Analysis of the causes of lithium-ion battery explosions and combustion
1. Internal short circuit: Structural or manufacturing defects can cause issues such as internally inserted tabs, insufficient diaphragm wrapping, burrs, or folded diaphragms. Internally inserted tabs often occur in thick batteries with internal parallel connections. Inadequate insulation at the tab positions can easily lead to acute internal short circuits during subsequent addition of protection boards or use, resulting in combustion or explosion. However, this situation is now extremely rare, unless caused by external forces.
2. External Short Circuit: Explosions caused by external short circuits in lithium-ion batteries below 1AH are rare. Usually, the batteries swell or the tabs burn out completely. My personal analysis focuses on combustion caused by external short circuits in power lithium batteries or high-capacity mobile phone batteries. This involves improper customer use, such as not considering tab insulation when installing the battery in a metal casing, leading to abnormal smoking and burning of the lithium-ion battery at the installation site. Insufficient structural fixing measures are also common in power lithium batteries. During user use, shaking of the battery pack can damage the external insulation film or the connecting wire sheath, ultimately leading to a short circuit and combustion.
3. Overcharge explosion: This is the most dangerous and the company's biggest fear, but it still happens occasionally. Based on our understanding, there are two main reasons: a) Users do not use the matching charger as required, thus damaging the protection circuitry. Users often charge without time limits, making an explosion almost inevitable; b) Improper lithium-ion battery packing and a malfunctioning protection board will also result in a disastrous explosion. The same applies to single-cell batteries.
The above three points are common causes. In summary, comprehensive structural design and users following the specifications are important directions for preventing lithium-ion batteries from burning or exploding. It is believed that major cell manufacturers have already implemented reasonable improvement measures. I think that developing safer materials is the key to achieving lithium-ion battery safety.
How to prevent lithium-ion batteries from exploding?
1. Use a qualified charger: Charging time is a high-risk period for lithium-ion battery explosions. Original chargers or qualified chargers from major manufacturers are more reliable in ensuring battery safety than compatible chargers.
2. Use reliable batteries: Try to buy batteries from reputable manufacturers or well-known brands of lithium-ion batteries on the market. Do not buy second-hand or grey market batteries to save money, as these batteries may have been repaired and are not as reliable as original batteries.
3. Do not place the battery in extreme environments: High temperatures and impacts are major causes of battery explosions. Try to keep the battery in a stable environment and away from high-temperature places.
4. Proper Assembly and Maintenance: Many people like to buy second-hand battery cells to assemble batteries, and some are even bolder and more meticulous enough to buy battery cells and assemble batteries themselves. However, improper assembly and misoperation can easily lead to accidents. In particular, the selection of battery protection boards, the arrangement and selection of good protection board components, and the reasonable layout of the printed circuit board (PCB) are all very important. Damage to the protection board often becomes a battery killer and the culprit for tragedies.
Lithium-ion batteries are ubiquitous in daily life, from electric vehicles to computer motherboard batteries; they have become an indispensable part of our lives. Therefore, accidents involving lithium-ion battery combustion or explosion can cause enormous losses and safety hazards. Thus, studying the explosion mechanism of lithium-ion batteries is of great significance for improving their safety.
