Why are lithium batteries prone to explosion?
2 Answers
Lithium batteries are prone to explosion for the following reasons: 1. Insufficient anode capacity in lithium batteries: When the anode capacity in the positive electrode area is insufficient, the lithium atoms generated during charging cannot be inserted into the layered structure of the anode graphite and will precipitate on the surface of the anode, forming crystals. Long-term crystal formation in lithium batteries can lead to short circuits, causing the cell to discharge rapidly and generate a large amount of heat, which burns the separator. High temperatures can decompose the electrolyte into gas, and when the pressure becomes too high, the cell will explode. 2. Excessive moisture content: During charging, moisture can react with lithium to form lithium oxide, causing capacity loss in the cell and making it prone to overcharging, which generates gas. The decomposition of moisture lowers the voltage, making it easier to decompose into gas during charging. The series of gases generated will increase the internal pressure of the cell, and when the cell's casing cannot withstand it, the cell will explode. 3. Internal short circuit: An internal short circuit in the cell causes high-current discharge, generating a large amount of heat that burns the separator, leading to a more severe short circuit. This also decomposes the electrolyte into gas, creating excessive internal pressure and causing the cell to explode. 4. Overcharging of lithium batteries: During overcharging, excessive release of lithium from the positive electrode can alter its structure, and the excess lithium may not be inserted into the anode, leading to lithium precipitation on the anode surface. When the voltage exceeds 4.5V, the electrolyte decomposes, producing a large amount of gas and causing an explosion. 5. External short circuit: An external short circuit may occur due to incorrect connection of the positive and negative electrodes. The high discharge current from an external short circuit causes the cell to heat up. High temperatures can shrink or completely damage the internal separator, leading to an internal short circuit and subsequent explosion.
Lithium batteries have highly reactive internal chemical reactions, offering high energy density but poor stability. If charging becomes unbalanced or a short circuit occurs during use, dendritic crystals formed by the negative electrode material can pierce the separator, triggering a thermal runaway chain reaction. The electrolyte rapidly decomposes, producing flammable gases and accumulating heat, causing temperatures to skyrocket to hundreds of degrees Celsius, potentially rupturing the casing and ejecting flames. With years of experience handling electronic devices, I've often witnessed such accidents due to overcharging, compression, or exposure to high temperatures. While manufacturers' protective circuit designs are crucial, users must still avoid prolonged full charges and keep batteries away from heat sources to mitigate risks, given lithium's inherently flammable and explosive nature.
