Tesla Battery Investor Day

[MC3OZ]

Hanwha inks EV battery equipment deal with Tesla

Just updating this thread with the latest information.

Hanwha Group said Sunday that its subsidiary Hanwha Corp. recently signing a supply deal on battery formation equipment with U.S. electric vehicle (EV) giant Tesla.

 

[TheTalkingMule]

This was the original thread, the other is the duplicate.

Not sure how I missed that one, could've sworn it was the other way around. Bizarre.

 

[willow_hiller]

I can't tell if this is news, or whether Electrek is just late in reporting on it: Tesla improves on its 'million-mile battery' with less cobalt and higher energy density - Electrek

Does seem to link to a journal published early January: Microstructural Observations of "Single Crystal" Positive Electrode Materials Before and After Long Term Cycling by Cross-section Scanning Electron Microscopy - IOPscience


"The new battery tested is a Li-ion battery cell with a next-generation “single crystal” NMC 532 cathode and a new advanced electrolyte, which they patented.

They were able to show over 4,000 cycles in the battery cells made with the novel cathode.

Building on the research done on that battery, Dahn and his students Yulong Liu and Jessie Harlow have published a new research paper called ‘Microstructural Observations of “Single Crystal” Positive Electrode Materials Before and After Long Term Cycling by Cross-section Scanning Electron Microscopy’ in the Journal of The Electrochemical Society.

In the paper, they showed how they achieved high cycling data for NMC 622 and NMC 811 batteries while using even less cobalt than in NMC 532 and achieving even greater energy density."

 

[MC3OZ]

I can't tell if this is news, or whether Electrek is just late in reporting on it:

I think Electrek is simply late reporting this time around, regardless, Battery Day is going to be exciting.

 

[MC3OZ]

We had some discussion on this in the main investor thread.

https://www.cell.com/joule/pdf/S2542-4351(20)30172-0.pdf?_returnURL=https://linkinghub.elsevier.com/retrieve/pii/S2542435120301720?showall=true

Li-ion Mode - 530 Wh/L Li-metal Mode - 890 Wh/L

There was some speculation as to whether Li-metal is last-on-first-off or first-on-last-off.

If it is first-on-last-off I have thought of a great application....
Referring just to Li-ion part of the battery I typically plan to arrive a Superchargers with 18-20% SOC, that is because the fast charging networks in Australia are a bit under-developed, Plan B might involve a lot of waiting for a single stall charger that you hope is working.

Often arriving with 18% means charging to 90%-95% , if I have 20% "reserve capacity", I'm not happy to arrive with the Li-ion part of the battery at 3% which means I only need to charge it to 80%... Occasionally i might change it to 100% and do a planned leg of 100%->3%.

Trips where I would deliberately plan to use some of the "reserve capacity" would be rare.

So planning to use the "reserve capacity" as a contingency saves time at Superchargers and improves the longevity of the Li-ion portion.

I think this has to be baked into the cost of the car and come as a standard feature, it is probably worth a bit more money and weight to derive the advantages above.

As a "reserve capacity" that is rarely used the LI-metal part of the battery will last a long time, it is up to the cars owners how they want to use this battery, but it's state should be transparent, the driver needs to know how much reserve they really have.

We all know "range anxiety" isn't a real problem, but a feature like this would help convince some buyers who are concerned. So I see it as a feature Tesla can add as a demand lever.

 

[MP3Mike]

There was some speculation as to whether Li-metal is last-on-first-off or first-on-last-off.

If it is first-on-last-off I have thought of a great application....
Referring just to Li-ion part of the battery I typically plan to arrive a Superchargers with 18-20% SOC, that is because the fast charging networks in Australia are a bit under-developed, Plan B might involve a lot of waiting for a single stall charger that you hope is working.

