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Silicon Anodes to Extend EV Range by 20 Percent

By
Laurance Yap
May 2, 2023
4
min
A new technology called silicon-based anodes will help increase the EV range of existing lithium-ion batteries by about 20 percent, while reducing dependence on Chinese-processed graphite. Expect silicon anodes to show up first on expensive electric cars, and become more common over time.
man holding a jar of Titan Silicon
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A Quantum Leap in EV Battery Tech

With all of the activity that’s happening in the electric car landscape, sometimes it’s easy to forge that modern electric vehicles are still a relatively new phenomenon – and at the start of their technological lifecycle. EVs have improved massively since the introduction of the first Nissan Leaf and Tesla Model S in the early 2010s, but much like internal combustion, batteries are going to go through several quantum leaps over the next decades as engineers find ways for them to generate more power and range while reducing costs.

The next big leap may be upon us, with a range-boosting battery technology called silicon-based anodes. After 12 years of development, Sila Inc., a battery materials company based in Silicon Valley, says it has finalized a mass-manufacturing process for silicon-based anodes, which could immediately boost electric vehicle range by up 20 percent. The anodes, made of the company’s “Titan Silicon” material, will go into production in early 2025, and Sila says it will be able to make enough material for up to 200,000 EVs annually by 2026 and a million EVs annually by 2028.

Lithium battery pack

How Silicon Anodes Work

Lithium-ion batteries, the most common batteries found in electric cars, were invented in the 1980s. The battery anode acts as a reservoir for lithium ions. When the battery is charged, the ions fill the spaces between layers of graphite, and when the battery is discharged, ions flow out of the anode and to the other side of the battery, the cathode. Until now, almost all anodes have been made from graphite, and most of the world’s supply of graphite is extracted or processed in China.

While graphite works well as a material for anodes, it is heavy, and it it’s not very dense, meaning that graphite anodes take up more space and weigh more than engineers would like. Some battery makers, including Tesla, have started to incorporate small amounts of silicon in their anodes, which helps batteries charge faster and store more energy. But manufacturers have, until now, not been able to overcome silicon’s major disadvantage – the fact that it physically expands as the battery fills up with lithium ions. Even at low concentrations of silicon, the anode can swell up, quickly degrading the battery; that’s why only about 5 percent silicon content has been feasible until now.

Sila’s solution to making anodes with higher silicon content is a structure around the silicon particles with lots of holes which allows the silicon to expand without damaging the outer shell of the anode. The Swiss cheese-like structure means that the silicon volume only expands by 6 percent; according to the company, that’s similar to graphite. After 1,100 charge and discharge cycles (which is about 300,000 miles of driving), Sila says that a battery with silicon anodes will also retain 80 percent of its starting capacity, which is also similar to batteries with graphite anodes.

Mercedes-Benz EQG G Wagon

Titan Silicon for the Mercedes EQG SUV

Sila says it tried more than 70,000 variations of silicon before settling on the final Titan Silicon formulation. Titan Silicon will allow almost 100 percent silicon anodes, significantly increasing the energy density of batteries it’s fitted to. Automakers working with Sila can choose the amount of silicon that will be used for battery anodes depending on targets for range and cost. The more silicon used, the higher the price; at least at the start, Titan Silicon will be sold at a price premium, and will be used in high-end vehicles whose drivers expect long range.

Indeed, the first vehicle that will use Sila’s Titan Silicon anodes is the upcoming Mercedes-Benz EQG SUV, the electric version of the company’s iconic G-wagon off-road vehicle. Priced above $150,000, the G-Class is a darling of celebrities and multi-millionaires, and a great launch platform for the expensive silicon anodes. Mercedes-Benz has stated that the EQG’s battery will have an energy density of 800 watt-hours per liter of volume; in layperson’s terms, the EQG’s battery should give it a driving range as impressive as its starting price.

CHARGING EV CAR

Other Players Entering the Market

Other companies are hard at work on silicon anode technology as well. Tesla, which already incorporates a small amount of silicon in its batteries, has spoken publicly about developing its own higher-concentration silicon anodes. Seattle-based Group14 Technologies already has a supply agreement with Porsche, which will incorporate Group14’s silicon anodes into its next generation of electric cars. And OneD Battery Sciences, based in Palo Alto, CA, is working with General Motors on premium silicon-anode batteries.

Like Sila, these companies anticipate that silicon anodes will start as an expensive technology for expensive vehicles. But over time, it is anticipated that silicon-based anodes, once in full production, will eventually cost less to make than graphite anodes, and will become more common in the industry. Sila’s CEO Gene Berdichevsky expects a third of the world’s electric cars will come with silicon-based anodes by 2030, and that by 2035, the majority of the world’s EV batteries will feature the technology.

While it’s not clear which player will be the first to scale up the technology, it will be fascinating to watch developments unfold over the next few years.

Front view of a Tesla Model 3 driving through canyon roads

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