GDI silicon anode hits testing and production milestones

US-headquartered anode company GDI has hailed promising safety results in third-party testing and a major production breakthrough as it aims to bring its silicon anodes into mass production.

“A silicon-containing anode, replacing or decreasing the graphite portion in the anode, offers potential advantages due to silicon's ability to store more lithium ions by weight, promising heightened energy density,” says electrification consultancy Alexec.

And GDI says that third party testing of its silicon anodes showed up to 30pc increases in energy density over conventional graphite anodes. This enables cells equipped with the anode to charge up to 80pc state of charge in fifteen minutes, as well as being able to repeat this charging speed “hundreds of times back-to-back”, GDI says.

The repeatability of this charging performance will address a problem of quicker degradation faced by silicon-based batteries.

The firm also reveals that the testing “proved GDI’s silicon anode is one of the world’s only battery technologies that increases energy and improves safety, with no change to standard electrolyte”.

Another potential boost for the commercial viability of the technology is that “the finished anode can be dropped directly into existing cell production lines” which would allow cell manufacturers to cut costs by avoiding redesigning components and reorienting production processes. GDI has “demonstrated MWh-scale ‘roll-to-roll’ production on [partner] AGC’s industrial equipment in Q4 2003”, the firm says.

The company therefore says that, unlike some other lab-scale breakthroughs in battery technology, its silicon anode tech has a clearer path to market, as “the anode can be produced at GWh-scale and delivered directly to cell makers”. Indeed, GDI is forthcoming in its commitments to a timeline.

“GDI and AGC have developed a clear roadmap to gigawatt scale production by 2028, so that this technology can used in tens of thousands of high-performance vehicles by 2030,” the company says.

It is currently stepping up its first MWh-scale roll-to-roll production facility in Lauenforde, Germany.

Silicon interest

The buzz around silicon is definitely increasing. Earlier this week, Japanese electronics heavyweight Panasonic signed on to buy silicon anodes from US start-up Sila. And Californian battery firm Enevate has struck a licensing agreement with German cell manufacturer Customcells to bring its “silicon-dominant” XFC battery to commercial scale.

“The two companies have had joint commercial discussions with leading OEMs in the e-mobility sector,” the partners say. Indeed, they will look to leverage Customcells’ longstanding supplier relationships with OEM and Tier 1s, which it describes “six of the world’s ten largest automakers and six of the top 10 German automotive suppliers”.

“Enevate looks forward to our collaboration with Customcells to commercialise the Enevate technology addressing the final hurdle to widespread electric vehicle adoption, by offering extreme fast charge, high energy density and improved cold temperature performance," says Enevate CEO Bob Kruse.

Graphite dependency

A pivot from graphite to silicon for anode material could score a geopolitical win for the US by diminishing China’s dominant role in that portion of the supply chain. “For graphite mining, we are at around 65pc from China. That is significant. For anodes we are above 90pc coming from China,” says Tom Moerenhout of Columbia University's School of International and Public Affairs.

But there is still a road for silicon anodes to travel. “Technical hurdles persist, notably volume changes and swelling during charge cycles leading to cracking and reduced longevity,” Alexec finds, suggesting instead that the near-term business case for silicon anodes is “integrating silicon into battery designs with up to 10pc of silicon content in silicon-graphite blend anode materials”.

But GDI is banking on a quicker path. “The next step is to show our anode can enable EV batteries that power vehicles with up to 500 miles of range, allows them to charge 250 miles in 15 minutes hundreds of times, and improves safety,” says GDI CEO Rob Anstey.