AG10 battery

Research on Fire and Protection of Power AG10 battery for New Energy Vehicles

"Once thermal runaway of lithium-ion AG10 battery occurs, it is difficult to terminate the reaction. A phased warning can be carried out at the early stage of thermal runaway." Professor Wang Jian of the University of Science and Technology of China said this at the "2018 Second China New Energy Vehicle Testing and Evaluation Technology Development Summit Forum" held by the Electric Vehicle Resources Network. At the meeting, he analyzed the causes of fires in power AG10 battery for new energy vehicles and proposed protective measures.

In recent years, there have been many safety accidents caused by thermal runaway of lithium-ion AG10 battery, among which the Boeing 787 aircraft, Tesla electric vehicles, and Samsung Note7 mobile phones have had a particularly wide impact.

According to incomplete statistics, Tesla has had many vehicle fire accidents around the world in recent years, including fires after collisions, fires caused by overheating during charging, and spontaneous combustion during driving. Tesla's lithium-ion battery pack spans the vehicle base. Once thermal runaway occurs, it will affect the entire vehicle. Tesla has improved the safety of the vehicle by adding titanium alloy protective covers to the chassis.

In addition, the Samsung Note7 incident was mainly caused by an internal short circuit caused by a battery defect, which caused an explosion. The Boeing 787 aircraft also had a fire caused by an internal short circuit in the battery and overheating.

Wang Jian said that the main cause of lithium-ion battery accidents is fire and explosion caused by thermal runaway, which manifests itself in the form of spraying, burning, and explosion, accompanied by toxic and harmful gases. He said that there is currently a lack of effective fire extinguishing technology for lithium-ion AG10 battery. From the properties of lithium-ion AG10 battery themselves, even if they are extinguished briefly, their re-ignition is very high. Therefore, once a lithium-ion battery has thermal runaway, it is difficult to prevent and control it. Therefore, analyzing the development process of thermal runaway of lithium-ion AG10 battery, studying the thermal safety of combustible components inside the battery, and proposing early warning, protection, and suppression measures are of great significance for the prevention and control of thermal runaway disasters.

Research on the relationship between thermal runaway of lithium-ion AG10 battery and atmospheric pressure, number of AG10 battery, and overcharging conditions

Wang Jian said that there are multiple stages in the development of thermal runaway, and once thermal runaway occurs, it is usually considered irreversible. Studies have shown that altitude has a significant impact on thermal runaway of lithium-ion AG10 battery. Under the same heating conditions at high altitudes, the thermal runaway will occur earlier than at low altitudes. In other words, from the perspective of personnel safety, if standards are formulated, high altitude conditions need to be considered. Otherwise, once the battery has thermal runaway, it may have an adverse effect on the escape of personnel in high altitude environments.

By studying the thermal runaway behavior of battery packs and monitoring the changes in parameters such as ignition time, mass loss, heat release rate and flame temperature, it was found that there is a linear relationship between mass loss and the number of AG10 battery, while there is an exponential growth relationship between the heat release of the battery pack and the number of AG10 battery.

The results of thermal runaway experiments of ternary nickel-manganese-cobalt NMC AG10 battery and lithium iron phosphate LFP AG10 battery under overcharge conditions (charging cut-off voltages are: 4.2V, 4.5V, 4.8V, and 5.0V, respectively) show that overcharging increases the risk of thermal runaway.

Wang Jian briefly summarized the above research. He said that the thermal runaway phenomenon of lithium AG10 battery can be divided into several stages. Although thermal runaway is difficult to avoid, the characteristics of different stages can be used to provide staged warnings of thermal runaway phenomena.

Research on thermal safety of combustible components of lithium-ion AG10 battery

Wang Jian also listed the results of thermal safety research on combustible components inside AG10 battery such as diaphragms, electrolytes, and mixed systems of electrolytes and electrode materials. The results of the research on the combustion characteristics of electrolytes show that the mean and peak values of the mass loss rate of electrolytes are positively exponentially related to pressure; the research on positive electrode materials and electrolyte systems shows that positive electrode materials with high nickel content will promote oxygen generation and reduce the thermal safety of AG10 battery, and the higher the cut-off voltage, the greater the battery reaction activity. However, the effect of electrolyte additives on battery safety is not obvious.

Power battery fire protection measures-cooling, insulation, and suffocation

Wang Jian said that the usual means of fire extinguishing are mainly cooling, insulation, suffocation, and termination of chemical reactions.

Cooling: The cooling system of electric vehicles is usually to maintain a stable working environment for power AG10 battery. It is hoped that the battery management system will be used for real-time monitoring, and in the initial stage of thermal runaway development, the cooling system will be used to quickly cool the working environment of the power battery to control the propagation speed of thermal runaway.

Thermal insulation effect: The application of fire-resistant flame-retardant thermal insulation coating can not only improve the ability of the battery pack to resist external flames, but also delay the spread of fire when the battery burns. For example, an insulation layer is added between the 8 units of the battery pack of the Boeing 787 aircraft to limit the spread of thermal runaway.

Suffocation effect: Taking the Boeing incident as an example, the AG10 battery of the Boeing 787 aircraft are placed in a more solid steel box, which plays a role in isolating external oxygen and limiting the spread of fire.

Wang Jian finally concluded that once thermal runaway of lithium-ion AG10 battery occurs, it is difficult to terminate its reaction. Phased warnings can be carried out at the beginning of thermal runaway, and different protective measures can be taken to suppress the spread of thermal runaway, such as strengthening the battery cooling system, covering the insulation layer, and isolating the air suffocation effect. At the same time, by modifying combustible components such as diaphragms, electrolytes, and electrode materials, the chain reaction in the thermal runaway process can also be suppressed, and the safety level of lithium-ion AG10 battery can be improved.

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