In the past I’ve pointed out that, while electric vehicles are a fine idea for Southern California, they’re less fine for Minnesota. An article at SLAC National Accelerator Laboratory by Nathan Collins documents that as well as explaining why it is the case:
Lithium ion batteries are a bit famous for their poor cold-weather performance, and that has consequences for some of their most important applications – everything from starting an electric car in a Wisconsin winter to flying a drone on Mars.
Now, researchers at the Department of Energy’s SLAC National Accelerator Laboratory have identified an overlooked aspect of the problem: Storing lithium-ion batteries at below-freezing temperatures can crack some parts of the battery and separate them from surrounding materials, reducing their electric storage capacity.
SLAC scientist Yijin Liu and postdoctoral fellow Jizhou Li made the discovery while looking at the cold-weather performance of the cathode, the part of the battery electrons flow into when it’s in use. Initial studies found that storing cathodes at temperatures below zero degrees Celsius led batteries to lose up to 5% more of their capacity after 100 charges than batteries stored at warmer temperatures.
The explanation provided is that below-freezing temperatures result in differential cracking within the cathodes of the batteries. While it’s possible that problem can be solved, solving it in a way that makes economic sense may be a different matter.
To put the finding in perspective below freezing is an expected temperature in unheated garages in winter in locations north of the Mason-Dixon line which is to say most of the country. I wouldn’t construe the finding as demonstrating that EVs are useless but that, as I have also suggested, that they are niche products. It also suggests that the economy of EVs may be less.
Again somewhat surprised. Comparative coefficient of thermal expansion considerations is part of design 101. Often it simply means surrounding adjacent parts with more elastic materials.
Its not clear whether they are strictly talking about the cathode, and a singular material. I don’t know what a “meatball” sized particle means. But they are clearly identifying microcracks in the cathodes. Smaller particle sizes is always a method of limiting fracture under load for non-homogenous materials. (A big issue in powder metallurgy) But that implies lack of homogeneity. I don’t know enough about these cathodes to comment.
Enthusiasm over the inevitable transition to EVs seems to have infected auto manufacturers despite lukewarm consumer demand.
I’m afraid we’re going to have a national shortage of new and used ICE vehicles alongside lots full of unsold mobile lithium Roman candles.
Should I tell all the guys driving Teslas for the last few years they should be having more problems than they have been seeing? (None of our hospitals have heated garages. All of my docs take overnight/24 hour call so they leave their cars in unheated storage for over 24 hours.)
Zero celsius is 32 fahrenheit. Pretty much the average high temperature here in north central Ohio during the winter.
You could keep you EV in your garage, but lithium batteries are also prone to catching fire, and the fires are very difficult to put out. GM’s recall notice on Bolt batteries recommends owners park their cars outside and some distance from their homes.
PS. We need to at least double (average demand) and perhaps quadruple (peak demand) electrical generation capacity and transmission capacity all the way to the end users house.
NIMBY that!
Under the low temperature situation, there is one rule to protect the lithium-ion battery from irreversible damage when charging up the battery. “Don’t charge them when the temperature falls below freezing (0°C or 32°F) without reducing the charge current.â€
What’s the Reason behind This Important Rule?
When the battery is charging up at moderate temperature, the lithium ions inside the battery can move normally to the negative terminal of the battery. Below freezing, the lithium ions aren’t efficiently captured by the anode. Instead, plating of metallic lithium can occur on the anode which means there’s less lithium available to cause the flow of electricity and the battery’s capacity drops. Besides, if the battery is charged at an improper charge rate, it may cause battery failure suddenly. When the temperature is below 0°C, then the charge current must be reduced due to the anode’s lowered diffusion rates. A much slower charge rate can reduce the damage. A research suggests that the charge rate that is allowed at the temperature of –30°C (–22°F) is about 0.02C. But the charging time would be so long with such a low current, which is an impractical solution. With the development of battery technology, there are certain lithium-ions that are able to charge down at the temperature of –10°C (14°F) at a lowered rate.
Any Solution for Charging in Below-freezing Conditions?
If there is no BMS to communicate with a charger to reduce current when necessary, the solution is to warm the batteries to above freezing before charging. A warmer room to help recover or a thermal blanket to warm up the battery or a heater near the batteries is good to help in subzero temperature. Also, a thermometer to monitor the temperature could be better while charging. It’s not the most convenient process. Using high-quality lithium-ion batteries like UFO LiFePO4 battery can help handle the cold temperatures situation better. Some of the batteries are cheaper, but there are some obvious limits and risk.
steve’s reaction: deny, deny, deny Something about follow the science…….or something.
I’m just reporting what the science says. I’m sure there are anecdotes which say something else.
Lithium may not be all that there is:
https://interestingengineering.com/sodium-ion-battery-graphene-tech-tenfold-capacity-boost
A single study says that you can lose UP TO 5%, meaning somewhere between 0.01% and 5%. So why dont we look at the real world? Looking at EV sales in 2018, latest I can find, there were 9000 in Mass, 16,000 in NY, 6000 in PA, 4000 in Mi, 3000 in Minnesota, 8000 in Illinois, 2000 in Wi, etc. Also in 2018 Vermont had the 5th highest number of EVs purchased as a percent of sales. If the study was correct then wouldn’t that affect sales and happiness with the purchases? The market is always correct isn’t it? So either UP TO actually means such a small number no one is noticing or people just dont care. Or, the study could be wrong.
Steve
The market says that EVs are a niche product and a pretty small niche at that. In 2018 about 360,000 EVs were sold in the U. S. of 13 million total vehicle sales. That’s barely a blip. The method you suggest would be reasonable if EV sales accounted for a larger percentage of the total. As a percentage EV sales have been pretty flat. Barnum said it best.