Battery technology is the heart of an electric vehicle (EV), influencing everything from range and performance to safety and cost.
The two most common aspects of EV batteries to understand are battery chemistries (the materials used to store and release energy) and packaging (the form factor in which these batteries are arranged). Here’s a breakdown of the key battery chemistries and how they are packaged into cells, modules, and packs.
EVs primarily use lithium-ion (Li-ion) batteries, which come in several different chemistries, each with its own strengths and weaknesses:
NMC batteries offer a good balance of energy density, power output, and cost. These batteries are widely used in EVs like the Chevrolet Bolt and BMW i3 because they provide long-range capabilities and decent lifespan. However, they rely on expensive cobalt, which is a limiting factor for scaling production .
This chemistry is known for high energy density and is primarily used in Tesla vehicles. NCA batteries offer excellent range and power, but their shorter lifespan and higher risk of thermal runaway (overheating) require sophisticated thermal management systems.
LFP batteries are prized for their safety, stability, and longer cycle life. Although they have lower energy density compared to NMC or NCA batteries, making them bulkier, their cost-effectiveness and safety make them a popular choice for budget EVs or vehicles in regions with hot climates, such as China’s popular EVs.
Though not yet widely available, solid-state batteries represent the next frontier in EV technology. They promise significantly higher energy density and improved safety by replacing the liquid electrolyte in traditional Li-ion batteries with a solid one. This innovation could increase range while reducing fire risks.
To power an EV, batteries are structured in layers from individual cells to large packs. Here’s how they break down:
A single battery cell is the smallest unit and contains electrodes and electrolytes to store and release energy. Cylindrical (used by Tesla), pouch (used by GM and Nissan), and prismatic (used by BMW and Volkswagen) are common form factors for cells. Cylindrical cells are highly standardized, while pouch and prismatic cells offer better space efficiency.
Cells are grouped into modules to form larger units that are easier to manage. Modules typically include multiple cells connected in series or parallel, and they often come with thermal management features to control heat. Tesla’s Model S battery uses modules made of thousands of cylindrical cells, while Nissan Leaf modules are composed of fewer, larger pouch cells.
Finally, modules are arranged into a battery pack, which includes the necessary electronics, cooling systems, and protective housing. The pack is what powers the EV’s motor. Depending on the EV design, the pack might sit under the vehicle’s floor (like in the Tesla Model 3) or in other configurations. The design of the battery pack is critical for vehicle safety and range.
In summary, the choice of battery chemistry and packaging format plays a crucial role in determining an EV’s performance, cost, and safety. As technology evolves, future innovations like solid-state batteries could revolutionize how EVs are powered.