Discussion on Protective Measures for Lithium Batteries.L822 battery

　　Lithium battery is a kind of battery with lithium metal or lithium alloy as positive/negative electrode and non-aqueous electrolyte solution. In 1912, lithium metal batteries were initially proposed and discussed by Gilbert N. Lewis. In the 1970s, M S. Whittingham proposed and began discussing lithium-ion batteries. Due to the highly reactive chemical properties of lithium metal, the processing, preservation, and use of lithium metal have high environmental requirements. With the development of science and technology, lithium batteries have become the mainstream.

　　Shell characteristics

　　Lithium, with atomic number 3 and atomic weight 6.941, is a very light alkali metal element. In order to improve safety and voltage, scientists have invented the use of materials such as graphite and lithium cobalt oxide to store lithium atoms. The molecular structure of these materials forms a nano scale fine storage lattice, which can be used to store lithium atoms. In this way, even if the battery shell ruptures and oxygen enters, the oxygen molecules are too large to enter these subtle storage cells, preventing lithium atoms from coming into contact with oxygen and avoiding explosion.

　　Maintenance measures

　　Lithium battery manufacturers tell you that overcharging the lithium battery cells to a voltage higher than 4.2V can cause side effects. The higher the overcharging voltage, the higher the danger. After the voltage of a lithium battery cell exceeds 4.2V, less than half of the remaining lithium atoms remain in the positive electrode data. At this moment, the storage cell often collapses, causing the battery to lose capacity. If you continue to charge, because the storage cell of the negative electrode is already filled with lithium atoms, subsequent lithium metal will accumulate on the surface of the negative electrode data. These lithium atoms will grow dendritic crystals from the negative electrode surface towards the direction of lithium ions. These lithium metal crystals will pass through the diaphragm, causing a short circuit between the positive and negative poles. Sometimes, before a short circuit occurs, the battery bursts first. This is because during the overcharging process, electrolyte and other data will differentiate into gas, causing the battery casing or pressure valve to bulge and crack, allowing oxygen to enter and react with lithium atoms stacked on the negative electrode surface, leading to explosion.

　　Therefore, when charging a lithium battery, it is necessary to set a voltage limit in order to take into account the battery's lifespan, capacity, and safety. The ideal charging voltage limit is 4.2V. When discharging lithium batteries, there should also be a lower voltage limit. When the voltage of the battery cell is below 2.4V, some data will begin to be destroyed. Also, because the battery will self discharge, the longer it is discharged, the lower the voltage. Therefore, do not stop discharging at 2.4V. During the period of discharging from 3.0V to 2.4V, the energy released by lithium batteries only accounts for about 3% of the battery capacity. Therefore, 3.0V is an ideal discharge cutoff voltage. During charging and discharging, in addition to voltage constraints, current constraints are also necessary. When the current is too high, lithium ions cannot enter the storage cell in time and will gather on the surface of the data.

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