Researchers at the University of Maryland have brought faster electric vehicle charging a step closer, developing a battery electrolyte that enabled a test cell to charge to 80% in just 12.8 minutes, according to Interesting Engineering.
Here's what to know
The team, led by Chang-Xin Zhao, a researcher in the laboratory of Distinguished University Professor Chunsheng Wang, changed how solvent molecules interact with lithium ions.
The approach addresses a bottleneck in the battery's liquid electrolyte, which allows lithium ions to move between electrodes.
A porous positive electrode needs liquid electrolyte to sustain effective charging.
That supply becomes depleted as lithium ions travel from the positive electrode to the negative electrode during charging, taking solvent molecules along with them.
The resulting shortage of liquid slows rapid charging because solvent cannot flow back quickly enough to keep the electrode replenished. At lower charging speeds, the returning solvent can keep up.
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The liquid could return more easily to the positive electrode once its solvent molecules were less strongly attracted to lithium ions.
To weaken that attraction, the researchers added fluorine-containing chemical groups to the molecules.
More background
The University of Maryland-led study revealed previously unrecognized effects of electro-osmotic drag in lithium-ion batteries.
Fuel cell researchers already knew about the solvent movement called electro-osmotic drag.
To avoid sacrificing energy storage, the Maryland team focused on electrolyte chemistry. Earlier attempts to accelerate charging had focused on redesigning electrodes, an approach that can reduce how much energy a battery holds.
In testing, the four-amp-hour pouch cell reached 80% charge in 12.8 minutes and 90% in 14.7 minutes.
Both milestones met the U.S. Department of Energy's goal of charging in under 15 minutes.
The team ultimately wants charging that takes about as long as a gas fill-up.
Delivering a full charge quickly, however, remains difficult without compromising other battery characteristics.
What's being done?
Wang plans to pair the fluorinated solvent with his team's adaptive electrolyte next.
That electrolyte separates to shield both electrodes from the stresses of fast charging, potentially addressing another challenge alongside solvent loss.
The researchers are aiming for charging times of around 10 minutes, which could make a charging stop easier to fit into a routine stop.
"By the time you finish your coffee, the vehicle is charged. That's what we want to achieve," Zhao explained.
Beyond faster charging, the team is also working toward batteries that last longer when idle and operate across a wider temperature range.
"We want to build a battery that can satisfy all the requirements, without sacrificing anything. That is our goal," Wang added.
Where can I learn more?
Other researchers and automakers are also working to shorten EV charging stops and improve battery performance. These stories explore high-powered chargers and battery chemistry designed to lower costs and extend range.
• Geely says its 2.2-megawatt charging technology could deliver full EV charges in four minutes.
• Chery claims its new EV charger can add 311 miles of range in five minutes.
• EVgo previewed 750-kilowatt fast chargers that could charge the quickest EVs in about 10 minutes.
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