December 14, 2021
Historically, electric vehicles were equipped with lead-acid batteries.1 In the 1990s, nickel-cadmium (NiCd) batteries dominated the market, but these were phased out due to the toxicity of cadmium, giving way to nickel-metal-hydride (NiMH) batteries in the 2000s. Today the lithium-ion (Li-ion) battery is the leading technology for electric mobility and consumer electronics.
The world of electric batteries is complex, but it also holds the key to tomorrow’s mobility solutions.
Verkor invites you on this deep dive to explain everything you need to know about the extremely important lithium-ion battery.
What is a lithium-ion battery?
Why lithium-ion? Lithium is a metal made up of electrons and protons. What makes this metal unique is its easy release of electrons that become ions, hence the term lithium-ion.
How does it work?
A cell consists of four principal elements: a cathode, an anode, a separator and an electrolyte.
As the battery discharges, the lithium ions will migrate: the electrons from the (negative) anode will move toward the electrons from the (positive) cathode, and vice versa when the battery is charging. This migration of electrons creates an electric current.
Lithium cations need to be able to flow from negative to positive. They do this through the electrolyte, which permeates the separator and the electrodes.
What is a lithium-ion battery pack?
A lithium-ion battery is an assembly of multiple cells integrated into a module, which in turn is integrated into a pack. It is this pack, combined with a BMS (Battery Management System), that constitutes the battery.
Which form factors are right for which uses?
Lithium-ion cells come in three form factors: Pouch, Cylindrical, and Prismatic. Verkor manufactures and develops Pouch and Cylindrical cells.
The five steps in li-ion battery production
Diagram showing the different stages of manufacturing a cylindrical lithium-ion cell.
Mixing: The active materials are mixed with a binder and a conductive carbon in huge tanks to obtain a black ink called slurry.
Electrode coating: The second step is to deposit the slurry on a current collector to form an electrode. The current collector is made of aluminium for the positive electrode, and copper for the negative electrode.
This winding or stacking step consists of assembling the positive electrode, the separator, and the negative electrode in alternating layers, called a stack or coil.
Formation is a charging and discharging step carried out in the factory under special conditions. This last step makes the cell operational and prepares the cell to optimise its performance (capacity, life span, etc.).
Once the formation step is completed, tests are carried out on the cells to assess their capabilities and internal resistance. The lithium-ion batteries are now ready and can be sent to the customer.
While all these steps of production are going on, R&D engineers are thinking about the type of materials to be used and their properties (thickness, strength, volume, etc.) in order to best meet the customers’ needs.
Lithium-ion batteries and the environment
More information on recycling in our article: Battery recycling: a beacon for change
Many solutions are being developed to achieve battery recycling.
Recycling: SNAM, a French battery recycling company, recovers and recycles mainly nickel-cadmium, nickel-metal-hydride and lithium-ion batteries from end-of-life electric vehicles.
Stationary storage: The Renault-Nissan Alliance recovers used batteries from electric vehicles for stationary use (e.g. to store energy generated by a wind turbine or photovoltaic panel).
Are more eco-friendly batteries coming?
Verkor’s ambition is to design and manufacture more environmentally friendly batteries.
The carbon footprint of the first batteries developed by Verkor will be only 20% to 25% that of batteries produced in China. This is thanks to France’s low-carbon energy mix, innovations in digitalisation and recycling, and vertical integration that covers the entire value chain, from battery manufacturing to recycling.
Verkor stands by its convictions and is committed to a green approach throughout the battery life cycle — from the choice of components to recycling.
The process of creating a lithium-ion battery is a long and thorough one. By now you understand the basics of lithium-ion batteries, which are both the driving force and main challenge of the energy transition.
Verkor aims to build one of Europe’s first Gigafactories by 2024. It will have an annual production capacity of 16GWh of lithium-ion cells, enough to equip 300,000 electric vehicles. Verkor’s ambition is to power tomorrow’s mobility solutions and invest in this sector in which lithium-ion batteries are a cornerstone of the energy transition.