For QuantumScape, Solid-State Batteries Are All About Fast Charging

QuantumScape Thinks Its Solid-State Cells' Superpower Is Fast Charging 10 photos
Photo: QuantumScape
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QuantumScape has a blog where it discusses key elements of its solid-state platform. In a recent post there, the company explained C-rates and made it clear which was the characteristic it praised the most about the technology it is developing: fast charging.
1C is equivalent to completely charging a battery from zero in one hour. If it takes two hours to fully charge a cell, you get C/2. If you speed things up and fully charge it in half an hour, you get 2C. The less time you spend charging a battery, the higher the C-rate.

For QuantumScape, electric cars will only be competitive with combustion-engined vehicles when charging times will be equivalent to those people spend filling a fuel tank. Yes, you can charge your car at home at slower paces, but not everyone can do that. On the contrary: carmakers have to count that most people will do that at charging stations.

This is why the solid-state platform startup focused on achieving a high C-rate with its technology. So far, QuantumScape has been testing its cells at 1C both for charging and discharging. According to the company, its cells have demonstrated that they can retain more than 80% of capacity after 800 cycles.

Recently, an independent test performed by Mobile Power showed that QuantumScape cells retained more than 90% of charging capacity. For a car with 300 miles of range, that would be equivalent to running 240,000 miles. Considering a battery pack with up to 70% of capacity would still be regarded as fit for automotive use, it means a QuantumScape battery pack would last way more than this, even being submitted to fast charging multiple times.

QuantumScape wants its battery packs to go from low charge to up to 80% of SoC (state-of-charge) in 15 minutes. The company also doubts other solid-state cell solutions – such as those based on sulfides – can deliver the same performance. QuantumScape said it knew they couldn't because it had also tried.

That’s the same argument SES used to say it did not believe in solid-state cells but rather in a hybrid solution that is fast to manufacture and can recharge from 10% to 90% of charge in 12 minutes. SES just needs to let us know how many cycles its batteries resist doing that.

Curiously, solid-state batteries will also be more energy-dense than current lithium-ion cells. By consequence, they will also allow a much lighter battery pack for a given capacity. It is an irony that such incredible advantages are not the primary goal of solid-state cells. If we take QuantumScape’s word for it, it is all about fast charging: all the rest is just a welcome bonus to make these cells even more of a breakthrough. They can’t arrive fast enough, can they?
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About the author: Gustavo Henrique Ruffo
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Motoring writer since 1998, Gustavo wants to write relevant stories about cars and their shift to a sustainable future.
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