Through this conference, BYD will make lithium iron phosphate batteries return to the mainstream position, and BYD will open up the whole new energy automobile industry and promote the popularization of "blade batteries".
In terms of application, BYD blade battery will be first installed on BYD Korean models, and this medium and large pure electric vehicle is planned to be listed in the middle of this year. Relevant parameters show that as the first product equipped with blade battery, BYD HANNEDC has a cruising range of more than 600 kilometers.
Bottleneck of power battery
The cost of power battery has always accounted for more than 40% of the cost of electric vehicles, so how to reduce the cost while ensuring the battery life is the research direction of battery manufacturers.
On the other hand, it is equally important to improve the energy density of the battery and increase the cruising range.
There are not many ways to improve the energy density of batteries, which are nothing more than developing battery types and ratios or optimizing battery structure. Obviously, the space for optimizing the battery ratio is getting smaller and smaller, so it may be a good idea to start with the battery structure.
BYD just chose to redevelop the battery structure and introduced the blade battery made of lithium ferrous phosphate, which improved the energy density of the battery and controlled the cost of the battery.
What is blade electricity?
Structurally, BYD's blade battery also belongs to one of CTP technologies. CTP is called Cell? Where to? Pack, the battery cells are directly integrated into the battery pack (the traditional battery pack adopts the grouping mode from monomer to module to battery pack).
The concept of CTP technology released by contemporary Ampere Technology Co., Ltd. is the same as CTP technology. They all integrate the battery directly into the battery pack, eliminating the intermediate module link.
But BYD's technology is obviously more "radical", completely non-modular, more difficult and more thorough; In Contemporary Ampere Technology Co., Ltd., large modules are used instead of small modules.
CTP is not a very advanced technology, so why not adopt it earlier? The main reason is that the safety redundancy of the previous battery pack design is too high, and now the technology is more confident. Through structural optimization, module components can be omitted or simplified, thus improving the energy density of unit battery.
Blade battery characteristics
According to the patent disclosed by BYD, the blade battery is an ultra-long battery of 430mm or even 2500mm, and both ends of the battery have tabs.
Compared with the traditional square battery, it is a battery design process that presents a "flat" and "long" shape, is arranged together in an array, and is inserted into the battery pack like a "blade", so it is called a "blade battery".
The existing battery pack structure has more side plates, end plates, fasteners, cross beams, longitudinal beams and other components of each module under the condition that the total volume of the battery pack is the same; BYD battery pack using CTP technology, except for battery management system, distribution box and other components, the space utilization rate is about 62%. Affected by different cell layouts, the space utilization rate in the package is 55% to 65% respectively, and can even reach 80% when necessary.
Due to the reduction of parts and weight, the energy density per unit mass can also be improved, and the cruising range of the whole vehicle can also be improved. The battery pack using CTP technology can increase the charge by about 20%-30% and the cruising range by 20%-30%.
In contrast, the specific energy density of BYD lithium iron phosphate battery (blade battery) with CTP technology reaches 180Wh/kg, which is equivalent to the battery with NCM8 1 1 cell.
Advantages of blade battery
1. Safety: lithium ferrous phosphate >; Ternary lithium
The thermal stability of lithium ferrous phosphate is the best among lithium batteries used in automobiles at present, and the peak value of electric heating is greater than 350℃. When the battery temperature is at a high temperature of 500-600℃, its internal chemical components begin to decompose.
Ternary lithium batteries have poor thermal stability and begin to decompose at about 300℃, so the requirements for battery management system are very high, and over-temperature protection devices and battery management system are needed to protect the safety of batteries. Therefore, the safety of lithium ferrous phosphate at high temperature is relatively high.
In BYD's puncture penetration test, under the same test conditions, the temperature of ternary lithium battery changed dramatically at the moment of acupuncture, the surface temperature quickly exceeded 500℃, and the extreme heat was out of control, and it began to burn violently, and the eggs on the battery surface were blown up;
After the traditional lithium iron phosphate battery was broken down, there was no open flame, and the battery pressure relief valve sprayed smoke. The surface temperature reached 200℃~400℃, and the eggs on the surface of the battery were burnt at high temperature.
BYD's "blade battery" has no open flame or even smoke after penetration. The surface temperature of the battery is only about 30℃, and the eggs on the battery surface have not changed.
Considering the cost and safety, BYD's blade battery is made of lithium ferrous phosphate. At the same time, compared with the traditional lithium iron phosphate battery, the inner core of the "blade battery" adopts a special tab structure design, which makes the probability of internal short circuit extremely low. Even in extreme cases, there will be no violent reaction inside the battery, which further reduces the risk of spontaneous combustion.
2. service life: lithium ferrous phosphate > lithium ternary.
Battery life is the battery's power decay after many times of complete charge and discharge. Generally, the battery of an electric vehicle will decay to 80% of the original power when it is fully charged, which means that the battery should be replaced.
The power of lithium iron phosphate battery will decay to the original 80% only after the complete charge and discharge cycle exceeds 3500 times. That is to say, if it is charged and discharged once a day, it will take nearly 10 years for the lithium iron phosphate battery to show obvious attenuation.
The "blade battery" continues the long-life advantage of lithium ferrous phosphate technology, and can achieve a life level of more than 3,000 charge and discharge cycles and more than 6,543.8+0.2 million kilometers.
In contrast, ternary lithium batteries will begin to decay after being charged and discharged for more than 2000 times, that is, about 6 years. Of course, battery management and vehicle electronic control system can slightly extend the battery life, but it can only be slightly delayed.
What are the risks of blade batteries?
There are advantages and disadvantages, and canceling or reducing module links will also bring some risks. Because of the existence of modules, the traditional three-level battery pack has an extra layer of protection for collision safety.
The battery pack using CTP technology will directly bear the impact of collision except the side beam of the battery pack.
In addition, CTP requires high consistency of the battery, and the battery deformation and poor heat dissipation caused by charging and discharging expansion can not be ignored. Once a single battery fails, it may involve replacing the whole battery pack, not just replacing a module, and the maintenance cost will increase greatly.
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In addition, at the press conference, He Long, vice president of BYD Group and chairman of Foday Battery, said: "Almost all automobile brands you can think of are discussing cooperation plans based on' blade battery' technology with us. I believe that everyone will soon see and hear more exciting news about "blade battery". "
BYD's "Blade Battery" will be open to the whole new energy automobile industry, which will promote the popularization of "Blade Battery" and benefit the industry and consumers. BYD hopes to accelerate the rapid elimination of low-safety batteries by "blade batteries" and lead the new energy automobile industry into the fast lane of benign development.
Lithium ferrous phosphate returns to the mainstream-reducing cost and improving efficiency
From the aspects of thermal stability, safety, service life and cost, lithium iron phosphate battery has advantages. In terms of energy density, the energy density of lithium iron phosphate battery is greatly improved by optimizing the battery structure.
In terms of the most critical safety, the structural advantages of the blade battery also make the battery no longer spontaneously ignite, which is undoubtedly subversive for the safety of electric vehicles.
It is believed that lithium iron phosphate battery will return to the mainstream through blade battery technology.
This article comes from car home, the author of the car manufacturer, and does not represent car home's position.