Nanotech Company Hones in On Increasing Battery Energy Density for EVs

Sila Nanotechnologies, in partnership with BMW, is working on silicon-based anode materials that could increase the energy density of batteries for electric vehicles by 10-15%.  The technology could help extend the range of electric vehicles which, thus far, has been one of the major drawbacks to this type of vehicle over conventional internal combustion vehicles.

From technologyreview.com

This battery advance could make electric vehicles far cheaper

For the last seven years, a startup based in Alameda, California, has quietly worked on a novel anode material that promises to significantly boost the performance of lithium-ion batteries.

Sila Nanotechnologies emerged from stealth mode last month, partnering with BMW to put the company’s silicon-based anode materials in at least some of the German automaker’s electric vehicles by 2023. A BMW spokesman told the Wall Street Journal the company expects that the deal will lead to a 10 to 15 percent increase in the amount of energy you can pack into a battery cell of a given volume. Sila’s CEO Gene Berdichevsky says the materials could eventually produce as much as a 40 percent improvement (see “35 Innovators Under 35: Gene Berdichevsky”).

For EVs, an increase in so-called energy density either significantly extends the mileage range possible on a single charge or decreases the cost of the batteries needed to reach standard ranges. For consumer gadgets, it could alleviate the frustration of cell phones that can’t make it through the day, or it might enable power-hungry next-generation features like bigger cameras or ultrafast 5G networks……

An anode is the battery’s negative electrode, which in this case stores lithium ions when a battery is charged. Engineers have long believed that silicon holds great potential as an anode material for a simple reason: it can bond with 25 times more lithium ions than graphite, the main material used in lithium-ion batteries today.

But this comes with a big catch. When silicon accommodates that many lithium ions, its volume expands, stressing the material in a way that tends to make it crumble during charging. That swelling also triggers electrochemical side reactions that reduce battery performance.

In 2010, CTO Gleb Yushin coauthored a scientific paper that identified a method for producing rigid silicon-based nanoparticles that are internally porous enough to accommodate significant volume changes. He teamed up with Berdichevsky and another former Tesla battery engineer, Alex Jacobs, to form Sila the following year.

The company has been working to commercialize that basic concept ever since, developing, producing, and testing tens of thousands of different varieties of increasingly sophisticated anode nanoparticles. It figured out ways to alter the internal structure to prevent the battery electrolyte from seeping into the particles, and it achieved dozens of incremental gains in energy density that ultimately added up to an improvement of about 20 percent over the best existing technology.

Ultimately, Sila created a robust, micrometer-size spherical particle with a porous core, which directs much of the swelling within the internal structure. The outside of the particle doesn’t change shape or size during charging, ensuring otherwise normal performance and cycle life.

The resulting composite anode powders work as a drop-in material for existing manufacturers of lithium-ion cells……

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