What Type of Batteries do Electric Vehicles Use? (Natural Elements)

Energy

Have you ever wondered exactly what’s under the hood of an electric vehicle? Specifically, what kind of batteries do they use and how different are they from the ones you find in a gas-powered vehicle? Research engineer Kathleen Lombardi answers our pressing questions about electric vehicle batteries.

Transcript

Lisa Edwards (Host): Electric vehicles are becoming more and more popular on our roads — and for good reasons. They’re energy-efficient. They’re low maintenance. And of course, they help reduce greenhouse gas emissions.
But have you ever wondered exactly what’s under the hood of an electric vehicle? For instance, what kind of batteries do they use? And how different are these batteries from the ones you find in a gas-powered vehicle?
We’ll have some answers to these questions and more on this episode of Natural Elements.

Music intro

This is Natural Elements, and I’m your host, Lisa Edwards.
Natural Elements is a podcast series brought to you by Simply Science, which is Natural Resources Canada’s online magazine. We talk to our experts about the work they do and how it relates to the world around us. We’ll give you a taste of the topic and let you know where you can find more information.
To find out everything about electric vehicle batteries, we reached out to one of our experts at the CanmetENERGY research centre in Ottawa:

Kathleen Lombardi: My name is Kathleen Lombardi. I'm a research engineer at Natural Resources Canada. I work at the CanmetENERGY Technology Centre in Ottawa. I work with a team to study transportation electrification. So we're looking at not just light vehicles but all kinds of medium- and heavy-duty vehicles as well and how they can accelerate the deployment of that technology.

Lisa Edwards: There are different types of batteries for electric cars, but many manufacturers favour lithium-ion batteries. Here’s why:

Kathleen Lombardi: We use lithium-ion technology in electric vehicles as the de facto technology for several reasons. First of all, they are rechargeable, and that's an obvious point but very important for vehicles. Second, lithium-ion batteries have a very high energy density and a specific energy density. That means they have a lot of energy per unit volume and a lot of energy per unit mass. So they're actually smaller and lighter than lots of the other battery technology. Another reason we use lithium-ion technology is because they have a relatively low self-discharge rate. Batteries actually naturally lose their charge when they're not being used. And lithium-ion batteries have one of the better discharge rates. Finally, they have a great temperature operating range compared with other technologies. Batteries are actually quite sensitive to temperature when they're being charged and discharged. They don't like to be too hot or too cold. I like to refer to them as a Goldilocks technology: they like to be somewhere in the middle. So lithium-ion technology has a wider operating range than many of the other batteries out there.

Lisa Edwards: As we just heard, there are many good reasons why EV manufacturers rely on lithium-ion technology. But there’s one challenge: the batteries themselves are still sensitive to temperature extremes. And during Canada’s long cold winters, this sensitivity could affect the overall performance of an electric vehicle.

Kathleen Lombardi: Electric cars actually work best in moderate temperatures between about 10 and 40 degrees Celsius. When you charge or discharge a battery in cold temperatures, below about 10 degrees Celsius — that happens a lot in Canada — the battery can actually be damaged. And that means its capacity is lowered: it can't store as much energy, and its lifetime is actually shortened. This is due to something called lithium plating, where some of the electrolyte attaches to the electrode and is no longer useful. On the other side of things, batteries don't like being charged and discharged when it's really hot, either. That could be detrimental to the health of the battery. It speeds up aging and leads to reduced capacity and increased internal resistance.

Lisa Edwards: So avoiding temperature extremes is one way to extend the life of an EV battery. But there’s more. Kathleen says lithium-ion batteries are different from traditional auto batteries in several ways. And that means they might require some special handling so drivers can get the most out of their electric vehicles.

Kathleen Lombardi: So if you want to maximize the battery life of your electric vehicle, I'll start off by giving you a quick background on a couple of aging mechanisms related to battery technology. One way a battery can age is just by sitting on a shelf. So if it's old, even if it's just in storage, it loses capacity. And the second way is when it's cycled. So when you use the energy and then recharge it, the battery life gets used up. So both of these are actually affected by temperature of where you store and where you charge your car. So if you want to extend the life of your vehicle, charging it in a temperature-controlled environment like a garage is a good practice to have. Another factor for battery life is how much charge you keep in your vehicle. When you think about storing your battery as a gas tank, if your tank was totally full, you would think that was a good way to go. But actually if you can store it with about 50 percent of the charge that's actually better for the battery, because time spent at high voltage is bad for the battery too. So lastly, I'll just mention that a lot of people, if they had the choice between a fast charger and a normal charger, they might choose the fast charger because it's more convenient. But actually if you want to make your battery life as long as possible, you want to use the slow charger. So I guess avoiding those highway trips as much as possible and just charging it overnight at a lower voltage is actually better for your battery and will make it last longer.

Lisa Edwards: If you want to learn more about electric vehicle batteries, check out the links in the episode description.

Buying an electric vehicle (Natural Resources Canada) – https://natural-resources.canada.ca/energy/efficiency/energy-efficiency-transportation-and-alternative-fuels/choosing-right-vehicle/buying-electric-vehicle/21034
Zero-emission vehicles (Transport Canada – https://www.tc.gc.ca/en/services/road/innovative-technologies/zero-emission-vehicles.html
Batteries for Hybrid and Plug-In Electric Vehicles (U.S. Department of Energy) – https://afdc.energy.gov/vehicles/electric_batteries.html
A comprehensive review of lithium-ion batteries used in hybrid and electric vehicles at cold temperatures (Science Direct) – https://www.sciencedirect.com/science/article/pii/S0306261915014841
Eight Tips to Extend Battery Life of Your Electric Car (PluginCars) – https://www.plugincars.com/eight-tips-extend-battery-life-your-electric-car-107938.html
How Lithium-Ion Batteries Age: Scientists Offer Insight (Green Car Reports) – https://www.greencarreports.com/news/1091003_how-lithium-ion-batteries-age-scientists-offer-insight

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Thank you, everyone, for listening! We’ll see you next month with a brand new episode.