https://phys.org/news/2018-07-electric-car-batteries-souped-up-fluorinated.html

"We have created a fluorine-based electrolyte to enable a lithium-metal anode, which is known to be notoriously unstable, and demonstrated a battery that lasts up to a thousand cycles with high capacity," said co-first authors Xiulin Fan and Long Chen, postdoctoral researchers at UMD's A. James Clark School of Engineering.

The new batteries can thus charge and discharge many times over without losing the ability to provide a reliable and high quality stream of energy. Even after a thousand charge cycles, the fluorine enhanced electrolytes ensured 93% of battery capacity, which the authors call "unprecedented." This means that a car running on this technology would reliably drive the same number of miles for many years.