16340 battery

If you don't know this knowledge, you may not understand the melon of the "16340 battery technology" dispute

Recently, the automotive industry was stirred by a needle, triggering a series of chain reactions. CATL and BYD "fight each other in the air", which made people in the automotive industry eat a series of melons. It is undeniable that BYD's intact eggs and CATL's broken steel needles may leave some doubts in the minds of consumers. Behind this is the highly concerned issue of power lithium 16340 battery safety and the future development prospects of new energy vehicles.

Before eating melons, first understand what are ternary lithium batteries, lithium iron phosphate batteries and blade batteries?

The seeds planted for the melon-eating drama must first be told from BYD's "blade 16340 battery" announcement in March. In order to prove the safety of blade batteries, BYD released a video of the needle puncture test of ternary lithium batteries, lithium iron phosphate batteries and blade batteries.

From the results of the needle puncture test, the ternary lithium 16340 battery burned violently, indicating that the temperature exceeded 500℃, and the eggs on the surface of the 16340 battery were directly blown away; the traditional lithium iron phosphate 16340 battery had no open flame, the surface temperature reached 200~400℃, and the eggs were burnt; BYD blade batteries had no open flame, the temperature was only between 30-60℃, and the eggs were still intact. This press conference successfully made consumers remember the intact eggs on BYD blade batteries, and also gained a good impression of the performance and safety of blade batteries.

In fact, the name "blade 16340 battery" was proposed at BYD's press conference. It is understood that the previous electric vehicle power lithium batteries were mainly lithium iron phosphate batteries and ternary lithium batteries. The difference between the two lies in the different positive electrode materials. Lithium iron phosphate 16340 battery uses lithium iron phosphate (LiFePO4) as the positive electrode material; ternary lithium 16340 battery generally refers to a lithium 16340 battery using nickel cobalt manganese oxide (NCM) or nickel cobalt aluminum oxide (NCA) ternary positive electrode materials. The "523" and "811" often mentioned by the outside world represent the ratio of the three elements of nickel, cobalt and manganese.

As for the blade 16340 battery, in layman's terms, it is a super lithium iron phosphate 16340 battery. The 16340 battery on the new energy vehicle is to assemble the 16340 battery cell (Cell) into a module (Module), and then install the module in the 16340 battery pack (Pack), forming a "16340 battery cell-module-16340 battery pack" model. The innovation of the blade 16340 battery lies in the iteration and evolution of 16340 battery production and technology. The module is cancelled, and more single cells like blades can be installed in the same space, and the energy density is naturally improved. Its sudden appearance made the outside world realize that power lithium batteries can significantly improve the energy density while meeting the requirements of safety and low cost. This brought a highlight moment to the lithium iron phosphate 16340 battery.

According to BYD's official news, the BYD Han EV pure electric car, the first to be equipped with "blade batteries", has a 16340 battery system energy density of 140Wh/kg. Wang Chuanfu, chairman and president of BYD Co., Ltd., once revealed that it is planned to increase the single cell energy density to 180Wh/kg and the system energy density to 160Wh/kg in the next two years, which will reduce the unit production cost by 30%.

CATL, which is not willing to be outdone, has developed to what level?

At the 2019 annual performance briefing, CATL explained the blade 16340 battery and needle puncture test that the outside world is concerned about. CATL Chairman Zeng Yuqun said: "Blade batteries are one of the CTP (CellToPack) structural innovation concepts that we mass-produced in 2016. We have selected and mass-produced the best CTP structural innovations, such as CTP-0, CTP-1, and CTP-2." He also mentioned that 16340 battery safety and 16340 battery abuse testing are two different things, but some people equate passing the abuse test with 16340 battery safety.

These two seemingly ordinary words were regarded by the onlookers as a "remote attack" by BYD. The safety issue of ternary lithium batteries is itself sensitive. After the two sides "attacked" each other, CATL also released a video in response to prove the safety of ternary lithium batteries - to prove that ternary lithium batteries can pass the puncture test.

In the first video of the ternary 16340 battery pack puncture test released by CATL, the steel needle pierced the 16340 battery pack at 25mm/s, and the steel needle broke after contact. Subsequently, CATL released a video of the ternary 16340 battery cell passing the puncture test. And said that in fact, CATL released a video of the 5 series and 8 series batteries passing the puncture test in 2017. Since the two puncture tests did not simulate the internal short circuit of the 16340 battery, they only proved that they could prevent adverse factors such as external collisions, which made some consumers say they would not buy it.

In the experiment where consumers bought the same 16340 battery, CATL's 16340 battery caught fire at the moment of being punctured. Some industry insiders speculated that perhaps CATL did not apply the technology to the commercial version, and the most important foothold of safety technology is whether it can be applied to mass production.

