For Jagdeep Singh, the CEO of QuantumSpace, the matter is absolutely clear: The current market share of electric cars is only two percent because the batteries are still too bad and too expensive: Too little range, not durable enough, too slow to charge and, in some cases, too flammable.
Singh believes normal improvements in current technologies are not enough. In his opinion, a quantum leap is needed. He believes this can only be achieved with new technology. QuantumScape’s credo: “The Future is solid” makes it clear which: Solid-state batteries.
Solid-state batteries with high potential
Battery researchers have long considered them to be the ideal solution because they make possible what has been the high potential of lithium batteries from the very beginning: the accumulation of pure lithium at the anode (negative pole). Maximilian Fichtner, Professor of Solid State Chemistry at the University of Ulm and Deputy Director of the Helmholtz Institute Ulm for Electrochemical Energy Storage, explains it this way: “The solid electrolyte is actually an aid. It is supposed to make the structure made of graphite on the negative pole side superfluous; you could then replace it with pure lithium. Indeed, the storage capacity of pure lithium is 2860 mAh/g. In current anodes, in which graphite stores the lithium, only 370 mAh/g is possible. This means that we are currently losing a factor of 8 on the negative pole side, as it were for safety reasons.
Graphite has been used so far “because pure lithium in a liquid electrolyte forms needle-like structures on the surface when it is repeatedly deposited and released. These so-called dendrites grow into the cell, piercing boundary layers. This causes short circuits, the cell becomes hot, the electrolyte evaporates, the battery bursts and begins to burn. With the ceramic layer of the solid electrolyte, it is hoped to have a mechanical barrier against dendrite formation, and the negative pole side could be massively improved as described,” Fichtner said. In addition, solid (ceramic) electrolytes do not burn.
Anode without anode material
According to Singh, the QauntumScape cell does not require any lithium at the anode at all; previous lithium anodes have always required additional lithium instead of graphite, which does not absorb or release any lithium ions but only serves as a buffer. The difference in volume of the anode during charging and discharging must apparently be compensated for by the new electrolyte. Although it is ceramic, it is flexible. In a photo in the presentation, you can see how pliable the layer is.
The big secret of the QuantumScape cell is in the interface between the electrodes.
Jagdeep Singh also points out in his Dec. 8, 2020 presentation that without graphite and additional, “unproductive” lithium at the anode, a massive improvement in volumetric energy density is possible: while current lithium-manganese-cobalt (L-LMC) cells are around 500 Wh/l and nickel-Rich cells are 700 Wh/l, QuantumScape aims to achieve 1000 Wh/l. For e-cars, in which the batteries currently occupy the entire area between the axles with a height of 12 to 15 centimeters, this is a giant leap forward.
QuantumScape sees the gravimetric energy density of the new cell at about 400 Wh/kg, while current Li-NMC (nickel-manganese-cobalt) cells are about 250 Wh/kg and even the emerging nickel-Rich cells or those with silicon are unlikely to exceed 300 Wh/kg.
By the way, the materials at the cathode (currently lithium-manganese-cobalt or nickel) do not play a role in the representations of QuantumScape – they are not even described in detail, but only as lithium metal. The big advance is the ceramic material of the electrolyte – which of course is not described in detail for a good reason.
No material at the anode except lithium – when it accumulates during charging.
Problems of the solid state battery solved?
The problem with solid electrolytes: Ions tend to migrate sluggishly in them, charging takes a correspondingly long time. In addition, says Professor Fichtner: “If the battery expands or shrinks a little, a liquid can follow suit, and the surfaces always remain wetted. With solid electrolyte, there is a risk that the surface contact breaks off, and then there is no longer any charge transport.” That’s also why solid-state batteries have worked well so far, especially at high temperatures (200 degrees); but excessive heating made a battery less efficient.
QuantumScape now claims to have solved these problems and published the test results of a single-layer prototype. It is said to
can be charged from 0 to 80 percent in 15 minutes
have a capacity of 80 percent even after 800 cycles
and promises an increase in volumetric energy density of 50 to 100 percent compared to current lithium-ion batteries.
From the 800 cycles, QunatumScape infers 240,000 miles (386,000 kilometers) of life, so it calculates a range of around 490 kilometers per cycle. If volumetric energy density were actually doubled, VW’s ID.3 (current maximum range 550 kilometers) could carry electrical energy in its battery box for more than 1,000 kilometers of range and the battery would still be considerably lighter.
To substantiate the seriousness and scope of the results, QuantumSpace presented the findings to renowned experts, including Jeffrey Brian Straubel, who sits on QuantumScape’s board of directors. The 45-year-old is a co-founder and longtime CTO of Tesla. Elon Musk said of him that had he not met him for lunch in 2003, Tesla would not exist. Straubel left the U.S. manufacturer in 2019, where his responsibilities included evaluating partners and suppliers as well as key technologies, including batteries. Straubel started his own business in battery recycling and teaches at Stanford on “Energy Storage Integration.”
He is enthusiastic about the results of the QuantumScape tests. He said he was particularly impressed with how QuantumScape solved the lithium coating, allowing the cells to work well at low temperatures and charge so quickly. Straubel calls 50 percent more volumetric energy density an incredible breakthrough in light of increases in the order of a few percentage points seen in recent years. As a result, he even believes that the QuantumScape battery could open up entirely new possibilities, such as electric aircraft.
Platforms and kits: How VW builds its e-cars
At the end of the presentation, Frank Blome, head of VW’s Center of Excellence for Battery Cells in Salzgitter, also congratulated the team and confirmed that they had already tested QauntumScape cells there as well. The results were very promising, he said. VW believes that the new cells are the beginning of long-range car batteries with great fast-charging capability.
Challenge of series development
Despite all the enthusiasm, QuantumScape also believes there is still a long way to go, albeit a viable one now: they need to develop the single-layer prototype into a multilayer cell and on to mass production. And this is where VW comes in: In a partnership with the world’s largest automaker, mass production of solid-state batteries with a capacity of 20 GWh per year should be possible from 2024 to 2025.
VW has invested a total of $300 million in QuantumScape, while the battery company has already raised a total of $1.5 billion in capital to date. By comparison, VW announced in November 2020 that it would invest 73 billion in research and development over the next five years, 35 billion of which would go toward e-mobility. VW last invested the equivalent of around 165 million euros in QuantumScape in June 2020.
Has VW thus secured the super battery?
That sounds like a smart decision. If the company can indeed equip masses of e-cars with solid-state batteries as early as 2025, which could then offer 50 to 100 percent range and charging times reduced by two-thirds. Fire hazards would also no longer be an issue.
In addition, a key advantage for a mass manufacturer is that the solid-state batteries should also make them cheaper. QuantumScape claims that production costs would fall because anode material would no longer be needed and would no longer have to be processed during cell production.
Translated with www.DeepL.com/Translator (free version)