Electric vehicles are advancing at an incredible pace, but we’re very much still in the early days. The Tesla Model S and X still use battery cell formats never imagined for use in cars. A lot is about to happen in the world of automotive batteries, though. We’re entering a new chapter of electrification, with new, ground-breaking technology already hitting the market. Most people just haven’t seen it yet.
The push toward the next generation of batteries has two schools of thought: advance current technology to new heights, or change gears completely into a new type of battery cell. Factorial, QuantumScape and Group14 are all companies with a horse in this race, and each has ideas about achieving the state of the art. All of them have partnerships with major automakers, which means what they’re doing today may have a big impact on the cars you’ll buy soon.
What’s Coming Next
Factorial and QuantumScape are developing solid-state cells. It’s still an emerging technology, and several companies beyond Factorial and QS have different perspectives on how they should work. The key attribute of all these batteries is solidifying the traditionally liquid electrolyte. A solid electrolyte doesn’t just enable advantages in a vacuum, though. It’s all about how you can change other parts of the battery as a result of solidification—mainly the anode. A better anode is key to unlocking the energy density, cost, and weight advantages of SSBs.
The anode, part of the negative electrode, is one of the primary components of lithium-based battery cells, along with the cathode (part of the positive electrode), the separator, and the electrolyte. Currently, almost all battery anodes are made of graphite; the first anode material ever used successfully in lithium-ion batteries. Graphite is near its performance peak, though, and finding a replacement is key to enhancing battery energy density both in terms of mass and volume.
Lithium is the best theoretical material for an anode because of its low weight and high energy capacity. Researchers have tried to use a lithium metal anode in conventional liquid electrolyte cells before. The experiments never left the lab. As the research paper Lithium Metal Anode: Past, present, and Future describes, crystals called dendrites formed on the anodes of these experimental cells after just a few cycles. As with all conventional cells today, the electrolyte was a fluid, and the separator was (and still is) effectively just an extremely thin piece of plastic. Neither could do much to prevent dendrite formation.
As the cell charged, these crystals penetrated the battery’s separator and shorted it out. The sort of funny part about this is that the cells were great for the few cycles they actually worked. The battery contained more energy thanks to the lithium metal anode, but because of the dendrite growth, this extra energy was just fuel on the fire when the cell inevitably shorted out, caught fire and exploded.
So these researchers weren’t really making lithium batteries in a lab. They were making little explosives that just happened to store a lot of energy.
After a lot more experimentation, the industry determined that solid electrolytes were probably the best way to prevent making rechargeable bombs. In other words, SSBs were more or less conceptualized and developed as a result of chasing an ideal anode. Most solid-state cells in development today from Factorial, QuantumScape and others like Solid Power, have lithium metal anodes.
Factorial’s founder Siyu Huang is a chemist who has been developing SSBs for several years. She said when one of her Boston-based company’s early cells achieved 25 cycles, that was a huge step. “25 cycles for a 100 amp-hour cell,” she recalled, “Everyone was so excited.” Today, her company’s batteries—of which thousands have been shipped to eager partners like Stellantis and Mercedes-Benz—are achieving over 600 cycles.
Huang was open about her cells’ capabilities, which isn’t always true for SSB companies. She claims Factorial’s automotive units achieve discharge rates between 4C and 10C, which is comparable to the conventional cells going into today’s electric cars. They operate in a slightly wider voltage range than regular lithium-ion cells and can charge from 20-80% in under 15 minutes. That’s also similar to today’s best batteries but with one huge advantage: Factorial’s solid-state packs are 40% lighter and 33% smaller than comparable batteries. Huang is excited about their potential but understands the skeptics who say the technology is still years away.
“The reason solid state hasn’t been [industrialized yet] is, first of all, the approach,” she told InsideEVs. “There are so many different types of solid state.” Indeed, Factorial has several competitors.
California-based QuantumScape is one of them. Like Factorial, it has shipped early cells to customers and is in the process of industrializing its batteries. Its CEO, Siva Sivaram, says its “secret sauce” is its unique ceramic separator. It functions like a conventional separator but also effectively replaces the electrolyte. It’s likewise non-combustible, unlike conventional lithium-ion separators.
QS’s cells are “anode-less,” meaning lithium metal flows from the cathode to a current collector on the other side of the separator every time the cell cycles. This transient lithium is effectively the anode, as compared to a conventional cell where the anode material remains on one side of the separator fixed to a current collector. QS’s batteries physically expand and contract as a result of this, but the company’s unique cell design means the unit’s outer dimensions remain relatively constant.
