Three years ago, Tesla acquired Maxwell Technologies, which specialized in the production of advanced ultracapacitors. But Tesla didn’t buy the company because of that. Maxwell was bought because of its dry cathode expertise, knowledge necessary to produce the 4,680 battery cells that Tesla planned.
This technology allows Tesla to eliminate the more complex and expensive wet painting process used in traditional battery cells, such as the 2170 cells that Tesla has used for years. This process is expensive as it needs a significant amount of electricity, machinery, factory space, time and a large number of workers.
To coat the electrodes in the wet process, battery manufacturers mix materials with toxic binder solvents. Once the electrodes are coated, they are dried in massive dryers with toxic solvents that evaporate during the process and are regenerated, treated and recycled. Thanks to the new technology, the electrodes are coated with various binders that use much less liquid. This means that it does not need to be dried, making the whole process cheaper, faster and less harmful to the environment. Due to its simplicity, the process allows Tesla to cut capital expenditure by a third and reduce both the factory’s footprint and its energy consumption to just 10% of what is needed for the wet process.
Increasing the production of the 4680 is challenging
Reuters says he’s spoken to a dozen experts with insight into the manufacturing process for Tesla’s 4680 cells. Nine have close ties to Tesla, and three of the nine have explored new and old Tesla battery technology inside and out through teardowns.
“They can produce in small volume, but when they started high-volume production, Tesla ended up with a lot of scrap, too much,” one of the sources said, adding that production yields are so low that all the expected cost savings from the new process failed to materialize — yet. Sources say Tesla is only halfway to its goal of producing larger battery cells in the quantities it will need to meet its future production goals.
Maxwell developed its dry coating process for ultracapacitors, and the problem with coating electrodes for EV batteries is that they are much larger and thicker, making them difficult to coat with consistent quality at mass production speeds.
The payoff for the 4680 is less expensive batteries
If all the potential efficiencies of dry coating and larger cells are realized, manufacturing costs for the Model Y’s 4680 battery should drop to $5,000 to $5,500 — roughly half the cost of the 2170 pack, sources said. Reuters. However, the rising costs of battery materials and energy pose a risk to these predictions, and Tesla has not yet been able to significantly improve the new battery’s energy density or the amount of energy it contains.
That’s because the dry-coating technique used to make the larger cells in the Tesla 4680 battery is so new and unproven that the company is having trouble scaling up production to the point where large cost savings are realized. “They are not ready for mass production,” said one expert close to Tesla. Still, the savings Tesla is expected to achieve will ultimately make the 4680 battery “best in class” for the foreseeable future, one of the sources said.
The 4680 cells are 5.5 times larger in volume than the 2170 cells. Tesla needs about 4,400 of the 2,170 cells to power the Model Y, and sources say 17,600 points need to be welded — four per cell — to create a package that can be integrated into the car. The 4680 battery for the Model Y only needs 830 cells, and Tesla changed the design so there are only two welding points per cell. With only 1,660 welding points needed, the cost of battery packs with larger cells should be significantly lower. The simpler design also means there are fewer connectors and other components, allowing Tesla to further save on labor costs and machining time.
The larger cells also have a stronger outer casing that allows them to function as a structural part of the car. This eliminates the need to bundle cells into modules that are then installed into a traditional battery pack. Sources said this “cell to vehicle” design means Tesla can reduce the weight of a traditional 1,200-pound battery by about 55 pounds.
That might not seem significant, but one source claimed that fact alone could save about $500 to $600 per car. Overall, the expanded use of the 4,680 cells is expected to halve battery costs for the Model Y and allow the company to cut car costs by 8%, according to people with direct knowledge of Tesla. operation.
Investors see Musk’s promised improvements in battery cost and performance as critical to Tesla’s bid to usher in an era where it can sell a $25,000 EV at a profit and have a better chance of reaching its 2030 goals. Read more. Battery systems are the most expensive single component in most EVs, so making cheaper, more powerful packs is key to making affordable EVs that can compete with their internal combustion engine rivals.
Sources predict that Tesla will struggle to fully implement the new dry coating manufacturing process by the end of this year, as Musk previously predicted. They suggest that 2023 is a much more likely timeline. Stan Whittingham, co-inventor of lithium-ion batteries and 2019 Nobel laureate, said Reuters Elon Musk was overly optimistic about the time frame for the commercialization of the new technology. “I think he’ll work it out, but it won’t be as fast as he’d like. It will take some time to actually test it,” he said.
Half way there
So far, according to experts, Tesla has only been able to reduce the cost of the Model Y battery by $2,000 to $3,000, about half the savings Tesla projected for the 4680 battery when it was unveiled two years ago. The savings achieved are mainly due to the design of the new 4680 cells, which are larger than those in Tesla’s current 2170 battery. The rest will come from solving the problems of dry coating production.
Based on the technology it acquired when it bought Maxwell, Tesla began manufacturing 4,680 dry cells this year, first in a pilot plant near its Fremont, California manufacturing facility and more recently at its new global headquarters in Austin, Texas.
“Enlarging the battery cell has done a lot to improve efficiency, but pushing for a 50% cost savings on the cell as a whole is another matter,” said one of the sources. “This will depend on whether Tesla can successfully deploy the dry paint process at the factory.” The Tesla faithful are betting that Musk and his band of merry pranksters will figure it out sooner rather than later, and when they do, it will be another leap forward for Tesla and keep it at the forefront of the EV revolution.
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