Tesla 4680 battery in big trouble, Nobel laureate cries foul

When electrodes are coated using a traditional wet process, battery manufacturers mix the material with a toxic binder solvent. Once the coating is complete, the electrodes are dried in large ovens, where the toxic solvents that evaporate during the process are recovered, disposed of and recycled, all of which adds to the cost.

The dry coating process is different. In this technology, the electrodes are coated using a different binder and almost no liquid is used, so they do not need to be dried. This means it's cheaper, faster and less damaging to the environment.

For its part, Tesla has said that the process has helped it cut costs by a third and slashed the factory's footprint and energy consumption to one-tenth that of the wet process.

In theory, the process does smell good, but the reality is quite boneheaded.

In 2019, Tesla acquired Maxwell Inc. for $235 million through a stock sale. The latter has developed dry electrode technology and a dry coating process for its supercapacitors.

It is understood that Maxwell's dry electrode technology and dry coating process can not only improve the range of electric vehicles, but the technology can also significantly simplify the manufacturing process, manufacturing costs can be reduced by 10 to 20 percentage points, and can also increase the energy density of the battery by at least 20 to 30 percentage points.

But the power cells used in electric vehicles are difficult to produce in large volumes with quality assurance using a dry coating process because they are larger and thinner.

"They can do small production runs, but once you ramp up production you run into very many problems, too many." An expert close to Tesla commented this to Reuters.

The experts said that because the production volume is so small, the cost savings that the process was supposed to bring simply cannot be realized.

The battery experts analyzed that the cost of the Model Y, which is currently equipped with a 4680 battery, can only be reduced by $2,000 to $3,000 (about $13,956 to $20,934). This figure is only half of what Tesla announced at the 4680 battery launch.

And the savings of more than two thousand dollars, mainly because the battery is bigger to achieve.

Tesla originally needed to use 4,400 2170 cells to power the Model Y, meaning workers needed to weld 17,600 points (4 solder points per cell) to assemble a battery pack.

With only 830 4680 cells, and only two solder joints per cell, the number of solder joints has been reduced to 1,660, a significant cost reduction. And the simpler design also means fewer connectors and other components, which allows Tesla to make further savings in labor costs and machine time.

And if the dry coating process can be mass-produced, it could reduce the cost of the 4680 battery pack in the Model Y by $5,000 to $5,500 (about half the cost of the $38,379) - half the cost of the 2170 battery.

In February, autoevolution reported that the 4680 cell yield in Tesla's California factory was still low, and that this could affect the quality of the battery, citing a blogger.