Silicon use in EV batteries to reduce cost of vehicles: Ferroglobe CEO

The use of silicon metal in electric-vehicle batteries could bring down the overall cost of such vehicles, making them more affordable, the CEO of a major silicon producer said.

At the same time, silicon could help battery manufacturers overcome problems that global shortages of both natural and synthetic graphite have caused, Marco Levi, the CEO of Ferroglobe, said in an Oct. 9 interview with S&P Global Commodity Insights.

At the moment, silicon use in batteries can replace about 2%-3% of graphite in a battery, but increased use of "silicon carbon composites could replace up to 30% of the graphite in an EV battery," Levi said.

In March, Ferroglobe and Coreshell, a US-based battery technology company, signed an agreement to produce the first battery-ready metallurgical silicon at a pilot plant for the development of high-range EV batteries, aiming to comply with the US Inflation Reduction Act.

Coreshell's proprietary technology features a "unique nanomaterial electrode coating," Levi said. He said the coating was "flexible when the silicon metal swells and the lithium ions discharge, the coating contains the swelling of the silicon metal."

Batteries account for about 30%-40% of the cost of EVs, according to the joint statement Ferroglobe and Coreshell released in March, which quoted the International Energy Agency's 2022 Global Supply Chains of EV Batteries report.

In addition to reducing cost, the use of silicon in batteries is also expected to improve performance and increase distances between charging, Levi said.

According to the companies' March statement, the use of silicon in batteries means they can store up to 10 times more energy compared with batteries that just use graphite in the anode. The statement said it could potentially result in a 30% increase in driving ranges between charges compared with current battery technology in use in EVs.

"It's not just the anode that makes the battery," he said. "Cost, cost, and cost" has been a major focus, followed by other considerations.

Silicon necessary for materials security

From a materials-security perspective, using silicon to replace graphite was crucial, as China was the main source of graphite supply.

"I don't know how long China is going to continue to export graphite for batteries," Levi said. "If you find solutions, like replacing graphite with silicon, then [the automotive sector] can decarbonize, because silicon is available in Europe and the US."

Levi explained that the silicon for batteries was micrometric silicon, the production of which starts with making lump silicon similar to the grades of silicon produced for use in secondary aluminum alloys production and also in chemicals. The silicon is then purified further in a furnace, where it is ground into powder, which can be and is used in polysilicon and also a purified form for use in batteries.

The silicon to be produced for batteries will be up to 99.995% purity, according to Ferroglobe's and Coreshell's March statement.

The lump silicon metal Ferroglobe produces is typically better than the 553 chemistry that most secondary aluminum alloy producers require and key to this is the use of high-purity quartz and Blue Gem coal, a unique, low-ash, low-volatile coking coal produced in a small region of Kentucky.

There are only two producers of Blue Gem metallurgical coal and Alden Resources, a wholly owned subsidiary of Ferroglobe, is one of those producers.

According to Levi, Ferroglobe's own Blue Gem resource is enough to last "for decades."

He added that Ferroglobe was about 80% back-integrated in quartz worldwide.

Levi said Ferroglobe and Coreshell would be testing new batteries in the first quarter, which were expected to show a "quantum step up in durability" compared with existing EV batteries.

No change for silicon production for aluminum

Levi said that the company's shift to producing silicon metal for the EV battery value chain would not change its existing products, which include silicon metal for secondary aluminum alloy production, ferrosilicon for the steel industry and magnesium ferrosilicon for foundries.

He added that commercial production would be carried out at the existing plants in Beverly, Ohio; Selma, Alabama; and Alloy, West Virginia.