Issues to note during the winding process of 18650 lithium battery Issues to note during the winding process of 18650 lithium battery 1. Objective: To prevent water absorption during the winding process of the positive and negative electrodes, resulting in zero voltage, self-discharge, and poor cycle performance; Method: Calculate the dew point value and Temperature value, the temperature and humidity value is obtained. 2. Dust control

　　Issues to note during the winding process of 18650 lithium-ion battery

　　Issues to note during the winding process of 18650 lithium-ion battery

　　1. Objective: To prevent the positive and negative electrodes from absorbing water during the winding process, resulting in zero voltage, self-discharge, and poor cycle performance;

　　Method: Calculate the dew point value and temperature value to obtain the temperature and humidity value.

　　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%

　　2. Dust control≤100,000PC/ft3 (particle size 0.5um)

　　Purpose: To prevent dust in the pole group during the winding process, causing short circuit, overheating, fire, self-discharge and other phenomena.

　　Method: Use dust measuring instrument.

　　3. Abnormal burr reduction

　　Process requirements: pole piece ≤8um; pole lug burrs≤12um; Test method: 1 Computer electric cell randomly selects the first one to inspect each machine at each transition, and cuts the burrs on the front and rear ends of the positive and negative electrodes and the positive side of the ear The negative electrode operates according to the burr detection instructions.

　　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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　　Adverse reactions: The burrs on the electrode plates or tabs exceed the technical requirements, which may cause perforation of the separator, short circuit of the positive and negative electrodes, overheating of the battery, explosion in severe cases, and serious safety hazards.

　　18650 lithium ion battery winding steps

　　4. The anode and cathode plate covers are not good

　　Process requirements: The centering of the positive and negative plates is 0.75 to 55 mm.

　　The negative plate and separator are aligned to 1?5 mm

　　Testing method: After changing the volume sampling, observe the degree of adverse reactions of 3 consecutive PCS batteries after calibration by There is no corresponding graphite embedded on the front side of the ion, and free accumulation on the cathode dendrites of the lithium-ion battery. The dendrites pierce the separator, causing an internal short circuit, which poses a safety hazard.

　　2) The alignment between the negative plate and the separator exceeds the technical standard, which may cause the negative plate to be extruded and deformed. Part of the negative electrode material on the electrode plate fell off, and the battery expanded during charging.

　　5. Covering test method differences (length of outer negative super positive material and inner negative super positive material) of winding pole piece direction: every 2h, each winding machine is sampled for inspection of the core anatomy of 3 PCs, and measured separately Two coverage of different dimensions with eyepieces and rulers.

　　Adverse reactions: The negative plate cannot cover the positive plate. During the battery charging process, after the lithium ions leave the positive electrode, they cannot find the corresponding graphite embedding, causing the free lithium ions in the battery to accumulate on the negative electrode and dendrites appear. The dendrites puncture the membrane, causing an internal short circuit and endangering safety.

　　18650 lithium ion battery winding steps

　　6. Short circuit test

　　Parameter settings (100V, 25nF250V,

　　Test method: The short-circuit sample testing machine should be used for initial inspection of each shift; adverse effects: self-discharge, heating, explosion and other short-circuit factors: cutting particles, metal dust, burrs, etc., causing the diaphragm hole to rupture;

　　7. Glue foil and tab tension

　　Process requirements: tensile strength≥15N bonding foil area>2/3 welding printing

　　Test method: Sample 1 PCS battery every 2 hours for tensile test and foil test

　　Adverse reactions: high internal resistance

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