18650 lithium rechargeable battery.18650 lithium-ion battery pack production process

　　In the lithium-ion battery production process, pole piece production is the foundation, battery cell production is the core, and battery assembly is related to the quality of the finished lithium-ion battery.

　　(1)Baking

　　Bake for 12 hours at a constant temperature and vacuum of -0.09MPa. The main purpose is to dry out the moisture in the battery core.

　　Low temperature lithium iron phosphate battery 3.2V 20A -20℃ charging, -40℃ 3C discharge capacity ≥70%

　　Charging temperature: -20~45℃ -Discharge temperature: -40~+55℃ -40℃ Support maximum discharge rate: 3C -40℃ 3C discharge capacity retention rate ≥70%

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　　(2)Injection

　　Inject electrolyte into the vacuum-baked battery core in a glove box filled with Ar gas. The amount of liquid injected varies according to the design of the lithium-ion battery pack. The battery must be weighed before and after injection. The weight difference is the amount of liquid injected. Use this to determine whether the injection volume is appropriate.

　　(3) Welding electrode tabs Weld the positive electrode tab (aluminum bar) and the negative electrode tab (nickel bar) to the scraper positions of the positive and negative electrode sheets using an ultrasonic welding machine. Pay attention to prevent welding deviation, welding misalignment, and false welding.

　　(4) Bottom welding. First put the insulating gasket into the steel case, then put the wound battery core into the steel case, and use a spot welder to weld the negative electrode lug to the bottom of the steel case. Check the outer surface of the bottom of the steel shell to find out the 18650 lithium-ion battery packs with weak spot welding such as yellow spots, black spots, defects, and fire.

　　(5)Sealing

　　Low temperature and high energy density 18650 3350mAh-40℃ 0.5C discharge capacity ≥60%

　　Charging temperature: 0~45℃ Discharge temperature: -40~+55℃ Specific energy: 240Wh/kg -40℃ Discharge capacity retention rate: 0.5C Discharge capacity ≥ 60%

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　　First use a spot welder to spot weld the steel shell and cap of the 18650 lithium-ion battery pack, and then use a laser welder to continue laser welding. Laser welding should ensure accurate positioning and clean parts to be welded. It is strictly forbidden to cause deformation or damage to the battery. Post-welding inspections should be carried out to repair welding of defective batteries with welding holes, explosions, etc.

　　(6) Winding

　　Place the ion exchange membrane flushly on the winding needle, and the front end extends out of the winding needle 2-5mm. There should be no wrinkles in the four corners of the pole piece. The pole piece should not fall off, the tape should be applied at an angle, the single-sided tape is too long, and the double-sided tape should not be Defects such as the left and right misalignment of the tape, the tape not covering the solder joints, etc. The positive electrode material must hug the negative electrode material, the pole piece cannot be rolled sideways, and the front end of the pole piece must be inserted to the top.

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