Lithium cell composition
As is known, lithium ion cells have two electrodes, namely, a cathode (positively charged, consisting of cathode material such as NMC, LFP, etc.) and an anode (negatively charged, consisting of anode material such as graphite or carbon).
Added to these is a central separator, a layer of thin material composed, as a rule, of a plastic or ceramic polymer that acts as an insulator between the two electrodes. Finally, there is an electrolyte, an organic liquid containing lithium salts which fills the inner volume of the cell and wets the electrodes, thereby joining anode and cathode.
But how are the anode and cathode sheets made?
There are essentially three steps to follow:
- Electrode material mixing phase
- Coating phase
- Drying phase
First of all, the raw materials, in the form of powders that will be used in the lithium-ion cell, are combined in a large mixer using different methods: dry, in liquid form, with solvents or in water.
The resulting chemical compounds must then be added with components (binders or other substances) to obtain a uniform layer that will be applied on the metal electrodes through the coating process. This operation is very similar to the screen-printing process, where a sheet of aluminium or copper is passed under a roller press and the resulting mixture is spread out perfectly so that the cell is uniform and high-performing.
Once the coating process has been completed, the drying phase begins in an oven that can reach 150 °C. This phase includes maintaining a steady temperature and humidity level and is relatively comparable to other production processes, such as those used in the ceramics industry.