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Tesla Battery Day invite shows silicon nanowires, hinting at battery tech breakthrough


Expansive Ellipses
Staff Member
May 30, 2004
This page is now live at Tesla's website, with invites to next month's Battery Day event:

Those strands are silicon nanowires, utilized in next-generation battery technology, but as of yet not at a commercial scale.

Tesla is teasing some sort of nanotechnology in a new Battery Day announcement ahead of the presentation next month.

The automaker’s Battery Day and Shareholders Meeting have been pushed several times.

Battery Day was delayed at first for unknown reasons and later they were both pushed at the same time due to the COVID-19 pandemic as Tesla looked to combine the events with limited in-person attendance.

Last week, Tesla announced that it will instead hold its Shareholders Meeting virtually and Battery Day mostly virtually with some limited in-person attendance for people randomly selected.

On the page where people can sign up to potentially be selected, Tesla has an interesting background:

A reverse Google search on the image shows that it is similar to silicon nanowires, a nanostructure that has been used to create batteries with higher performance though it has yet to be commercialized.

One of the main companies developing the technology is Amprius:

“Developed on a patented technology platform that includes a 100% silicon nanowire anode, Amprius Technologies batteries provide significantly more energy and power with less weight and volume than any other lithium-ion battery technology. Amprius Technologies batteries provide up to 50% higher energy density than standard lithium ion batteries with carbon anodes”

Interestingly, Amprius is based right next to Tesla’s 901 Page Ave. building in Fremont, California.

That building is actually where Tesla plans to hold battery day and it is also home to Tesla’s “Tera battery manufacturing facility” using the company’s Roadrunner battery manufacturing process.

There’s no other clear link between Tesla and Amprius, but we found out that Tesla hired Yi-Lei Chow last year from Amprius where he had been a long-time engineering and manufacturing leader.

Tesla will hold its Battery Day on September 22.

Electrek’s Take
That would be an interesting turn of events. We know that Tesla is planning to announce its own plan for large-scale battery manufacturing of its own cells.

We also know that Tesla plans to announce some updated battery chemistry, but the extent of the improvements Tesla plans to announce is unclear.

If it would be a new battery based on the Amprius technology, it could potentially mean a massive improvement:

This could be a game-changer. The silicon nanowire battery company, Amprius, has this to show about its tech:

It's possible that these silicon nanowire batteries may power the upcoming Tesla Roadster, to provide its 600+ mile range and ball-busting power to weight ratio which analysts don't think is possible with current battery tech.
Feb 25, 2013
Depending on how compact they can make these in order to be used in small consumer devices... This could be huge outside of what it already means for Tesla cars.

Heck, even for solar. Which would be huge for residential as well as their space initiatives.

Really wishing I had the money to buy some stocks right about now...


Expansive Ellipses
Staff Member
May 30, 2004
If silicon nanowire battery tech could be utilized at scale, at that 500+ Wh/Kg energy density, we'd even be a lot closer to viable electric airplanes, which need that number at about 1000.

“There’s already been a lot of progress,” says Venkat Srinivasan, a battery scientist at Argonne National Lab in Chicago. Battery energy density is rising by a non-negligible 2 to 3 percent per year. Tesla’s cars go farther with each iteration. “It’s not the same ballpark as Moore’s Law progress because it’s chemistry, not electronics, but it’s still very good.”

Besides, batteries don’t need to match liquid fuel pound for pound to catch on. If it can get to five times its current density—that would be 1,000 watt-hours per kilogram—it would work for small-scale commercial aviation, says Don Hillebrand, director of the Argonne's Center for Transportation Research. Estimated time of arrival: 2045.

“That 1000 watt-hours/kg number reflects the approximate equivalent of one third the energy density of gasoline, but that’s enough,” Hillebrand says. “At our current pace of innovation, and factoring the relative differences in efficiency of the powertrains, that’s when we can expect batteries to be good enough to power small aircraft for practical uses.”

Others suggest a shortcut of sorts. “Electric propulsion permits new design architectures,” says Venkat Viswanathan, a battery scientist at Carnegie Mellon University. “Future electric aircraft will look nothing like the aircraft of today, and they will be able to fly with much less energy—as little as 400 watt-hours/kg—thanks to distributed motors and reduced drag. We’ll redesign aircraft around electric motors.” Faster said than done. Because aircraft development times are measured in decades, it’s unlikely the planes Viswanathan imagines will arrive before those 1,000 watt-hours/kg batteries.