After studying the amber/mica battery released by Lantu, the main points are summarized as follows:
"Amber/mica battery" is a battery pack safety technology called "3D heat shield", not battery cell technology.
The Lantu conference expressed a meaning: Lantu does not produce batteries, but comprehensively develops its own battery system safety technology, and uses technology to better fulfill the brand's understanding of the safety of car owners.
Before understanding Lantu's "amber/mica battery" technology, let's briefly introduce the safety technology of new energy batteries.
<h1 class="pgc-h-arrow-right" > safety technology for lithium batteries</h1>
When it comes to lithium battery safety, we often hear the term "thermal runaway": mechanical abuse, electrical abuse, and thermal abuse can all lead to thermal runaway.
Mechanical abuse, electrical abuse, thermal abuse and thermal runaway
When I first heard this statement, I was a little upset: Isn't it possible that after a battery collision, short circuit, and overheating, it may catch fire? Why use the strange term "heat out of control" and hanging book bags?
It was later learned that thermal runaway is not a fire of "flammables + fire source" in the general sense, but has the characteristics of "chain reaction" [2].
The first meaning of the chain reaction is that the side reaction of the battery is usually exothermic, if the heat dissipation conditions are not good, the side reaction of the exothermic heat may cause a higher temperature side reaction, and even up to 450 degrees to cause the electrolyte to burn. That is, the temperature of the side reaction 1 exothermic → reaches T2→ the exothermic temperature of side reaction 2 reaches T3→ the temperature reaches T3→ the side reaction 3 exothermic → thermal runaway. The following figure is an expression of an image:
Battery side reaction and reaction temperature
The second meaning of the chain reaction is that the thermal runaway of the single battery will be a large amount of heat dissipation, if the thermal insulation / heat dissipation conditions between the single battery is not good, the heat may cause the thermal runaway of the adjacent battery, and then cause the entire module (module) or even the entire battery pack (Pack) thermal runaway. In the 2019 Shanghai Tesla spontaneous combustion accident, a total of 4 modules were burned, and if fire protection measures were not taken, a large amount of water was sprayed to cool it down, and the most likely result was that other modules were also burned.
The thermal runaway of the cell battery triggers the thermal runaway of the adjacent monomer
Compared with the fire accident of "flammables + fire source", the "chain reaction" characteristics of lithium battery thermal runaway are actually relatively mild, which provides us with the idea of lithium battery safety management, which is basically:
Battery pack protection: As far as possible to protect the battery from infringement, especially the squeeze and puncture caused by collision.
Algorithmic diagnosis: early stage of exothermic side reactions of batteries, early detection, early strangulation.
Prevent thermal diffusion: After the thermal runaway of the monomer battery, "in-place isolation" measures are taken to prevent spread to other batteries.
Reduce losses: If the overall thermal runaway of the battery pack is difficult to prevent, the first step is to ensure the safety of the occupants, followed by the reduction of the scale of the accident.
National mandatory standard <GB38031-2020 Safety requirements for power batteries for electric vehicles> Detailed requirements for the protection battery pack at level 1, requiring the battery pack not to explode and not fire in the overcharge, over-discharge, external short circuit, heating, temperature cycle and extrusion test.
As for the 2nd, 3rd and 4th levels, the national standard requirements are not so detailed, such as broadly requiring effects: 5 minutes in advance when "heat diffusion" occurs to give the occupants sufficient escape time; and the national recommended standards <GB/T 31498-2021 electric vehicle post-collision safety requirements> there are also some relevant regulations.
Observing whether the standard language in these countries is unclear or shallow, we can see the degree of importance that a car company attaches to safety and the level of technical accumulation.
<h1 class="pgc-h-arrow-right" > Amber and mica: three-dimensional insulated walls that prevent the spread of heat</h1>
Most of the thermal runaway accidents we see in electric vehicles are fierce; even if the fire brigade comes, it will not help, and in many cases we can only wait quietly for it to burn out. In this way, the battery thermal runaway is too fierce, and it is impossible to stop it!
As the saying goes, the of a thousand miles is destroyed by the ant nest - unless the nest can be found and filled in in advance; the spark of the stars can be burned - unless the fire is extinguished at the moment of the rising.
In fact, the characteristics of the battery thermal runaway "chain reaction" hint at the fire of a single cell, exaggerated that I can subdue it with a piece of cloth; if the single cell can be "isolated in place" to prevent the leakage of heat from thermal runaway to thermal diffusion, the entire battery pack will not be a big problem.
