After the cathode and anode plates are produced in the electrode manufacturing process, the first step of making batteries, the next step is cell assembly. In the process, the four elements of secondary batteries including the separator and electrolyte are assembled together.
Order of Assembly Process
After notching is completed in the final process of electrode manufacturing, cell assembly begins with drying fine droplets remaining on the cathode and anode. While the electrode-making process is the same for all cylindrical, pouch, and prismatic types, the assembly process varies in the ways of stacking electrode and inserting electrolyte as well as the order of sealing the batteries by each shape. Also, each battery maker employs different technology.
Assembly Methods by Battery Shape
There are two ways to stack electrodes. One is to wind the electrode like toilet paper and another is to stack up flat electrodes like facial tissues. The first method is applied to cylindrical and prismatic batteries while the latter is useful on a pouch battery.
The winding method is similar to making toilet paper. Electrodes are rolled up like in winding paper onto a cardboard tube, a process that can be done quickly. The stacking method is to pile up the cells one by one. It requires more advanced technology than the winding method, but it causes fewer distortions between cells and enables higher energy density since it eliminates empty spaces inside the battery cell.
Once the plates are stacked in a way that fits battery types, the electrodes and separator are combined to produce *bi-cell. Then, when electrolyte is injected into it, we get the battery as we know it. For a cylindrical battery, electrolyte is injected before sealing. And a pouch battery also goes through the same process as a cylindrical battery.
*Bi-cell: A cell with the structure of cathode (anode)/ separator/ anode (cathode)/ separator/ cathode (anode)
As such, each shape of battery has different order and way for assembly. Next time, we will dig into the order and way of assembly by different batteries such as pouch batteries and cylindrical batteries.