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In 2019, Tesla acquired Maxwell Technologies, a company that claimed to have invented a dry coating process for making supercapacitors. Tesla wasn’t interested in supercapacitors; it wanted the rights to the dry coating process so it could make its planned 4680 batteries cheaper. The traditional way of manufacturing electrodes for lithium-ion batteries involves mixing a powder containing the active materials with solvents and other chemicals to form a paste, which is applied in a thin layer to the carrier film. The electrodes are then dried in very large ovens, an energy intensive and very expensive process. With dry coating, that is no longer necessary, nor are the costly ovens and the factory space needed for the drying operations.
According to Chinese news source Late Post, Elon Musk wants to mass produce the first 4680 cells with dry coated electrodes before the end of 2024 and use them in customer vehicles. If this does not work, Tesla could give up on its 4680 cell. It says the 4680 cells that Tesla is currently installing in the Cybertruck are kind of a hybrid — the anode is dry coated, but the cathode is not. Tesla reportedly still buys them from suppliers such as LG, where they are coated using the classic wet process.
The production of cathodes with dry coating is the most difficult part, but also the biggest lever for reducing costs. Even though there are currently still challenges in transferring the production process to cathodes, according to one confidential source, it could give Tesla a “serious boost” if the process could be mastered. However, the cell has reportedly not yet reached the level of performance and cost Tesla had hoped for.
Dry Coating Progress By Year’s End
According to a report by The Information, Musk is said to have asked the battery team to reduce costs by the end of the year and to develop “one of the most important innovations” by then — probably referring to the dry coating of the cathode. The Information says three informants contributed to its report and two of these people also stated that Musk may give up on the cell if the problem is not resolved by the end of the year. However, that is not certain and would only affect Tesla’s own production of 4680 cells. It would not mean the end of 4680 cells in Tesla models. The manufacturer could still buy the cells from suppliers such as Panasonic, but it remains to be seen at what cost if dry coating is not a viable option.
When the Maxwell Technologies acquisition took place, Dr. Maximilian Holland wrote that Tesla’s cell costs were around $100/kWh. The Maxwell dry battery electrode manufacturing technology was expected to lower battery production costs by 10 to 20 percent compared to traditional wet electrode manufacturing techniques. Those savings, if realized, would pay for the acquisition of Maxwell Technologies in just a few years. Time savings and environmental benefits also provide significant potential gains, together with a number of other performance benefits that Maxwell hinted at and Tesla is no doubt interested in. These include an energy density of 300 Wh/kg with a path to 500 Wh/kg.
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Manganese Cathode Progress
There are also reports that Tesla succeeded in developing cathodes with a high manganese content. Manganese-rich cathodes are cheaper than materials with a high nickel content, for example, but their cycle stability was so low that they could not be considered for use in electric vehicles. The doped, manganese-rich cathode active materials, for which a patent application has now been filed, could have extended the service life of such cells. However, only 94 per cent of the original capacity has been achieved after 50 cycles. Although this is better than previous manganese cell chemistries, it is still well below the level required for electric cars.
According to a research paper published by the journal Nature in February of this year, lithium- and manganese-rich layered oxide materials (LMRO) are recognized as one of the most promising cathode materials for next-generation batteries due to their high energy density. Both transition metal cations and oxygen anions are involved in the redox reaction, which enables a specific capacity larger than 250 mAh and an average discharge voltage of 3.6V. However, the redox of lattice oxygen leads to the formation of localized defects, oxygen loss in the form of gas release from the surface, and migration of TMs, resulting in low initial Coulombic efficiency, rapid capacity fading, and voltage decay. Therefore, practical applications of LMRO need to solve these drawbacks and meet waste management challenges at the end of the device’s useful life.
These are the sorts of obstacles Tesla engineers are trying to solve, with Elon looking over their shoulders and breathing down their necks. They no doubt are keenly aware of what happened to their colleagues at the Supercharger team a few weeks ago. Unfortunately, innovation seldom arrives on schedule, no matter how emphatic the boss might be.
Elon Remains Optimistic
Two weeks ago, Zachary Shahan wrote that in the Q&A session after the company’s annual meeting, Musk said, “And we’re also innovating a lot in battery production with the 4680 that’s built right here. It is — it’s a hard problem, you know, like there are entire companies that just make battery cells. That’s all they do. But we’re making good progress. All the Cybertrucks that you see use the 4680 cell. And we have a clear path to the 4680 being, we think, probably the most competitive cell from a manufacturing efficiency standpoint.”
Musk added, “We’re making steady progress, and we also have the cathode refinery, which you can see behind the main factory. So, you can sort of see in the picture there: that’s the cathode refinery. And then we’ve got the lithium refinery in South Texas. So, we’re just kind of making sure we’ve got the pieces of the puzzle.” It is notable and impressive that Tesla is engaged in its own cathode and lithium refining, Zachary said. Musk continued, “If you were to look at sort of a video of how Tesla does, say, cathode and lithium refining, and how the rest of industry does it, it’s night and day. I mean, you can sort of eat off the floor in the Tesla refinery, and I would not recommend doing so in the others.”
The Takeaway
There is always plenty of speculation about what is going on at Tesla, but hard information is difficult to find. It appears in this instance that the dry coating of cathodes is not progressing as quickly as hoped and that until that conundrum is addressed, the full benefit of the vaunted 4680 battery cells may remain unrealized. Does Tesla have a fallback position? “We’ll see,” said the Zen master.
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