Types of Batteries for Electric Vehicles

Electric vehicles continue to gain popularity as the world transitions towards more sustainable modes of transportation. At the heart of every EV is its power source, the battery, responsible for storing electricity. This electricity powers the electric motor that in turn drives the wheels and propels the car forward. The battery also powers various other vehicle systems, such as lighting, infotainment, power steering, climate control, and more. 

Modern EVs employ various types of batteries, and the kind of battery used has a direct impact on cost, performance, range, charging time, and environmental impact. Let’s take a closer look at the most common types of EV batteries in use today. 

Lithium-Ion Batteries (Li-ion)

Most modern electric vehicles on sale today incorporate lithium-ion batteries. Reasons for their growing popularity include their high energy density, which boosts range, and their ability to retain their charge for long periods. They also weigh less than other rechargeable batteries of similar capacity and have a long cycle life, so are rechargeable hundreds or even thousands of times without much degradation. 

While the above points favour the use of Li-ion batteries for electric mobility, they do come with a few disadvantages. The first of these is the cost; Li-ion batteries are quite expensive to produce, and this drives up the price of vehicles that use them. 

Lithium-ion batteries are also prone to overheating if not managed properly, leading to thermal runaway and the possibility of fire breaking out. Lastly, the mining of lithium and other rare metals required for the construction of these batteries is extremely resource intensive and brings with it various environmental concerns. 

Nickel-Metal Hydride Batteries (NiMH)

A precursor to Li-ion batteries in the EV space, NiMH batteries were commonly used in early hybrid and plug-in hybrid electric vehicles as they offer a longer lifespan than conventional lead acid batteries. They are less energy dense than Li-ion batteries and hence offer limited range, although they are more durable and less prone to overheating. 

Although they have proven their reliability in hybrid applications, the usage of NiMH batteries has declined steadily with the advent of Li-ion battery technology over the last decade. Certain manufacturers, however, continue to use them in hybrid models where cost, durability, and longevity are more important than outright energy density. 

Lithium Iron Phosphate Batteries (LiFePO4 or LFP)

LFP batteries, like their Li-ion counterparts, generate electricity through a chemical reaction during which lithium ions move between the cathode and anode. However, this is where the similarities end; they differ in their construction, chemistry, and characteristics. 

LFP batteries are less energy dense than Li-ion batteries and also cost less to manufacture, as they forego the use of expensive metals like nickel and cobalt in their construction. Their main advantage is that they are extremely stable and can handle high temperatures without the risk of thermal runaway, and are hence considered a safer option. LFP batteries are commonly used in commercial EVs, as well as in some Tesla and BYD cars.

Solid State Batteries

Widely considered the next step in EV battery technology, solid state batteries are still in the development and testing stage. They do away with the liquid or gel electrolyte used in contemporary batteries and incorporate a solid electrolyte instead. This construction allows for higher energy density, faster charging, and better heat resistance. 

While the advantages of solid state batteries are many they are yet to reach full scale mass production, and are hence expensive to produce and not widely available. Major manufacturers have invested heavily in their development and testing, and we can expect to see solid state batteries become more mainstream in the coming years. 

Supercapacitor (SC)

Also known as ultracapacitors, SCs work in conjunction with other energy sources, rather than as standalone batteries for EVs. While their low energy storage capacity doesn’t allow for long distance trips, they are capable of storing and subsequently releasing their stored electrical energy extremely fast. This makes them ideal for rapidly absorbing the energy created during regenerative braking or providing a short burst of acceleration to supplement the primary battery. 

Aside from offering extremely fast charging and discharging, supercapacitors also offer a long operational life. They are, however, expensive to build and complex to integrate into electric vehicles. 

Different Types of Batteries for Electric Vehicles: Advantages and Disadvantages

Refer to the following table for the advantages and disadvantages associated with each of the above battery types:

Buying a Pre Owned EV

If you are planning on purchasing a used electric car, you would want to ensure that the battery isn’t past its prime.  Ask the owner to provide a battery health report, or arrange for a diagnostic scan to verify the state of the battery. This is important, since replacing an EV battery can be an expensive proposition. 

Most EVs come with a five to eight year warranty for the battery. Check the validity of the warranty, and ensure that it is transferable. It’s also a good idea to look into the charging history. Frequent fast charging can lead to faster battery degradation, so a vehicle that has been mostly charged with a slower AC charger is a better bet.

Conclusion

As EVs continue to evolve, so does the technology that powers them. While lithium ion batteries are the most widely used today, emerging technologies like solid state batteries and supercapacitors are being rapidly developed and perfected. 

The pre-owned EV space is also busier than ever before, with most of the used electric cars available today powered by either Li-ion or NiMH batteries. It is, however, important to verify the health of the battery pack before making a purchase. 

The main reason behind the widespread use of Li-ion batteries in the EV space is the balance between energy density and efficiency that they offer. LFP batteries are a safer and more cost effective option, while NiMH batteries make sense in hybrid applications. 

Innovations in energy storage will continue to drive developments in electric mobility, promising to make EVs more affordable, practical, efficient, and sustainable as we move towards the future.