Electric cars: A bit about lithium-ion batteries

Lithium-ion battery cells are the dominant power source for modern electric cars. From the first Tesla Roadster to the upcoming Chevrolet Bolt EV, they’ve proven durable enough for automotive applications, and capable of providing the energy storage needed to make electric cars practical.

But a decade ago, lithium-ion cells were still used only in consumer electronics, and even then, they were things of mystery. Many of the myths of lithium-ion batteries have been debunked over the past decade, notes Australia’s ABC, which is a good thing, considering how important they’ve become to multiple industries.

Anyone who purchased an early iPod might remember being told not to charge it unless the battery read fully empty. Conventional wisdom of the time stated that charging a battery that wasn’t completely empty could damage it, although that was later found to not be the case. Of course, whether it’s an electric car or a smartphone, “empty” doesn’t usually really mean “empty.” Completely draining a lithium-ion battery really can damage it.

Lithium-ion batteries also generate quite a bit of heat, which is one reason why some manufacturers were initially reticent about putting them in cars. There are still lithium-ion fire scares every once in awhile, like the recent hoverboard fiasco. A few highly-publicized Tesla Model S fires have confirmed that lithium-ion cells are flammable, but there have been no recorded instances of spontaneous combustion that we’re aware of.

Like the lead-acid batteries used in 12-volt car electrical systems, lithium-ion batteries have a limited lifespan. The exact length of that lifespan has been the subject of intense debate among analysts (as well as anxiety for consumers), but one thing that is clear is that lithium-ion battery packs from electric cars still have plenty of life left in them even after they’re no longer suitable for automotive use. Companies like General Motors and Nissan have begun to experiment with energy-storage arrays made of decommissioned packs.

And while lithium-ion cells have proven useful in electric cars so far, they’re not perfect. There are still limits on energy-storage capacity, charging times, and cost that make electric cars less attractive to many consumers than internal-combustion. That’s left researchers scrambling for a new chemistry, but for now it seems lithium-ion will remain on top.