Independent testing shows the 4680 batteries have more cobalt and a lower energy density, but a simple fix would make the Tesla cells more efficient than those of rivals.
A joint study by UC San Diego and The Limiting Factor, a science and technology YouTube channel, has unearthed interesting data about Tesla's 4680 battery cells.
Jordan Glesige, the man behind the channel, purchased a used 4680 cell that formed part of a Tesla Model Y battery pack. With just 420 miles, the $800 cell is as close to new as possible. The analysis from UC San Diego shows the 4680 cell - produced at Giga Austin - has a nominal energy density of 244 watt-hours per kilogram. The usable figure is even lower, at 230 Wh/kg.
That's significantly less than the Panasonic 2170 battery, which has a nominal energy density of 269 Wh/kg and a usable density of 255 Wh/kg. The 4680 cells can't match the LG 2170 (used in Chinese-made Long Range models), which has a nominal energy density of 252 Wh/kg and a usable figure of 238 Wh/kg.
However, that's not all UC San Diego found when examining the battery cell. Researchers found the 4680 battery has more contains more cobalt than comparable batteries. "The Tesla cell uses much more cobalt and less nickel. This is an area where Tesla will need to improve in the future," explains the presenter.
"Cobalt [has a] lower energy density than nickel, is more expensive, and carries more public relations risk." The last point refers to the heightened risk of electric vehicle fires, which can quickly spiral out of control and prove difficult to extinguish.
It's not all darkness and gloom, however. Should Tesla redesign the battery to use silicon in the anode, the adjusted energy density would increase to 280-292 Wh/kg. "The 4680 [cell] has greater potential energy density when it starts using even a small amount of silicon."
The video above goes into greater detail and is well worth the watch if you're fascinated by battery technology.
4680 batteries have been pushed into the spotlight for several reasons. The larger cells are cheaper to produce and should, therefore, reduce the cost of electric vehicles. And according to some Tesla owners, these batteries charge faster too.
There are drawbacks, though. Due to the tabless design, the 4680 cells are susceptible to contamination. Fragments could work their way into the battery pack and cause short-circuiting. It's also tougher to keep these batteries cool.
BMW is developing a similar battery setup for its future models. The German automaker says its similarly-sized cell will have more silicon on the anode side and a greater nickel content on the cathode side, with less cobalt. All in all, this will provide a 20% improvement in volumetric energy density.