improvement on the previous model which only featured a 90 kWh battery.

The company boasts that the new version is the fastest car available for purchase as it can reach 60 miles per hour in just 2.5 seconds.

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