Are you interested to know about the assembly process of lithium batteries? If yes, you have come to the right place. In this guide, I will explain the entire assembly process. You can use this as a beginner’s guide.
There are multiple processes involved in the manufacturing and assembly of lithium batteries. But we can divide this entire assembly process into 6 steps. These steps are listed below. These steps are to be followed in sequential order.
1. Preparation of the Material
The material required for the manufacturing of lithium batteries needs to be prepared first. It is the first and most important step in the lithium battery assembly process. A standard lithium battery will require 5 materials. They are the electrolyte, a negatively charged electrode, a positively charged electrode, a current collector, and a separator. One needs to be very careful while selecting these ingredients. The reliability, safety, and performance of the lithium battery will fully depend on the quality of these materials. So, make sure to select materials of good quality.
There are two choices for the positive electrode of a lithium battery. They are Lithium iron phosphate or lithium cobalt oxide. An aluminum foil is taken as the current collector.
Now, we will need the negative electrode. For the negative electrode, the current collector used is copper foil. This copper foil needs to be coated with graphite to form the negative electrode of the lithium battery.
Next comes the separator part. A porous polymer is generally used for the separator part. This separator will be made of a combination of paper and plastic in most cases. This separator needs to be kept between the positive and the negative electrodes. The role of the separator is to ensure that these two electrodes do not touch each other inside the battery. At last, we have the electrolyte. The electrolyte ensures that there is the movement of ions between the positive (anode) and negative electrodes (cathode).
2. Coating on the Electrode
Now, you are ready with all the materials to assemble a lithium battery. The first step of the assembly process is to coat the respective electrodes. Each of the current collectors needs to be coated with appropriately selected materials. This procedure can be done in two ways. One way is to use the doctor blading process. Another way is to use the roll to roll coating process. Both of these processes are equally good. So, the manufacturer can choose any.
Basically, both these processes involve the application of the electrode slutty on the current collector to create the positive and negative electrodes. When a blade is used to apply the electrode slurry on the current collector foil, it is called doctor blading process. When a network of rollers is used to apply the electrode slurry on the current collector foil, it is called roll to roll coating process.
Proper drying of the electrodes is essential after the successful application of the electrode slurry. There can be the presence of solvents on the electrodes even after drying. So, heating the electrode is necessary to remove all such unnecessary solvents. Once this process is complete, you can see a thin layer of the electrode material on the current collector foil.
The thickness of the electrode will be different for different types of lithium batteries. It will depend on the capacity and voltage levels of the battery. It is also essential to meet the right amount of thickness according to the design requirements. Otherwise, the lithium battery may not have the desired performance.
3. Cutting of the Electrodes
Once, the electrode coating process is over; they need to be cut into appropriate sizes for the assembly of the lithium battery. The exact size of the electrode will be specified in the design requirement of the lithium battery. Most lithium battery manufacturers make use of a laser to cut the electrodes.
Now, these electrodes need to be arranged in such a way that it forms the jelly roll structure. The stacking of the electrode is done in such a way that the separator comes in between two successive electrodes. This whole structure will be inserted inside a metal enclosure. This metal enclosure is the outer battery casing.
Once this process is completed, the inside structure moves on to the next phase, the formation. The electrodes of the lithium battery get activated in this phase. This activation is done with the help of continuous charge and discharge of the lithium battery. The performance of the lithium battery is fully dependent on the success of this process. So, proper care is taken to ensure that this process happens without any issues.
4. Filling of the Electrolyte
Now, the electrolyte needs to be filled inside the battery. This filling process will only happen after the successful activation of the electrodes. A narrow opening is created on the metal enclosure of the battery for filling the electrolyte. The vacuum process is adopted here for the filling.
5. Sealing of the Battery
After the successful filling of the electrolyte inside the metal can, it needs to be sealed properly. Otherwise, any leakage can cause a fire. Once the sealing process is complete, the battery is passed for all the quality checks to ensure that it is safe for use.
6. Testing of the Battery
There are multiple tests to be performed on the lithium battery once it is sealed. These tests are essential to ensure that the assembled lithium battery meets all the safety and other standards. The battery will be fully fit to use only after it passes all these tests. The first test will be the capacity test. During this test, the charge holding capacity of the lithium battery will get tested.
After completing the capacity test, the battery will be subjected to a cycle test. Here, the battery will be tested to check the number of charge and discharge cycles it can do, delivering a consistent amount of power all the time during the test. Next comes the temperature tests. Here, the battery will be subjected to cold and hot environments. The performance of the lithium battery will be tested in extreme temperature conditions. The exact testing value of the hot and cold temperatures will vary for different lithium battery models.
Once it passes the temperature tests, it will be moved to the safety test. All the safety aspects of the battery will be tested in this phase. It includes a short circuit test, physical damage test, and overcharging test. This test is essential to ensure that the battery does not pose any damage to the user.
 Final Thoughts
Now you know the entire assembly process of a lithium battery. The process is slightly complex. Proper monitoring is essential for each stage of the assembly process to ensure defect free and safe lithium batteries. Also, it is essential to ensure that all these activities are carried out in a clean and safe environment.