4680 Is Coming

2020 Tesla battery day release 4680 cells. Panasonic, LG, Samsung, EVA, Ningde Time and other battery companies have invested in research and development. 4680 is expected to become Tesla's main battery cell, driving the development of the related industry chain. 4680 adopts new technologies such as large cylindrical, full pole lug, dry electrode, etc., which significantly improves energy (5 times more than 2170 battery) and power (6 times more than 2170 battery). In addition, it reduces the cost of battery (14% compared to 2170 battery), optimizes the heat dissipation performance, production efficiency, charging speed, energy density, cycle performance, etc.

The full lug significantly reduces internal resistance, improves power, safety, fast charging performance, and doubles the required laser cutting process. Conventional batteries have only two lugs, one for the positive terminal and one for the negative terminal. 4680 batteries have full lugs (lugs cut out directly from the positive/negative terminal), which greatly increases the current path and shortens the lug spacing. This significantly reduces the internal resistance and increases the multiplier type. Since the number of lugs is much higher than conventional designs, more laser cutting processes are required.

Advantages of 4680:

The 4680 large cylinder has better adaptability with high nickel, stimulating the development of high nickel industry chain. Lithium iron material has lower price and higher safety performance, continuously squeezing the market share of ternary material. Large cylindrical cells have better adaptability with high nickel, and Tesla adopts high nickel NCM811 cathode material, which helps to enhance high nickel market share.

4680 large cylindrical and silicon cathode better adaptability: silicon cathode theoretical maximum battery capacity up to 4200Wh/kg, much higher than the graphite 372Wh/kg. tesla first generation 4680 cells do not use silicon cathode, because tesla's first foray into the field of battery cells, not using very radical design.

1. cylindrical battery development history review

Sony: the earliest inventor, eventually withdrew from the industry. 1992 invented lithium-ion batteries, once introduced to ultra-high energy density crushed the traditional nickel-metal hydride batteries. 1994 Sony became the largest laptop manufacturer Dell's battery supplier. 2006 a meeting on Dell laptop fire, Sony recalled 10 million batteries. And then the rise of South Korea and China battery manufacturers, Sony is deep in the loss mire. 2016 sold lithium business.

Panasonic: mutual achievement with Tesla. 1994 research and development of lithium-ion batteries, 1997 Toyota Prius using Panasonic cylindrical 18650 battery, 2008 acquisition of Sanyo Electric, and supply Tesla Roasder. 2010 transformation of power batteries and shares in Tesla, 2014 U.S. factory, and Tesla mutual achievement.

LG: Tesla has a high moment. 1999, mass production of 18650 batteries, but only in 2019 to enter the supply chain of Tesla.

SDI: big company with small business. 1999, the largest capacity 1.8Ah battery in the mass production industry, once held a dominant position in the notebook market, but has been hesitant in the power battery.

2. square battery development history review

SDI: the former leading square battery. 1999 developed a square power battery, in 2009 became a BMW power battery supplier, in 2016 due to China's white-list policy, turned to the European layout, lithium battery business in the company's revenue accounted for a relatively low.

CATL: the biggest beneficiary of subsidy policy, the rise of trillion leader. 2011 cooperation with BMW, independent out of specializing in power batteries. 2014 due to subsidy policy shipments increased sharply, in 2014 turned to research and development of high energy density ternary materials. 2016 white-list policy as well as subsidy policy tend to high energy density materials, shipments breakthrough.

BYD: The company was established in 1995, the fourth largest cell phone battery shipped worldwide in 1997, entered the automotive field in 2003, developed F3e pure electric car in 2006, mass-produced pure electric bus in 2009, mass-produced pure electric passenger car e6 in 2010, benefited from the subsidy policy and became the leader in China. 2016 subsidy policy tends to ternary materials, and BYD does not supply batteries. In 2016, the subsidy policy favors ternary materials, and BYD does not supply batteries, so the volume of shipments is decreasing, and in 2020, blade batteries and DMI models will be released, and the market share will continue to rise.

3. soft pack battery development history review

AESC: the early king. established in 2007, focusing on lithium manganate technology route. 2010 equipped with AESC's classic Nissan Leaf market, creating a 9-year quality story of zero battery safety accidents. 2017 because of lithium manganate advantage is no longer, AESC is no longer the exclusive supplier of Leaf, acquired by Vision in 2019.

LG: soft pack battery set master. LG entered the power battery market in 2009 after years of precipitation in cell phone batteries. The first model for the Hyundai hybrid, 2010 supporting the Chevrolet Volt, 2017 Chevrolet Volt and Bolt sales exceeded 50,000 units, 2018 and VW cooperation to develop MEB, LG soft pack battery reached its heyday. 2021 Hyundai and GM recall due to battery safety issues, VW battery day announced the choice of square standard cells, soft pack battery suffered a setback.

Judging the technical route must be evaluated from the perspective of the system/whole vehicle, and the advantages and disadvantages of individual cells cannot be extrapolated to the system. High energy density of the cell is not the same as high energy density of the system. The energy density of soft pack cells is high, but the weight of the structural parts of soft pack batteries at the system level is much higher than that of hard-shell batteries, making the difference in energy density at the system level not significant. Good cell safety is not equal to good battery system safety. The heat dissipation path, fastening status, and high-voltage connection of the cells in the battery pack will affect the thermal runaway protection effect. Soft pack batteries have better safety performance than hard shell batteries at the cell level, but the system level protection is also very difficult and costly, and there is no significant advantage overall.

