BMW's visit to Nanshan Battery was more grand than Cao Yang imagined.

President of Asia Pacific Region Phillips, General Manager of Huaxia Branch and General Manager of BMW Huacheng, Executive Vice President, Deputy General Manager, Director of R&D Center, Director of Technology Department, Director of Purchasing Department of BMW Huacheng ......

A group of more than a dozen people came to Nanshan Battery.

This level of attention is absolutely needless to say.

However, the more BMW pays attention to it, the more it shows that this time people are serious.

Otherwise, everyone has so many meetings every day, where do you have time to fly over and visit your factory?

"Mr. Cao, I've heard of the name for a long time, and we finally met today."

Phillips speaks Chinese very authentically, if it weren't for the appearance that you can see at a glance, you wouldn't know that this is a foreigner.

"Everyone is welcome to visit Nanshan Battery, and we are very much looking forward to more in-depth cooperation with BMW."

"In recent years, with the development of China's economy, there are more and more wealthy people, and the sales growth rate of luxury cars is significantly higher than that of other cars."

"I believe that BMW's sales in China will increase year by year, and eventually become one of the world's top markets for BMW."

Cao Yang exchanged business cards with Phillips and others in the large conference room, and after a brief greeting, Lin Cheng came to the stage to personally introduce the situation of Nanshan Battery.

If you want to visit, you must listen to the introduction of the factory before visiting, and you will have a greater harvest by going to the site in a targeted manner.

Otherwise, the effect will be greatly reduced.

"Mr. Cao, I would like to ask you, now the industry is generally optimistic about lithium iron phosphate batteries, why your company is developing lithium iron phosphate batteries at the same time, but also vigorously develop ternary lithium batteries, and strongly promote ternary lithium batteries to use in passenger cars?"

After listening to the introduction of Nanshan battery manufacturers, Phillips first raised a question that many people are concerned about.

"Cobalt in ternary materials is a relatively rare metal, and the reserves on the earth are limited, which causes the price of batteries with this element to not fall."

"And lithium iron manganese phosphate, these elements are very rich on the earth, and there will be no day when they are exhausted, so from an economic point of view, so everyone thinks that you should choose the route of lithium iron phosphate batteries, right?"

Cao Yang did not answer this question directly, but followed Phillips's meaning and asked rhetorically.

"From the analysis of market demand and the general trend of national policies, since the energy of ternary material monomer can reach 180Wh/kg, and the ultimate density can reach 250~260Wh/kg, ternary materials will be the development trend of power lithium batteries in the future."

"At present, the reserves of cobalt elements used in ternary lithium batteries in China are very small, and most of them need to be imported from overseas, and the price is limited, but the reserves of related elements in lithium iron phosphate batteries in China are very rich, which is conducive to reducing costs."

"Therefore, we Nanshan Battery insists on going the two routes together to promote lithium iron phosphate battery technology in commercial vehicles."

"Promote ternary lithium battery technology in passenger cars."

"Compared with our peers, whether it is a lithium iron phosphate battery or a ternary lithium battery, we can achieve higher compaction density, lower internal resistance, and stronger output power."

"The most important thing is that in the case of meeting these requirements, the uniformity of each cell of our battery is very good."

"Even I can say with great pride that in China and even in the world, there is no one whose car battery cell uniformity is better than our Nanshan battery."

"When you go to the site, you will find that our battery production line has a very high degree of automation."

"Everything that can be solved by automation, we use equipment."

"Whether it is in terms of material formula or processing technology, our Nanshan battery has many unique advantages."

Cao Yang is still very confident in Nanshan Battery's technology.

To put it mildly, it will take at least five years for other domestic battery manufacturers to catch up with the pace of Nanshan battery.

This is enough for Nanshan Battery to completely sit in the position of the industry leader.

The most critical thing is the battery industry, the more you produce, the cheaper the cost will be.

Nanshan battery, which occupies the first opportunity, is not only advanced in technology, but also lower than other manufacturers in cost.

In this case, if others want to surpass Nanshan Battery, it will not be a little difficult.

"Compared with ternary lithium batteries, lithium iron phosphate batteries have other unique advantages in addition to cost, such as stronger thermal stability, and it is not easy to spontaneous combustion or collision and deflagration of ternary lithium batteries."

"And the cycle life is longer, the lithium iron phosphate battery will only begin to decay after the number of charging and discharging cycles is greater than 3,500 times, but the number of charging and discharging cycles of ternary lithium battery is only 2,000 times."

"How does Nanshan Battery consider the impact of this?"

