Tesla Battery Day

TESLA BATTERY DAY TESLA BATTERY DAY TESLA BATTERY DAY

Hello and welcome to Intercalation Station - we’re Andrew & Nick, two energetic individuals in the battery space. We hope this newsletter will be your stop for the latest battery innovations in research and industry, intercalated monthly into your inbox. We’d love it if you share & subscribe! 

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Still haven't read enough about Battery Day?

We’ve got you covered.

Tesla CEO Elon Musk and Senior VP Drew Baglino gave a whirlwind tour of Tesla’s battery strategy over the next 2 - 5 years, with an overarching benchmark: by how many years did we accelerate sustainable energy?

They listed cumulative changes at all stages of the battery-chain to improve range, cost, and production towards widespread EV adoption. We may expect pack prices around $60/KWh by 2025 (from a 2020 $135/kWh), which will be necessary to reach their eventual goal of 20 million vehicles/year on the TWh scale. 

Disruption Research @DisruptResearch

Reaction to Tesla battery day by a major Korean battery company insider: “We wouldn’t have been so nervous if Tesla announced a pie-in-the-sky plan such as solid state batteries. But what was announced looked like something they’re actually going to execute on, which is scary.”

The largest improvements came from engineering and design, with what appeared to be minimal smoke-and-mirrors. Notably, Tesla was conservative on material chemistry innovations, perhaps revealing some insight into their outlook on next-gen battery technologies in the near term.

At a glance, here’s how we’ve categorized which claims to expect on what timelines:

People in the battery research field were perhaps relieved that Tesla did not bet big on any emerging chemistries, afraid to find out: had we missed a glaring solution?

Instead, Tesla chose to increment on current technologies by flexing its manufacturing muscles and their ability to push the envelope on all of us. Their presentation also included a spectacular overview of batteries which we hope will inspire another generation to join the cause.

Sure you can’t please everyone from mining through to BMS, but we were satisfied with this peek behind the revered iron (phosphate?) curtain.

Hans Eric Melin @hanseric

#TeslaBatteryDay was about expanding boundaries. From Giga to Terra. From niche player to saviour of the earth. To show that Tesla not only is leading the race in EVs but as well in developing the platform they rely on. It was PR. And now they own the story.

Jay Roberge @jmroberge

“Nothing Musk discussed about batteries is a done deal,” said Roth Capital Partners analyst Craig Irwin. “There was nothing tangible.” #Tesla #TeslaBatteryDay https://t.co/1g3Jk4Lqfn

Matt Lacey @mjlacey

The scale of their ambitions (TWh scale, 20 million cars/year etc) is enormous and there are obviously going to be plenty of questions and arguments about this (I have my own too). But the direction of travel is increasingly clear, and they have everybody's attention

Read on for discussions on specific announcements.

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🔋 CELL DESIGN

4680 cells with tab-less electrodes

Andrew Wang @ndrewwang

Thought I would try "un-wind" the new @Tesla 4680 cell (please be gentle) More than doubling (21 -> 46 mm) diam. means you get 5x electrode (blue vs red) wound up, 1.15 m vs 5.5 m - matching Teslas 5x density claim. From this its clear why tab-less was a necessity: (cont)

Tesla’s new 4680 cell (46mm diameter, 80mm height), is >2x in diameter and slightly taller than its current 2170 cell. Larger cells hold more active material with comparatively less packaging deadweight and are cheaper to manufacture. Now “any fool could make a bigger form factor” but it becomes harder to maintain supercharging and thermal control.

Cue the tab-less electrode (or should we say tab-more electrode). This patented technology laser patterns the current collector overhang into many small tabs so that when wound up, form a “shingled spiral” providing electrical contact.

Traditional cylindrical cells have a single welded tab that constricts electron travel. This tab-less design allows for more uniform current distribution, which is important as the electrode is now 5x longer. Going tab-less also alleviates some high-rate heating effects in a cell with larger thermal mass.

• Improvements: 5x energy per cell, 6x power, +16% range, 14% $/kwh reduction

• Can it be done?: We think this should be easily achievable 

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🌒 ELECTRODE MATERIALS

Silicon and a cobalt-free portfolio

David Snydacker @dsnydacker

Armies of PhDs across every top engineering school have tried using simple silicon-polymer composites as anodes. The lack of a dimensionally stable SEI kills it every time. If Tesla has gotten better results, their material is a lot more complicated than what they presented.

A lot of confusion was raised about just how much metallurgical silicon Tesla planned to use in their new anodes. Volume expansion and SEI degradation of silicon or “the cookie crumbling and getting gooey” is well understood, but hasn’t stopped Tesla using some in current cells. Their new plan is to use cheaper raw silicon, but buffer the expansion with a conductive polymer electrolyte. This approach [1, 2] may have been developed through their recent acquisition of SilLion. There are doubts though, that anode Si% will be high without further development.

David Snydacker @dsnydacker

However, going to ultra-high nickel with no cobalt poses serious thermal risks. Delithiated NiO2 is a powerful oxidant and so pack- and systems-level safety controls become ultra important. E.g. moving cells to center of vehicle and using autonomy to avoid crashes.

