What is an electric vehicle and how do they work?

In an era where sustainability and technology intersect more than ever, electric vehicles (EVs) are steering the conversation toward a cleaner, greener future. As pivotal components of this transformative journey, EVs and their batteries are not just redefining automotive mobility but also showcasing how innovation can lead to a sustainable world. 

This article discusses the importance of electric vehicles, the heart that powers them—EV batteries—and the impact they are poised to make on our planet and economy.

What is an electric vehicle (EV)?

An electric vehicle (EV) is a vehicle powered by one or more electric motors, using energy typically stored in rechargeable batteries. This marks a significant departure from traditional internal combustion engine vehicles that rely on gasoline or diesel as fuel. 

EVs encompass a wide range of vehicles, including cars, buses, trucks, and motorcycles, and they are a key component of the global initiative to reduce carbon emissions and combat climate change.

As technology continues to evolve, the future of electric vehicles looks promising, with innovations such as solid-state batteries, faster charging technologies, and more sustainable production methods paving the way for a cleaner, more efficient, and accessible electric transportation system.

How do electric vehicles work?

Electric vehicles work by using electricity to power an electric motor, which drives the wheels. This electricity is stored in rechargeable batteries. When you accelerate, the EV’s battery sends power to the motor, converting electrical energy into mechanical energy that moves the car. 

Unlike traditional cars with internal combustion engines, EVs don’t use gasoline or diesel fuel, making them quieter and more environmentally friendly since they emit no exhaust pollutants. 

To keep going, you just need to recharge the battery, much like you charge a mobile phone.

The Power Within: Understanding EV Batteries

Most electric vehicle owners have a simple understanding of what electric vehicle batteries are: their car’s sources of power and energy reservoir. However, the “humble” EV battery is, in truth, an amazing piece of technology that evolved over decades, from powering simple gadgets, like flashlights and now to electronic devices like the smartphone.

Today, lithium-ion batteries are the most prevalent type used in EVs, favored for their high energy density, longevity, and ability to recharge. These batteries work by moving lithium ions through an electrolyte from the anode to the cathode during charging, and in reverse when discharging, to generate electric current.

Let us delve deeper into EV batteries by taking a closer look at the most basic elements in its hierarchy, namely its battery cells.

What are EV batteries made of?

An EV battery cell consists of six major components, made from base and precious metals and elements, which enable the battery to function in its dual role as power provider and energy storage.

Below are a battery’s major components and what they are made of:

• Anode – Graphite
• Cathode – Aluminum, nickel, manganese, cobalt, iron, lithium
• Separator – A micro-porous polymer called polyolefin
• Electrolyte – Lithium hexafluorophosphate
• Current collectors – Aluminum, copper
• Casing – Aluminum, steel

EV battery design hierarchy: key elements

All batteries have a unique EV battery design, the key elements of which form a distinctive design hierarchy:

• EV battery cell: The smallest and most basic packaged form of the battery. At present, EV batteries contain units of Lithium-ion cells delivering one to six volts per cell.
• Modules: Individual cells are connected together in parallel or series and are enclosed in a housing.
• Battery pack: The final, deployable form of the EV battery, consisting of multiple modules connected together in parallel or series, providing the required output for specific applications in the EV.

EV battery cell formats

EV battery cells come in three formats, found and described below:

Cylindrical cells

Among the formats, cylindrical cells are characterized by a symmetrical shape, which makes for efficient packing.

Comparatively speaking, cylindrical cells are the least expensive to manufacture because their casing allows for superior containment and provides efficient mechanical resistance from both external and internal stresses.

Prismatic cells

Prismatic cells are much larger than cylindrical cells. Enclosed in a hard, robust casing of welded aluminum or steel, these EV batteries can provide more power and store more energy.

The casing design also provides improved heat management compared to cylindrical cells. While these cells used in electric car batteries manufactured in China are primarily prismatic, the main drawback to this cell format is that they are expensive to manufacture.

Pouch cells

Among the EV battery cells, pouch cells are distinctive for their unique pouch-like EV battery design. 

While similar to prismatic cells, their difference lies in their casing. Prismatic cells have a hard casing while pouch cells are contained in laminated foil or soft plastic casing. 

Although their packaging efficiency is higher, pouch cells have the lowest mechanical resistance, greater vulnerability for penetration, and a higher tendency for swelling.

Most common cell chemistries in EV batteries

Various cell chemistries found in EV battery components help to identify the type of electric vehicle batteries installed in an electric car.

Lithium-ion

These batteries can be found in many of today’s EVs. Aside from their cost-efficiency, lithium-ion batteries provide superior energy storage capacities. They also come in a variety of cell chemistries. For instance, lithium nickel cobalt aluminum oxide batteries are commonly found in Tesla Model 3 cars.

Nickel Manganese Cobalt

Noted for its balanced power delivery and energy storage, these batteries can be found in Chevy Volts.

Nickel Metal Hydride

Thanks to their inexpensive manufacturing, these batteries were used in the first hybrid cars, among them the Prius. Despite the popularity of lithium-ion batteries, nickel metal hydride batteries can still be found in some hybrid EVs, like the 2020 Toyota Highlander.

Lithium Sulfur

These batteries can be found in EV buses because of their large energy storage capacity. However, their main drawback is that they need to be sufficiently heated up before they can generate the amount of power needed for the EV to run.

Lead Acid

Lead acid batteries are primarily used nowadays in low performance EVs, such as golf carts. Unlike the others, these batteries are noted for their low maintenance and are easy to replace.

What are busbars?

In the manufacture of EV batteries, there are components that can be put in to improve the battery’s overall performance.

Some of these additions include next-generation EV batteries such as busbars.

A busbar is a conductor enabling the flow of current through an electric vehicle’s subsystems.

As the EV battery is the heaviest part of an electric car, there exists the need to make the battery more compact yet still deliver on the right power requirements.

This EV battery interconnect should also be adapted to meet the new EV battery design on two fronts: using smaller footprint busbar interconnects to the printed circuit boards (PCBs); and improving flexibility in the configuration of these same busbars.

EV battery safety

Electric vehicle batteries pose a risk of combustion because of its organic liquid electrolyte content, which are made of compounds with volatile, corrosive, and flammable properties. 

Physical damage, short circuits due to overheating, and unreliable charging may compromise EV batteries. 

EV battery manufacturers perform various compliance tests to ensure that the EV battery design – starting from the basic cells to modules to the final battery pack – are safe. These include vibration, thermal and mechanical shock, anti-leakage and immersion, fire resistance, and overcharging tests.

Finally, every EV battery is equipped with a Battery Management System (BMS) which monitors the battery during charging and discharging and a Battery Thermal Management System (BTMS) to control its temperature to prevent overheating.

The Road Ahead

With the expansion of battery technologies and infrastructure, electric vehicles are becoming increasingly accessible and practical for the average consumer, signaling a significant step toward decarbonizing transport. 

As we accelerate into this new era of mobility, it’s clear that electric vehicles and their batteries are not merely transient trends but foundational elements of a sustainable, zero-emission future.