The question of which one is more suitable for the technical route of the battery is still not answered within BMW.

Taking this opportunity, Phillips naturally wanted to see what Nanshan Battery's point of view was.

"Conventional electrodes can lead to the formation of an impurity called a lithium substrate during the synthesis process, and while this can be reduced by reducing the lithium content in the battery, it can also make its electrochemical properties worse."

"According to our current tests, ternary lithium batteries can fully meet the problems of safety and the number of charging cycles."

"Our company uses a special electrode synthesis method that can adjust the ratio of lithium to other metals, thereby reducing the impurities formed by the battery material during the production heating process, thereby improving the charge-discharge cycle life of the battery."

"According to the current experimental results, this technology can allow ternary lithium batteries to support 3,000 charge-discharge cycles and make their life reach 1 million kilometers."

"Of course, while we attach importance to the development of ternary lithium batteries, we have also made a lot of technological revolutions in lithium iron phosphate batteries."

"Even if it is a lithium iron phosphate battery, we can also achieve the endurance level of ternary lithium batteries from other manufacturers, this is because Nanshan battery has a unique patented design."

"In this patented design, the cathode material effectively inhibits the dissolution of sulfur and polysulfide by forming a metal sulfide shell in situ, and the capacity of the battery assembled by the cathode material coated with the metal sulfide shell can be further improved, and the cycling performance of the battery can also be significantly improved!"

"This is also an important reason why our lithium iron phosphate buses can reach 300 kilometers of range, and ternary lithium battery passenger cars can reach 400 kilometers."

Since it is necessary to attract the attention of BMW, let the other party regard Nanshan battery as the most promising battery supplier.

Naturally, it is necessary to throw out some dry goods.

Among the people who came to investigate, there were also technical experts.

After Cao Yang answered Phillips's words, someone immediately asked: "Does your company's ternary lithium battery support fast charging?" ”

Obviously, BMW is most interested in Nanshan Battery's ternary lithium battery.

It is also the most suitable battery for use in passenger cars.

However, they may feel that Nanshan Battery's ternary lithium battery can achieve a range of 400 kilometers, and some special arrangements have been made in terms of charging and discharging.

In response to this question, Cao Yang simply said directly: "Ternary lithium batteries will face the problem of battery capacity attenuation under frequent fast charging. ”

"This is mainly due to the high DC power of fast charging, and a large number of electrons continue to accelerate the flow from the positive electrode to the negative electrode of the battery during the charging process."

"The high heat generated in this process will rupture the semi-permeable membrane on the surface of the battery's anode and cause a reaction, forming foreign matter on the electrode and decomposing the electrolyte."

"Over time, the maximum capacity of the battery will slowly decrease."

"This can be solved or mitigated by technical means."

"To give a few examples, Nanshan Battery's ternary lithium battery uses fully nano-sized nickel-cobalt-manganese cathode materials to build a superelectronic network that extends in all directions, reducing the resistance of lithium ions to get out during the charging process, thereby accelerating the movement of lithium ions."

"In terms of anode material innovation, we use fast ion ring technology to modify the graphite surface, increase the lithium-ion intercalation channel and shorten the embedding distance, and build a highway for current conduction."

"In terms of electrolyte conduction, we have developed a new ultra-high conductivity electrolyte formulation, which effectively reduces the viscosity of the electrolyte and significantly improves the conductivity."

"In addition, Nanshan Battery also optimizes the ultra-thin separator to further reduce the conduction resistance."

"At the same time, we have improved the high porosity and low curvature of the separator film, which improves the lithium-ion liquid phase transport rate."

"In this way, fast charging can be achieved without affecting the durability of the battery, thus ensuring the authenticity and durability of the range."

Although the content of what Cao Yang said was relatively professional, Phillips and Aimoha and others did not particularly understand it.

However, when they saw the frequent nodding of those technical experts in their own company, they knew that what Cao Yang said was probably not simple.

The two sides communicated in the conference room for more than an hour before moving to the production site.

"A battery cell is the smallest unit of a battery system."

"Multiple battery cells form a module, and then multiple modules form a battery pack, which is the basic structure of automotive power batteries."

"The battery is like a container for storing electrical energy, and the amount of capacity that can be stored is determined by the amount of active material covered by the positive and negative electrode sheets."

"The design of the positive and negative electrodes needs to be tailored to different models."

"The gram capacity of the positive and negative electrode materials, the ratio of the active material, the thickness of the electrode piece, and the compacted density are also very important to the capacity."

After entering the scene, the work of narration was handed over to Lin Cheng.

The group came to the first process of the battery factory.