Lantu's "three-dimensional thermal insulation wall" is to make full use of the "chain reaction" feature of thermal runaway, and strive to "isolate" the thermal runaway of the single cell in place, thereby protecting the safety of the entire battery pack:
Lantu's "3D firewall" technology
"Amber" and "mica" are the technical means for Lantu to achieve "three-dimensional thermal insulation wall":
1. Amber battery
In lantu FREE's pure electric version of the battery pack, the composite material of silicone polymer + low-density thermal insulation material + flame retardant agent is filled to form an efficient thermal and flame retardant insulation layer, so that each cell unit is fully wrapped like "amber".
The specific effect is that the heat of a single cell is out of control and accidentally "fever", but under the measure of "in-situ isolation", it will not spread to the surrounding cells.
Lantu's three-dimensional insulation wall technology
This kind of thinking is not difficult to think, the difficulty is the realization of the project. Dr. Huang Min, Director of New Energy Technology of Lantu Automobile, introduced on the spot: "In order to make the gap between each battery cell of the three-dimensional insulation layer evenly filled and overcome process problems such as bubbles, we use a unique module opening scheme to try dozens of composite materials."
Personally, I think that the technical difficulties of amber batteries do not stop there. For example, in battery thermal management technology, one of the main ideas to ensure temperature consistency is to enhance thermal conductivity[4], and some people even propose to simply put on thermal grease!
Lantu added amber from the "thermal insulation material", which means that more research and development work must be done on battery thermal management in order to take into account safety and life. Pulling the whole body together, positive independent research and development is never easy. I am also very interested in how Lantu takes into account these two points, I have not yet seen the dismantled Lantu battery pack, and I will have the opportunity to see it in the future and then study it in depth.
2. Mica battery
Layered Al-Si mica and aerogel are added to the battery pack of Lantu FREE's extended range, and the battery cells, mica and aerogel will be stacked like mica stone, so it is named "mica battery".
Mica is characterized by its high temperature resistance, which can prevent the further spread of thermal runaway, especially to prevent the accelerating effect of open flames on thermal diffusion. Tesla has adopted a similar scheme in
@Engineering Man Lao Wang's car dismantling video is introduced:
<h1 class="pgc-h-arrow-right" > amber and mica: protection, diagnosis, and future layout</h1>
The amber and mica battery technologies described above belong to the "prevention of thermal diffusion" technology at level 2.
In fact, at this conference, the protection technology of level 1 and the diagnostic technology of level 2 were also announced.
1. Battery pack protection
In the event of a collision, to protect the battery cell from deformation, it is necessary to follow the "strong-weak-strong" sandwich structure:
First of all, the body and battery frame should be "strong", protecting both the battery pack and the occupants. Lantu FREE car height strong steel accounted for up to 75%, of which 1500MPa or more than 31%; especially in the side structure, B-pillar, threshold, door anti-collision beam are used on 1500MPa on the ultra-high strength steel or hot stamped steel.
Secondly, the peripheral structure of the battery pack should be "weak" to collapse and absorb energy. If the collision is more serious and affects the battery pack, then try to deform the peripheral structure and absorb energy collision energy, thereby protecting the safety of the battery inside the battery. Lantu designed a deformation energy absorption space of 30mm+, which is actually similar to the principle of body design.
Then the internal structure of the battery pack must be "strong" - if the external structure collapse has not fully absorbed the collision energy, it is no way, can only be "naked" hard to carry! LanTu designed a number of horizontal and vertical reinforcement beams inside the battery pack to form a three-dimensional structure of horizontal and vertical interweaving - as long as the bones are hard enough, the internal organs can also be well protected.
The most stringent crash test for battery packs is the European E-NCAP's 75-degree angle side column bump test. In addition to the layers of protection that are reasonably designed, the Landu FREE beam only collapses to a small extent, while the battery module and battery cell are not affected by extrusion, thus protecting the battery safety.
In addition, although Lantu does not produce batteries, it has developed unique explosion-proof valves and fusing devices for the batteries as the "last layer of protection". Once there is an extreme impact intrusion, the battery cell causes a short circuit or the pressure in the cell increases, and the battery double insurance can immediately start the protective effect, cut off the short circuit circuit in the battery, release additional pressure, and ensure that the battery does not catch fire and does not explode.
