Autobayng News Team
- Two U.S.-based battery companies claim to have reached a breakthrough with silicon anodes.
- The anode is the part of the cell that stores electrons and impacts its energy density.
- Automakers and electronics giants are trying to reduce their dependency on graphite for battery production.
Just like cars and gadgets, battery technology evolves in phases. Sometimes you get breakthroughs, other times things get incrementally better with small year-over-year improvements.
But there’s a big breakthrough on the horizon: In the quest to squeeze more range and faster charging times out of lithium-ion cells, the battery industry has long been looking to replace graphite anodes—the part of the battery which stores electrons—with a better, more energy-dense material. Some battery companies like Group14 believe that the ideal graphite replacement will come in the form of silicon. And now, they have a pretty good proof-of-concept.
Porsche-backed Group14 Technologies has teamed with New York-based battery materials firm Sionic Energy to develop silicon anodes. The companies announced joint results on Monday, concluding that its 100% silicon-carbon anodes had achieved stable performance at high temperatures during charge-discharge cycles and storage. The anodes were tested in 4-amp hour, 10-Ah and 20-Ah pouch cells, where the companies claim the cells delivered stable performance at 45 degrees Celsius (113 degrees Fahrenheit) and 60C (140F).
Porsche Cayenne Electric battery.
Photo by: Porsche
If you’re new to the battery world, don’t worry, I’ll explain that in plain language. The anode is the part of a battery where lithium ions are stored during charging, and what they leave during discharging, when the battery is in use. The anode is essentially responsible for how much energy a cell can hold and how quickly it can charge.
Graphite has long been the staple anode material thanks to its stability and high energy density. However, mining graphite is dirty, expensive and poses geopolitical risks, with China continuing to be the world’s top graphite producer and exporter—processing over 90% of the world’s graphite as of 2023. To move away from this expensive China-centric graphite supply chain and make Western companies more independent, battery makers have been experimenting with alternatives such as silicon and synthetic, lab-produced graphite.
The anode is also the single largest component in a battery by volume, becoming the primary contributor to pack weight, according to the European Carbon and Graphite Association. A battery contains more graphite than lithium or cathode active materials (such as nickel, cobalt and manganese). Replacing it with a lighter silicon anode would not only allow battery makers to reduce pack weight, but also shrink the overall battery size without compromising energy density and range.
“I’ve spent years watching the industry chase silicon’s promise and hit the walls of complexity, cost, development time, and narrow performance,” Ed Williams, president and CEO of Sionic Energy, said in a statement. “That’s why I’m proud to share this Sionic benchmark and the Group14 partnership that breaks through those walls and accelerates silicon’s broad market adoption,” Williams added.
Rimac Technology high-voltage battery
Photo by: Rimac
The companies claim that the silicon anodes can help a battery achieve up to 400 watt-hours per kilogram of energy density, substantially more than the 200-300 Wh/kg energy density that’s common today. They also claim that the technology is “market ready” with a cycle life of over 1,200 cycles. They acknowledged some of the drawbacks of silicon over graphite, such as swelling of the electrolyte, cell expansion and irreversible capacity fade under duress. But in a white paper published online, the companies claim to have solved these issues with Sionic’s proprietary anode binder and design architecture.
Group14 claims its silicon anode can charge a battery in less than 10 minutes (depending on the size and application) and deliver 55% more energy compared to traditional packs. The anodes themselves are “drop in,” the company said, which means across cell formats and chemistries, battery makers can integrate them into any manufacturing line or cell without retooling their processes. Sionic Energy has also developed a similar drop in silicon anode, which it says will enter the EV market next year, followed by energy storage systems in 2027.
Silicon-anode batteries are already delivering blowout battery capacity on high-end Chinese smartphones that would put the latest iPhones and Google Pixels to shame, without making the phones bulky. McMurtry Spéirling Pure
That begs the question: Can the tech also deliver similar results on mass market EVs? So far, the technology has been limited to performance and high-end models. Group14’s silicon anode tech is present in the 100-kilowatt-hour battery pack of the McMurtry Spéirling, the single-seater rear-wheel-drive hypercar with a downforce fan, which can sprint to 60 miles per hour in just 1.5 seconds and run a quarter-mile sprint in eight seconds.
Mercedes-Benz said in 2022 that the G-Class with EQ Technology would use Group14 rival Sila’s silicon anodes to deliver up to 40% more energy density compared to traditional packs. The 116 kWh usable battery capacity on the electric G-Class is enough for 239 miles of EPA range, which isn’t bad for a brick-shaped SUV that weighs 6,700 pounds. Still, it’s not exactly indicative of any battery performance breakthrough. It’s unclear if Mercedes-Benz ended up deploying the tech on the production version, or if it’s coming on a future variant. The automaker did not respond to InsideEVs’ request for comment at the time of writing.
Still, given that the tech has already been commercialized in smartphones, wider rollout in EVs may not be far away. General Motors is also developing silicon anodes, with one GM executive telling InsideEVs early this year that silicon batteries will help shrink battery sizes, reduce weight and bring prices down.
So even if automakers continue to make big claims about radical solid-state technology, they’re seeing a big room for improvement on current lithium-ion tech with things like graphite-free batteries, which have the potential to make EVs longer range, faster-charging and better than ever.
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