“
A while ago, Xiaomi SU7 has not yet come out, and the Internet has been hot, making the popularity of Xiaomi cars and even electric vehicles rise sharply. I have to say that Xiaomi's marketing is too successful! It didn't cost a penny, it all relied on word of mouth from netizens.
After experiencing the game of "national price guessing", at the Xiaomi car press conference held on March 28, Mr. Lei said that he was going to start "rectifying" the electric vehicle industry again.
"对标保时捷 Taycan"
“超越特斯拉 Model 3”
"There is no opponent below 2 million, and it is floating"
"There is no opponent within 500,000"
"The second one is far ahead."
The scene of the Xiaomi car press conference
At this press conference, Lei Jun invited the "Three Musketeers of New Energy Vehicles": Weilai Automobile: Li Bin, Xiaopeng Motors: He Xiaopeng, Li Auto: Li Xiang, before the press conference, the bigwigs smiled happily and wanted to see how Xiaomi Auto met the expectations of the majority of netizens this time.
With a lot of foreshadowing, throwing jokes, and wanting to promote and suppress first, Mr. Lei finally showed the price, and the audience cheered: Thor, Mr. Lei, you are my god!
Although the price is 20,000 more than 19.99, it gives away three pieces for free. But if you don't buy it, you will save 200,000 yuan, and if you accidentally save 200,000 yuan, it is worthy of me.
However, more than 200,000 is indeed not cheap, can the price of Xiaomi cars be lowered again? !
"Refrigerator, color TV, sofa, all move home"
"Let me show you the pattern of our big technology companies"
"It's true that they are far ahead in technology, but we have technology to do it"
The three brothers in the audience were sweating, knowing that Xiaomi was playing big this time, but they didn't expect to dare to play so big for the first time.
On April 3, at the first batch of delivery ceremony of Xiaomi SU7, the first batch of users to pick up the car also had Mr. Lei personally open the door service. Mr. Lei's operation is as fierce as a tiger, and even the "rice noodles" next door who are also Mi families come to pay tribute to Mr. Lei, and pay tribute to the real Thor with practical actions!
This is after Tesla, another phenomenal electric car appeared in China - Xiaomi SU7, the emergence of the little brother, is to replace the big brother, by the way, rectify the industry, do you say it is menacing.
And Xiaomi SU7 pays tribute to Porsche in appearance, which who is not confused when you see it. However, now on the streets of Beijing, really driving a Porsche may not have a high return rate of Xiaomi SU7, and Xiaomi has won this time.
Xiaomi knows the time, when spring happens, "Baoshi rice" is really good-looking
01
What exactly is the battery life of the Xiaomi SU7?
After revisiting the press conference of Xiaomi Auto, let's explore the Xiaomi SU7.
Xiaomi SU7 launched three models with different configurations this time: standard version, Pro version and Max version, these three models not only meet the needs of various novel and commonly used use, but also perform well in terms of range, which is also an important criterion for measuring electric vehicles.
Based on Continental's CLTC conditions (emphasis added!), the standard version has a starting range of 700 km, and the Max version has a range of up to 810 km. Among them, the standard version uses BYD's blade battery, and the Max version uses CATL's Kirin battery.
However, after reading the recent SU7 evaluation on the Internet, the SU7 standard version is on the highway with the highest speed limit of 120km/h in Guangdong, starting from full power and driving continuously until the power is 0, at an average speed of 97.7km/h, the actual endurance of the Xiaomi SU7 standard version is only 495km, and it is a "seven fold".
Why is the measured range so much different from the 700 kilometers at the press conference, is Lei always committing fraud in front of the majority of netizens?
02
What is CLTC?
Indeed, we were deceived.
Here we have to mention the CLTC working conditions mentioned at the press conference.
CLTC (China Light - Duty Vehicles Test Cycle) is a standard developed by Continental for road traffic conditions and driving habits in mainland China. It is segmented into CLTC-P for Chinese passenger cars and CLTC-C for light commercial vehicles in China.
CLTC-P, the standard used in sedans like SU7, includes three sections of low-speed, medium-speed and high-speed, corresponding to urban, suburban and high-speed working conditions, with a total duration of 1,800s and a total mileage of only 14,480m, which is not a test of full power.
The maximum test speed of CLTC-P is 114km/h, and the average speed is 28.96km/h, which is lower than the EU's NEDC condition and the United Nations Economic Commission for Europe's WLTC condition.
CLTC is set because the maximum speed limit on the mainland highway is 120km/h, and the proportion of time in the idle condition of 0km/h is increased, simulating traffic jams and waiting for traffic lights, so it is more suitable for the physique of Chinese babies.
