How lithium-ion batteries are made and work
Today they are everywhere. The rechargeable lithium-ion batteries that power everything from mobile phones to drones and cars. But how do they work and how are we at Lyma involved in the manufacturing process?
The world's first commercial lithium-ion battery saw the light of day in 1991 when Sony launched it in one of its electronics products. The result was revolutionary and other manufacturers quickly followed suit. Since then, a lot has happened and today's batteries are significantly more powerful than those launched in the 1990s.
But what exactly is a lithium-ion battery and how does it work? In simple terms, a lithium-ion battery is an electrochemical battery that uses lithium ions to move electrons and generate voltage.
Three main components
A lithium-ion battery consists of three main components: a cathode, an anode and an electrolyte. The cathode, the positive pole of the battery, consists of a thin aluminium foil coated with lithium compounds. The anode, the negative pole of the battery, consists of a thin copper foil coated with graphite. Between them is a separator of electrolytes that prevents the two poles from coming into contact with each other.
Ions in constant movement
When the battery is charged, the positive lithium ions travel from the positive terminal through the electrolyte to the negative terminal, where they join the graphite carbon atoms. When the current is reversed and the battery is discharged, the positive lithium ions return to the positive pole. During this process, electrons are released, creating current that is used to power electronics. This creates a perpetual loop that allows the battery to be charged and discharged over and over again.
How manufacturing works
Due to high demand, the production of lithium-ion batteries has increased significantly. Today, there are several major battery manufacturers in the Nordic countries. The first and most important step in the manufacture of lithium-ion batteries is the production of the electrode. That is, the anode and cathode of the battery.
Battery slurry
The anode, which is a mixture of carbon and graphite, and the cathode, which consists of nickel, cobalt, manganese and lithium, are each mixed together to form a viscous mass called slurry. During the process, the material is mixed together with solvents in the form of acids to create the highest possible purity. When the slurry is ready, it is transported to a coating machine that evenly distributes the mass on a thin film. The mass for the anode is distributed on a copper foil, while the mass for the cathode is distributed on thin aluminium foil, which is finally allowed to dry under several different temperature stages.
Lateral T-pipe with PTFE plastic lining. The white media contacting parts protect against corrosion.
Lyma experts on slurry
When it comes to the production of slurry, we at Lyma have a great deal of expertise. In addition to expertise on the acids needed in the purification step, we can provide knowledge on which pipes and pumps to treat the slurry. The hot viscous slurry is a corrosive liquid that requires applications with durable materials.
Titanium is a good material but due to its high price and long delivery times, plastic is preferred instead. To use plastic here PTFE wound metal tubes and valves, for example, can be a good idea. Centrifugal pumps with plastic lining, where the plastic is chosen based on the medium, for example PE or PVDF, provides high reliability and a good working environment.
When the slurry is to be pressed piston diaphragm pumps preferable because they can handle very high pressure classes and are dry-running safe. Piston diaphragm pumps are able to provide good filter press feed, resulting in drier and more even filter cakes.
Find out more about the products suitable for slurry handling here.
electrolyte
After the cathode and anode slurries are dried on aluminium and copper foil respectively, the foil is pressed in a hot cylinder before being cut into decimetre-long pieces that are finally punched out into even smaller parts. A machine then stacks the anode and cathode parts on top of each other, interspersed with separators. The stack is welded together to form a cell, which is then placed in a foil pack that is finally filled with electrolyte.
The electrolyte is dripped by hand into the cell through a sealed glove box with controlled atmosphere. Once the electrolyte is in place in the cell, it is deflated until a vacuum is created. After a formation cycle, where the cell is recharged two to three times, it is permanently sealed and is now ready for use.
Lyma can handle electrolyte
When it comes to electrolyte management, we at Lyma also have extensive knowledge. Electrolyte is a clear corrosive liquid consisting of lithium salts (LiPF6), solvents and additives that are important to handle properly. Here too, plastic pipes, pumps and valves are preferred as steel applications become contaminated in contact with electrolyte. We at Lyma have a wide range of applications in different types of plastics optimal for the treatment of electrolyte.