• The buzz around silicon-based anodes, which promise improved power and faster charging capabilities for EVs, has been growing in recent months – just as the hype around solid-state batteries seems to have fizzled.
• It comes as increasing EV sales continue to drive up global battery demand, prompting auto giants to team up with major cell manufacturers on the road to full electrification.
• "If there's a horse race, silicon does seem to be ahead at least at this moment," said Venkat Srinivasan, director of the Collaborative Center for Energy Storage Science at the U.S. government's Argonne National Laboratory.

Silicon anodes appear to be leading the way in the race to commercialize next-generation battery technologies for electric vehicles.

The buzz around silicon-based anodes, which promise improved power and faster charging capabilities for EVs, has been growing in recent months — just as the hype around solid-state batteries seems to have fizzled.

It comes as increasing EV sales continue to drive up global battery demand, prompting auto giants to team up with major cell manufacturers on the road to full electrification.

While some OEMs (original equipment manufacturers) have inked deals with solid-state battery developers, carmakers such as Mercedes, Porsche and GM have all bet big on silicon anodes to deliver transformative change in the science behind EVs.

A recent report from consultancy IDTechEx described the promise of advanced silicon anode materials as "immense" for improving critical areas of battery performance, noting that this potential hadn't gone unnoticed by carmakers and key players in the battery industry.

It warned, however, that challenges such as cycle life, shelf life and — perhaps most importantly — cost, need to be addressed for widespread adoption.

Venkat Srinivasan, director of the Collaborative Center for Energy Storage Science at the U.S. government's Argonne National Laboratory in Chicago, said silicon anodes appear to have the edge over solid-state batteries.

"If there's a horse race, silicon does seem to be ahead at least at this moment, but we haven't commercialized either one of them," Srinivasan told CNBC via videoconference.

Srinivasan said five years ago silicon-anode batteries had a calendar life of roughly one year, but recent data appears to show a dramatic improvement in the durability of these materials, with some tests now projecting a three to four-year calendar life.

Unlike the cycle life of a battery, which counts the number of times it can be charged and discharged, the calendar life measures degradation over time. Typically, the calendar life of a battery refers to the period in which it can function at over 80% of its initial capacity, regardless of its usage.

Srinivasan said solid-state batteries, long billed as the "holy grail" of sustainable driving, still have a long way to go before they can match the recent progress made by silicon anodes.

"That transition still has to be made in solid-state with their metal batteries and that's why I think you're hearing from people that, hey, it looks like that promise hasn't panned out," Srinivasan said.

"That doesn't mean we won't get there. It may happen in a few years. It just means that it feels like today silicon is in a different part of the technology readiness level."

Silicon anodes vs. solid-state batteries

Analysts say silicon anodes theoretically offer 10 times the energy density as graphite, which are commonly used in battery anodes today. Yet, these same materials typically suffer from rapid degradation when lots of silicon is used.

"Silicon anodes and solid-state batteries are two emerging technology trends in the EV battery market aimed at pushing the boundaries of high-performance battery cells," Rory McNulty, senior research analyst at Benchmark Mineral Intelligence, told CNBC via email.

It has typically been the case that better battery performance comes at the cost of longevity or safety, McNulty said. Silicon anodes, for example, are known to swell significantly during charging, which reduces the battery's longevity.

By comparison, McNulty said solid-state batteries were claimed to greatly improve the stability of the electrolyte to high performance electrode materials, combating the challenges of using high energy density materials such as silicon and lithium.

As the name suggests, solid-state batteries contain a solid electrolyte, made from materials such as ceramics. That makes them different from conventional lithium-ion batteries, which contain liquid electrolyte.

Japan's Toyota and Nissan have both said they are aiming to bring solid-state batteries into mass production over the coming years, while China's SAIC Motor Corp reportedly said in early September that its MG brand would equip cars with solid-state batteries within the next 12 months.

Nonetheless, analysts remain skeptical about when solid-state batteries will actually make it to market.

A strategic opportunity?

"Silicon based anodes promise to be the next-generation technology in the anode field, providing a solution for faster charging," Georgi Georgiev, battery raw materials analyst at consultancy Fastmarkets, told CNBC via email.

Georgiev said several industry players have been looking into the potential of silicon anodes, from well-established anode suppliers in China and South Korea to new players like Taiwan's ProLogium and U.S. manufacturers Group14 and Sila Nanotechnologies.

"Especially in the West, advances in the area of silicon anodes [are] seen as strategic opportunity to catch up with China, which dominates the graphite-based anode supply chains with Chinese anode producers holding 98% of the global anode market for batteries," Georgiev said.

"However, there are significant technical challenges going to 100% silicon anode such as silicon expansion affecting the longevity of the batteries and currently there are several routes to produce silicon anodes," he added.

Taiwanese battery maker ProLogium debuted the world's first fully silicon anode battery at the Paris Motor Show last month, saying it's new fast-charging battery system not only surpassed traditional lithium-ion batteries in performance and charging efficiency but also "critical industry challenges."

ProLogium, citing test data, said it's 100% silicon anode battery could charge from 5% to 60% in just 5 minutes, and reach 80% in 8.5 minutes. It described the advancement as an "unmatched achievement in the competitive EV market," which will help to reduce charging times and extend the range of EVs.

Fastmarkets' Georgiev said a big question mark over the commercialization of silicon anodes is the cost of production and whether any of the major silicon-anode producers "could produce material at scale with a consistent quality and at a competitive price — [a] major requirements of OEMs."

"At this stage silicon anodes are used more as an additive to graphite-based anodes and in the years to come we expect to see increase of silicon share in anode, but in combination with graphite, while 100% silicon anodes will take longer time to enter the mass market," he added.