The Samsung cell is a good choice for many applications. The 18650 cell has a diameter of 18mm and a length of 65mm. Today, we will dismantle a 18650 cell and check its internal structure to understand how the 18650 battery works. Make sure there is no voltage when dismantling any battery cells since there is a danger of dismantling batteries(explosion or caught fire). Non-professionals should not disassemble them for safety sakes.
For safety reasons, a gray insulating sheet is usually placed at the positive battery position
Small parts of 18650 cell.
The safety valve is standard for every 18650 cell and is also the most important explosion protection barrier, not one. The working principle of the safety valve: When the internal temperature of the battery is abnormal and the air pressure rises to 1.0-1.2 Mpa, the safety valve opens to eliminate the internal gas and avoid the explosion caused by high pressure
After dismantling it, we discovered that the cylindrical 18650 cell uses an all-metal shell to protect the internal materials and prevent leaks. The inside is a roll of film. The positive and negative electrodes are designed at both ends of the battery core.
The inner film is a specially shaped polymer film. The film is designed with a microporous structure that allows lithium ions to pass freely. Nowadays, the common 2000-3000mAh capacity Samsung, Panasonic, Sanyo, LG and other batteries, the internal cathode material has been upgraded from the first generation of LiCoO2, ternary material, chemical name LiNi-Co-MnO2. The direct benefits: Longer life, greater safety, and better performance
Internal immersion electrolyte
Connect the positive film
A special white plastic film is also interposed between the positive electrode and the negative electrode of the connecting battery. The film is immersed in the electrolyte and wet, but the moisture is not so large, and the volatility is particularly good and there is a pungent odor.
The internal electrolyte of the 18650 battery is usually a lithium carbonate hexafluorophosphate solvent. The charge-discharge process of a lithium-ion battery is, in short, the process of intercalation and deintercalation of lithium ions. The amount of lithium ions embedded directly affects the capacity of the battery cell.
Through the above dismantling, we can find that the 18650 battery consists of: housing, positive, negative, thin film and electrolyte，altogetherr five parts, they perform their duties respectively to ensure the normal charge and discharge users.
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