If the lithium battery shell slightly damaged, it will "set fire".

Jan 11, 2019   Pageview:99

Lithium batteries are the most commonly used power source for smart phones and tablets. However, some time ago, the explosion of lithium batteries in several mobile phones was chilling. On July 21, a truck loaded with nearly 40 tons of used lithium batteries caught fire, causing the Xinyu Jiangxi section of the Shanghai-Kunming Expressway to be interrupted for nearly five hours. In these news reports, lithium batteries seem to be a "dangerous product" that is very fragile and prone to fire and explosion.


Yesterday (24th), the reporter confirmed in the Longtan Lake Fire Squadron that the lithium battery will explode and smoke if it is physically damaged. Especially after the water is absorbed, the lithium battery will release more heat.




Lithium battery love angry


In order to guarantee the experiment have a higher reference, the reporter specially prepared three different types of lithium batteries, are respectively applied to the tablet soft package lithium-ion batteries, applied to cylindrical lithium-ion batteries, laptop computer and mobile phone on the commonly used scale lithium battery.


Firefighters in the trials will be soft package first lithium battery flat on a scrap of the bench, and then use pliers to soft package lithium battery shell cut a small opening. As lithium battery shell burst, soft bag out in the lithium-ion batteries, gaps began to take white smoke outside. Firefighters then pour water on the lithium battery, white smoke more severe, also issued a "stab thorn" voice, poured on the lithium battery of the bubbling phenomena emerged in the water.


Then, the firefighters broke the cylindrical lithium battery and the hard-shell lithium battery. After the two lithium batteries were cut, there was not much white smoke at first, but when the water was poured on it, a lot of small bubbles appeared from the crack. In less than two minutes, the temperature around the lithium battery began to rise, and the water trace was actually baked by the heat radiated from the lithium battery. Firefighters said that this is the characteristic of the lithium battery after physical damage.


In January of this year, the Dongcheng district stadium road a fire happened in a house, when the firefighters put smoking electric vehicle battery is buried in snow, battery had come up to the fire. Later learned, electric vehicle battery is lithium battery.




Why is it on fire?


It is understood that lithium metal is very active in chemical properties and is a dangerous item that is in danger of being exposed to moisture. It will release flammable gas when exposed to water or humid air. In fact, the phenomenon of heating or burning of lithium batteries is mainly caused by short circuit and excessive current. For mobile phones, the charging and discharging currents are too large. There are many factors that cause a short circuit in a lithium battery, including physical damage to the battery, temperature of the environment, and short circuit between the positive and negative electrodes. If the lithium battery case is damaged, it will cause a short circuit inside the battery core, which will generate heat.


Yang Yong, an associate professor at the School of Electrical Engineering, Huazhong University of Science and Technology, told the reporter that under normal circumstances, the electrolyte contained in the lithium battery is in a sealed state and will not react. However, when the outer casing of the lithium battery is broken and the electrolyte inside encounters air or water, a chemical reaction occurs, generating gas and heat. "When the reaction is severe, it will burn or even explode."




Avoid knock against violence


Just because of the characteristics of lithium battery, in the international air transport association (IATA), the relevant provisions of the lithium battery is classified as dangerous goods (DGR).Believe that many people have such experience, when flying, electronic equipment containing lithium batteries are not allowed to check in, only with you. And passenger carrying lithium battery total energy should not exceed 160wh (watts), when carrying, lithium batteries and put them in separate plastic bags, and wrapped him in insulation.


In the remote control model to play in the home, Lithium polymer battery is widely used. But the later, more mature technology of lithium battery still exist certain risk. Once the player will lithium Polymer battery Result on the windowsill, sun exposure results in pressure inside the battery, battery burst, and smoke. In addition, when the player is flying the helicopter model, the lithium polymer battery is thrown onto the propeller, and several batteries are smoked in the air instantaneously, and the fuselage is also deformed by the high temperature when the lithium battery is damaged.


In the tablet computer, the lithium polymer battery is used as the same, but since the tablet computer has far less capacity for charging and discharging the battery, when the battery is physically damaged, the energy released instantaneously is not so large, but the high temperature is released. "For example, if the tablet is rolled by the wheel, then first observe whether it is smoke. If not, then touch the outer casing of the battery to see if the temperature is normal. Do not rush to put it in the bag, so as not to cause a bigger fire accident." Hongyu Wang, the squad leader of the Longtan Lake Squadron, suggested that for electronic devices such as tablet computers that use lithium batteries, care must be taken to avoid exposure and to avoid violent bumps.


The page contains the contents of the machine translation.