"Therefore, the pulping of active materials, that is, the mixing process, is very important, and it can also reflect the technical secrets between different battery manufacturers."

"Stirring is the mixing of the active material into a slurry by a vacuum mixer."

"This is the first process of battery production, and the quality control of this process will directly affect the quality of the battery and the qualified rate of the finished product."

"Moreover, the process flow is complex, and there are high requirements for raw material ratio, mixing steps, mixing time, etc."

"In this process of mixing, the dust needs to be strictly controlled to prevent the dust from affecting the consistency of the battery, and the level of dust control in the production workshop of Nanshan Battery is equivalent to that of pharmaceutical grade."

Lin Cheng took a microphone and started the introduction directly in English.

Although both Phillips and Amoha knew Chinese, some of the visitors did not have a high level of Chinese proficiency.

If it was passed on through a translator, Lin Cheng was worried that the information in the middle would be transmitted incorrectly, so he directly turned on the mode of English introduction.

This made Phillips and others feel the professionalism of Lin Cheng even more.

"After the mixing process, the mixed slurry needs to be applied to the copper foil, which is the second process in the production of battery cells - the coating process."

"In this process, the slurry that has been stirred after the previous process is evenly applied to the top and bottom of the 4,000-meter-long copper foil at a rate of 80 meters per minute."

"The copper foil before coating is only 6 microns thick, which can be described as 'as thin as a silkworm wing'."

"Coating is critical, and the thickness and weight of the electrode pieces need to be consistent, otherwise the consistency of the battery will be affected."

"The coating must also ensure that no particles, debris, dust, etc. are mixed into the pole piece."

"Otherwise, it will cause the battery to discharge too quickly, and even cause safety hazards."

With Lin Cheng's introduction, Phillips and the others also stared intently at each piece of equipment, wanting to see something.

Before coming to Nanshan Battery for inspection, they did not visit other battery manufacturers.

But as soon as you enter the scene, you can feel the difference between other manufacturers and Nanshan battery.

In particular, the automated production line and the particularly clean and tidy site are still significantly different from the situation of some other battery factories in this era.

According to Phillips' understanding, the Panasonic battery he once visited has this level at the site of the Higashiei Hamamatsu factory.

This made Phillips and BMW seem to pay more attention.

While Lin Cheng introduced the process, the technical experts of BMW who came to inspect also frequently asked some questions.

As long as some core secrets were not involved, Lin Cheng and Cao Yang both gave each other a relatively satisfactory answer.

For a short time, Cao Yang knew that BMW did not yet have the idea of producing its own batteries.

So there's no need to worry about them asking so many questions because they want to steal Nanshan battery's technology.

"After the coating process, the anode material on the copper foil needs to be pressed and then slit, which is our third process - cold pressing and pre-slitting."

"In the rolling workshop, the pole pieces attached to the positive and negative electrode materials are rolled through rollers, which on the one hand makes the coated material more compact, improves the energy density, ensures the consistency of thickness, and on the other hand, further controls dust and humidity."

"What we are seeing now is the cold pressing of the anode material, and the process of the positive electrode is similar."

After Lin Cheng said this, a BMW expert couldn't help but ask: "In your process, how do you confirm that the product burr after slitting can meet the requirements?" ”

"The burrs on the electrode need to be fully cleaned, and because the burrs are particularly small and need to be seen under the microscope, in order to avoid the burrs from piercing the diaphragm and causing serious safety hazards, we have adopted some unique control methods."

Lin Cheng stopped talking halfway through his words.

The other party quickly comprehended that this is probably one of the core secrets of Nanshan Battery.

"The next process is die cutting and slitting of the tabs."

"We know that the battery is divided into positive and negative poles, and the tabs are the metal conductors that draw the positive and negative electrodes from the cell.

"Die cutting of tabs is simply to make small ears with positive and negative poles, and then proceed to the next winding process."

"Here, the positive electrode sheet, negative electrode piece, and separator film of the battery are combined into a bare battery cell in a winding way."

"Nanshan Equipment is an advanced photographic inspection equipment developed separately for our factory, which can realize automatic detection and automatic deviation correction to ensure that the electrode piece of the battery cell is in good position."

"Then ......"

Lin Cheng had to stop near the equipment of each process and give a good introduction to Phillips and others.

In addition to not being able to take pictures, some of the contents involving secrets are not explained in detail, and other things are basically known.

Such an on-site visit naturally allows Phillips and others to fully feel the technological advancement of Nanshan Battery.

If just when they were communicating in the conference room, Phillips and others just felt that the introduction of Nanshan Battery was good, and they still had doubts about the technology.

