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On March 29, BYD’s “blade battery”, which has been discussed for a long time in the industry, completed its “first show”. It can charge and discharge more than 3000 times, support a driving range of more than 1.2 million kilometers, and have a battery life of 600 kilometers on a single charge, challenging the acupuncture test.
Judging from BYD’s live broadcast conference, this is a major turning point for BYD. The battery is stripped off and a new generation of battery technology is released. BYD’s battery technology is constantly undergoing iterative updates. So what are the benefits of the blade battery for consumers? Today we will analyze the underlying logic of BYD blade batteries from a technical perspective.
The core selling point of blade batteries-effectively avoiding spontaneous combustion of electric vehicles
When it comes to blade batteries, there is a core "selling point"-high safety.
The blade battery uses lithium iron phosphate, which has the characteristics of long life, and the group technology can make the vehicle have the characteristics of long battery life. This is mainly due to the increase in the volume utilization rate of the blade battery to make the lithium iron phosphate The cruising range of the vehicle has reached the same level as the high-energy ternary lithium battery. Blade batteries will be safer than ternary lithium and will reduce the possibility of electrolyte fire when encountering oxygen.
This attribute has returned to BYD’s previous technical route. It is the determination to hope that the blade battery can solve the safety pain points of new energy vehicles. "The word'self-ignition' is completely erased from the dictionary of new energy vehicles." For consumers, the advantage of a simple summary is that the car will not encounter natural dangers.
From the structural point of view, the blade battery is relatively thin and long. The current LFP (lithium iron phosphate battery) batteries made on the soft case are actually similar to this.
From the point of view of the blade battery, the battery cell can be made into a 138Ah battery cell on our previous 355/390 soft pack. This is currently a relatively large advantage. However, LFP and large-capacity square shell ternary batteries with different structures and capacities are better than the national standard acupuncture test. This problem was concluded in 2017: At that time, BYD’s own Roadmap was also the main force of the three yuan. In 2018-2019, a lot of energy of various ministries and commissions was to manage the spontaneous combustion and safety of new energy vehicles in order to solve this problem. , Various car companies have done a lot of work.
(Note: From the context, the ternary battery product line is used by all BYD's pure electric vehicles in 2019, and the next step is to go to lithium iron phosphate. The density is reduced and the grouping rate is compensated by the structural characteristics of the battery. At present, it is equal to two product lines running side by side. From the perspective of safety and cost, the LFP blade is the preferred route that BYD thinks)
BYD Battery’s third-generation battery system iteration
From the perspective of battery system design, the blade battery is mainly through structural innovation, and the “module” can be skipped when forming a group, and it can be installed in the same space by improving volume utilization. Into the design goal of more batteries. In order to solve the differences in the range and comprehensive characteristics of new energy vehicles, BYD has developed three-generation battery systems. On the surface, they all provide a certain range of battery life, but in fact, the characteristics and layout of the battery cells are different. We respectively introduce the three generations of battery systems:
Gen0: The design of early pure electric vehicles, using 75Ah lithium iron phosphate batteries. The first-generation battery system (BYD Dynasty series): Based on the original model design and reform, taking the Qin EV as an example, the module adopts a composite module with several different shapes. The main feature is to insert the battery as much as possible , This time is represented by the batteries of NCM523 and NCM622, the capacity of the battery cell is upgraded from 100Ah to 135Ah (173*112.5*50).
Second-generation battery system (e-net models): The e-platform system is adopted. This has begun to change from the above-mentioned first-generation to a flat, single-layer module design. The focus is on a battery system Covering multiple models, it is modular like the drive system, and the battery core is also 135Ah (173*112.5*50). The second-generation battery has been engineered and optimized to make the electric vehicle last longer than the first-generation .
Third-generation battery system (Han EV): This generation of battery, selling point is flattening, safety , the cost of this 138Ah battery is still unclear, it should be better than three Yuan route is lower.
We can see that if this battery cell is to meet the specifications of MEB, BEV3 or e-TGNA, it needs to be adjusted in the length direction of the battery cell. That is to say, BYD’s battery company uses the battery cell Released as a product, it can make matching improvements to the battery design currently done by BYD passenger cars.
Due to the structural changes of the battery, the design of the tray has also been completely changed. The structural beam of the battery shell is eliminated. Each cell shell of the blade battery is used as the beam of the battery, which improves the structural strength of the battery system. Built on the structure of the cell. And learn from the structure principle of honeycomb aluminum plate, the upper and lower sides, glue two high-strength plates to form the honeycomb aluminum plate.
Problem: Once a single cell is damaged, it is not easy to repair
blade battery. There will be a problem at present-if there is a side collision or other collision, the structure of the cell will directly bear the force. Almost all the previous collision designs of car companies used the structural combination of the body and the battery system to prevent the collision from being squeezed into the battery core. After the collision, the battery core is as complete as possible. If you follow this design idea, it is actually difficult to move the blade battery to the ternary. With this overall structure design idea, the battery needs to be damaged under extreme conditions, and its own safety must be guaranteed.
In addition, if the blade battery is impacted or subjected to other forces, after a single damage, the series connection is not easy to repair, and this structure needs to be disassembled and combined. For the glue between the upper and lower parts + the glue between the batteries The requirements are relatively high.
The evolutionary route of the square shell cell introduced by the honeycomb battery a few days ago, from the cell width of 148 to the cell width of MEB220, and then to about 330-400mm, if the stacking process is around the direction of the piece The thickness can be increased from 10-14mm for the soft package to 25-30mm. I think the blade method is a bit radical. But this evolutionary route represents the planned development direction of battery cell technology.
Summary:
This time BYD’s blade battery has indeed triggered a big discussion on battery technology and battery design, but whether LFP is right, and it uses a particularly aggressive battery stick. We still have big doubts about connecting + bottom board bonding, making the battery one-time assembly (without maintenance).
From the perspective of practical value, BYD officially stated that under a certain degree of safety, the long life and long battery life of the vehicle can be guaranteed. However, as to whether the blade battery technology will be adopted by other related car manufacturers one after another, it is still unknown, which involves the internal layout of the battery transformation and the specifications of the modified battery. This is not so for the car companies. easy.
Generally speaking, it has played a positive role in promoting the development of power batteries. We have added an idea to solve the contradiction between the safety and cruising range of new energy vehicles.
Author: Zhu Yulong
Editor: Lu Island
