EV battery guide: what are electric car batteries made of?

In this article, we’ll look at what electric vehicle (EV) batteries are made of, how they store their energy and how the technology and ownership model for batteries might develop. Fully understanding your electric car helps you get the best from it, so read on for our comprehensive guide. 

The majority of EVs use lithium-ion batteries, similar to those in consumer gadgets such as laptop computers and smartphones. Just like a phone, an electric car battery is charged up using electricity, which then is used for power, in this case to drive the car. 

Whereas the batteries for most gadgets have a defined time before they are depleted, EV batteries have a ‘range’ – i.e., a distance that the car can travel before the batteries run out of charge. After this, they will need recharging again. 

Electric car batteries are not a single unit, but consist of hundreds of cells. As a rule, a larger number of cells generally means a larger capacity battery, and therefore a longer range of miles that the car can travel.

Hybrid cars often use nickel-metal hydride batteries rather than lithium-ion. Their long life cycles, safety and resistance to misuse make them appealing for hybrid car manufacturers. However, they have a high cost, and can lose heat or discharge themselves at high temperatures. 

In comparison, lithium-ion battery technology has a high energy density, and is suited to quick charging cycles – ideal for an electric car. It also retains that energy density over thousands of such charge cycles.

EV batteries are made from a combination of raw materials. ‘Base’ metals such as aluminium, copper and iron are important ingredients, but the most expensive materials are ‘precious’ metals such as cobalt, nickel and manganese, along with elements such as graphite and lithium. 

These materials have to be extracted or mined from the earth in a complicated and expensive way, which is one reason why electric vehicles are more expensive to buy than combustion cars. The most costly component of an EV is its battery.

The extraction of these materials are considered by some to be controversial. Many such metals are only found in selected areas of the world, such as China and South America. Mining them can lead to issues with world politics and supply chain dominance, as well as humanitarian concerns. Lithium also uses a lot of water when being mined, causing potential problems for agriculture.¹

Unfortunately, similar ethical issues exist around the world with the production of petrol and diesel. Crude oil production in Eastern Europe may also be subject to political, financial, and environmental tensions, for example, and the constant fluctuations in fuel prices can reflect this.

In terms of local emissions, and if they are recharged from renewable energy sources, electric vehicles are generally seen as being much better for the environment. 

A report from the EEA found a typical electric car in Europe produces fewer greenhouse gases and air pollutants compared with a petrol or diesel equivalent. Emissions are usually higher in the production of electric cars, but these are generally offset by lower emissions during the usage cycle.²

Volkswagen is one car manufacturer that is establishing sustainable battery production using renewable energy sources. This will become more common as increasing numbers of companies pour money and thought into environmental production processes.³

Even if the electricity used to charge an EV has been generated partially by burning fossil fuels, the increased volume and weight of these power plants allow them to be far more efficient than the internal combustion engines of petrol and diesel vehicles which are constrained by both size and weight.

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Electric (and hybrid) cars have proven to be some of the most reliable vehicles on the road. This is backed up by long warranties for EV batteries, which generally exceed the overall manufacturer warranty for the car (eight years or 100,000 miles is typical).

Just like the lithium-ion batteries in consumer electronics, EV batteries do degrade over time and through repeated charge cycles, but the drop-off in performance is far less severe than in many smaller electronic devices, such as smartphones. That’s because the number of charge cycles is far more frequent in these devices than in an EV; a much more important factor in battery degradation than age.

There are things you can do to preserve your electric car battery. 

Keep the charge level between 20 percent and 80 percent to make your battery last longer, and don’t always use DC rapid chargers, as this can have a negative effect on battery life. Read more tips in our guide to how long EV batteries last. 

Rather than the amount of horsepower it has, the power output of an EV is ideally measured in kW (kilowatts). The battery’s energy storage capacity is measured in kWh (kilowatt hours) – rather like the number of litres a conventional car’s fuel tank can hold. 

EV batteries are expensive, so it’s often the most upmarket cars that offer the highest performance and the longest range. The smallest capacity batteries tend to be in the smallest cars, and vice versa.

