Thursday, July 13, 2017

Experimental Electrode Designs May Reduce Charging Times From Hours To Minutes

Researchers at Drexel University School of Engineering claim they have created a new highly conductive two dimensional material they call MXene that will permit faster battery charging. Led by professor Yuri Gogotsi, the team says electrodes made from MXene will allow ordinary batteries to charge as fast as supercapacitors but with the energy storage potential of a conventional battery.


“This paper refutes the widely accepted dogma that chemical charge storage, used in batteries and pseudocapacitors, is always much slower than physical storage used in electrical double-layer capacitors, also known as supercapacitors,” Gogotsi says. “We demonstrate charging of thin MXene electrodes in tens of milliseconds. This is enabled by very high electronic conductivity of MXene. This paves the way to development of ultrafast energy storage devices than can be charged and discharged within seconds, but store much more energy than conventional supercapacitors.”
Put simply, MXene has more places to store electrons than the electrodes in use today. More electron storage equals more electrical energy stored and transmitted. The team has recently published its work in the journal Nature Energy. Working with professors Patrice Simon and Zifeng Lin at the Universit√© Paul Sabatier in France, the team developed a hydrogel electrode with greater volumetric performance, an important measure of a battery’s ability to store energy.
“In traditional batteries and supercapacitors, ions have a tortuous path toward charge storage ports, which not only slows down everything, but it also creates a situation where very few ions actually reach their destination at fast charging rates,” says Maria Lukatskaya, the lead author on the paper. “The ideal electrode architecture would be something like ions moving to the ports via multi-lane, high-speed highways instead of taking single lane roads. Our macro-porous electrode design achieves this goal, which allows for rapid charging — on the order of a few seconds or less.”
The primary advantage of MXene electrodes is their superior conductivity, which is equivalent to metals such as copper and aluminum. MXene was first created in Drexel labs in 2011 and researchers have been exploring its many and varied uses ever since — from energy storage to electromagnetic radiation shielding and water filtration.
“If we start using low dimensional and electronically conducting materials as battery electrodes, we can make batteries working much, much faster than today,” Gogotsi said. “Eventually, appreciation of this fact will lead us to car, laptop and cell-phone batteries capable of charging at much higher rates — seconds or minutes rather than hours.”
Henrik Fisker is also going down a similar path. He says his latest car, the Fisker EMotion, will use a proprietary system that is similar to a supercapacitor that will permit the car to have a 400 mile range and a 9 minute recharge time. Sitting idle waiting for an electric car to charge may be one of the biggest road blocks to mainstream acceptance of EVs.
Even Tesla, which has the largest high power charging network in the world, requires its drivers to wait 30 minutes of more to charge their batteries while travelling away from home. If someone could cut that wait time to a few minutes, the impact on the electric car market would be enormous.
The usual caveats apply. Researchers around the world on working on improvements that will make EV batteries, lighter, more energy dense, and less expensive while slashing charging times. Breakthroughs in battery technology are announced almost daily. But getting new tech out of the lab and into the real world is often fraught with danger.
More startups fail than succeed. So for the moment, this announcement from Drexel must be taken with the proverbial grain of salt. But if the promise shown in the Drexel lab can translate to reality? It’s game over for fossil fueled vehicles.
Source and photo credit: Drexel University via Science Daily

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