RC model battery packs are usually assembled from multiple battery cells, and the battery cells currently used in RC models are mainly pouch cells, which are lithium-ion batteries that use aluminum-plastic packaging film as the package material.
The production process of pouch cells is as follows:
- Material configuration: Mix the electrode raw materials, including active materials, inactive materials, binders, and solvents in a certain proportion, stir and disperse them to form a slurry. The positive and negative electrode materials must be prepared separately.
- Coating: coat the slurry uniformly on the front and back of the collector metal foils by a coating machine. The positive electrode slurry is coated on the aluminum foil, and the negative electrode slurry is coated on the copper foil.
- Rolling: Roll and squeeze the coated pole piece at a high pressure, which compacts the active and the collector to reach the thickness that meets the technical requirements.
- Cutting: Cut the pole piece into a certain width by the cutting machine.
- Punching: Punch the cut pole pieces into the actual size of the positive and negative pole pieces required by the battery.
- Stacking: Stack the positive electrode, the negative electrode and the separator into a battery cell by the stacking machine.
- Tab welding: Weld the tabs of the stacked cells by special welding equipment.
- Aluminum-plastic film molding: Punch a hole in the aluminum-plastic film that can hold a cell in the condition of heating with a forming mold.
- Top and side packaging: Put the cell in the aluminum-plastic film, and use the sealing machine for top and side packaging, leaving only one opening.
- Drying: After the pouch cell is sealed on the top side, do X-ray to check the parallelism of the cell, and then go to the drying room to remove the moisture inside the package.
- Liquid injection: Inject the electrolyte from the reserved liquid injection port. After the liquid injection is completed, it needs to be pre-packaged immediately to isolate the inside of the cell from the external environment.
- Standing: The prepackaged cells needs to be left standing. According to the process, they will be divided into high temperature standing and normal temperature standing. The purpose of standing is to allow the injected electrolyte to fully.
- Activation: Charge the battery cell with a small current to form a stable SEI layer on the surface of the electrode, which is called the battery activation. A certain amount of gas will be generated in this process, that is why the aluminum plastic film needs to reserve an air bag.
- Air extraction and edge sealing: Evacuate the activated cells and do a second edge sealing. Cut and fold the air bag part to form a finished battery cell.
- Inspection: Perform performance inspection of finished cells, including capacity inspection, appearance inspection, voltage test, etc. After completion, the finished cells will be packaged and put into storage.