The contrast is too obvious! Witness the acupuncture experiment of blade battery VS ternary lithium battery

On June 1 day, I was invited to visit BYD Chongqing Fudi Lithium Battery Factory, which is the only production base for blade batteries! Come and see what's inside!

■ Make a knot first!

Before officially visiting the factory, BYD decided to put a big move first-no charge! The participants in this acupuncture experiment are ternary lithium battery and blade battery produced by BYD.

As can be seen from the figure, after the ternary lithium battery was punctured, the voltage dropped to zero in almost one second (that is, a short circuit occurred), and then smoke caught fire and made a loud noise.

The picture shows the breakdown experimental image of ternary lithium battery. The red line represents voltage, the green line represents safety valve temperature, and the yellow line represents breakdown point temperature.

However, after 20 minutes of puncture, the battery voltage of the blade only dropped at a very slow speed, and there was no smoke and fire. The contrast is still obvious.

I wrote two articles about BYD and Contemporary Amperex Technology Co., Ltd. before, and found that many netizens questioned whether the voltage dropped to zero after the blade battery was punctured. There are two kinds of experimental videos of blade battery acupuncture circulating on the Internet, and the voltage dropped to zero and did not drop to zero, so I will tell you the truth this time.

Looking at this experiment alone, BYD's blade battery has not dropped to zero in 20 minutes. I asked the field engineer, and he said that they had a flat tire one day and the battery was left, and the voltage did not drop to zero.

The initial voltage of the experiment is 3.42 volts, the starting time is about 10:47, and the picture is 10:57, where1-1is the real-time voltage,1-/kloc-0.

■ Blade battery can suppress internal short circuit?

So why is this? BYD's engineers said that after the puncture, there were many short circuits inside the battery, and they suppressed the serious short circuit inside the battery through structural design.

Then I asked, since it is "structural design" rather than the characteristics of the material itself, can this technology be applied to ternary lithium batteries?

Engineers said that research in this area is currently under way. So maybe we can expect BYD to develop a safer ternary lithium battery?

After watching the wonderful acupuncture experiment, let's talk about several issues that everyone cares about.

■ BYD has not ignored system security!

In the previous incident between Contemporary Ampere Technology Co., Ltd. and BYD, Contemporary Ampere Technology Co., Ltd. "insinuated" that BYD equated the abuse test with battery safety, which made people feel that BYD was only obsessed with battery safety, regardless of system safety. In fact, BYD is also very concerned about the security of the whole system. They guarantee the safety of blade batteries from seven dimensions, four levels and five aspects. In addition to acupuncture, BYD is also equipped with corresponding safety measures in the dimensions of overcharge and collision.

For example, we are concerned about overcharging. According to BYD's data, when the blade battery is charged 2.6 times higher than the maximum voltage, only smoke appears, and there is no fire and explosion.

When one battery cell is out of control, its adjacent batteries will not catch fire or explode, and the whole battery pack will not catch fire due to chain reaction.

In this extreme working condition, only smoke can not catch fire, that is to say, there will be no safety problems in daily use under mild working conditions; To take a step back, even if the heat is out of control, the model equipped with blade battery can provide enough escape and rescue time.

■ Poor low temperature performance? Does not exist!

We all know that lithium batteries are not frost-resistant, especially lithium ferrous phosphate. Due to congenital problems, the low-temperature performance is often criticized. Even Li Xiang, CEO of Li, once questioned the low-temperature performance of blade batteries in Weibo.

BYD gave the measured data, which showed that the discharge capacity of the blade battery remained at 90% at minus 20 degrees Celsius. But in the case of low temperature and low SOC, it is better than lithium ternary.

Regarding the low-temperature charging ability of blade batteries, BYD also gave data. The data shows that the low-temperature charging time of blade battery is no different from that of ternary lithium battery, but it lags behind in low-temperature charging power.

These data also confirm the words of Mr. Li Yunfei, Deputy General Manager of BYD Sales: "The low temperature performance is too poor, and we dare not sell it." .

However, before getting a real car for winter testing, we can't just conclude that the blade battery is really not afraid of low temperature based on BYD's data. I am more inclined to trust the evaluation of the third party and the media, and please look forward to the subsequent winter measurement of the electric state.

■ Get to know Chongqing Fudi Factory quickly.

The factory has invested 65.438+0 million yuan in the production of batteries and supporting materials, covering an area of about 65.438+0.500 mu, with a total construction area of about 950,000 square meters. A new production workshop was built, 958 sets of related equipment were purchased, and 8 lithium-ion battery production lines were built. After the project is completed, the capacity of lithium-ion batteries will be 20GWh, with an annual output value of 20 billion yuan.

The factory started construction in February 20 19, and the blade battery was officially listed in March 2020. It only took 1 year to have a lean, automated and information-based manufacturing management system, as well as a blade battery production line and production equipment independently developed by BYD, as well as a number of highly confidential core technologies.

■ How is the blade battery produced?

Finally, talk about how the blade battery is produced. In fact, the blade battery is also a kind of power battery in essence, so its manufacturing process is similar to that of ordinary batteries, which is completed by batching, coating, winding and laminating.

Firstly, active substances, nano conductive materials, solvents and binders are automatically mixed according to a predetermined ratio to form uniform and stable electrode slurry.

The next step is coating, that is, coating the slurry on the copper foil to ensure that there are no particles, sundries, dust, etc. Is mixed into the pole piece. The machine used looks like a loom.

Roller pressing is to compact the coated electrode sheet according to a predetermined thickness with a roller to obtain an electrode sheet with a predetermined thickness and volume density.

Followed by lamination, the length of the blade battery pole piece is nearly one meter. BYD's original lamination process can control the alignment tolerance within 0.3 mm, and the lamination speed reaches the highest level in the industry-0.3 seconds/piece.

Subsequently, the machine will automatically convey the structural parts and realize accurate positioning, and assemble them into batteries through insulation, welding, casing, sealing and other processes. After baking to remove water, adding electrolyte and testing, the blade battery core was completed.

Finally, each battery cell will form a battery pack. BYD's CTP technology (the battery is directly connected to the battery pack without modules) can improve the volume utilization rate of the battery pack and help to improve the energy density.

The following figure shows the advantages of CTP technology:

BYD said that the blade battery can reduce the structural parts of ternary lithium battery caused by insufficient battery safety and strength, thus reducing the weight of the car. Therefore, although the single energy density is not as high as that of ternary lithium batteries, it can also achieve the same endurance as the mainstream ternary lithium batteries. For example, BYD Korea EV has a comprehensive cruising range of 605 kilometers.

Recently, there is a hot word called "Industry 4.0", which you can simply understand as smart factory, intelligent production and intelligent logistics. Chongqing Fudi Factory is also a practitioner of Industry 4.0. In addition to high precision and automation, digital construction is not backward. Each blade battery product has its own "ID card". In the future, the data of products in use will also provide important reference for BYD to continuously improve its technology and products.

■ National review

Sun Huajun, deputy general manager of Foday Battery Company, said, "Today, almost all the automobile brands you can think of are discussing cooperation schemes based on blade battery technology with us." This shows BYD's ambition and strength. We know that the world's auto giants, such as Volkswagen and Tesla, want to take the production and research and development of batteries into their own hands. BYD has obviously done this first, and has started to sell batteries to the outside world, which gives BYD a lot of advantages in the competition with domestic and foreign rivals.

Finally, I am very much looking forward to the early test drive of the Korean EV equipped with the blade battery to see what surprises this battery can bring to us with BYD's flagship model. Please also look forward to the follow-up report of Dianbang.

This article comes from car home, the author of the car manufacturer, and does not represent car home's position.