li ion 18650 battery pack

　　18650 lithium-ion battery pack production process

　　(1) Baking

　　Bake for 12 hours under the condition of constant temperature and vacuum degree of -0.09MPa. The main purpose is to dry the moisture of the battery cell.

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

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

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　　(2) Injection

　　Inject the battery cell after vacuum baking into the electrolyte solution in the glove box filled with Ar gas. The amount of liquid injection is different according to the design of the lithium-ion battery pack. Use this to judge whether the injection volume is appropriate or not.

　　(3) Welding tabs Weld the positive tab (aluminum strip) and the negative tab (nickel strip) to the scraper positions of the positive and negative tabs with an ultrasonic welding machine. Pay attention to prevent welding deviation, welding dislocation, and false welding.

　　(4) Bottom welding. First put the insulating gasket into the steel shell, then put the wound battery core into the steel shell, and weld the negative tab to the bottom of the steel shell with a spot welder. Check the outer surface of the bottom of the steel shell, pick out yellow spots, black spots, defects, fires and other poor appearances, and try to pull the tabs, pick out 18650 lithium-ion battery packs that are not firmly spot welded, such as fires, weak welding, and desoldering.

　　(5) sealing

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

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

　　First spot weld the steel shell and cap of the 18650 lithium-ion battery pack with a spot welder, and then continue laser welding with a laser welder. Laser welding should ensure accurate positioning, and the welded parts are clean. It is strictly forbidden to cause deformation or damage to the battery. Check after welding, and repair welding for defective batteries such as welding holes and explosions.

　　(6) Winding

　　Place the ion-exchange membrane on the winding needle evenly, and the front end protrudes 2-5mm from the winding needle. There should be no wrinkles at the four corners of the pole piece. If the adhesive tape is misaligned left and right, the adhesive tape does not cover the solder joints and other defects, the positive electrode material must hug the negative electrode material, the electrode sheet cannot be rolled, and the front end of the electrode sheet must be inserted to the top.