18650 battery assembly method.
When assembling lithium batteries, it is important to pay attention to these issues.
Precautions for using battery cells include cell selection, aluminum-plastic composite film, top sealing edge (pole end sealing edge), side sealing edge, pole protection, and measures to avoid mechanical impact and short circuit.
1. How to distinguish between good and bad battery cells after receiving them. Internal resistance tester and capacity tester must be used. What is the nominal MH for testing and what is the actual MH. If the difference from the nominal parameters is larger, it represents poorer quality. The lower the internal resistance of the battery, the better. The battery cell is a pit. If there is equipment, check and test it. If there is no equipment, buy lottery tickets
2. Aluminum plastic composite film outer packaging protection: mainly to avoid damage caused by sharp parts piercing. For this reason, the surrounding environment of the battery should be cleaned regularly, and sharp parts should not come into contact with or collide with the battery cell. When using, gloves can be worn to avoid scratching the surface of the battery cell with fingernails.
3. Protection of top and side sealing edges: To avoid damage to the top and side sealing edges and damage to the sealing effect, bending of the top and side sealing edges should be prohibited; At the same time, reliable insulation isolation measures must be taken in the design of battery cells to avoid short circuits between the negative electrode and the aluminum-plastic composite film.
4. Pole protection: The positive terminal of polymer lithium battery cells uses aluminum pole handles, and the negative terminal uses nickel pole handles. Due to the thin handle, bending should be prohibited; At the same time, it is necessary to avoid contact between the pole handle and the aluminum-plastic composite film during the production process, and strictly isolate them with a sleeve film.
5. Insulation protection: When assembling multiple individual battery cells in series to prevent polarity short circuits, insulation treatment is necessary. PC film or silicone film is used to separate and wrap multiple layers of insulation tape around the battery terminals to fix them. Then, a layer of insulation is added to the welding wire position, and striped adhesive is used to fix it.
6. Avoid mechanical impacts such as falling, hitting, bending battery cells, and accidentally stepping on batteries.
7. It is prohibited to use metal objects or wires to short-circuit and connect the positive and negative poles.
8. Waterproof protection: After assembling the lithium battery, pour insulation glue on the whole before packaging. Alternatively, choose a waterproof battery box
9. The battery pack requires shock resistance! Electric vehicles should not be used as off-road vehicles during use! It is also not possible to use the outer skin of the battery pack to buffer collisions, as deformation can cause short circuits! Try to use a grille bracket, buffer pad, and outer box as much as possible. Without a grille bracket, the battery pack may experience nickel sheet detachment due to prolonged activity and compression over the years!
10. Take good care of heat dissipation, use thermal conductive silicone grease pads as the medium, and guide the heat to the stainless steel shell. Alternatively, the battery pack may have the ability to provide thermal conduction channels, allowing for timely thermal conduction during energy conversion to achieve optimal battery performance. Steel outer box and fan assistance are both conventional solutions.
11. Corrosion prevention issue: The battery has rusted after being stored for a long time. If possible, take measures to prevent corrosion.
After a battery cell is completed, the next step is to correctly combine it with the casing and battery cell protection circuit module to make it a polymer battery. The precautions during this process include:
1. Shell design:
(1) Sufficient mechanical strength to avoid external mechanical damage to the battery cell,
(2) When installing the battery cell into the casing, avoid scratching the cell with sharp edges and corners of the casing;
(3) Prevent the pure aluminum interlayer of aluminum-plastic composite film from short circuiting due to external contact.
2. It is necessary to design a battery cell protection circuit, including scientific settings for the highest/lowest voltage, overcurrent protection, and overcharging and overdischarging protection for individual battery cells when using battery cell combinations.
3. The conversion of the positive aluminum pole handle through nickel strips, as well as the connection between the battery cell and the circuit board, should be implemented using ultrasonic welding or spot welding technology.
4. The reliable positioning of the battery cells, after assembly, should be securely fastened within the casing without any looseness, ensuring that the entire lithium battery structure is in a fixed state.
