What is the reason behind the difficulty in mass production of Tesla 4680 batteries?

1. 4680 battery was introduced two years ago
2. What is dry coating technology?
3. The purpose of developing 4680 battery is partially achieved
4. China’s battery companies make arrangements in advance

Most of the manufacturing steps can be eliminated by the dry coating technology of the battery pack, thereby reducing the cost of battery manufacturing. Experts say that small batch production of 4680 batteries can be achieved, but in mass production, the quality of the product has problems due to dry coating technology.

4680 battery was introduced two years ago

Tesla said two years ago that it would launch 4680 cylindrical batteries to increase cruising range and reduce production costs to support the mass production of pure electric products such as cybertruck pickups.

The 4680 cylindrical battery has been innovated from the structure and material of the cell. In China, the cylindrical battery has been developed quite mature and there appear lots of successful manufacturers. You can click our article of top 10 cylindrical battery manufacturers in China to know what they are.

It adopted a larger shape (diameter 46mm, height 80mm), canceled the tab inside, replaced the carbon-based negative electrode with a silicon-based material, and further reduced the content of cobalt in the positive electrode. According to the layout, it will achieve mass production by the end of 2022.

At that time, the 4680 battery claimed to be able to increase the battery life of electric vehicles by 54% with the help of several new designs such as electrodeless ears and silicon-based negative electrodes, and the battery cost could be greatly reduced after combining with CTC technology. This series of strong performance indicators has attracted close attention.

The 4680 battery needs to be wet-processed on the electrode during production, and then introduced into the dry electrode technology. The specific process is to press the powdered material into a film, and then perform dry electrode coating. The process of this processing is also more complicated, and Tesla has not yet achieved mass production at that time.

But the advantage is that after adopting this technology, the difficulty of battery production operation is also reduced by 10 times. At present, the 4680 battery is indeed mass-produced, but only on a small scale.

What is dry coating technology?

According to experts, the dry coating technology allows Tesla to forgo the more complicated and expensive wet coating process. The latter is expensive because it requires a lot of electricity, machinery, factory space, and more time and labor to produce. Once coated, the electrodes are put into large ovens to dry, and the toxic solvent that evaporates in the process needs to be disposed of and recycled, all procedures that add to the cost.

Tesla acquired the dry coating technology in 2019 with the acquisition of Maxwell. Maxwell’s dry coating technology (Dry Electrode Process) forms a self-supporting film of negative or positive material by fibrillating PTFE (Teflon) mixed into active negative or positive material particles.

In this process, the negative electrode and positive electrode material films are laminated on the metal foil current collector to prepare the negative electrode and positive electrode, and the separator is wound between the positive electrode and the negative electrode to make the battery core. Crucially, Maxwell’s process makes the battery’s negative and positive electrodes solvent-free.

Traditional lithium battery manufacturing uses solvents with binder materials, and NMP (N-Methyl-2-pyrrolidone) is one of the common solvents. After mixing the solvent with the binder and the negative electrode or positive electrode powder, the slurry is applied on the electrode current collector and dried. Toxic solvents must be carefully recovered, purified and reused. And a huge expensive and complicated electrode coater is required.

It is understood that when applying the electrodes using the traditional wet process, battery manufacturers mix the material with a toxic binder solvent. In the dry coating process, the electrodes are coated with a different adhesive and almost no liquid is used, so they do not need to be dried. That means it’s cheaper, faster and less damaging to the environment.

Tesla has said the process has helped Tesla cut costs by a third and cut the factory’s footprint and energy consumption to one-tenth of the wet process. But the reality is that because the power batteries used in electric vehicles are larger and thinner, it is difficult to mass-produce them with dry coating processes with guaranteed quality.

In addition, in addition to the difficult breakthrough of dry coating technology, it is reported that industry problems such as silicon-based anodes are also restricting the mass production of 4680 batteries.

However, another kind of anode used in lithium battery is more easy to find and use. You can read our article of lithium ion battery anode to get more information. The lack of technology may be one of the factors that prevent models equipped with 4680 batteries from improving their battery life.

The purpose of developing 4680 battery is partially achieved

Although mass production is currently impossible, with the experience of small-scale production, it is still very possible that 4680 batteries can be mass-produced, but it will take time.

For example, the number of solder joints in Tesla batteries has been reduced from 17,600 to 1,660. Using the older technology, Tesla needed about 4,400 cells to make up the battery pack to power the Model Y, and 17,600 points of welding, experts say. The 4680 battery pack requires only 830 cells, resulting in significant cost savings. The simpler design also means fewer connectors and other components, which allows Tesla to further save on labor costs and machine time.

Another source of efficiency is the stronger case of the larger battery. Tesla can now use adhesive to bond the cells into a rigid SVOLT battery pack, which is then attached directly to the Model Y’s interior body structure.

China’s battery companies make arrangements in advance

According to the data, the 4680 battery production lines of battery suppliers such as Panasonic, LG and Samsung are gradually being rolled out, and Chinese battery manufacturers are also making arrangements in advance. In February of this year, it was reported that Panasonic was refurbishing factory equipment and would trial production of 4680 batteries.

Panasonic also said at the time that if the 4680 batteries could be delivered, they would be the first to be supplied to Tesla. However, it may not be until next year that Panasonic will be able to mass-produce 4680 batteries, and the relevant production lines are currently under construction.

LG also announced that it will invest 580 billion won to build a 4680 battery production line, but the production time is also next year. BAK revealed that the 4 series (diameter 46mm battery products) are currently mainly customized products, and customers can jointly develop with BAK to formulate specific battery parameters.

EVE also said that they are equipped with two large cylindrical batteries of 46800 and 430029. They will gradually market large cylindrical batteries after 2023. It is expected that the annual production capacity will reach 20GWh in 2023 and 40GWh in 2024.

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