“We have the equivalent of the Coca-Cola formula. The ceramic separator is unique,” Siva said. “Power and energy, weight and volume-wise, these solid-state batteries with no anode, as created, are the best.”
The company has yet to release a detailed spec sheet for its cells, but it has shared some preliminary data to indicate its innovations are meaningful. Both Factorial and QS are backed by major automakers and have garnered hundreds of millions in investment. Not everyone thinks lithium-ion is dead and buried, though.
Despite the best efforts of SSB developers, dendrites still form in solid-state cells. That’s how they die. This currently limits them to hundreds of cycles as opposed to the thousands expected of many conventional lithium chemistries. They are improving constantly, but conservative automakers may hesitate to hop on the bandwagon. Right now, they are also limited to the pouch form factor, as opposed to conventional Li-ion batteries, which can be made in cylindrical or prismatic formats, as well. Every battery format has pros and cons, and being stuck in one isn’t ideal (see GM’s latest investor day presentation). “We will be trying other formats based on our customers needs,” Siva said, but SSBs will stay as pouches for now.
Conventional Competition
Rick Luebbe is the CEO of battery material company Group14, which is not making solid-state cells. Instead, Group14 is pioneering the use of high-silicon anodes in conventional lithium-ion batteries, which enables impressive energy densities and vast improvements in power density. He believes solid-state cells have a lot of potential, but his company’s technology is ready now. It’s already in consumer electronics, and it’s likely entering the world of electric vehicles within the next several months.
Group14 doesn’t make batteries; just anode materials. It delivers these in huge quantities to companies like Molicel, which use them in its cells. Creating this technology has been a long road, but it enables some unique improvements. The first is more energy, which is effectively a must for any new battery. Luebbe says improvements of up to 50% are possible, although initial figures from Molicel are more in the range of 20%. The more relevant improvement is power density, though, which came as a surprise to Luebbe and his team.
“We were able to make the silicon work, and the industry said, ‘Wow, we can get as much as a 50% improvement in energy density’, which was fantastic,” Luebbe told InsideEVs. Later, though, one of Group14’s customers, StoreDot, published intriguing figures. “They were charging their cells in sub ten minutes.”
“[High-silicon anodes] are good for energy density, but they’re fantastic for power density.”
Power density is how fast a cell can charge or discharge in the context of a given capacity. Conventional lithium-ion cells have been able to achieve high power density in terms of discharge rates, but high charge speeds are more elusive without a serious hit to energy density. As a result, today’s electric vehicles with fast charge speeds are typically equipped with large battery packs or operate at very high voltages. Both of these approaches are necessary to make up for the shortcomings of existing cells.
Group14’s partners indicate its anode material addresses this problem. Molicel’s upcoming batteries boost charging currents to nearly double that of its current state-of-the art cells, along with the aforementioned increased energy. This translates into more range and faster charging when used in an EV’s battery pack.
Intentionally aiming for less energy in a cell—optimizing for a certain attribute—can likewise push power densities into ranges never before seen in lithium-ion cells. “The new cell that [Molicel is] coming out with, the X series, boy, they’re claiming they can charge that from zero to 100% in 90 seconds,” Luebbe said. He added that Group14 has tested [existing cells/the next-generation cells] and found that they lived up to those claims.
Molicel isn’t the only one developing batteries with Group14’s anode material, either. The company’s partners are vast, and its capability to produce its current generation of silicon material, known as SCC55, is growing rapidly. Soon, its facilities will produce enough SCC55 for 30 gigawatt-hours of new battery cells per year. That’s about enough for about half a million electric cars.
Timelines
QuantumScape, Factorial, and Group14’s respective CEOs didn’t see fit to comment on each other’s technology very much. Perhaps that’s because there’s just so much nuance to any potential comparison, or perhaps because they all understand what it means to industrialize battery technologies. It’s a difficult business and, naturally, the car-buying public doesn’t often see it that way.
Their battery technology is real, though. Group14’s high-silicon anode cells will arrive in cars just as soon as an automaker can stuff them into a pack. SSBs are close behind, especially considering the typical half-decade length of automotive product cycles. Thousands of solid-state cells have already been made and are being tested by automakers. They are out of the lab and on their way to industrialization.
If you think electrification is stalling, think back to where we started. The Tesla Model S and X are still using 18650s, a cell format designed for consumer electronics. Advances up to now in EVs have been mostly architectural: Raising voltages, changing battery form factors, streamlining car bodies and hardening tires. Batteries have improved, but not like they’re about to. This change will seem like it happened overnight, but these technologies have been developing for decades. They’re just finally coming in to roost.