With the continuous development of lithium battery technology, Custom lithium battery pack is widely used in many fields such as consumer electronics, electric bicycles and other mobile products, electric vehicles and energy storage solutions.
However, if there is insufficient safety awareness and improper handling during use, storage, disposal, etc., Custom lithium battery pack will become a “ticking time bomb.”
Generally speaking, the safety problems of lithium-ion batteries mainly manifest themselves as combustion or even explosion.
Lithium batteries are both flammable materials and sources of ignition. Once collision, extrusion, overcharge, short circuit, etc. occur, it can easily cause fires, explosions and other safety accidents, resulting in casualties.
The root cause of these problems lies in thermal runaway inside the battery.
After the thermal runaway of the lithium-ion battery, the decomposed flammable gas mixes with air to form an explosive mixed gas. When encountering the high-temperature particles ejected from the lithium battery, deflagration will occur in a local space, resulting in an explosion sound in the early stages of a fire.
The characteristics of custom lithium battery pack fires: fast ignition, long duration, high combustion temperature, difficulty in extinguishing, spontaneous combustion or even explosion for a long time.
Causes of lithium battery fire and explosion
Lithium batteries mainly rely on the movement of lithium ions between the positive and negative electrodes to achieve the charging and discharging process. From a principle point of view, the main factors that cause lithium battery explosions are overcharging and short circuits.
Overcharging mainly occurs during the charging process of lithium batteries. Due to the resistance of the battery, the battery will accumulate a large amount of heat during the charging process. The protection device in lithium batteries can provide a certain degree of protection against overcharge by detecting voltage.
However, when the overcharge time is too long and the voltage continues to be too high, dendritic short circuits are likely to occur inside the lithium-ion battery, causing the temperature and pressure of the lithium battery to continue to rise, resulting in the risk of explosion and fire.
Short circuit mainly occurs during the use of lithium batteries. When the lithium battery is in use, its own temperature will continue to rise, and the battery also maintains normal heat dissipation.
If the battery temperature is too high due to external factors, it will easily cause damage to the battery separator and cause a short circuit, which will cause excessive internal heat accumulation, trigger a chain chemical reaction, and cause the battery to explode and burn.
According to statistics from the emergency management department, in the first quarter of 2023 alone, the spontaneous combustion rate of new energy vehicles increased by 32%, with an average of 8 new energy vehicles catching fire (including spontaneous combustion) every day.
Lithium battery safety tips
Purchase regular and qualified lithium battery products and tools.
When lithium battery products and tools are not in use, try to remove the batteries and store them separately.
Li ion customized battery packs should avoid being stored in humid, high-temperature locations, and should be kept away from flammable and combustible materials.
After the lithium battery is fully charged, the power supply should be disconnected promptly and do not be charged continuously for a long time.
Do not squeeze or drop lithium battery products and tools during daily use.
Lithium battery fire fighting tools
When a lithium battery catches fire, a dry powder fire extinguisher can only extinguish the surrounding flames, but cannot effectively prevent the lithium battery from thermal runaway. Water or water-based fire extinguishers are the first choice for emergency response to lithium battery fires.
The basic principle of dry powder fire extinguisher is chemical suppression. It can generally extinguish solid fires, and can also extinguish incipient fires of flammable liquids, combustible gases and electrical equipment. Although dry powder fire extinguishers can extinguish open flames under initial circumstances, dry powder fire extinguishers cannot reduce the temperature inside lithium batteries. At this time, the internal temperature of the lithium battery is still very high, and the internal chemical reaction continues. After the heat is accumulated, it is easy to reignite or even explode.
Water/water-based fire extinguishers can not only eliminate open flames, but also have a certain cooling effect, so they are the first choice for emergency treatment of lithium battery pack fires.
Key points: The method of extinguishing fires with water/water-based fire extinguishers is suitable for lithium batteries with relatively low voltage, because there is no risk of electric shock. If a lithium battery plugged into AC catches fire, be sure to unplug the power before watering. Otherwise, there will not only be a risk of electric shock, but also a secondary fire caused by the electrolysis of water by 220V AC.
Lithium battery fire fighting
- Disconnect or remove external power from the fire equipment.
- Immediately and continuously saturate the electronic device on fire with water or other non-flammable liquid to lower the temperature of the lithium battery cell core, block heat dissipation, and prevent adjacent battery cells from catching fire.
- If the device was previously connected to an electrical outlet, unplug the power from all remaining electrical outlets until the system is confirmed to be fault-free.
- Do not attempt to move burning or smoking electronic equipment to prevent serious personal injury.
- Do not cover or attempt to lower the temperature with ice. This method of isolating the equipment will prevent the heat from being dissipated in a short period of time, which in turn increases the risk.
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