At the press conference, Lantu performed a squeeze test, a simulated crash test and a high-temperature water test on the battery pack[6], and the battery pack was safe and sound.
Top left: High temperature water test Bottom left: Squeeze test Right: Simulated crash test
Some people ask, why not do a needle prick test? The test criteria that explicitly require puncture tests are inherently few [7]. Even in these few puncture trials, the effectiveness of the trials has been widely questioned:
It does not correspond to the actual situation: the phenomenon of puncture testing is very different from the phenomenon of real accidents. (There are few accidents that can now puncture the battery cell)
Cannot represent an internal short circuit: the consequences of a puncture cannot represent the consequences of an internal short circuit.
The test parameters are not clear: the material, speed, diameter and battery SOC of the puncture will greatly affect the test results. The test was less reproducible
2. Stronger monitoring and diagnostic system
The traditional diagnostic algorithm is placed inside the on-board BMS, and can only be diagnosed based on the information of the bicycle. The future cloud BMS can make full use of big data information and super computing power to diagnose hidden dangers earlier and more accurately, and kill accidents in the cradle.
I understand that when it comes to big data and cloud computing power, it makes people feel a bit virtual. However, specific to the field of BMS battery safety, this technical solution is really useful.
In fact, a long time ago, our country built a new energy vehicle big data monitoring system, stored a large amount of data, but if you want to query and analyze the status of a car, you need special personnel to query and reprogram analysis, overall is not very good to use...
I have also seen the prototype of a more advanced car company's cloud big data system, want to query the data or analyze the problem can basically do real-time response, but also from the massive data to find the bicycle is easy to be ignored data, this system also helped the car company to eliminate some of the accidents that would have occurred.
Because of this, I feel that cloud BMS is the right technology path. The press conference also announced the lantu exclusive cloud BMS, claiming to have a deep self-learning function; with the increase of vehicle access and use time, fault prediction and life prediction models, but also can continuously optimize the model parameters to improve the prediction accuracy, the more "smart" the use.
Whether the effect is good or not, it is useless to just say that it is useless, we still have to observe the follow-up effect. However, at least Lantu's thinking is correct; i am still surprised that a "new force" born out of a traditional car company is not lagging behind in the technical path.
3. Future layout
At the end of the press conference, Lantu released the future main direction of battery technology: high-nickel soft pack battery, solid-state battery and high-power fast charging technology.
Among them, the high-nickel soft pack battery plans to achieve completely no thermal runaway, but also to achieve the industry's best energy density and power density, and the introduction of 330Wh/kg battery technology. How to combine high energy density with high safety? This is still very surprising! In addition, solid-state battery technology has also entered the commercial development agenda.
Fast charging technology also lists specific technical indicators: 60% of the power in 20 minutes; based on the next generation of 800V and SiC technology, to achieve the goal of 10 minutes and 400km. Insiders revealed that Lantu supercharging technology will also be officially unveiled at the end of September; investment in infrastructure reflects Lantu's determination in the electrification of vehicles.
< h1 class="pgc-h-arrow-right" > summary</h1>
Through the Zhihu Automobile Dismantling Laboratory, it was learned [8]: Another mainstream extended-range electric vehicle model on the market adopted the whole package supply of the Ningde era, and the supplier packaged the design and manufacturing, and the main engine factory only needed to purchase it.
Dismantling Laboratory | Ideal ONE battery pack design analysis Acupuncture experiment meets the national mandatory standards
It is said that the advantages of this model are: save time, effort, and spend money; the disadvantage is that the design discourse power is not in their own hands, especially in the Ningde era, where the supplier is still very strong.
You might say that the supplier is a big factory, and the level is also very high; as for the design discourse, is it important? In my opinion, the design discourse determines whether the product can reflect the brand tone - a luxury SUV of more than 300,000 should be added to the security design, but the supplier does not necessarily respond to your needs. As mentioned in the video [8], the following car has no fire insulation design, nor explosion-proof valve design, anyway, it does not affect the passage of the national standard.
From the very beginning, Landu FREE has launched an extended range version and a pure electric version, indicating that it has made a good future-oriented battery technology reserve, which can also feed back the current extended range battery technology program. Both the range and pure electricity, the research and development difficulty is more stringent, the research and development investment is greater; from a technical point of view, Lantu is more trustworthy as a "national team"