Electric-car batteries recharge in ten minutes when the heat is on - NATURE 10-2019

[wweiss]

ENERGY
31 OCTOBER 2019
Electric-car batteries recharge in ten minutes when the heat is on

A high temperature allows fast charging of the lithium batteries used in electric and hybrid vehicles.

A lithium car battery can power a 320-kilometre drive after just 10 minutes of charging — as long as its temperature is hiked up to 60 °C while it is replenished.
Lithium batteries, which use lithium ions to create a current, charge slowly at room temperature. Charging can take two to three hours, making for a road trip that lasts far too long.
To solve that problem, Chao-Yang Wang and his colleagues at Pennsylvania State University in University Park heated a lithium battery to 60 °C, which allowed the researchers to charge the battery at a high rate in just 10 minutes.
High-rate charging usually encourages the lithium to coat, or plate, one of the battery's electrodes, blocking the flow of energy and eventually rendering the battery useless. But pre-heating the battery allows fast charging without plating.
A commercial battery charged with the team's high-temperature, high-speed system retained 80% of its capacity after 1,700 charge–discharge cycles. A battery charged at room temperature could only handle the fast charging for 60 cycles before its electrode became plated.

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I wonder if this has some useful merit to charging our batteries. This is counter to what I thought in that heat was bad for the cells.

 

[Random Dan]

I don't try to fully charge my batteries in 10 minutes so I don't think that the mentioned plating issue is relevant, but I'm far from an expert.

 

[archimedes]

Even max safe storage temp is listed as 50°C for typical 18650, and lower than that during charging.

I think there could be a difference between what might be theoretically optimal for preserving capacity ... versus best for maximizing safety :shrug:

 

[wweiss]

Yes, and yet some EV's use 18650's in huge banks. They do have circulated coolant, however as my EV pump went out and had to be replaced as the car would not charge otherwise.

I'll report back if there is more detail on this.

 

[iamlucky13]

I believe this is the paper (probably behind a paywall, but I have journal access through my library):
https://www.cell.com/joule/fulltext/S2542-4351(19)30481-7

One of the keys here is the temperatures are asymmetric: you want it hot only for extra fast charging. For normal charging or for discharge, as well as storage, you want normal temperatures to avoid the capacity loss and increased internal resistance that occurs at high temperatures.

To accomplish this, they made a cell with a heat strip built into the battery to prewarm it rapidly for around 30 seconds prior to charging to get to the target temperature, then they charged at 6C to 80% and discharged at 1C to 2.7V. The batteries cooled down on their own while discharging, although in a large battery pack, they would need active cooling.