The CLTC is only for the reference of general consumers, in fact, it is used for publicity, and the measured average speed of the SU7 is 97.7km/h, which is mainly in high-speed scenarios, much higher than the CLTC's 28.96km/h. And in a shorter period of discharge, the lower the capacity of the battery will be, just like a person who slowly drinks ten bottles before pouring, and he will faint after drinking three bottles in a row.
03
Reveal the actual battery life of Xiaomi SU7
You can't drink alcohol while driving, so how does it work?
If we disassemble the Xiaomi SU7 friendlyly, find its battery pack, and disassemble the battery module, we will find that it is composed of many single cells.
Each cell is roughly the following structure, consisting of a positive electrode on the left, a negative electrode on the right, a diaphragm separating them in the middle, and an electrolyte represented by blue, including the outermost shell.
When we fully charge an electric car, the battery stores the energy. When we use electricity, that is, when the external circuit is connected, the negative electrode will come out of ions and electrons, and these two processes will occur at the same time. Electrons flow to the outward circuit, through an electrical device, to the positive electrode, and ions migrate through the electrolyte, through the diaphragm, and eventually to the positive electrode.
But these two processes are not completely synchronized in time, the speed of electrons is very fast, close to the speed of light, but the transport of ions is relatively slow, and the macroscopic manifestation is that there is a large internal resistance, and the phenomenon of "polarization" occurs.
When our car needs to run faster, the battery needs to provide a larger discharge current, that is, the negative electrode needs to provide more electrons, because the migration of ions can not keep up with the electrons, the electrons of the negative electrode will reach the positive electrode in advance, and the ions of the negative electrode and the electrons of the positive electrode will gradually crowd on the surface of the electrode, and there will be greater polarization, and the discharge process of the battery will be terminated early, that is, the power display will be used up, and the capacity of the battery will be lower.
In the same way, when we charge, the process is just the opposite, if we increase the speed of charging, the amount of power that the battery can charge into will also decrease, will you?
On the other hand, from the aerodynamic point of view, the faster the speed of the car, the greater the wind resistance, and the more energy the car loses, so the faster the electric car drives, the lower the battery life, which is a phenomenon under the influence of comprehensive factors.
04
Why is the battery different between the standard version and the Max version?
Here is the PPT shown at Xiaomi's press conference:
Let's zoom in to compare the parameters:
The standard version uses lithium iron phosphate cathode, while the MAX version uses ternary lithium cathode, and both of these batteries are domestic self-developed batteries, which must be praised.
The price of the standard version is 215,900 yuan, and the price of the MAX version is 299,900 yuan, a difference of 84,000 yuan, which is enough to buy 42 Redmi phones. Where is the difference between the 80,000 yuan, maybe the answer can be found from the battery.
According to the current market scenario, the power battery accounts for 30% ~ 40% of the cost of electric vehicles, and is the component with the highest cost of the whole vehicle. That is to say, spend 300,000 to buy the Max version, in fact, 100,000 may lie in that battery, of course, the battery is also the heart of electric vehicles, and its importance is self-evident.
Is that to reduce the cost of the power battery, the price of electric vehicles can be lowered again, really!
Because the world's lithium reserves are limited, just like gold, it all depends on the amount of mining. Therefore, the price of cathode raw materials for lithium-ion batteries is not cheap, especially the ternary lithium cathode, which contains a precious metal called cobalt, so the price is more expensive, while the price of lithium iron phosphate is much cheaper, because there is no precious metal.
However, at present, only the low-profile version of the car will use lithium iron phosphate cathode, because the quality and volume energy density of lithium iron phosphate batteries are not as good as ternary lithium batteries. The energy density of ternary lithium batteries is generally 200Wh/kg, and may reach 300Wh/kg in the future, while lithium iron phosphate batteries are basically hovering at 100~110Wh/kg, and some reach 130~150Wh/kg, but it is very difficult to break through 200Wh/kg.
For cars with limited space, the greater the energy density, the weight and volume of the battery will be much smaller when the total energy of the battery pack is the same, so the speed will be faster and the battery life will be stronger. Therefore, the Max version uses ternary lithium, and the standard version uses lithium iron phosphate, we can compare the detailed parameters:
In addition to the price, users are more concerned about the high and low temperature performance of the battery, which has a lot to do with the cathode material.
Lithium iron phosphate LiFePO4 is an olivine-type structure, and the crystal structure is composed of FeO6 and PO4 to form a spatial skeleton, because the LiFePO4 structure has a strong three-dimensional P-O-Fe bond, it is not easy to discipit oxygen at high temperature, so the structure is very stable.
