Analysis of external factors affecting the safety of lithium-ion batteries

External factors that affect the safety of lithium-ion batteries. One is overcharging and overdischarging. Overcharge or overdischarge can easily cause the cathode material or electrolyte of the lithium ion battery to decompose, release gas and heat, make the battery expand, the internal pressure rises sharply, and even smoke, fire, and explosion occur. The second is an external short circuit. External short circuit The positive and negative short circuit of the protection circuit board caused by improper operation or malfunction. When the short circuit occurs, the battery discharge current is very large, which makes the battery heat, and the high temperature will shrink or completely destroy the diaphragm in the cell, causing an internal short circuit in the battery, resulting in an explosion ; The third is the temperature is too high. Excessive external temperature can cause deformation of the battery's metal casing, melting of the internal separator of the battery, decomposition of the positive and negative electrode materials or electrolyte, etc., all of which can easily lead to a short circuit of the battery. Mobile power uses polymer batteries and polymer batteries are safer than lithium-ion batteries. Polymer battery packaging is usually made of aluminum-plastic film, short circuit or other abnormalities. When the internal gastrointestinal bloat and break through the hot melt discouragement, explosion accidents generally do not occur, but when the internal short circuit of the battery generates a smoldering fire phenomenon, the battery itself There was no explosion, the explosion caused the combustion to explode because of the other components of the battery. (1) Internal factors affecting the safety of polymer batteries. There are two forms of short circuit in polymer lithium-ion batteries: one is the short circuit formed by the charging liquid of the positive and negative electrodes breaking through the electrolyte membrane during the filming and soft packaging of the battery. The other is in the battery charge and discharge cycle process, due to the chemical change of the electrode active material and the electrolyte diaphragm material itself, which causes local electronic conduction, which is called a chemical short circuit. (2) External factors that affect the safety of polymer batteries. One is overcharging and overdischarging. The mismatch between the charger and the mobile power source can easily lead to overcharging of the battery, which increases the possibility of polymer lithium-ion battery expansion. When the battery is charged and discharged, the battery continues to heat up, the gas that appears during the activation process expands, the internal pressure of the battery increases, and the pressure reaches a certain level. The second is edge protection. The outer packaging material sandwich of the aluminum-plastic composite film on the sealing side is made of pure aluminum, which has good electrical conductivity. When in use, reliable insulation and isolation measures must be taken to prevent short circuits between it and external components, which may cause corrosion and gas in the battery. The third is an external short circuit. The positive electrode (or negative electrode) of the battery is short-circuited with the aluminum layer on the outer layer of the aluminum-plastic composite film of the battery. As the application of mobile power sources becomes more and more widespread, people have higher and higher requirements for the capacity and safety of mobile power sources. While ensuring the capacity of the mobile power supply, how to ensure the safety of the mobile power supply has become a problem for designers. It is believed that with the advancement of material technology and people's deepening of understanding of the design, manufacture and use of mobile power supplies, the future of large-capacity mobile power supplies will be safer. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous post: Test steps for voltage and capacity of lithium-ion batteries