We've outlined a few examples of EVs with small and large capacity batteries below.

As EV battery technology evolves and gets better all the time, ranges are increasing. Mercedes-Benz has recently broken the 1,000km (621 miles) barrier with its VISION EQXX concept car.⁴

It’s worth pointing out that larger batteries don’t necessarily equate to longer charging times. More premium EVs tend to offer fast-charging capability that easily compensate for a bigger capacity battery. 

Electric car batteries are very heavy, which can affect how a car handles. However, to combat this, they are usually stored beneath the car’s floor which gives a lower centre of gravity to aid handling. This has another benefit, too. The ‘skateboard’ chassis – so-called because when viewed from above, the chassis resembles a skateboard with the battery in the middle and the wheels at either end – liberates additional interior space. 

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Unlike with some toys at Christmas, when you buy a new electric car, the batteries are included. These should last the lifetime of the vehicle. In the past, Renault, Nissan, and Smart all offered electric car battery leasing schemes, intended to reduce upfront cost and worries around EV battery degradation. However, the idea was unpopular.⁵

Used electric cars such as the Renault Fluence Z.E, Renault ZOE (2012-2019), Nissan LEAF (2013-2018, Flex model only) and Smart Fortwo Electric Drive (2009-2014) were available when new with battery lease options. This brought the purchase price down, but meant drivers had to pay a monthly fee for the battery.

Benefits included a performance guarantee and cost-effectiveness for higher-mileage drivers, plus free battery replacement if capacity dipped below the typical 70 percent charge-level guarantee. On the used EV market, prices of these models are still lower than equivalent cars purchased with their batteries.

Some EV battery lease deals required a mileage limit, unless the driver stumped up for an unlimited-mileage option. If you are buying any of these models as a used EV and don’t want to take on a battery lease, check if they are a ‘battery owned’ vehicle.

Battery swapping is another solution to the issue of charging on the move and keeping up with fast-moving tech. The idea is being pioneered by Chinese car brand NIO, which has recently opened its first European battery-swap station in Norway.

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Solid state EV batteries could be the next game-changer. With a chemical reaction very similar to lithium-ion technology, solid state EV batteries replace the liquid-based electrolyte with a solid one. This means solid state electric car batteries are lighter, and can be smaller than conventional lithium-ion batteries. These benefits help increase energy density and reduce the battery weight.⁶

Solid state batteries should last longer and be able to charge faster. Safety is improved, too.⁷

However, they are still technically demanding to manufacture, and much of the technology is still being researched, which means they could still be five years from production.⁸

In the meantime, electric car batteries will come down in price – led by new lithium-iron phosphate technology – while maximum ranges will increase to 500 miles and beyond. Charging speeds will also increase, with increasing numbers of EVs able to use ultra-rapid chargers.

The RAC is the first breakdown assistance company in the UK to introduce a mobile charging unit for electric vehicle owners who have run out of charge. We are the number one provider of breakdown cover for electric vehicles. ​Find out more about RAC EV Boost.​

Are you sold on EVs? Or are you planning on holding on to your petrol car as long as possible? Leave us a comment below.

Sources

^{1 https://www.automotiveworld.com/articles/risky-business-the-hidden-costs-of-ev-battery-raw-materials/}

^{2 https://www.eea.europa.eu/highlights/eea-report-confirms-electric-cars}

^{3 https://www.volkswagen-newsroom.com/en/press-releases/volkswagen-invests-a-further-500-million-in-sustainable-battery-activities-with-northvolt-ab-7246}

^{4 https://www.mercedes-benz.co.uk/passengercars/the-brand/eqxx/stage.module.html}

^{5 https://www.buyacar.co.uk/cars/1523/electric-car-battery-leasing-should-i-lease-or-buy-the-batteries}

^{6 https://www.samsungsdi.com/column/technology/detail/56462.html?listType=gallery}

^{7 https://cosmosmagazine.com/technology/energy/are-solid-state-batteries-safer-than-lithium-ion/}

^{8 https://www.just-auto.com/analysis/how-far-away-are-mass-market-solid-state-ev-batteries/}