Tesla & Amprius — What Is Going On?

Tesla fans have zeroed in on a battery startup called Amprius. A number of clues indicate that it may be acquired by Tesla in the future, or that it at least plays a role in Tesla’s battery innovation and coming announcements at Tesla Battery Day. I’ll come back to the Tesla–Amprius connections in a minute. First, once I saw the name popping up, I recognized it and decided to check the CleanTechnica archives for it. Let’s start there.

Amprius History

We wrote about Amprius once in 2012, three times in 2014, and then I included it on my list of “43 Battery Storage Companies To Watch” in January 2015 — a list that was quite popular for a year or two. My summary of the company in that 2015 article was: “Amprius develops high-capacity lithium-ion batteries that originated at Stanford University. Amprius definitely has the simplest website on this list, but it is still able to slip in the fact that investors include Trident Capital, VantagePoint Capital Partners, IPV Capital, Kleiner Perkins Caufield & Byers, SAIF Partners, Chinergy Capital, Google Chairman Eric Schmidt, and Stanford University. Former Secretary of Energy Steven Chu sits on the board.”

Well, that doesn’t tell us much, but it tells us that the research at Stanford that led to the startup was interesting enough to pull in some big names — some very big names.

The first time Amprius was mentioned on CleanTechnica was in an article from Stanford University’s SLAC National Accelerator Laboratory. The articles started off with these two paragraphs:

“For more than a decade, scientists have tried to improve lithium-based batteries by replacing the graphite in one terminal with silicon, which can store 10 times more charge. But after just a few charge/discharge cycles, the silicon structure would crack and crumble, rendering the battery useless.

“Now a team led by materials scientist Yi Cui of Stanford University and SLAC National Accelerator Laboratory has found a solution: a cleverly designed double-walled nanostructure that lasts more than 6,000 cycles, far more than needed by electric vehicles or mobile electronics.”

Over the previous 5 years, Cui’s research teams had “progressively improved the durability of silicon anodes by making them out of nanowires and then hollow silicon nanoparticles,” with the hot news solution of 2012 consisting of “a double-walled silicon nanotube coated with a thin layer of silicon oxide, a very tough ceramic material.”

“This strong outer layer keeps the outside wall of the nanotube from expanding, so it stays intact. Instead, the silicon swells harmlessly into the hollow interior, which is also too small for electrolyte molecules to enter. After the first charging cycle, it operates for more than 6,000 cycles with 85 percent capacity remaining.

“Cui said future research is aimed at simplifying the process for making the double-wall silicon nanotubes. Others in his group are developing new high-performance cathodes to combine with the new anode to form a battery with five times the performance of today’s lithium-ion technology.”

The article ended with the note that Cui founded Amprius in 2008 and that the company “licensed rights to Stanford’s patents for his silicon nanowire anode technology” and that “its near-term goal is to produce a battery with double the energy density of today’s lithium-ion batteries.”

Hmm, double the energy density, you say? That sounds up Tesla’s alley. Of course, that was back in 2012, 8 years ago, at basically the same time the Tesla Model S was hitting the market. Both companies had a long way to go before arriving in the dumpster fire that is 2020, but which also has some good news.

Heading over to our first article actually about Amprius itself, it was rather short and didn’t tell us a lot more, but there was a bit of new info there. Nicholas Brown reported in January 2014 that Amprius had raised $30 million in Series C funding to keep developing “compact lithium-ion batteries which utilize silicon nanowire anodes.”

“Initially, a solid silicon anode was developed, but it was prone to cracking, so a nanowire version of it was developed, as the high energy density of silicon anodes was a major benefit worth pursuing (1,000 Wh/kg),” Nicholas added. “However, the nanowires still weren’t reliable enough. There have been developments since then which significantly improved reliability, but now, Amprius apparently has silicon nanowire batteries ready for commercialization.”

(Side note: ironically, Tesla CEO Elon Musk has been very critical of the term “nanotech” in the past. Did some nanowire anodes hook him nonetheless?*)

Green Car Congress provided more detailed details in 2014: “The company introduced its first generation of batteries in May 2013, and is supplying smartphone and tablet OEMs with its first two product families, based on an 1,850 mAh (580 Wh/L) battery and a 4,060 mAh (600 Wh/L) battery. Amprius’ first-generation batteries are made with silicon anodes — not silicon nanowire anodes, which will appear in the subsequent generations. The company has demonstrated greater than 650 and 700 Wh/L batteries with its second-generation and third-generation technology platforms.”

Another 2014 piece was just a press release about former US Secretary of Energy Steven Chu joining the Amprius board of directors.

So, that was our history on Amprius.

Amprius & Tesla Today

If you go to the Amprius site today, somewhat humorously, the WordPress logo is the favicon that you see in your browser tab — the company hasn’t bothered to fully customize and brand its website. However, it has surely been working hard and proudly proclaims a bold statement right up front:

“Setting a new standard for battery performance, Amprius® Technologies manufactures the highest energy density lithium-ion batteries in the world. Employing our patented, 100% silicon nanowire anode, Amprius Technologies provides up to 50% improvement compared to standard lithium-ion batteries.”

Further down, it states, “Approaching 500 Wh/kg, our batteries provide ultra-high energy density and excellent cycle life, which means aircraft, drones, satellites and spacecraft can fly longer and farther.” Does that sound familiar? Yes, we just wrote an article yesterday about the implications of a fresh tweet from Tesla CEO Elon Musk that said, “400 Wh/kg *with* high cycle life, produced in volume (not just a lab) is not far. Probably 3 to 4 years.” The point there was that this energy density at high cycle life could enable commercially competitive electric airplanes, and perhaps Tesla would even build electric airplanes someday.

Amprius has moved in across the street from Tesla. It is located at 1180 Page Ave, Fremont, CA 94538 USA. A common hunch, therefore, is that Amprius is joining Tesla.

Directions from Tesla corporate office in Fremont to Amprius, via Google Maps. It is a one-minute drive across the street.

As a final note, someone noticed that one young Tesla employee who works on cell engineering and R&D worked at Amprius from March 2015 to June 2016, has worked at Maxwell Technologies (which Tesla bought) from October 2016 to the present, and has worked at Tesla since June 2019.

Hmm … any connections there?

I know — you’re thinking what I’m thinking. Amprius is going to buy Tesla!

Well, I’m not sure when Yi Cui leased his Model S, but it looks quite likely his batteries — or some portion of them — will be in his next Tesla.

*Addendum to the side note: When Tesla rolled out ultrafast 250 kW “version 3” Supercharging, Kyle Field, Chanan Bos, and I had just toured Tesla factories in Fremont and interviewed Tesla President Jerome Guillen, were exhausted, and had a revelation as to why Supercharging should be renamed “nanocharging.” Of course, it was a joke that was deep down a rabbit hole, and Tesla PR wasn’t too thrilled with it since it was confusing people and Tesla was apparently being peppered with questions about this new “nanocharging.” So, we retitled the article (but you can still see “nanocharging” in the URL). Here is what Kyle and I consider to be the hilarious conversation that birthed “nanocharging,” but which others may think is more psychologically concerning than funny:

Original Publication by Zachary Shahan at CleanTechnica.

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