Lithium-ion battery is a kind of lithium battery. Due to the lithium metal material used in lithium-ion battery, its chemical characteristics are abnormal during operation, which causes the previous lithium battery to explode and burn when it is improperly used. Therefore, in order to control the active chemical properties of lithium-ion batteries, technology development engineers will add manganese and cobalt or other metal materials to the positive electrode materials of lithium batteries, which has enhanced the safety index of lithium-ion batteries to some extent. However, in the process of using lithium-ion batteries, if the operation is not proper, such as overcharge, there will still be safety risks.
Many electric bicycles have already used lithium ion batteries. The charge and discharge of a lithium-ion battery is a chemical reaction process. Under a calm surface, lithium ions travel back and forth between the positive and negative electrodes. When a lithium ion battery is charged, the lithium atom of the positive electrode loses electrons and oxidizes to lithium ions, and lithium ions enter the negative electrode through the electrolyte, and an electron is obtained to be reduced to a lithium atom. When discharging, the process is reversed.
The problems of flatulence, high temperature, explosion, etc. of lithium batteries are usually related to overcharge, overdischarge and high current, and the three will cause damage to the battery. When overcharge occurs, the amount of lithium atoms remaining in the positive electrode material is too small, resulting in a permanent decrease in battery capacity. At the negative terminal, after the lithium atoms are saturated, recharging causes lithium metal to accumulate on the surface of the negative electrode material to form dendrites. For a long time, lithium dendrites will break through the diaphragm, causing a short circuit between the positive and negative electrodes. When overcharging, materials such as electrolytes tend to crack and generate gas, causing the battery casing or pressure valve to bulge and rupture, and the lithium atoms that accumulate on the surface of the negative electrode react and cause an explosion. Similarly, when over-discharged, it can also cause damage to materials.
In addition, when the current is too large, lithium ions do not reach the inside of the material and will accumulate on the surface of the material. When these lithium ions acquire electrons, lithium atoms crystallize on the surface of the material. Since lithium is the most active metal on the chemical periodic table, lithium atoms It is easy to oxidize with oxygen and explode.
When a fire associated with a power battery occurs, it is always reminiscent of the quality of the power battery, which is the biggest misunderstanding of the power battery.