Ternary lithium is a ternary cathode material of lithium nickel-cobalt-manganese or lithium nickel-cobalt-aluminate, which is a layered rock salt phase structure, which will dissolve oxygen atoms and collapse the structure at high temperatures, so the high temperature resistance of the material is not as good as that of lithium iron phosphate.
For low-temperature performance, lithium iron phosphate can exert a capacity at low temperature due to its low electronic conductivity, while ternary lithium can still exert 70% of its capacity at minus 20 °C. In terms of low-temperature performance, ternary lithium has more advantages.
However, in fact, in electric vehicles, the battery will also have a heating system and a cooling system, and the high and low temperature performance of the battery depends on the specific use scenario.
05
BYD and CATL are the winners behind it
As one of the battery suppliers of Xiaomi SU7, BYD previously showed at the press conference that their battery is very safe under the acupuncture test, simply put, the battery cell is pierced, and the positive and negative poles in the battery will be in direct contact to simulate the thermal hazards that may be caused by short circuits.
Although this experiment alone cannot fully simulate various situations in real accidents, BYD's blade battery is indeed a subversive creation.
We opened the patent of the blade battery, and from the comparison of the published data, the traditional battery pack uses a cylindrical single battery, which has a large gap between the stacks, wasting a lot of space, in fact, this is the scheme adopted by Tesla before.
Although it may seem outdated now, it was extremely imaginative to be able to connect many cylindrical batteries in series and parallel to enable the operation of automobiles at that time.
BYD's "blade battery" uses a self-developed large battery cell with a length greater than 0.6m, and the shape of the battery cell is more flat and narrow, arranged together through an array, and inserted into the battery pack like a "blade", so it is called a "blade battery".
Because the blade battery has a longer circuit, a larger surface area, and better heat dissipation, it is safer, and it eliminates the need for more support structures, which improves the space utilization rate by nearly 20% compared to the traditional arrangement.
(For details, please refer to Patent CN110379963B, Power Battery Pack and Electric Vehicle; Patent CN110165116B, Battery Pack, Vehicle and Energy Storage Device)
CATL's Kirin battery adopts the third-generation CTP (cell to pack) battery technology, which is based on a high-nickel ternary lithium architecture, eliminating the module link and directly integrating the battery cells into the battery pack or larger modules.
A sleeve connection mode is adopted between the module and the module to be closely adhered to, and the sleeve is connected with the vehicle through a fixed device simultaneously, and the whole module directly simplifies the structure, realizes the lightweight of the battery pack, and also improves the connection strength of the battery pack in the whole vehicle. (Patent CN209658278U, battery pack)
There are three main advantages of Kirin batteries: first, CTP battery packs can be used in different models because there are no standard module restrictions, and they are widely used; Second, by reducing the internal structural components, the CTP battery pack can improve the volume utilization rate and indirectly improve the energy density of the system. Third, its heat dissipation effect is higher than that of the current small module battery pack.
The specific parameters of the two can be seen in the following table:
06
Where are batteries and electric vehicles headed?
With the consciousness of the editor, of course, it is the East (China)!
Whether it is the BYD Qin Plus benchmarking Japanese gasoline cars, or the recent Xiaomi SU7 press conference, it proves that the current attention of electric vehicles in the mainland has far exceeded that of 7 years ago - the era of Model 3.
And not just because electric cars are getting cheaper, they can be the best option for daily commuting. What's more important is that because the continent's electric vehicles are gradually leading the world, realizing the corner overtaking of the automobile industry. There is technology, not stuck, this is the fundamental.
Of course, the development of battery technology has contributed to it, and CATL and BYD account for more than half of the world's installed battery capacity, which is due to the support of national policies and the continuous accumulation of domestic companies' own technology.
Today, the low-end models of the domestic Model 3 are equipped with lithium iron phosphate batteries provided by CATL, but in fact, Tesla does not produce batteries itself, just like the Xiaomi SU7.
Therefore, the mainland has long been far ahead in the research of battery technology, but Sony, which produced the world's first lithium-ion battery, is no longer engaged in batteries, and the future trend of global batteries has to depend on my flower family!
China's batteries are far ahead
In the past two years, battery technology has continued to make breakthroughs, and solid-state batteries are one of them, whose energy density is significantly higher than that of traditional lithium batteries, and there is no risk of electrolyte combustion.
The team of academician Chen Liquan of the Institute of Physics of the Chinese Academy of Sciences has been deeply engaged in the field of solid-state batteries for decades and has achieved a series of achievements, but all-solid-state batteries still face many problems, such as the solid-solid contact between the electrolyte and the electrode interface. If all-solid-state batteries are actually realized and mass-produced, perhaps the safety and range of electric vehicles will no longer be an issue.
Let's wait and see......
Edit: TT