Technology Behind Electric Vehicle Batteries

Electric vehicles (EVs) represent the forefront of automotive technology, offering a cleaner, more sustainable alternative to traditional internal combustion engine vehicles. Central to their operation is the EV battery, a marvel of modern engineering that stores electrical energy for propulsion. 

This article delves into the technology behind electric vehicle batteries, exploring the components, types, and innovations driving the future of transportation.

How are electric vehicle batteries manufactured?

The beauty of EV battery design cannot be appreciated by looking at each individual cell, but at the entirety of the EV battery pack design and how the cells combine to provide power for an electric vehicle.

In this section, we will explore the process that goes into the assembly of a battery pack.

What are EV batteries?

As the power sources of an electric vehicle, it’s hardly a surprise they are called the “heart” of the EV. 

Thinking of EV batteries as a single cell, such as those used for everyday gadgets, is inaccurate. EVs cannot run on just one or two cells. The term “EV battery” actually refers to the battery pack, since it contains many individual EV battery cells that provide sufficient power for your EV to run.

What are EV battery components and what are they made of?

To better understand how EV batteries are manufactured, we must look at EV battery components.

A single cell consists of: an anode, the negative electrode; a cathode, the positive electrode; the electrolyte; and the separator.

EV battery components are generally made of base metals, namely aluminum, copper, and iron. Battery types are distinguished by materials in the anode and cathode.

Here are the EV battery types available today and the materials that are found in them:

BATTERY TYPE	ANODE	CATHODE
Nickel-cadmium Batteries	Cadmium hydroxide	Nickel hydroxide
Lead-acid Batteries	Lead	Lead (*electrolyte is mild sulfuric acid)
Nickel-metal hydride Batteries	Hydrogen absorbing alloy	Nickel oxy-hydroxide
Lithium-ion Batteries	Lithium and graphite	Lithium, nickel, cobalt, manganese

What is an EV battery cell, module, and pack?

Below are three major elements in electric vehicle battery systems.

• EV battery cells: The smallest units of electric vehicle battery systems. It can be in the following formats: pouch cell, cylindrical cell, or prismatic cell.
• EV battery modules: single battery cells are connected together in series or in parallel and contained within a sturdy housing.
• EV battery packs: This is the final form of the EV battery. Modules are connected together in series or in parallel to produce the amount of power needed for specific applications in an electric vehicle.This is almost always the heaviest part in an electric vehicle.

How long do EV batteries last?

On average, an EV battery, specifically lithium-ion EV batteries, have a lifespan of between 10 and 20 years before they need replacing. EV batteries do not just die fully, instead they lose charging capacity slowly over a period of time. For example, the Tesla Model S battery loses 5% of its original capacity after driving for the first 50,000 miles.

What is the assembly process in manufacturing EV batteries?

EV battery design must be taken into consideration in manufacturing them. This refers to its size, frame, and power requirements.

The assembly process of EV batteries begins with the single cell: the anode and cathode are placed inside the housing with a separator keeping them apart. The fluid electrolyte is then poured inside, immersing the two electrodes. The housing is then sealed. Each cell is first tested for electrolyte leaks, which may cause disastrous fires or explosions. The next step is a moisture check to see if moisture from the external environment enters the EV battery cell.

The individual cells are combined into another larger and sturdy housing to form battery modules. A typical module may contain 12 cells. Specialized battery collector plates are used to create robust connections to the individual cells and aggregate the power for output from the modules. The housing is necessary to protect the cells from external shocks which may cause damage to both the individual cells and the modules. Similar leak and moisture checks are done to the module to ensure that its structural integrity is retained and can withstand environmental stresses.

The final stage in the EV battery pack assembly process is the combining of the modules into robust battery packs. A technician manually makes the connections to the battery pack, and from it to the various systems in the electric vehicle. However, to make the seals in the pack more secure, robot arms are used to insert and tighten screws and other parts.

Can you recycle EV batteries?

Despite future EV battery technology being geared towards extending the life cycle of the battery, they will eventually reach the end of their lifespan.

Therefore, strategies for the recycling and reuse of these EV battery packs should be in place. The main goal is to keep EV batteries and their chemistries out of global waste streams to prevent negative environmental and human health impacts.

These include manufacturing sustainable EV batteries, by utilizing materials recycled from old batteries. Recycling processes in which old batteries are destroyed while recovering valuable materials is called “destructive dismantling”:

• Smelting: Organic materials are burned at high temperatures. Valuable metals are then recovered and sent to a refinery to make them suitable for reuse. 
• Direct Recovery: This process specifically recovers all the reusable battery-grade materials. Components are separated and the active materials are recovered. Direct recovery uses low temperatures with a minimum energy requirement.
• Intermediate Processes: In-between the above processes, these allow for the processing of various types of batteries and the recovery of reusable materials is greater.

Sustainability in manufacturing EV batteries

To “green-minded” individuals, sustainability is part of the appeal of electric vehicles. 

As mentioned earlier, an EV battery has a lifespan of between 10 to 20 years, which means that it will take two decades before the battery ultimately “dies”. However, this does not necessarily mean that they become unusable.

Additionally, it is not true that all EV batteries are totally depleted of their capacity. These can be reused for secondary storage of solar and wind energy.

Due to the finite nature of metal resources and the high cost of mining new materials, future EV battery technology is focused on reclaiming metals found in old batteries and putting them towards the manufacture of new batteries.