On April 16, 2021, an explosion and fire broke out at an energy storage power station in Fengtai District, Beijing, killing two firefighters, injuring one firefighter and missing one employee of the power station. The cause of the accident is still under investigation.
Many people will wonder why there was an explosion and fire at the energy storage power station. It is well known that lithium batteries will self-ignite. Why do fatal explosions occur?
In this regard, industry experts said that there is indeed the possibility of explosion in the energy storage power station.
There are lots of energy storage batteries in energy storage power station. at present, energy storage batteries are mostly lithium-ion batteries, which have more advantages in performance-to-price ratio and energy density than other batteries. However, lithium-ion batteries are prone to internal short circuit, which can lead to spontaneous combustion. A battery is composed of positive and negative electrodes, the battery is insulated between the positive and negative electrodes through the diaphragm, and the electrolyte plays the role of lithium ion conduction. If the diaphragm is damaged, the positive and negative poles will be short-circuited, and the heat will continue to release heat, and the heat accumulation will aggravate the decomposition of all the internal structures of the battery, giving off more heat, which will eventually lead to spontaneous combustion, which will spread to the surrounding battery. The electrolyte itself is a flammable solvent, which is very easy to burn, which is the reason why the lithium battery will develop rapidly after a fire. At the same time, the battery decomposes to produce combustible gas and oxygen, which will also aggravate the combustion.
The reasons for the short circuit in the battery are as follows: 1. With the aging of the battery, the negative electrode of the battery forms dendritic crystals and grows continuously, puncturing the diaphragm. two。 There are production quality problems in the diaphragm. There are defects immediately after leaving the factory. Dust or burr of positive and negative poles in the production process will cause internal short circuit. 3. The high temperature of the battery during use will lead to the decomposition and melting of the diaphragm. 4. Other external factors, such as transport vibration, collision, puncture, etc.
The explosion of the energy storage station should be the combustible gas produced after the battery spontaneous combustion, but the gas accumulated in the energy storage container can not be released, after the concentration reaches the explosion limit, the whole container explodes, which is powerful enough to cause casualties.
To put it simply, the lithium battery is an electrical product, which will catch fire when there is a short circuit, and there are a lot of combustibles in the lithium battery. The fire is very violent and produces combustible gas. The energy storage container is a sealed box in which a large number of lithium batteries are stored, and when the combustible gas produced by the battery's spontaneous combustion is filled, the whole box may explode, just as an empty oil tank has a Mars explosion.
At present, there are also relevant standards for energy storage fire safety in the industry, "GB/T50148-2014 Chemical Energy Storage Power Station Design Code", the main content is the electrical safety of energy storage power station, fire configuration and so on. However, the fire safety monitoring is still based on the traditional fire smoke alarm and temperature alarm, which belongs to the post-accident alarm. On the other hand, the short circuit in the battery can give early warning and stop loss in time through the abnormal changes in battery voltage and temperature, and it can also be used to solve the early micro-faults that lead to the internal short circuit in advance, so as to prevent from "burning". It is suggested that the energy storage power station should do a good job in the on-line monitoring and detection of battery data to prevent accidents and reduce the occurrence of similar tragedies in Fengtai energy storage station.