On the cathode end, things appear to be business as usual as they aim to cut all cobalt from the battery by using high nickel, nickel + manganese, and LFP material tiers. These will be stabilized by novel coatings and dopants developed with Tesla’s Canadian friends.

• Improvements: 20%/4% anode/cathode energy increase, 5%/12% anode/cathode cost savings

• Can it be done?: Cathode goals are feasible, while silicon remains to be proven

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🏭 PRODUCTION EFFICIENCY

Increase throughput, dry coating electrodes

Elon Musk @elonmusk

The extreme difficulty of scaling production of new technology is not well understood. It’s 1000% to 10,000% harder than making a few prototypes. The machine that makes the machine is vastly harder than the machine itself.

Tesla is designing factories to eke out every efficiency and hit “terafactory” scale. This includes speeding up assembly 7x and installing parallel lines while minimizing footprint. Other improvements include no-weld tab-less tabs and bespoke power-electronics to parallelize the formation step during production.

Sam Jaffe @samjaffe

They were both super enthusiastic about all the other technologies. When they talked about progress in making dry electrodes, they hemmed and hawed and said "We hope we get there". Makes me wonder if the Maxwell tech will get dropped at some point.

Ying Shirley Meng @YingShirleyMen1

Dry coating is absolutely not easy!!! Happy to hear Maxwell's technology will make a difference.

Dry electrode coating technology from Maxwell looked promising at lab-scale, but you couldn’t miss the hesitation in Elon’s voice. Powder-to-film is a dramatic innovation as it would replace the need for using toxic NMP solvent in the coating slurry.

• Improvements: 18% cost reduction, 34% CapEx reduction

• Can it be done?: Tesla has been to production hell with cars, we’re confident they can do it with batteries. TWh scale is an eventual goal. At-scale dry coating is at least another 3+ years down the road.

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♻️ SUSTAINABLE SUPPLY CHAIN

Lithium clay, recycling, and cathode manufacturing

David Snydacker @dsnydacker

Hey @elonmusk, great presentation today, but one minor correction on leaching of lithium clays using brine: it has been done before, albeit not commercially. Here is one report published in 2018. Nice proof of concept but certainly needs more work. cypressdevelopmentcorp.com/site/assets/fi…

Tesla has secured mining rights to lithium clay in Nevada. They plan to use saline extraction of the sedimentary lithium instead of the typical acid-leeching process to minimize the impact. It was noted that Nevada alone has more than enough lithium to electrify the US - whether that is thermodynamically or economically competitive compared to brine lakes remains to be seen.

Hans Eric Melin @hanseric

Few EV batteries are recycled after only 10 years. Average yearly mileage for Tesla Model S in the US is around 10,000 miles per year. That's 48 cycles per year. Unless cars are crashed they might very well live after 20 years. And if they don't the batteries will be reused.

Pilot full-scale in-house recycling is scheduled to begin in Reno later this year. Currently, Tesla outsources its recycling. After second life applications in Tesla-energy products, these retired batteries will eventually form a closed-loop when recycled as a richer element source than raw ores.

Brian Heligman @BrianTHeligman

@BatteryBulletin The nickel manganese stuff is generally done by simultaneous coprecipitation of metal sulfates, a technique that was pioneered for batteries by Dahn himself. Even making spherical Ni(OH)2 is often done by coprecipitation. I wonder, do they just mean switching to nitrate/acetate?

Perhaps the vaguest portion of the presentation was Tesla’s entry into cathode material production. Tesla claims to have replaced the metal sulfate precursor co-precipitation step with nickel metal and water process. Eliminating waste-water would be huge for sustainability but we need more than “less stuff happens” to believe it on face value. We’re eager to see their team with 10+ years of BASF cathode production experience pull this off.

• Improvements: -76% cathode process cost with 0 wastewater, steady-state recycling, sustainable Li extraction

• Can it be done?: New cathode production will take 3+ years, recycling will take 10 years to ramp-up to steady-state, Tesla will continue to rely on their lithium suppliers in the near term

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🚗 CELL TO VEHICLE

Structural batteries

David Howey @DavidHowey

@anishUCD_its @sdmoores @VivasVK7 were/are the cans _really_ load bearing though? difficult to see in the pictures shown. Or is it just that the outside case (not the cans, the thing outside that) was the bottom of the car? cc @ndrewwang

While cylindrical cells pack less efficiently compared to their pouched siblings, Tesla aims to make up for that by integrating the new 4680 cells as a structural element to stiffen the car. This would require simplifying the pack and module design while using some patented novel aluminum alloys. We note the true innovation may be building load-bearing properties into the flame-retardant glue between the cells.

• Improvements: 7% cost reduction at pack level, 14% range improvement

• Can it be done?: Many OEMs are already looking at structural packs, and we believe this is an intuitive step forward

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More heated-takes and commentary on Tesla Battery Day may be found in our September “This Month in Battery Twitter”.

We’d like to thank the #BMWS community for providing their insights.

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🌞 THANKS FOR READING!

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About the writers: Andrew is an engineering science PhD student at the University of Oxford (@ndrewwang). Nicholas is a business manager at UCL Business and involved in physical science and computer science innovation in London (@nicholasyiu).