The ignition of the electric lithium battery system is a very extreme event. The previous article discussed several reasons. It is actually difficult to pass an independent event (by simply bypassing all safety mechanisms), but through case and various research materials. , research reports, etc. to define the thermal release of battery fire.
Here is an example of a simple battery system that removes the coolant and leaves only the battery system itself.
The battery system burns up, as shown above, let's see what are combustibles?
Battery module: flammable
Boiler volatilized flammable gas battery broken / damaged electrolyte leak
High-voltage power harness: flammable
High-voltage sampling harness: flammable
BDU: flammable
Low voltage signal harness: flammable
Others such as brackets, battery restraints, bottom covers and upper covers use non-combustible materials. These are the key to converting electrical energy into heat (in other words, the primary ignition point).
Lithium battery cells electrochemical energy storage units and chemicals have in fact a detailed risk of fire, which is assessed by various abuse tests. "Try to avoid extreme things, take a look at several reasons for the fire in lithium battery systems":
The first part of the battery related
Battery pack or battery cell overcharge: Overcharge is generally a common cause of heat release. Battery pack level thermal runaway events can be subdivided into multiple batteries (module, single overcharge), battery over The charge and electrolyte evaporate, causing a thermal event. In the overcharge and SOC state caused by the SOC calculation error, the overcharge due to the charge control program jam caused by the energy recovery that is not performed according to the protection.
Mechanism analysis for thermal runaway:
The second part of the line related = "battery =" line itself + battery temperature rise
Short-circuit over-current heat release: battery pack / high-voltage circuit failure leads to short-circuit = "heat"; here mainly due to internal short-circuit and external short-circuit of the battery pack, causing overheating of the conductor & connector, and overheating of the monomer to cause subsequent thermal events. Further subdivision can also be broken down into overheating of the components caused by the short circuit of the module. The short circuit at the module level, the short circuit in the battery pack, and the short circuit caused by the ingress of corrosive/conductive liquid in the battery are combined into this point. The combination of mechanical and electrical and materials causes the fire to be diversified.
Compare this:
The collision of the battery caused a lot of changes, and the mechanical structure and electrical structure changes caused a short circuit, causing further changes in the battery.
In reality, in a complete system, we mainly consider various countermeasures, and separate each content from multiple angles. Here, we decompose the countermeasures for each content.
However, the overall direction is that it tends to do more of the battery cells, and the system is gradually simplified. The temperature detection point of BMS itself is limited due to what BMS can do, and the means are directly done in the monomer.
1) BMS detection and means closed loop:
To put it bluntly, it is to turn off the relay. What we are worth learning now is the early warning. If it doesn't work, it will make people have more reaction time. The means that BMS can use is really rare.
2) Therefore, the subsequent innovations and innovations are all done at the level of single security and built-in means. The BMS keeps a little bit simplified and the confidence of the whole system is higher.
This part of the red is more clear with the structure of Samsung.
In addition to detecting the cut-off, the overcharge part does something at the monomer level, and there are more means.
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