1.2V Ni-MH battery.18650 lithium battery production process

The production process of 18650 lithium battery. Common 18650 lithium batteries are divided into lithium-ion batteries and lithium iron phosphate batteries. The nominal voltage of lithium-ion battery is 3.7v, the charging cut-off voltage is 4.2v, and the nominal voltage of lithium iron phosphate battery is 3.2V.

The production process of 18650 lithium battery. Common 18650 lithium batteries are divided into lithium-ion batteries and lithium iron phosphate batteries. The nominal voltage of lithium-ion battery is 3.7v, the charging cut-off voltage is 4.2v, the nominal voltage of lithium iron phosphate battery is 3.2V, the charging cut-off voltage is 3.6v, the capacity is usually 1200mAh-3350mAh, the common capacity is 2200mAh-2600mAh .

18650 lithium battery production process

The 18650 lithium battery is a commonly used lithium battery in electronic products and is often used as a battery core in laptop batteries. The definition rules of its model are: For example, type 18650 refers to a cylindrical battery with a diameter of 18mm and a length of 65mm.

Production process of 18650 lithium battery cell one: coating

First, let’s start with the coating process. In this process, you can see large rolls of copper foil (yellow) and aluminum foil (silver). Aluminum foil is used to coat nickel cobalt manganese NCM ternary material; conversely, copper foil is used to coat negative active material graphite; the white one is the separator. Global lithium battery separators are mainly occupied by Asahi, Celgard, SK, Toray, W-SCOP and other manufacturers. These foreign companies control nearly 70% of the market share. The market share of Chinese separator companies is about 30%, and the independent localization of lithium battery separators is making breakthroughs. The capacity of the battery core is obtained based on the proportional area of these formulas.

A full roll of coated positive and negative electrode materials is about 126mm wide. Next, it needs to be cut into 7 small rolls with a width of about 18mm. Each roll will be evenly divided into several sections, each section representing the materials required for a battery core. According to Xugong, an engineer at the battery 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 battery cells; the current daily average production capacity of battery cells is 500,000, and 10 tons are needed For ternary cathode materials, this expenditure alone requires 600,000 yuan per day.

The automated machine will mark each section with nickel tape and insulating and high-temperature-resistant Mylar. The next step is to weigh it in five levels, namely heavy, A1, A2, A3, and light. This is the same as CPU wafer selection. The same batch of cutting process will also have different physical properties. According to the different physical properties, the corresponding capacities will be divided and paired for shipment.

18650 lithium battery production process two: assembly

The sorted positive and negative electrodes will be fully automatically rolled and packed here. The white material is the separator. The 18650 lithium battery cell cannot work properly like this. It is necessary to add electrolyte as a medium to allow a chemical reaction between the positive and negative electrodes, so that lithium ions can migrate between the positive and negative electrodes and generate charge ions to output energy before the lithium battery can be charged and discharged. After the automatic roll is wrapped, it rolls directly onto the assembly line and enters the next assembly step to install the steel shell.

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

In this step, the negative electrode tab is connected to the bottom of the steel case by spot welding. Spot welding accuracy and product quality are ensured. The spot welder cannot weld the bottom of the steel shell. The assembly girl has a copper nail in her hand. First insert it into the bottom through the reserved small hole, then put it into the spot welder. With a click, the negative electrode is 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 gloves must be less than 10 ppm to prevent electrode oxidation. The electrolyte argon gas is input into the sealed box through the circulation purification device. There are catalysts and reducing agent hydrogen in the device. The oxygen can be removed by generating water through the hydrogen-oxygen reaction. 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 battery core, the cap and the steel shell have been connected through laser welding. Rows of them are stacked neatly and orderly, ready to go. A new 18650 lithium battery cell was born. Each battery cell needs to be put on "new clothes" PVC sleeves classified according to capacity. Different capacities correspond to different PVC envelopes.

18650 lithium battery production process three: first charging and testing

After the electrolyte is injected into the 18650 lithium battery, it has not actually been charged, and the state of the positive and negative electrode surfaces has not reached stability 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, additional electricity needs to be charged to create a protective film on the surface of the electrode. This protective film is the secret of the low self-discharge of lithium-ion batteries. At the same time, the nature of the protective film also affects the performance and life of the battery. Therefore, the chemical formation process is very important. The formation is completed using volume dividing cabinets.

Battery cores are chemicals. In order to ensure safety and longevity, they need to be paired and packed in boxes before leaving the factory. Each box contains 200 batteries. Ensure three consistency: consistent capacity, consistent internal resistance, and consistent voltage. Only in this way can they leave the factory normally, otherwise they will be relegated to the cold palace and reduced to B- and C-class batteries.

The internal structure of 18650 lithium battery

Lithium battery positive electrode

The 18650 lithium battery is wrapped in a metal casing. If you destroy the casing, you can see the battery cells inside.

Negative electrode of lithium battery

The negative pole of the battery cell has a blue plastic insulating gasket as well as the positive pole.

Taking it apart, we found that the cylindrical 18650 battery cell is wrapped in a full metal casing, which can protect the internal materials well and prevent leakage.

Inside the battery core, the film is soaked in electrolyte

The interior of the 18650 lithium battery cell is a roll of film, with positive and negative electrodes designed on both ends of the cell. The internal film is a specially formed polymer film. The film is designed with a microporous structure, which allows lithium ions to freely shuttle through it.

How to judge the quality of 18650 lithium battery?

1. Use a multimeter to test the DC range at a range greater than the rated voltage of the battery. For example: test 9V and 1.5V dry batteries in DC10V and DC2V ranges.

2. After selecting the gear according to the rated voltage of the lithium battery, use test leads to connect the positive and negative poles of the battery respectively. When the test voltage is greater than or equal to the rated voltage marked on the battery. The battery is intact. When the test voltage is 10% lower than the rated voltage, the battery can be used on electrical appliances with small discharge depth.

3. Please be reminded that the voltage of rechargeable batteries is generally 15%-25% lower than similar batteries. For example, the voltage of 5# battery is 1.5V, while rechargeable batteries are generally only 1.2-1.3V. Therefore, the rated value marked on the battery should be carefully confirmed.

Nowadays, the 3.7V 18650 lithium battery generally has a cycle life of about 500 to 1,000 times, and the 3.2V 18650 generally has a lifespan of more than 2,000 times. Of course, the premise is that the battery is a qualified battery produced by a regular manufacturer. If it is a defective or counterfeit battery, the lifespan will be very short.