On December 23, the WEIMA EX5 next to a street in Haikou City, Hainan Province, spontaneously combusted again, directly burning the vehicles next to it.
This is also the third spontaneous combustion accident in WM within 4 days after spontaneous combustion in Zhengzhou on December 20 and spontaneous combustion in Sanya, Hainan on December 22. In October 2020, WM also had "3 consecutive burns", and the accident of that year even directly delayed the listing of WM for an indefinite period of time, but I did not expect that after more than a year, the old thing would happen again.
Regarding the spontaneous combustion of WM, most of them point to its power battery suppliers. Although the annual sales volume is only more than 40,000 vehicles, there are four battery suppliers in WM, namely ZTE High Energy, Ruipu Energy, Tafil and Ningde Times. On the one hand, this is to ensure the safety of supply, on the other hand, it is also to achieve better cost control. But judging from the results of the output, it seems that it is not satisfactory.
In the end, how to solve the safety problem of the power battery? In fact, friends and businessmen have still done a lot of work, which can be used as a reference for Weima.
(1) GAC Aean magazine battery, the construction of super thermal insulation "safety compartment"
Like WM, GAC Aeon is also a large household that uses ternary lithium batteries, after all, this battery has high energy density and excellent low temperature performance. But instead of handing over the safety concerns to suppliers, Aehanco redesigned the cell modules and named the new battery "magazine battery."
The design of the magazine battery is divided into four parts, the first is the design of the battery cell, which uses a new cathode material formula, electrolyte and diaphragm material, so that the heat resistance of the cell itself is improved by 30%; then the cell module is built into a super heat insulated safety compartment, through the high temperature resistant upper shell and the mesh nanopore thermal insulation material to make a "magazine" shape, the thermal runaway is firmly limited to a single "magazine".
Then there is the fast cooling system that can achieve active cooling, its liquid cooling system is 40% higher than the cooling efficiency of ordinary power batteries, once the heat is out of control, it can quickly achieve cooling; then the last step, the fifth generation battery management system with full-time control, which can carry out 10 times of uninterrupted data collection per second, maintain a "patrol" state at any time, and quickly start the liquid cooling system once an abnormality is found.
Strictly speaking, Aeon did not change the nature of the battery itself, it only through this extreme design, so that the risk of battery loss of control is minimized.
Looking directly at the results, Aehan's magazine battery pack can directly "participate" in the needle prick test, and after encountering a steel needle puncture, the battery pack only appeared briefly smoked, and did not catch fire and explode. And after 48 hours of standing, the internal voltage of the battery is directly reduced to 0V, and the temperature is maintained at the normal room temperature level, which is a historic breakthrough for the safety of ternary lithium batteries.
In short, the magazine battery will be the battery cell module firmly limited to each "magazine", no matter the collision, needle prick, local heating or good, it will only affect a single "magazine", and will not spread to the entire battery pack, and will not burn the entire vehicle like Weima.
(2) Universal Ultium battery, wBMS system can be monitored and upgraded
GM also has a lot of experience in electric vehicle manufacturing, and in 1996 it launched the industry's first mass-produced pure electric vehicle EV1. Even the domestic pan-Asian technology center completed the research and development of the "Phoenix" fuel cell concept car as early as 2001. GM's latest Ultium battery also incorporates GM's own safety design concept.
The first is the design of the battery cell formula, Ultium battery using a general optimization formula of ternary lithium battery cell, compared with the ordinary cell thermal stability increased by about 10%, and has the advantages of low attenuation, long life. Secondly, it adopts the "thermal insulation wall" patent and the integrated patented liquid cooling system between the batteries, and there are multiple protections such as large-area explosion-proof valves and tensile arcs.
The new tic-tac-toe shape high-strength frame structure makes its battery pack anti-extrusion ability reach 3 times that of the national standard, in addition to IP67 dustproof and waterproof capabilities and IP6K9K high-pressure water spray protection capabilities, so that its sealing has reached a new level.
Even more surprising is its wBMS wireless battery management system, a new technology that reduces the wiring harness inside the battery by 90%, reduces weight while greatly increasing the volume energy density of the battery, and reduces the failure rate failure rate. Through wireless communication, the performance of each cell and battery module is monitored, so that its accuracy reaches the battery cell level. Other battery packs, to the entire area fault system to be aware, the general Ultium battery single cell out of control can be identified, which makes its monitoring accuracy greatly improved.
Of course, since it is a wireless battery management system, its underlying architecture supports software updates, that is to say, the universal Ultium battery supports OTA upgrades, which is also the first time in the industry.
In general, the universal Ultium battery is the culmination of various protection skills, maximizing the safety of the battery.
(3) BYD blade battery, module-free design subverts industry cognition
As a leader in the field of new energy, BYD also attaches great importance to battery safety design, but it is not like Aeon and GM to chase and block, but simply changed the material of the battery cell.
BYD's power battery is actually a lithium iron phosphate battery, but through its own special design, it has achieved the same energy density as the ternary lithium battery, which is known as the "blade battery".
Although the energy density of the lithium iron phosphate battery itself is not as good as that of the ternary lithium battery, it is actually much stronger than the ternary lithium battery in terms of stability. This is also easy to understand, after all, the essence of stability is because the chemical properties are not active enough, which also affects its energy density.
Using this feature, BYD directly skipped the concept of "module" when creating blade batteries, that is, the battery is directly composed of batteries, rather than first forming groups and then forming battery packs through modules. In this way, although the energy density of the lithium iron phosphate battery itself is not dominant, it puts more cells in a smaller space, and the volume utilization rate is increased by a full 50%, achieving an energy density similar to that of the ternary lithium battery.
Of course, BYD through special design, so that the battery cell itself can withstand huge pressure without deformation. This new type of battery almost completely eliminates spontaneous combustion, after all, its essence is actually a lithium iron phosphate battery, which itself has little to do with the word spontaneous combustion.
BYD is also relatively refreshing, at the beginning of the launch of the blade battery to do the needle prick test, in fact, its performance is not only much stronger than the ternary lithium battery, compared to the traditional lithium iron phosphate battery is also more excellent.
The key is that the advantages of this new type of battery are not only safety, in fact, its life is extremely long, and even the concept of "million kilometer battery" was proposed for the first time. In fact, the cycle life of the blade battery can reach more than 3,000 times, which translates to the BYD Han EV, which means that it can support a driving range of at least 1.2 million kilometers, which is also quite leading in the industry.
(4) Kung Fu shooting
Aeon, GM and BYD are all leading manufacturers of battery technology in the industry. BYD needless to say, even before making batteries, GM also has more than 20 years of technical accumulation. As for Aeon, its technical accumulation should not be underestimated, and even the recent rise of AVIC lithium battery also has the shadow of Aeon behind it.
If WM wants to solve the problem of spontaneous combustion, it may wish to learn more from these few. After all, in the current state of WM, there is still no hope of listing in the record-breaking financing, and it may really have "burned".