25 Year EV Battery Created by Tesla Researchers

Researchers affiliated with Tesla have discovered a way to make lithium-ion batteries that could see them last a million miles or more.

The researchers, from Dalhousie University in Canada, have published a paper in the Journal of The Electrochemical Society, detailing how changes in battery cell chemical construction, plus changes in cooling and charging techniques, could mean that batteries could be used for almost 2 million miles before seeing capacity decreases, as well as advances in vehicle-2-grid (V2G) storage, used for storing energy in the car’s battery until it’s needed at peak times, taking pressure off a country’s national grid.

The lead researcher, Jeff Dahn, also leads Tesla’s battery research group since June 2016, and has been one of the main developers of lithium-ion battery technology over the past decades.

Two of the most vital variables in lithium-ion batteries retaining charge capacity, especially in EVs, are cooling and depth of discharge (DOD). Since many vehicles are not run through their entire discharge cycle – 0% to 100%, then to 0% again, and so on – the individual cells which make up the battery are not heated and cooled sufficiently, decreasing the capacity of electrical charge they can hold over their lifetimes.

When cooled at 20°C and charged from 0% to 100% in 4000 cycles, the batteries lost 4% of their capacity over 2.25 years. In 1.3 years, the batteries lost 0% capacity. Over 25 years, cooled at 20°C, the batteries would lose 10% capacity, whereas at 40°C, they would lose 30%. This assumes a full DOD every cycle, and 217 miles per charge.

Since cars spend most of the time not doing anything at all, either sitting stationary on a driveway at work, home or in a parking lot, the paper also details how vehicle-2-grid technology could be used. While V2G is of increasing importance in a world trying to save energy, the main problem is since it relies on a car’s battery capacity and is constantly charging and discharging the battery, it decreases the capacity and overall lifespan. However, with this new research, it may be possible to have V2G used frequently in many EVs and not see the battery capacities decrease dramatically.

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