Cylindrical Lithium ion battery manufacturing steps

The following is an outline of various steps used in Lithium ion battery manufacturing process.

Winding:

In cylindrical cell manufacturing process cathode, separator and anode are fed into a winder where it uniformly winded into a cylinder.  The radius of the cylinder varies depending on the cell design.  After the specified length of the electrode assembly is wound then it is cut and taped.

Clamping:

In this step the anode and cathode electrode tabs are connected separately using clamping process to avoid accidental shorting.

Casing:

The wound electrode roll is inserted into the appropriate metal casing.  

Sub Assembly:

During this process terminals, vents, safety devices, O-rings, washers and other connections are done.

Welding:

During this process the anode tabs are welded to the case at the bottom and the cathode tabs are welded to the top cover.

The next three steps vacuum drying, electrolyte filling and sealing process are done in a dry room where the humidity is controlled.

Vacuum Heating:

This process will remove any moisture absorbed by the electrodes during the proceeding processes.  

Electrolyte Filling:

After the moisture is removed appropriate amount of electrolyte is filled.  I general there are two types of filling process is used.  1.  Fill with particular amount of electrolyte 2. Overfill with the electrolyte,, followed by soaking and dumping the excess electrolyte.

Sealing:

Once the electrolyte filling process is done then the cell is sealed.

Formation:

All the cells will then go through formation process where they will be go through predetermined charge, discharge, procedures.

Storage/Aging:

The formed cells are stored for several days.  Number of days may vary depending upon the manufacturer and their quality process.

Testing:

At the end of the above storage process the cells will be tested for Open Circuit Voltage and capacity.

Sorting:

Based on the capacity the cells will be sorted and labeled accordingly.

Packaging and shipping:

The cells will then be packaged and shipped or stored.

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