The cylindrical battery production process is the simplest and most efficient among the three packaging methods. The main production processes include: dosing, coating, laminating, die-cutting, winding, welding, and other processes.

The difficulties in the production process of 4680 all-ear cells are:

• Die-cutting: When the all-ear cell is coated with poles, an empty foil area is reserved at the edge of the collector fluid. After roll pressing and slitting, the empty foil area at the edge of the collector is cut into multiple lugs and then wound. Laser-cut pole lugs have the following problems: (i) the pole piece tends to jitter when cutting; (ii) the problem that the scrap cannot be discharged effectively after cutting; and (iii) the length and number of die cuts are much higher than those of conventional pole lugs.

• Kneading: In the manufacturing process of 4680 cylindrical battery, the whole lug of the battery core needs to be kneaded, and then welded with the pole plate after the section of the battery core is flat. There are a lot of difficulties in the kneading process: ① when the kneading speed is too fast, the pole piece will turn out ② when the kneading speed is too slow, the production efficiency is low ③ when the kneading level produces more metal chips, resulting in internal short circuit ④ live material shedding and other problems ⑤ friction generates a lot of dust ⑥ produces lug folds.

• Welding: 4680 battery lug welding due to the increase in the number of lugs makes the welding volume increased. The midway process of core welding generally includes lug welding (including pre-welding), spot welding of the pole belt, pre-welding of the core into the shell, sealing welding of the shell top cover, sealing welding of the liquid injection port, etc. The welding circumference and time increase, the full pole lug and collector fluid have limited white space, there is a thermal buildup effect, which will affect the consistency, and the welding process is prone to thermal buildup.

• Die-cutting: Through the slitting machine, the milled pole rolls are slit into the width required for cell production according to the actual demand. 4680 cells are formed by cutting the lugs directly on the empty foil, which puts forward higher requirements for laser cutting accuracy, speed and quality for high-speed production equipment.

  
  

4680 all-ear battery part solution:

• Die cutting: Die cutting the positive and negative full lugs into multiple parallelogram lug monoliths, which not only can prevent the lug from turning out during the kneading process, but also cannot scratch the inner wall of the battery shell when assembling with the battery shell; and can reduce the generation of metal chips to avoid short circuit; at the same time, this parallelogram structure can effectively reduce the roller pressure when kneading, thus avoiding the shedding of active material and greatly improving the yield rate.

• Kneading: Kneading process varies greatly from manufacturer to manufacturer, and the patent CN11356039A shows that the kneading sleeve is applied to the outer sleeve of the full pole lug. The flattening head approaches the flattening sleeve while rotating, and after contacting the flattening sleeve, it will directly rotate on the flattening sleeve, and drive the elastic deformation of the flattening sleeve to transfer the rotating force to the full lug to complete the flattening; since the flattening head no longer directly contacts the full lug, it can effectively prevent the full lug from being partially crushed, thus eliminating the impact on product quality and better improving the yield rate. The patent shows that: ultrasonic kneading pre-treats the end face of the core with ultrasonic waves, and then performs mechanical kneading. The ultrasonic kneading includes an ultrasonic kneading head set at both ends of the core, and the ultrasonic kneading head has a groove, and the two ends of the core are inserted into the groove of the corresponding ultrasonic kneading head. The core is transported into the ultrasonic kneading unit, and the ultrasonic kneading head vibrates and kneads the two ends of the core to achieve a flattening effect and improve the compactness of the core ends in preparation for subsequent mechanical kneading. The mechanical kneading head is a ceramic kneading head. The mechanical kneading head rotates and squeezes the core to flatten it. CN213878154U patent chooses to apply insulating material at the edge blank after coating, and the insulating material is at the same level as the active material, so that the collector forms a complete plane after winding, without the need for kneading.

• Welding: Pole lug welding is currently usually performed with a laser. Precise adjustment of welding speed, welding depth, welding width and other advantages to adapt to the welding of different materials and products, to achieve precise welding, more reliable quality and neat appearance.

The above problems are expected to be alleviated, we believe that 4680 will accelerate the column share increase:

1) increase in quality supply: white list liberalization, trillion leading entry. 21 June 2019 "automotive power battery industry specification conditions" officially repealed, meaning that China's power battery market is officially open to foreign battery companies, LG, Panasonic, etc. can provide quality cylindrical batteries for the Chinese market. Domestic Ningde Time and YIWI Li-energy have already invested in 4680 cylindrical battery research and development, and the companies that have publicly expressed their commitment to 4680 battery research and development include: Tesla, LG, Samsung, SDI, CATL, YIWI Li-energy, etc.

2) Lower number of batteries, lower integration difficulty: Tesla is now using 4416 21700 batteries, and will use 960 4680 batteries in the future, so the threshold of system integration is significantly reduced.

3) Increased capacity and reduced cost gap: The capacity of 4680 cylindrical batteries is 5 times higher than that of 21700 batteries, combined with high production efficiency and high yield of cylindrical batteries, higher nickel content of cathode material and more silicon cathodes, the cost gap between 4680 batteries and square batteries is reduced.

4) BMW is the first to switch to cylindrical batteries: Cylindrical cells will be used in the battery system of BMW Gen6. As CATL's borer, BMW had steadfastly chosen the square battery technology route, and now it is taking the lead to switch to the cylindrical battery technology route, which will surely have a profound impact on other car companies.