These safety common sense is very important lithium ion battery fire characteristics, fire characteristics and fire extinguishing methods

In recent years, the fire accident caused by lithium batteries has been common, the emergence of lithium batteries, brought a lot of product innovation, but if the lack of safety awareness, use, storage, waste and other aspects of improper disposal, lithium batteries will become a “time bomb”, it is flammable, explosive items, both flammable and ignition source, once collision, extrusion, overcharge and short circuit, etc. Easy to cause fire, explosion and other safety accidents, and once the spontaneous combustion explosion is difficult to extinguish, easy to cause casualties.

Previously reported

On the afternoon of August 20, the “Nanjing Jiangbei New Area” wechat public number issued a notice that at 11:42 on August 20, 2023, at the Nanjing Civitian Camp section of 104 National Road, an intercity bus (Anhui M03799D) from Lai ‘an County, Anhui Province to Forest Farm Station, suddenly caught fire during the driving process.

After a preliminary investigation, the cause of the fire was spontaneous combustion of a lithium battery battery carried by a passenger. The fire killed 2 passengers, and another 5 people were partially scalded and sent to the hospital for treatment, none of them are in danger of life.

Understanding the safe use of lithium batteries is too important for us. However, lithium batteries are both flammable and ignition sources, and improper use is a small “bomb”!

Lithium-ion battery fire characteristics

First, common security risks

In general, lithium-ion batteries have safety problems as combustion or even explosion. The root cause of these problems is the thermal runaway inside the battery, in addition, lithium-ion batteries may also be affected by some external factors, such as overcharge, fire source, extrusion, puncture, short circuit and so on.

According to statistics, over the years, electric vehicle lithium-ion battery fire accidents, 68% due to internal or external short circuit caused by 15% due to charge and discharge, 7% due to accidental start of equipment, 10% caused by other reasons. From the point of view of the cause of the fire, electrical failure and spontaneous combustion are the main causes of electric vehicle fire, and overcharge, battery failure, electrical circuit short circuit is the root cause of the fire.

2. Fire characteristics

Gas escape is one of the main manifestations of runaway lithium-ion batteries. Lithium-ion battery fire, will quickly emit a large number of white smoke, the main component of the lithium battery electrolyte vapor or decomposition products. In the early stage of the fire, the difference in smoke color is one of the most obvious features to distinguish between lithium battery fires and common fires.

After the lithium ion battery is out of control, the decomposed combustible gas is mixed with the air to form an explosive mixture of gas. In case of the high temperature particles emitted by the lithium battery, dehydrogenation will occur in the local space, resulting in the initial stage of the fire often accompanied by an explosion sound.

Characteristics of lithium-ion battery fire

The ignition speed is fast and the duration is long. According to the NFPA(National Fire Protection Association) experiment, the fire only took a few seconds to spread rapidly in the power lithium-ion battery module, lasting about 27 minutes.

High combustion temperature. One of the characteristics of lithium-ion battery combustion is high temperature, according to NFPA’s experiment, the highest temperature outside the battery can reach 283-1090 degrees Celsius, and the temperature inside the battery can reach 572-1121 degrees Celsius, so high temperature is enough to ignite the battery module inside and other combustible materials in the car, resulting in a larger fire.

Put out the difficulties. For lithium batteries, most of the combustion reaction occurs in the battery housing, the battery housing hinders the action of fire extinguishing agent, in practice, the lithium battery fire extinguishment time often exceeds the oxygen supply time carried by the fireman, which poses a certain threat to the personal safety of firefighters.

Spontaneous combustion or even explosion for a long time. Lithium-ion batteries are capable of spontaneous combustion and then explode due to overheating. Causes of overheating include electrical short circuits, rapid discharges, overcharging, manufacturing defects, poor design or mechanical damage. Overheating can lead to a process called “thermal runaway”, which is most likely to occur during the charge and discharge process, in which the exothermic reaction inside the battery causes the temperature and pressure inside the battery to rise at a rapid rate, thereby wasting energy.

What fire extinguishing method is most effective for lithium battery fire?

(1) Cut off the power

(2) Prevent flammable materials

(3) Sprinkling water (or other non-combustible liquid) on the device

Lithium battery fire can not be put out with dry powder fire extinguisher. Due to the spontaneous combustion of the battery inside the explosion, at this time with a dry powder fire extinguisher can not work, the best way is to use a lot of water or other non-flammable liquid to cool down, in order to prevent the spread of heat to other battery cells in the battery. If no water is available, any non-flammable liquid can be used to cool the unit.

(4) Warning

Do not attempt to remove/pick up or move the device.

Do not cover or wrap the unit and do not use ice or dry ice cooling units. This way of isolating the equipment will cause the heat of the equipment to be unable to disperse in a short time, but increase the risk.

After the device has cooled (e.g., after about 10 to 15 minutes), take the appropriate empty container and submerge the device in the non-combustible liquid.

Lithium batteries used in electronic products, new energy vehicles, etc., are mostly wrapped in delicate product shells, and must not ignore hidden risks because they are not seen by the naked eye, and must be careful with the use of products. Do daily maintenance.

Remember, safety first!