Text | Announced that it will start mass production of a new module-free power battery structure - CTP power battery pack. CATL said that in terms of cost, the volume utilization of CTP battery packs has increased by 15%-20%, the number of parts has been reduced by 40%, and the production efficiency has increased by 50%. After being put into application, it will significantly reduce the manufacturing cost of power batteries.
We know from the planning of CATL that the power battery pack of CATL, which uses high-nickel ternary cells with a single energy density of 240Wh/kg, will achieve a system energy density of 200Wh/kg in 2020. At the same time, BYD plans to increase the energy density of its lithium iron phosphate monomer to more than 180Wh/kg by 2020, and the system energy density will also increase to more than 160Wh/kg.
China's two leading power battery companies have announced the start of mass production of a new structure of CTP power battery packs. What are the differences between the so-called CTP power battery packs compared to previous power battery packs?
What is a CTP power battery pack? It literally means Cell To Pack. Generally speaking, domestic pure electric vehicles before this used battery cells connected in series to form battery modules. The battery modules are then connected in series to form a complete package. The CTP battery pack is a power battery pack composed of battery cells directly. The main benefits of this are reduced production costs and increased energy density.
In fact, the so-called CTP power battery pack is nothing new in the entire development process of pure electric vehicles. Starting from the first generation of Tesla Model?s, Tesla has begun to use the CTP structure to design the structure of the power battery pack.
Early Tesla Model?s used the 18650 model lithium cobalt oxide battery produced by Panasonic and originally widely used in 3C products as a power battery cell. Tesla will have a quantity of 7,000- More than 8,000 18650 batteries are connected in series and parallel to form four large "modules", supplemented by a passive cooling system and BMS assembly to form a power battery pack.
In the later period, 21700 specification nickel-cobalt-aluminum cathode material was used. The single energy density of the Tesla battery pack exceeded 300Wh/kg, and the highest system energy density exceeded 167Wh/kg. At that time, domestic power The system energy density of the battery pack is still around 140Wh/kg. After going through the development process of 111NCM, 523NCM, 622NCM, and 811NCM, the energy density of Chinese power battery cells has continued to improve.
In the second half of 2019, the single energy density of domestic mass-produced high-nickel 811NCM power batteries using carbon anodes reached 240Wh/kg. However, although the high-nickel 811NCM power batteries using silicon-carbon anodes have not yet entered the mainstream It is currently in the mass production stage, but the single energy density of more than 300Wh/kg is already comparable to the most advanced international level, and the mass-produced high-nickel 811NCM power battery system using carbon anode has an energy density of more than 170Wh/kg.
If you want to further improve the system energy density of power batteries, there are only two ways left for domestic power battery companies. One is to accelerate the mass production plan of high-nickel 811NCM power batteries with silicon carbon anodes; It is to further find solutions on the application side based on existing battery technology. CTP technology, which is best implemented on the application side, has become the best choice for domestic power battery companies.
According to CATL’s statement, the power battery pack using the CTP structure can achieve an upgrade of the system energy density of 200Wh/kg, and at the same time, the manufacturing cost will be reduced accordingly. In addition, as a power battery company, the original business model of selling single units or modules has been directly transformed into a complete package supply, which not only increases the profits of power battery companies, but also reduces the need for some vehicle manufacturers to develop packages. Mistakes in the process lead to the loss of interests and reputation of power battery manufacturers.
In this way, power battery companies as suppliers can achieve multiple things with one stone. Why not?
Since the use of CTP structure to develop power battery packs is of great benefit to power battery suppliers, CATL and BYD, as the leaders of China’s power batteries, must be the first and fastest to go. . However, in terms of the technological development direction of CTP structure power batteries, CATL and BYD are making completely different attempts.
From official statements and patent information, we can know that CATL’s CTP is a power battery pack based on high-nickel ternary development with lower cost and higher system energy.
According to CATL’s plan, the system energy density of CATL’s CTP and power battery packs will reach 200Wh/kg in 2020. If calculated based on the current compact passenger cars generally carrying a power battery weight of about 400kg , we can know that if the power battery of CATL CTP structure is used, the battery capacity of the power battery pack of about 400kg will reach about 80kWh. If according to the current working conditions, a compact pure electric model with a cruising range of 500km will generally be equipped with a 65kWh power battery pack. According to rough calculations, a compact pure electric vehicle equipped with CATL's CTP structure of the same weight will be able to achieve a cruising range of more than 600km or even 650km.
Since it adopts a structural layout similar to Tesla's multi-row single battery large module (in fact, the module is not completely eliminated), the single row of batteries is supplemented by a columnar structure as a The installation and fixing position of the vehicle's power battery avoids the problem of insufficient structural strength of the power battery caused by the complete removal of the module from the power battery pack while the vehicle is running.
BYD’s CTP structure power battery has undergone more complete changes compared to the CATL era.
First of all, in terms of power battery materials, BYD does not use high-nickel 811NCM power batteries like CATL, but uses a newly developed lithium iron phosphate "blade battery", similar to the "Green Arrow" The chewing gum-shaped "blade battery" is longer and thinner than ordinary power battery cells. The short "blade battery" is about 600mm in length, while the long specification reaches about 1500mm.
In this way, BYD's CTP structure is further simplified. The power battery completely cancels the module and is placed directly on the power battery tray in a direct series and side arrangement. The lower part of the package uses insulation materials. The upper part of the package body uses a "harmonica tube" to set up a liquid-cooled active circulation system to dissipate heat, and the side structure of the package body is strengthened to fasten the battery cells, and the structural strength of the battery tray and the battery cell itself is used to achieve higher packaging efficiency. Structural strength.
Compared with the CATL era, BYD's CTP structure has evolved more thoroughly, the package structure is simpler, production cost control is better, and the assembly process is more simplified. However, the structural strength of the package body will be worse than that of the CATL era. , only relying on the battery tray, the power battery cell itself, the side structural parts, etc. to resist the deformation and stress generated by the power battery pack during vehicle driving, at least on the surface it looks a little thin. It may be necessary to further strengthen the structure through the body's "battery compartment" structure.
According to BYD's description, BYD's lithium iron phosphate CTP battery pack will use 180Wh/kg lithium iron phosphate single battery, and the system energy density can reach a maximum of 160Wh/kg. This figure is compared with CATL. The 200Wh/kg seems slightly behind, but since the current cost of lithium iron phosphate batteries has been reduced to less than 600 yuan/kWh, as a cost-effective power battery pack product, BYD's CTP battery pack is still quite competitive.
This means that in the low-end pure electric vehicle market, BYD CTP battery packs may become a very competitive force.
At present, simplifying the structure and reducing costs is an extremely important thing for every power battery company, especially in 2020 when subsidies for new energy vehicles are about to be withdrawn. Whether it is BYD's CTP "blade battery" or CATL's high-nickel ternary CTP battery, they are the direction of market demand.
The cost-oriented low-end market has a large scale and high demand. BYD's lithium iron phosphate CTP battery pack may become a leader in this field with its excellent cost performance; with the continued development of power battery technology, 300Wh/ The mass production of high-nickel ternary monomers with silicon-carbon anodes of more than 1 kg, and lighter, thinner, and larger-capacity power batteries will be hot commodities in the high-end market.
CATL's CTP based on high nickel ternary has an absolute advantage in energy density and weight energy density. In the mid-to-high-end market with high requirements in all aspects, CATL's CTP may become a mainstream force.
This article comes from the author of Autohome Chejiahao and does not represent the views and positions of Autohome.