Lithium-ion battery explosion-proof technology -Lithium - Ion Battery Equipment

Lithium-ion battery explosion-proof technology -Lithium - Ion Battery Equipment

Lithium battery explosion-proof circuit and explosion-proof cell technology

Lithium-ion batteries have become the batteries of choice for portable electronic devices. Batteries, with their high capacity density and competitive prices, are expected to remain the mainstream of the market in the next few years. But lithium-ion batteries are always in danger of exploding. As applications rose, so did the explosion. In fact, with proper battery system design and battery level determination, Li-ion batteries are very safe. At present, explosion-proof circuits and explosion-proof core technologies have matured, and explosions should be less and less.(Lithium - Ion Battery Equipment)

Lithium-ion battery characteristics

Lithium is the smallest and most reactive metal on the periodic table. Due to its small size and high capacity density, it is deeply loved by users and engineers. However, the chemical nature is too reactive and poses a high risk. When lithium is exposed to air, it undergoes a violent oxidation reaction with oxygen. To improve safety and voltage, scientists have developed materials such as graphite and lithium cobalt oxide to store lithium atoms. The molecular structure of these materials forms tiny nanoscale memory lattices that can be used to store lithium atoms. That way, even if the battery case ruptures and oxygen enters, the oxygen molecules are too large to fit into the tiny battery, preventing the lithium atoms from coming into contact with the oxygen and exploding. This principle of lithium-ion batteries allows people to achieve high capacity densities while achieving safety

When lithium-ion batteries are charged, lithium atoms lose electrons and oxidize into lithium ions. Lithium ions travel through the electrolyte to the cathode, where they enter the cathode cell, gain an electron, and are reduced to lithium atoms. When unloading, the whole process is reversed. In order to prevent the battery from short circuit due to the direct contact between the positive and negative electrodes, separator paper with many small holes is added to the battery to prevent short circuit. A good separator paper can also automatically close the tiny holes when the battery temperature is too high, so that lithium ions cannot pass through, so as not to waste time and prevent danger.


Li-ion batteries start to have side uses when the charging voltage exceeds 4.2v. The greater the stress, the greater the risk. When lithium-ion battery voltages are higher than 4.2v, less than half of the lithium atoms remain in the cathode material, and the battery often collapses, resulting in a permanent drop in battery capacity. If the battery is charged, subsequent lithium metal will accumulate on the surface of the material because the negative battery is already full of lithium atoms. These lithium atoms grow dendrites from the cathode surface towards the lithium ions. These lithium crystals will pass through the separator paper, short-circuiting the anode and cathode. Sometimes the battery explodes before the short circuit occurs. This is because during overcharging, the electrolyte and other substances will decompose to form gas, causing the battery casing or pressure valve to expand and burst, allowing oxygen to enter and react with the lithium atoms accumulated on the surface of the negative electrode, causing the negative electrode to explode. Therefore, when charging a lithium-ion battery, an upper voltage limit must be set to take into account the battery life, capacity and safety. The optimal upper limit of the charging voltage is 4.2v. Li-Ion battery discharge must also have a lower voltage limit. When the battery voltage is lower than 2.4v, part of the material starts to damage. And because the battery will self-discharge, the longer the voltage is lower, therefore, it is best not to discharge to 2.4V to stop. During 3.0v to 2.4v discharge, Li-ion batteries can only release about 3% of their capacity. Therefore, 3.0v is the ideal discharge cut-off voltage.

When charging and discharging, in addition to voltage limitation, current limitation is also necessary. When the current is too high, the lithium ions don't have time to enter the storage battery and build up on the surface of the material. When these ions gain electrons, they crystallize lithium atoms on the surface of the material, which is as dangerous as overcharging. If the battery case is broken, it will explode. Therefore, the protection of lithium-ion batteries should at least include: the upper limit of the charging voltage, the lower limit of the discharge voltage, and the upper limit of the current. The general lithium-ion battery pack, in addition to the lithium-ion battery, will also have a protection plate, which is mainly to provide these three protections. However, the protection of the three kinds of protective plates is obviously insufficient, and explosion accidents of lithium-ion batteries are still common.



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