However, according to the information in the declaration catalogue of the Ministry of Industry and Information Technology, the system quality of the new generation of blade batteries (pay attention to this word, it is very important) is only 140Wh/kg, which is not only not brilliant enough, but even a little behind many products 160 or even 180Wh/kg ... So where is its bright spot?
First of all, let's look at the difference between blade batteries and other mainstream batteries at present.
This is a square aluminum shell battery. At present, more than 95% of BYD's products and many other mainstream brands are in use.
This is a flexible battery cell, which is different from the square battery cell in that the shell is packed with aluminum-plastic film, which is smaller and thinner.
Next, we look very familiar with the cylindrical battery used by Tesla. The specification is as shown in figure 18650, and the larger specification is 2 170. Due to the small size and capacity of single batteries, there are thousands of such batteries on each Tesla.
Finally, there is BYD's blade battery. As there is no physical drawing at present, I will make do with a patent drawing to give a rough idea. ...
As can be seen from the size data, the height and thickness of the blade battery are fixed, with the height of 1 18mm and the thickness of13.5mm. Mainly in the length part, the blade battery has various specifications ranging from 435mm to 2500 mm.
The maximum length can reach 2.5 meters, which has never appeared in previous battery forms.
Because the length is enough, some articles can be done inside the battery. BYD can connect the pole cores of a plurality of blade batteries with different specifications in series or in parallel, and there are partitions between the pole core groups to divide the space of the batteries into a plurality of accommodating cavities, forming a honeycomb-like structure with sealing and liquid injection channels.
Blade battery can simplify the layer-by-layer integration structure of mainstream batteries at present, without the fixed group mode of "Cell-module-battery pack", and can directly form a battery pack through cells, that is, cell? Where to? Packaging (CTP)
The picture above shows BYD Qin Pro? EV's power battery pack structure is composed of grouped square battery modules, which are connected by wire harness and liquid cooling pipeline, and many structural members and brackets are added. The volume integration efficiency of battery to module is about 78%.
In contrast, the grouping of blade batteries is much simpler, which reduces the structural parts at the module level, greatly simplifies the assembly support structure on the battery pack, obviously simplifies the structure of the whole battery pack, and the volume integration efficiency from the battery cell to the module can reach 90%, thus improving the volume energy density.
Because the chassis space of passenger cars is limited, it can't accommodate large battery packs. The lower the chassis, the more prominent this requirement is. Therefore, if we want to discuss the improvement of integration efficiency, volume utilization efficiency is the most direct and effective index, rather than just clinging to the common mass energy density Wh/kg.
In order to ensure that the traditional module has good mechanical properties as an independent unit, it needs protective structures such as side plates and end plates, because multilevel integration also needs electrical components such as low-voltage wiring harness and high-voltage connection.
These structures can be greatly simplified after using the blade unit technology. The design of larger batteries/approximate modules significantly reduces the complexity and cost of battery assembly and production, making them more compact in mass and volume and higher in utilization. A more integrated design concept can also improve the integration of water cooling, heating and other components.
Although the blade battery made of lithium ferrous phosphate material can not reach the high level of ternary battery in quality and energy density, it can load more batteries in a certain volume, and its actual battery life is not much worse than the mainstream products of ternary battery. The comprehensive cruising range of BYD Han EV and mentioned above is as high as 605km, which is almost the highest level of domestic independent brands.
Some people say that if more batteries are inserted, won't the kerb quality of the car go up? Don't forget BYD's unique e-platform technology. Through the integration of high-voltage system and low-voltage system, BYD has great advantages in light weight, which is reflected in BYD Korea EV, a pure electric vehicle nearly 5 meters long, with a curb weight of only 2020kg, which is not so exaggerated.
In addition, don't forget the advantages of lithium iron phosphate battery in cost. The reduced cost can directly make consumers get the greatest benefits in the terminal price of vehicles.
As for why BYD doesn't simply use ternary blade batteries, I think Lao Wang may have more feelings for lithium ferrous phosphate than some technical reasons.
This article comes from car home, the author of the car manufacturer, and does not represent car home's position.