Now, after visiting the factory, most of the doubts are gone.

"Mr. Lin, what tests will your battery cells do before they go offline?"

Production is important for a product like a battery, but it's also important to make sure that the parts produced meet the requirements of the drawings.

And that's what needs to be done through testing.

"Before our battery goes offline, we will check the full performance of the module, including module voltage and resistance, battery cell voltage, withstand voltage test, and insulation resistance test."

"Each battery pack contains several battery cells, integrated with connectors, controllers and cooling systems, and is packaged in an aluminium case."

"It is automatically tightened by bolts and connected by electrical connectors, even if it fails, it is only necessary to replace a separate module, and it is not necessary to replace the entire battery pack, and the maintenance workload and danger are greatly reduced, and the replacement of the module only requires the disassembly of the cooling system, and no other components are involved."

"In addition, we will also do a series of tests such as vibration test, extrusion test, crash test and so on to ensure that the battery pack meets the needs of use."

"Of course, the test items in this area can also be fully adjusted and increased according to the needs of customers."

Lin Cheng is very confident in Nanshan Battery's factory.

Along the way, he also watched the reactions of Phillips and others.

Obviously, the other party is also very satisfied with Nanshan battery.

"Mr. Lin, can you tell us more about how the extrusion test works?"

Phillips remembered that when the BMW MINI E was doing road tests in Europe, it was in a car accident, and the battery caught fire after being squeezed, which affected the listing work.

Now when I heard that Lin Cheng said that there was a squeeze test in the test project, I was immediately full of interest.

"The extrusion test is used to simulate a situation where a battery is crushed during a traffic accident, and as the degree of battery deformation increases, the positive and negative current collectors will be torn first."

"A very large current is generated at the short-circuit point, and the heat is released in a concentrated manner, causing a sharp rise in temperature at the short-circuit point, so it is easy to cause thermal runaway, which in turn can cause a fire or explosion."

"In the extrusion test, pressure will be applied until the battery pack shell is significantly deformed, the internal structure is destroyed, the battery cell is punctured by internal parts, and a high-voltage short circuit occurs, resulting in thermal runaway."

"For the passing standard of the extrusion test, it is generally no fire and no explosion."

"And Nanshan Battery's products can continue to work normally to a certain extent even in the case of extrusion deformation."

"Phillips, you see, this is our extrusion test bench, and the force that this machine exerts on the battery pack is ten tons."

"The 12-meter bus weighs 7 tons, plus the weight of passengers and luggage is close to 10 tons, which means that this can at least simulate the squeeze of a 12-meter bus when it hits."

"As for the simulation of the crush test of passenger cars, it is even more problematic."

Listening to Lin Cheng's words, Phillips breathed a sigh of relief.

This problem that I am more worried about, it seems that Nanshan battery has a good solution.

Then the cooperation between the two sides is really promising.

When the group finished visiting the production site and returned to the conference room to communicate, the atmosphere became significantly more relaxed and harmonious.

BMW people took the initiative to say that they would send various requirements of BMW for battery packs and battery cells to Nanshan Battery, so that Nanshan Battery could confirm whether it could meet all the above requirements.

As long as it is determined that Nanshan Battery can meet these requirements, BMW will issue a formal RFQ (request for quotation), and the two sides will officially enter a new stage of fixed-point cooperation.

Once Nanshan Battery's offer meets BMW's expectations, it will be possible to directly sign a strategic cooperation agreement to discuss how to supply batteries to BMW's new models.

In this regard, Nanshan battery naturally does not have any problems.

Even in the next few days, Lin Cheng arranged for a group of people to interpret and confirm the technical requirements of BMW overnight.

Hundreds of pages of content, page by page confirmation, that's really time-consuming.

However, the technical level of Nanshan battery is very high, and most of the requirements of BMW cars are relatively basic requirements.

Therefore, although there are many clauses, it is not very difficult to correspond.

Occasionally, there are one or two requests that you don't understand very well, and you can quickly solve them by communicating directly with the other party.

Therefore, less than a week after Phillips and others visited and inspected, Nanshan Battery gave its own reply to the technical requirements of BMW.

All of them can be satisfied!

There are even quite a few indicators that exceed the technical requirements!

In this regard, the people of BMW are naturally also very happy.

Not only did they immediately issue an RFQ, but they also set up a matter for further communication between the R&D personnel of the headquarters in Germany.

At this time, the news that Nanshan Battery was going to cooperate with BMW began to spread.

Some people are in a hurry.

(End of chapter)