In recent days, the Tesla accident has caused incidents such as fires in vehicles, and once again pushed new energy vehicle batteries to the cusp.
As an alternative engine to become the "heart" of the car's power battery, its performance is closely related to the performance of the car, with the continuous upgrading of battery technology, the car's cruising range is gradually increasing, charging time begins to shorten, but the battery safety uncertainty that comes with it It has also become a hidden danger that hinders the development of electric vehicles.
Lithium batteries and lithium ion batteries are the most mainstream batteries in the market. They are widely used in electronic products and automobiles, and their applicability and reliability stand the test of time. However, due to the influence of some designs and even its own characteristics, battery spontaneous combustion events such as Samsung mobile phone doors have occurred in history. Therefore, battery safety issues deserve our attention.
For the car, the reason for the self-ignition of the power battery is mainly thermal runaway, and the most common cause of thermal runaway is intense collision and short circuit.
First let's talk about the first point, the burning caused by the collision. Just as the charging treasure will spontaneously ignite, the power battery will also spontaneously ignite. For lithium-ion batteries, the severe deformation caused by the intense collision will cause a short circuit inside the lithium-ion battery. The energy of the battery will release a breath from the short-circuit point, causing local heating, which will cause the positive and negative electrodes and electrolyte to decompose. , the formation of thermal runaway.
It can be said that spontaneous combustion caused by collision is the best prevention and the most difficult to prevent. At present, electric vehicles and power battery packs are arranged at the bottom of the vehicle or at the bottom of the trunk. These positions avoid the intense collision as much as possible. At the same time, the design of the battery box can protect the battery pack to a certain extent, which is easy to prevent. At the office.
Just like a traditional fuel car will also lead to a fuel tank after a violent collision or rollover. When the speed is too fast, the power battery pack of the electric vehicle will still suffer severe impact. At present, C-NCAP has made specification requirements for electric vehicle crash test. The test standard is 64km/h frontal collision, which means that even a five-star safe electric vehicle will collide above this speed, and the power battery may still have spontaneous combustion. .
The spontaneous combustion caused by the short circuit of the system is related to the aging and life of the power battery. In order to isolate the battery pack from the outside, the air battery assembly is usually very tight, and generally needs to pass the IP67 standard. However, as the use time increases, the airtightness is bound to decrease, and the infiltration of rainwater or the like may cause a short circuit of the battery to cause spontaneous combustion.
On the other hand, the aging of the battery itself will also bring about a certain crisis. Affected by the service life, the aging of a single battery unit itself will affect its performance, and at the same time, the overall consistency of the battery will become more and more different, which has a certain impact on battery safety. In addition, due to manufacturing process limitations, the impedance caused by aging of the laser spot of the battery pack also causes local high temperatures, causing spontaneous combustion. It can be seen that the power battery also needs frequent maintenance and maintenance, and the battery condition is regularly checked.
It can be seen that there are many safety hazards in the power battery pack, and friends who use electric vehicles also need to pay some attention to daily maintenance.
So how can we improve these defects? Some experts pointed out that in terms of performance and safety, lithium-ion batteries may have reached the upper limit, and solid-state batteries may be the new power source for future electric vehicles.
It is understood that solid-state batteries do not contain flammable electrolytes, so they are safer than lithium-ion batteries. At the same time it is also better in power storage. However, due to the impact of cost and longevity, large-scale popularization may take time.
During this period, the all-resin battery researched in Japan may have a certain market. It is wrapped with a gel-like resin containing an electrolyte to enclose an electrode material such as lithium. It does not ignite in the face of drilling and cutting, and the cost is slightly lower than that of a conventional lithium ion battery.