18650 lithium battery cells

　　What is the production process of 18650 lithium battery

　　The 18650 lithium battery is a lithium-ion battery commonly used in electronic products, and is often used as a battery cell in a laptop battery. The meaning rule of its model is: For example, 18650 type refers to a cylindrical battery with a diameter of 18mm and a length of 65mm.

　　18650 lithium battery production process 1: coating

　　First of all, from the understanding of the coating process, large rolls of copper foil (yellow) and aluminum foil (silver) can be seen in this process. Aluminum foil is used to coat nickel-cobalt-manganese NCM ternary material; on the contrary, copper foil is used to coat graphite as the negative electrode active material; the white one is the diaphragm. The global lithium-ion battery separator is mainly occupied by manufacturers such as Asahi, Celgard, SK, toray, and W-SCOP. These foreign companies control nearly 70% of the market share. The market share of my country's separator companies is about 30%, and the independent localization of lithium-ion battery separators is constantly breaking through. The capacity of the battery cell is obtained according to the proportion area of these formulas.

　　A whole roll of coated positive and negative electrode materials is about 126mm wide, and then cut into 7 small rolls with a width of about 18mm. Each roll will be evenly divided into several sections, and each section represents the material required for a battery cell. According to Xu Gong, an engineer at the cell factory, the current price of ternary cathode materials is 120,000 yuan per ton, and each ton of material can be used to produce 50,000 cells; the current average daily output of cells is 500,000, and 10 tons are needed The cost of ternary cathode materials alone is 600,000 yuan per day.

　　The automated machine stamps each segment with nickel strips and insulating high-temperature-resistant Mylar sheets (Mylar), and then weighs them in five levels, namely heavy, A1, A2, A3, and light. This is the same as the selection of CPU wafers. The same batch of cutting processes will also have different physiques. According to different physiques, the corresponding capacities will be divided and shipped in pairs.

　　18650 lithium battery production process two: assembly

　　The sorted positive and negative electrodes will be fully automatic packaged here, and the white material is the diaphragm. The 18650 lithium battery can't work normally. It needs to add electrolyte as a medium to let the positive and negative electrodes undergo a chemical reaction, so that lithium ions can migrate between the positive and negative electrodes, and the lithium ion battery can be charged and discharged only when the charged ions output energy. After the automatic roll is wrapped, it rolls directly on the assembly line, and enters the next assembly step to be loaded into the steel shell.

　　The steel shell is stamped and formed in one piece, and the thickness is less than 1mm. Therefore, the requirements for the strength and quality of steel are very high. This 18650 lithium battery factory uses imported Korean steel materials.

　　This step connects the negative electrode lug to the bottom of the steel case by spot welding. Ensure spot welding accuracy and product quality. The spot welder can't weld the bottom of the steel shell. There is a copper nail in the hand of the assembling girl. First insert it into the bottom from the reserved hole, then put it into the spot welder, click once, and the negative electrode will be connected with the nickel strip to the bottom of the steel shell. alright.

　　The electrolyte is injected into a glove box filled with inert gas argon in a sealed box. The oxygen concentration in the sealed box glove must be lower than 10ppm to prevent electrode oxidation. The argon gas of the electrolyte is input into the sealed box through the circulation purification device, and there are catalyst and reducing agent hydrogen in the device, and the oxygen can be removed by generating water through the reaction of hydrogen and oxygen. At the same time, the desiccant in the device absorbs moisture to ensure the dryness of the atmosphere in the box.

　　After the electrolyte is injected into the cell, the cap and the steel shell have been connected as a whole by laser welding. Stacked neatly and orderly in rows, ready to go. A new 18650 lithium battery was born in this way. Each battery cell must be put on a new PVC sleeve classified according to capacity. Different capacities correspond to different PVC envelopes.

　　18650 lithium battery production process three: the first charge and test

　　After the electrolyte is injected into the 18650 lithium battery, it is not actually charged, and the state of the surface of the positive and negative electrodes is not stable at this time. It must be charged for the first time before it can be used normally. This first charge is called formation. When charging for the first time, extra electricity should be charged to form a protective film on the electrode surface. This protective film is the secret of the low self-discharge of lithium-ion batteries. At the same time, the properties of the protective film also affect the performance and life of the battery. Therefore, the chemical formation process is very important. Formation is done using subcontainers.

　　Batteries are chemicals. In order to ensure the safety and longevity of use, they must be paired and packed in boxes before leaving the factory, with 200 pieces in each box. Ensure three consistency: consistent capacity, consistent internal resistance, consistent voltage. Only in this way can it leave the factory normally, otherwise it will be relegated to the limbo and reduced to B-level and C-level batteries.