autoevolution
Car video reviews:
 
QuantumScape Fast Charges Its Solid-State Cell More than 400 Times
QuantumScape made a strong point with its latest tests. It submitted single-layer samples of its solid-state cells to fast charging at 4C, which means doing so in about 15 minutes. After doing it 400 times, the solid-state battery startup could confirm its cells still retained more than 80% of their capacity. It even teased Tesla a bit, even if in a seemingly respectful way.

QuantumScape Fast Charges Its Solid-State Cell More than 400 Times

QuantumScape fast charged test cells 400 times at 4C and they were still okQuantumScape fast charged test cells 400 times at 4C and they were still okQuantumScape fast charged test cells 400 times at 4C and they were still okQuantumScape fast charged test cells 400 times at 4C and they were still okQuantumScape fast charged test cells 400 times at 4C and they were still okQuantumScape tested the Panasonic 2170 Li-ion cell and it lasted onlyQuantumScape fast charged test cells 400 times at 4C and they were still okQuantumScape fast charged test cells 400 times at 4C and they were still okQuantumScape fast charged test cells 400 times at 4C and they were still ok
QuantumScape tried to make sure people would not doubt the relevance of its findings. According to the white paper that it released, the tests were performed with single-layer solid-state cells made “with separators of commercially relevant areas (70×85 mm) and cathode loadings (3.3 mAh/cm2).”

The company also said that “at 4C rates, this translates to a peak current density of ~13.3 mA/cm2, which to our knowledge, far exceeds anything shown by any competing next-generation lithium-metal cell, whether based on liquid or solid-state electrolytes.” At this point, QuantumScape also teased SES, a company that said it does not believe in solid-state cells: they would be too difficult to manufacture.

According to QuantumScape, those 400 cycles would be equivalent to 160,000 miles (257,495 kilometers) in a vehicle with a 400-mile (644-km) range. However, considering the battery only goes from 10% of charge to 80%, the numbers do not seem to match. After all, the company is comparing those cycles to driving an EV from 80% until it had only 10% of its capacity left before fast charging again. In other words, you would not use 30% of its capacity between the fast charges.

That said, a battery pack with 430 miles (692 km) of range would have about 343 miles (552 km) of range when charged until 80% of its total capacity. It could run until it had 43 miles (69.2 km) (10%) left of the range to charge again, resulting in 300 miles (483 km) between each fast charge cycle. In that case, these 400 cycles would be equivalent to 120,000 miles (193,121 km).

Although these numbers are 25% lower than those presented by QuantumScape, the truth is that the company seems to be conservative when it mentions the battery retains “well above 80% of the initial energy.” Checking the graphic on the white paper it released about these tests shows that the battery lost only about 10% of its capacity, which would place it in around 90% of capacity left even after these aggressive charging sessions.

To allow us to compare what that represents, QuantumScape also tested “the cycle life performance of a cylindrical lithium-ion cell from a commercial EV under similar room temperature, fast-charge test conditions.” There’s not a single reference to which cell it was, but the graphic with the results makes it clear: it is a Panasonic 2170 Li-ion cell, like the ones Tesla still uses on the Model 3 and the Model 3.

After being submitted to the same fast-charging cycles, QuantumScape’s solid-state batteries had to endure, “the cell degrades rapidly, falling below 80% of the initial discharge energy after only a dozen cycles, and at such high rates of charge, it carries a risk of catastrophic failure (explosion or fire)."

This comparison shows why QuantumScape is so confident with its technology. The company believes cars with the commercial version of its solid-state cells should offer an experience similar to that of ICE vehicles when it comes to getting energy back.

Although QuantumScape still has to present A samples as SES did and submit them to the same tests, the results it just presented are really encouraging. We’ll keep following its progress toward a commercial solid-state cell. With the promise to start mass production by 2024, the startup still has time to pursue its goals and respect its schedule.

press release
 
 
 
 
 

Would you like AUTOEVOLUTION to send you notifications?

You will only receive our top stories