Precautions for winding process of 18650 lithium battery

Problems to be paid attention to in the winding process of 18650 lithium battery 1. Goal: Prevent water absorption during the winding process of positive and negative electrodes, resulting in zero voltage, self-discharge, and poor cycle performance; method: calculate the dew point value and Temperature value, get the temperature and humidity value. 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 a dust analyzer. 3. Burr reduction abnormal process requirements: pole piece ≤ 8um; pole ear burr ≤ 12um; test method: 1 computer electric cell randomly selects the first one to check each machine at each transition, and the positive and negative electrodes at both ends before and after the burr cut The positive and negative electrodes of the ear are based on the operating instructions of the burr detection. Adverse reactions: The burrs of the electrode plate or the electrode ear exceed the technical requirements, which may lead to the perforation of the diaphragm, the short circuit of the positive and negative electrodes, the overheating of the battery, the explosion in severe cases, and the serious safety hazard. 18650 lithium battery winding step 4. The anode and cathode plates are not well covered. Process requirements: the centering of the positive and negative plates is 0.75-55 mm. The negative plate and the diaphragm are aligned to 1.5 mm. Detection method: After changing the volume and sampling, observe the degree of adverse reactions after 3 PCS batteries are calibrated by X-ray wi test: 1)-Process alignment beyond the specification may lead to negative excluding positive In the process of charging the battery, the lithium ion can not find the corresponding graphite embedding on the front of the battery, and there is free accumulation on the dendrites of the cathode of the lithium battery. The dendrites pierce the diaphragm and cause an internal short circuit, which poses a safety hazard. 2) The alignment of the negative plate and the separator exceeds the technical standard, which may cause the negative plate to be squeezed and deformed. Part of the negative electrode material on the electrode plate falls off, and the battery swells during charging. 5. Covering the test method difference (the length of the outer negative super positive material and the inner negative super positive material) winding pole piece direction: every 2h, each winding machine is sampled for inspection 3 personal computer core anatomy, and separate measurement The two reports have different dimensions with eyepieces and rulers. Adverse reaction: The negative plate cannot cover the positive plate. During the battery charging process, after the lithium ions are separated from the positive electrode, the corresponding graphite can not be embedded, which causes the free lithium ions in the battery to accumulate on the negative electrode, and dendrites appear. The dendrites pierce the membrane, causing internal short circuits and endangering safety. 18650 lithium battery winding step 6. Short-circuit test parameter setting (100V, 25nF250V, test method: short-circuit sample testing machine should be used for the first inspection of each shift; adverse effects: self-discharge, heat, explosion and other short-circuit factors: cutting particles, metal dust, Burr, etc., cause the diaphragm hole to rupture; 7. Adhesive foil and tab tension process requirements: tensile strength ≥ 15N bonding foil area> 2/3 welding printing test method: sampling 1PCS battery every 2H for tensile test and foiling test Adverse reaction: High internal resistance Statement: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete the previous article: Analysis of the advantages and disadvantages of soft pack lithium batteries