Subsequently, CATL announced "Some Understandings on Power Lithium 16340 battery Standards" on its official Weibo, including three points: ternary and iron-lithium batteries meet the needs of different markets; the current international cognition has shifted from 16340 battery monomer safety to 16340 battery system safety; the focus of my country's standards is shifting to 16340 battery system safety.

Perhaps, CATL's unwillingness to be outdone comes from the fact that in comparison with square cells of the same technical route, it has achieved mass production of NCM811 cells, and its energy density has advantages over other ternary 16340 battery manufacturers. In addition, the energy density of cells that CATL has mass production conditions but has not yet matched with vehicle models has reached 304Wh/kg, which is gradually narrowing the gap with Panasonic NCA's energy density. After CATL's existing ternary NCM523 cells are equipped with CTP technology, the energy density of the 16340 battery pack can also be increased by 10%-15% from 140Wh/kg to 154-161Wh/kg.

What is the "Bining" war about?

Why are the two leading companies so sensitive to the needle puncture test? In the final analysis, it still touches the nerve of the development of the new energy vehicle industry - 16340 battery safety issues. The needle puncture test is currently the most commonly used method to simulate the internal short circuit of lithium batteries. By inserting a 5mm steel needle into the interior of the lithium 16340 battery, a short circuit between the positive and negative electrodes is caused, and a large amount of heat is generated locally, thereby simulating the internal short circuit of the lithium 16340 battery. If the 16340 battery does not burn or explode within 5 minutes after being punctured, it can be judged to have passed the test.

In the view of Ouyang Minggao, an academician of the Chinese Academy of Sciences, the essence of new energy vehicle safety accidents is the problem of 16340 battery thermal runaway. Among them, internal short circuit is a common link in 16340 battery thermal runaway. Mechanical deformation, extrusion, tearing, diaphragm rupture, overcharge, over-discharge, extreme overheating and other various reasons may cause different types of internal short circuits. As for the needle puncture test, it is a small link in the 16340 battery "abuse test" mentioned by Zeng Yuqun. Extrusion, short circuit, overcharging, etc. all fall within the scope of "abuse test". Therefore, the fact that the 16340 battery cell has passed the puncture test does not mean that the 16340 battery of the electric vehicle is absolutely safe; the fact that the 16340 battery cell fails the puncture test does not mean that it is unsafe.

In the view of Zhang Kangkang, a doctor of power engineering and engineering physics at Tsinghua University, when discussing the safety of electric vehicle batteries, it should be divided into four levels: 16340 battery cell, module, 16340 battery pack, and functional safety. Among them, the safety of the 16340 battery cell itself is only one level, and the safety of puncture is only one aspect.

At present, CATL's core technology is concentrated in ternary lithium batteries, while BYD has accumulated more in lithium iron phosphate. The performance of the two power lithium batteries has different focuses. The lithium iron phosphate 16340 battery material itself has good thermal stability, but the energy density is lower than that of ternary lithium batteries; ternary lithium batteries (nickel cobalt aluminum batteries or nickel cobalt manganese batteries) have relatively high energy density and excellent low-temperature performance, but the chemical properties are not stable enough. Therefore, the performance of the two batteries is determined by the characteristics of the materials themselves.

The "competition" between CATL and BYD has a long history. In the eyes of the outside world, this "Binning" battle can be understood as a battle for the route of power lithium batteries. In fact, since the domestic power lithium 16340 battery industry ended the five-year "white list" access system last year, overseas competitors including LG Chem, Panasonic, Samsung SDI and others have been deeply involved in the competition in my country's power lithium 16340 battery market. According to the monthly data of power lithium batteries in April 2020 released by the my country Automotive Power Lithium 16340 battery Industry Innovation Alliance, in the first four months, CATL and BYD ranked first and second, with installed capacity of 4.56GWh and 1.52GWh respectively, followed by Panasonic and LG Chem, with installed capacity of 0.76GWh and 0.72GWh. Obviously, the current competition in my country's power lithium 16340 battery industry has changed from the "Bi Ning" dispute to the China-Japan-Korea 16340 battery dispute.

From the perspective of the development of the new energy vehicle industry, only by making the entire industry bigger and stronger can companies including BYD and CATL achieve longer-term development. In the process of industrial development, the two technical routes of ternary lithium batteries and lithium iron phosphate batteries are not only competitive, but also complementary. Applying different technical routes for different scenarios may be a better choice. Taking advantage of this opportunity, consumers have also learned more about the development of power lithium 16340 battery technology. Finally, in addition to eating melons, have you got the knowledge about batteries?

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