Obviously, under the dual force of policy and cost competition, new energy technologies need to continuously evolve towards low cost, modularity and standardization. The drop in "technical costs" is definitely not a bad thing at this time, including the reduction of precious metal material costs, R&D and manufacturing costs, which will greatly reduce the planning pressure of the entire vehicle. On the one hand, it will reserve more space for quality improvement and maintain the price. Advantages to improve the overall cost performance.
In fact, the 21700-based integrated large modules used in the Tesla Model 3 have already shown the effect of this trend. Compared with the previous Model 3, the battery cost alone has been reduced by 35%, which helps the Model to a large extent. 3 Become a blockbuster in the global market.
As the exporter of domestic new energy technology, CATL and BYD have already released their own battery integration technology on this trend. The CTP (Cell To Pack) technology route of CATL is based on the high nickel ternary lithium architecture. Its core is to reduce the number of modules, directly form a standardized battery pack from multiple large-capacity cells, and then flexibly stack to form a larger battery module. Adapt to the energy storage needs of different car models. And BYD’s "blade" battery is based on the lithium iron phosphate technology that it is good at. The battery cell has also evolved to large capacity, but the shape of the cell is flatter and narrower (the long side can be customized and the maximum stable length of the cell can reach 2100mm), so it is named "blade" visually. Multiple "blades" are bundled to form a battery pack module, and a few large modules are combined to form a battery module. The two technical states of
can be said to have the same goal in terms of reducing module structure and improving packaging efficiency, greatly reducing monomer connection wiring harness and related process cost, and greatly improving group efficiency (energy density), but from an application perspective Look, there are still some differences.
is a large-mass single component arranged on the bottom of the vehicle, and the battery module must consider the adaptability of the structural strength to the complex vehicle environment. The ability to withstand side collisions is the most obvious requirement, and manufacturers often improve this ability through the structure and material use of the battery pack casing. However, for private cars that are used for a long time, non-load-bearing bodies are generally used, without beams, and the battery structure needs to be able to withstand long-term stress changes caused by repeated body deformation.
Through structural analysis, we can see that in the Ningde era, CTP technology takes into account the maximization of volume packaging efficiency, and the connection reliability between large modules is more susceptible to the impact of repeated diagonal shear stress. For high-voltage wiring harness and cooling The connection challenge of the system is relatively large, and the reliability of long-term use needs to be verified. The BYD "blade" battery actually still retains the overall configuration of the module package and the battery pack package. At the same time, it can be seen from the patent drawing that the battery pack package may reserve deformation space according to the needs of the model to avoid ultra-thin and large batteries. The core is directly stressed. From the perspective of structural durability, BYD blade battery packaging is easier to make reliable products.
However, such an insurance structure will also bring other problems. Judging from the currently published data, BYD uses volumetric power density as a measurement index, instead of publishing the weight power density data that everyone has commonly used. It can be guessed that the structure weight is superimposed. The specific energy of the iron battery itself is not high, resulting in no significant breakthrough in its weight power density on the standard measurement platform of the Ministry of Industry and Information Technology. According to previous information, it is estimated that the weight power density of blade batteries may reach about 180Wh/kg, which is in the current mainstream. Level.
from the structural matching point of view. As a single battery and related technology supplier, CATL needs to face more considerations about product matching. However, judging from the current patent details, the height of the large CTP module cannot be changed (and it is not thin enough), and a matching shell is required to fit and install on different models. Such a structure requires vehicle manufacturers to make corresponding adjustments in product planning. The more difficult problem is that there is currently no large-scale sales to support development. The risk of manufacturers making design adjustments for the matching of a single battery supplier is very high. . This may also be one of the reasons why it has a loud voice, but the real plan to start production is small (it is currently known that BAIC is sure to install vehicles and start production).
For BYD, which produces new energy vehicles by itself, the "blade" battery may have taken into account the multi-specification adaptability needs of its own products from the beginning. The narrow side of the "blade" is doneThe volume is small, which means that the vertical height can be more easily adapted to the needs of high and low chassis models. In the future, multi-function vehicles with ultra-thin chassis can be developed based on this, allowing users to use more space and tap the advantages of new energy vehicles. At the same time, we also see the possibility of stacking applications of such ultra-thin batteries, which may be prepared for commercial and high-chassis large SUV products, which can store more energy.
Another feature of CTP batteries in the Ningde era is the large-capacity of the single cells. The single cell capacity has changed from 50Ah at the beginning to more than 200Ah now, which greatly reduces the proportion of the shell while maintaining the same charge-discharge rate. Next, a simple series structure can output or receive a larger current (improving power and charging convenience). In addition, the current public information of CATL shows that CTP battery packs will still be packaged in a square shell. Considering the current stability of high nickel batteries, this package should be a better choice.
The single design of BYD's "blade" battery surprised me at first. First of all, such a long cell length is not a stable mechanical structure, and its resistance to deformation when subjected to lateral force is very weak. Usually, internal pressure will cause the shell to expand when the battery is working, and then pressure the surrounding battery. Therefore, it is necessary to carefully consider the issue of clearance when forming a group. On the one hand, it is necessary to prevent earthquakes, on the other hand, to eliminate the lateral force. There is still a lack of evidence in this regard.
Another technical challenge may come from the internal winding method of the cell. It is guessed that it will adopt the form of multiple electrodes + multiple independent winding units. In fact, it can be regarded as multiple small batteries forming a large battery. These small batteries share a package. This poses a great challenge to the uniformity of each unit, because the battery performance will always follow the barrel principle, and the worst one determines the overall performance!
final summary. On the whole, CATL CTP batteries and BYD "blade" batteries have their own merits. Ningde CTP has higher power density and higher group efficiency. It is more cost-controlling for most OEMs, and it is easier to launch products with longer battery life under the premise of a certain weight; BYD’s "blade" battery It is more valuable and imaginative in terms of structural flexibility and durability, greatly increasing the performance of iron batteries, allowing them to return to the mainstream from commercial or low-end products. This is also a considerable improvement.
From another point of view, the difference in the technical architecture of the two also shows the fact that although the two companies are both technology exporters of new energy vehicles, BYD itself has an advantage in technology accumulation as a vehicle manufacturer. This advantage may not depend on the improvement of a single indicator, but more on the understanding and rationalization of the user environment. I think it should also become the foothold of its long-term value.
This article comes from the author of Autohome and does not represent the viewpoint of Autohome.
