_ What is a blade battery?
First, correct a misunderstanding. Some people think that blade battery is a new type of battery, which is different from ternary lithium battery and lithium iron phosphate battery. In fact, the "blade" is just the shape of a single battery, and its essence is lithium iron phosphate battery. Blade battery flattens a single battery cell, and the thickness becomes thinner after the width is lengthened, and the dimensions of length, width and height are reduced to 960mm * 90mm *13.5mm..
From top to bottom, thermal insulation cotton, thermal management module and thermal insulation materials are distributed inside the battery pack. The battery case is outside. Water-cooled heat dissipation plate and strength mechanism for supporting battery are also entrained inside.
Traditionally, cylindrical single cells will form more gaps after stacking, and then the space utilization rate can only reach more than 40% except for supporting heat dissipation and supporting components. Flat-bladed battery can reduce the invalid gap between single cells, and the increase of area also plays a very important role in heat dissipation. After the overall arrangement, the space utilization rate of the blade battery is as high as 60%.
_ Acupuncture test
BYD selected two most popular batteries for pure electric vehicles as test objects, namely ternary lithium battery and lithium iron phosphate battery.
Of the three, ternary lithium battery is the worst. After the steel needle was pierced, the eggs on the battery were blown up, and the battery itself burned violently, and the surface temperature exceeded 500℃.
Ordinary lithium iron phosphate bulk battery performed slightly better. Although the temperature also rose to 200 ~ 400°C and the eggs were burnt, there was no open flame, only a little smoke.
Blade battery performed best in this experiment. The shape of eggs observed by naked eyes has not changed much. The battery has no open flame explosion and smoking, and the surface temperature is controlled between 30 ~ 60℃.
_ Advantages of blade batteries
1, the energy density per unit volume of the battery is improved, which is more than 1/3 than that of the traditional battery.
2. The cost of materials is reduced by about 1/4, including materials and human resources.
3. The battery is small, which can bring better space performance to the vehicle.
4. The battery is light in weight, so the energy consumed to overcome its own resistance is reduced, and the battery life is further increased.
5. Better safety performance. Under the conditions of high temperature, overcharge, extrusion and acupuncture. The probability of battery fire and explosion is reduced.
_ Disadvantages of blade batteries
1, poor charge-discharge performance at low temperature. This is an "occupational disease" in lithium ferrous phosphate, and the battery capacity will be greatly reduced under cold conditions in winter. The lower limit of low temperature in lithium iron phosphate is -20℃, while that of ternary lithium battery can reach -30℃ ... The low temperature attenuation of lithium ternary is about 10%, and that of lithium iron phosphate reaches 20%.
2. It is difficult to repair the battery after being collided. Because the blade battery saves the structure of supporting the battery cells, each battery cell itself is a bracket. It is difficult to ensure the integrity of the battery under the impact of external force. If one battery is damaged, other batteries in series will also be affected.
_ Blade battery questioned the storm
At that time, the "Korean" model of blade battery had not yet been listed, and everything remained at the point of slogan, which had caused BYD's market value to skyrocket by nearly 14%. There is a particularly prominent article that comprehensively attacks BYD's "liar" behavior, and those who are interested can search for it themselves. These comments are summarized as follows:
1, BYD's battery technology innovation did not involve battery electrodes or other important components.
2. The density of the blade battery is increased, which actually increases the battery volume and puts in more battery packs.
3. The decline characteristic of lithium ferrous phosphate has not been solved, and the annual decline is 100km.
4. BYD's patent on blade technology is very difficult, because it takes a long time to apply for a patent, while BYD only took one year.
......
The article criticized and questioned BYD at length. I dare not say whether there is any point, but at least there are many prejudices in my speech. To this end, BYD also specifically clarified this issue.
Blade battery is BYD's declaration to return to the battlefield. After 20 17, BYD was surpassed by Contemporary Ampere Technology Co., Ltd. and lost the first position of domestic batteries. BYD has always insisted on lithium iron phosphate battery, squeezed by ternary lithium battery with high energy density and low price. The "blade battery" we are hearing now is actually the "super battery" plan proposed by BYD in 20 19. Contemporary Amperex Technology Co., Ltd. has opened an era, but can BYD end it? In a war without smoke, the outcome is quietly carried out under the undercurrent, and the sieve of the market will hand over the final answer.