Because the collision site is overhead, the next 72 hours are still a critical period. This incident not only ignited a Tesla, but also rekindled public doubts about the safety of electric vehicles, so I want to spend some time talking about this case and its safety factor.
First of all, according to the police, drunk driving has been ruled out and the main accident is still under investigation. The results are based on the investigation report. But we can guess the possibility here first: Jimmy Lin himself is driving the vehicle, and the operation error causes the car to hit the column; At this time, the car enabled the assisted driving Autopilot, but the system failed on the fork road, which caused the safety accidents at this stage to be speculation. We have to wait until the driver recovers, or Tesla released the uploaded data at that time, and everyone does not distinguish.
Second, the causes of fire in new energy vehicles can be divided into internal and external causes: when the outside world is hit by the outside world, the battery structure is damaged, and the internal heat of the lithium battery core is out of control, which will lead to fire. In fact, some cars have not been hit, and the battery is out of control. At this time, the reason comes from the inside of the battery. For example, the internal short-circuit fault is caused by defects (such as tiny metal slag) in the lithium battery core introduced in the battery manufacturing process; Or the battery ages after long-term use, forming twin lithium in the battery core, causing short circuit failure in the battery.
This kind of internal short-circuit fault has a certain probability of causing fire under high power consumption. Especially when the battery is charged and fully charged, the battery is more active. In this case, it is the incubation period of all fires. In this accident, the front end of Tesla ModelX collided and deformed. In fact, Tesla has considered the protection of vehicle frontal collision in its design-there are three ways to transmit force in the front engine compartment to ensure the effective transmission of collision force and the safety of the battery, namely, energy absorption box+side beam (the key safe passage for transmitting force), lower bearing beam+subframe and shotgun.
However, this time Tesla caught fire, which seems to be very impactful at this stage, resulting in the ineffectiveness of the above safeguards and the damage of the battery, which eventually led to a fire. This is caused by typical external reasons. At this stage, all over the world are trying to design the safety of batteries: focusing on blocking the uncontrollable chain reaction between lithium batteries after the heating of a single battery is out of control, so that the whole package is not easy to catch fire. Technical improvement is mainly in two directions: lithium battery level and system level.
At present, the technical means are: the difference of organic chemical management system, from the design difficulty coefficient or the activity degree of battery system, ternary 811>; Ternary 5 series >: lithium ferrous phosphate; The stability of the battery is just the opposite, and lithium polymer is the safest. At present, the key difficulty is still the battery cell level test of high nickel lithium battery.
Thermal insulation materials in the middle of lithium batteries: At present, thermal insulation materials (such as nanofibers) will be added between lithium batteries to prevent thermal runaway between lithium batteries. Thermal insulation materials can be used in the middle of some battery differences. Continuous high-temperature thermal insulation composite material is used between the total number of lithium batteries, and then combined with the design scheme of protective cover, continuous high-temperature steam flow is discharged.
Pressure relief and exhaust: according to the design scheme, change the design scheme of various types of commodity flow channels, control the fluidity of heat sources according to the predetermined motion trajectory, and reduce the thermal impact on adjacent battery blockchains; Moreover, by controlling the steam flow discharged from lithium batteries due to thermal runaway to be evenly distributed in the safety channels with different structures, a vertical safety channel (the bottom of which is replaced by a commodity flow channel) is designed to prevent large-scale thermal shock of adjacent lithium batteries from causing secondary thermal runaway.
Insulation layer design: insulation protection for high-voltage components in battery pack; Design scheme of continuous high-temperature insulation protection for high-voltage connection and high-voltage safety area in battery pack.
Third, how to treat the fire accident of new energy vehicles? Fortunately, passers-by helped in this accident. If you are in a new energy vehicle and suddenly encounter a fire, how can you protect yourself if you can't open the door? Does the new energy vehicle catch fire mean that all the actual operations in the vehicle will be invalid? At present, the latest safety requirements for power batteries for electric vehicles in China clearly stipulate that when the battery is out of control, the battery should not catch fire and explode, and should be vacated for 5 minutes for passengers to escape.
If the thermal diffusion coefficient does not appear in the system software when the battery cell fails, the smoke damage after thermal runaway can be greatly reduced; In buildings, it is easier to control the range of smoke exhaust system only when some lithium batteries produce gas out of control. In that case, people will have more confidence in enjoying new energy vehicles on a large scale in the next stage, and their cognitive ability on the safety factor of new energy vehicles will be more sufficient, so as to maintain life safety to the maximum extent.
Scorpio figure 6. Difficulties caused by thermal runaway of power lithium battery in confined space. I think this data will increase to more than 30 minutes. When this kind of alarm occurs in new energy electric vehicles, the emergency fire department must be notified at the first time. If the driver can really park in the emergency lane, open the door and let the passengers off. Don't panic. If there is a thermal runaway alarm, it must be handled and stopped as soon as possible.
China leads the world in technology. First, we have learned a lot from the experiment of thermal runaway expansion of batteries: the batteries of new energy vehicles are easy to catch fire after being impacted, and the causes of fire also include: the batteries suffer from other hazards, such as aging after long-term use, and the batteries are soaked in water. In addition, the high temperature environment is not friendly to the battery. Compared with gasoline vehicles, the development trend of electric vehicles is very mature, and there are indeed some places that can be improved; Technology has really developed a lot in recent years. That's all. What else would you think?