Researchers may have figured out a way to keep batteries from draining when not in use, while also setting them for faster recharge times.
The patent-pending tech uses a thin plastic membrane to prevent battery discharge by controlling how charge flows within a battery. Developed by Ohio State engineers, the so-called “smart” membrane was inspired by how cell membranes in living organisms transport proteins throughout a body.
Possible future applications include supercapacitors for EVs and fire prevention for certain types of electronic consumer products, such as hoverboards.
The most relevant EV application would be what the engineers call “redox transistor batteries” which would recharge quickly and allow for greater range.
OSU’s engineers figured out that EVs have hit a limit for performance – a limit of around 0.4 miles per minute of charge, or 200 miles per hour eight-hour charge. A gasoline-powered car needs just one minute at a gas pump to cover the same distance. The engineers are hoping to get EVs up to tens of miles per one minute of charge.
“That’s still an order of magnitude away from the equivalent measure in gasoline, but it’s a place to start,” Vishnu-Baba Sundaresan, the study’s leader and an assistant professor of mechanical and aerospace engineering at OSU, told Phys.org.
He said limits to charge storage in current batteries is why EVs are hitting the limit.
“Research over the last 50-plus years has focused on advancing the chemistry of battery electrodes to increase capacity,” he 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.”
Also called an “ionic redox transistor”, the membrane could be used to help develop a new battery in energy will be stored in a liquid electrolyte, which can either be recharged or discharged and then refilled, a la 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.”
Lithium-ion batteries already have membrane separators that conduct charge while keeping key components separate, but even the highest-quality lithium-ion batteries lose charge as times goes by, because the membranes can’t prevent some charge from leaking. Not only does this lead to power drain, but in some cases, it can cause fires due to overheating.
The OSU team believes their membrane will prevent this from happening due to openings in the membrane that can expand or contract based on electric charge. During testing, they found they could reliably control the openings.
OSU will license the tech for further research. While the new membrane tech could work with existing batteries, the team would like to use it as the basis for a new type of battery called a “redox flow battery,” in which an electrolyte would move from anode to cathode to provide power.