Improving the Capacity and Performance of Batteries Used in Electric Vehicles

From the issue of Car and Driver that was published in July/August 2023.

In 2011, a Nissan Leaf had a battery that was around 21 kWh in capacity, which provided it with an EPA range of 73 miles. The battery pack for the 2023 Nissan Leaf has nearly three times the capacity and range of its predecessor, although having slightly increased dimensions overall.

Despite efforts such as the 170 kWh pack in the 866-pound GMC Hummer EV SUV (shown above), developing an electric vehicle (EV) with a larger selection does not often have to automatically require a larger and heavier battery.

This article discusses the factors that battery engineers take into consideration as well as the trade-offs that vehicle design teams will need to consider.

Chemistry of the Cell

When it comes to developing an electric vehicle (EV) battery, the choice of the specific chemistry to employ is the most important option. Engineers working on batteries will need to strike a balance between electrical power capacity, available capacity, cost, and volatility. Quite often, a mobile provider and an automaker would buy motor vehicle-specific applications together. Examples of this include Tesla and Panasonic or GM and LG Electrical power Answer.

A significant number of electric vehicles (EVs) on the market in the United States use lithium-ion cells, which also include nickel, manganese, cobalt, and aluminium in addition to the lithium. These are known as NMCA cells in the scientific community.

In China, lithium-iron-phosphate, sometimes known as LFP, is the most common type of chemistry. It operates with less difficult-to-supply minerals, costs less money, and is generally safer than excessive conditions; however, the engineering holds significantly less strength in a given volume. Tesla has started using LFP for certain of its designs sold in the United States, while Ford has said that it will construct an LFP cell plant in order to power its electric vehicles.

Mobile Format

Engineers who work on batteries should determine the state (also known as “structure”) that each individual cell should be in. However, in practise, not every manufacturer offers every mobile chemical in every structure. Tesla was the first company to use a battery pack that contained thousands of tiny-structure cylindrical cells (equal to AA batteries). Since then, several other manufacturers have opted for hundreds of bigger sized cells in pouch or prismatic formats, which are two variants of rectangle designs. Tesla was the pioneer in this field. In order to construct the pack, several cells are arranged into modules, and these modules are then placed inside of a massive rectangular container. There are batteries that have eight modules, and there are batteries that have dozens of modules. The wiring of the modules itself is done in parallel, whereas the wiring of the cells contained within the modules is done in sequence.

GM’s Ultium family battery pack, which makes use of cells with a nickel-manganese-cobalt-aluminum (NMCA) mix.

Vehicle and Operator of the Vehicle

In order to facilitate direct current rapid charging of up to 300 kilowatts, the new GMC Hummer pickups and SUVs are equipped with two 400-volt module teams that operate in simultaneously and may be switched to an 800-volt collection.

The Ratio of the Cell to the Pack

When there are standard measurements for spherical cells, some of the other cell forms are manufactured in sizes that are specific to a given automobile manufacturer. The challenge that engineers face is to cram the most power into a battery pack that is as small as is physically possible while still ensuring that there is sufficient space for liquid-cooling channels, all of the wiring that connects cells inside of modules and modules to each other, and correct separation of modules for basic safety.

Almost all electric vehicles on the market today that have a range of 200 miles or more have a battery pack installed below the floor of the cabin that runs from door to door and axle to axle. Typically, there will also be a raised hump under the back seat for additional possibilities, and sometimes what the Germans call “foot garages” are recessed into the pack to give enough rear-seat legroom in lower vehicles. Both of these features are intended to maximise the amount of space that may be utilised. These large underfloor packs do have the benefit of lowering the vehicle’s centre of gravity, which ultimately results in improvements to the vehicle’s balance and control.

Capacity (i.e., Array)

At last, battery engineers, administrators of automotive items, and their accountants will discuss what kinds of battery capacities they can give to customers like you. The goal is to develop an electric vehicle (EV) that they are able to sell at the appropriate price and that has a large enough battery capacity to persuade customers that it can be a useful answer for their life and trips. It has come to our attention that in the United States, a range of approximately 250 miles appears to be the bare minimum that must be met before people will seriously consider replacing their internal combustion engines with electric motors for day-to-day transportation. GM has stated that it believes a range of 300 miles is the threshold at which buyers stop worrying about the availability of options. However, there are very few electric vehicles that are capable of actually achieving the EPA range that is printed on the label that is attached to the car’s window.