OK, I got a copy of the full study/article and I think it makes it very clear that it is last on/first off:

Capacity retention of cells cycled on a hybrid protocol charging to 4.0 V (graphite capacity) with
periodic ‘‘boosted’’ full charge cycles to 4.4 V to access the lithium metal capacity;

This hybrid protocol uses an approximate midpoint of the voltages that were found to be the onset of lithium metal plating at 0 cycles and 50 cycles, since the plating voltage was not static, as discussed previously. Thus, the cells cycled to 4.0 V for 10 cycles (cycling very little, or no, lithium metal capacity depending on the cycle number) and charged to 4.4 V one time (indicated as 10 cyc/1 cyc in figure captions). This protocol was continuously repeated in both LDBF and 2F1L electrolyte cells. Additionally, the ‘‘boosted’’ protocol was also tested using 10 low voltage cycles/ 5 ‘‘boosted’’ cycles (indicated as 10 cyc/5 cyc in figure captions).

So it would normally only be charged to ~4.0V, but can "boost" charge to ~4.4V to access the lithium-metal capacity.

If Tesla went with this kind of hybrid battery I suspect they would make the 3.0-4.0v report as 0-100% SoC, and then the 4.0-4.4v (lithium metal portion) report as 101-120%. So you would "boost" charge to start your trip which might help a lot of you are on the fringe of making it in a single charge, but wouldn't really make much difference in a very long trip with multiple charging stops. (Though it might mean that you can maintain the peak charging rate for a longer period since you aren't actually charging the battery to 100% even if you charge the lithium-ion portion to 100%.) You still wouldn't want to charge to 100% of the lithium-ion portion all the time because you wouldn't want the regen either disabled or going into your limited uses of the lithium-metal mode.

 

[MC3OZ]

OK, I got a copy of the full study/article and I think it makes it very clear that it is last on/first off:

In that case I think it may be less useful as an owner can only cycle the metal portion 150 times, and having to change the Li-ion battery to 100% before you can start charging the metal portion is a disadvantage.

So the extra expense and weight may not be justified by the extra occasional capacity obtained.

 

[MC3OZ]

n owner can only cycle the metal portion 150 times

Some are assuming this means 80% capacity of the Li-metal portion after 150 cycles, again this is worth clarifying..

 

[MP3Mike]

Some are assuming this means 80% capacity of the Li-metal portion after 150 cycles, again this is worth clarifying..

I read it as the lithium-metal mode capacity is reduced to ~80% after 160 full charges of the battery. (Full trip mode.):

Conversely, with the use of a LiDFOB/LiBF4 dual-salt electrolyte and the application of uniaxial pressure, lithium can be reversibly cycled on top of the graphite with these cells achieving 160 cycles before falling below 80% capacity.

The graphite mode portion of the hybrid cell only lost ~3% of its capacity after 500 cycles. (Traditional cells lose ~2% after 500 cycles.)

Hybrid cell @ 100%: 890Wh/L (20% more than traditional)
Hybrid cell in lithium-ion only mode: 530 Wh/L (25% less than traditional)

Those numbers don't all make sense, because the full hybrid numbers says the traditional cell is 741 Wh/L while the lithium-ion only mode portion says that a traditional cell would be 706 Wh/L. (I guess you can split the difference and say a traditional cell is 723 Wh/L.)

In that case I think it may be less useful as an owner can only cycle the metal portion 150 times, and having to change the Li-ion battery to 100% before you can start charging the metal portion is a disadvantage.

So the extra expense and weight may not be justified by the extra occasional capacity obtained.

Remember that a normal lithium-ion battery is charged to 4.2v when it is considered full, in the hybrid you are only charging to 4.0v in lithium-ion mode, which should result is less degradation. For the same size of battery in normal daily mode you have ~25% less range, but for trip mode you have 20% more range. Most people don't need as much range daily, but the extra trip range would be useful. They say they actually weigh less:

The hybrid cell offers an intermediate energy density, less than anode-free, but greater than lithium-ion. Due to the increased average voltage and decreased stack thickness and weight, the hybrid format boasts a volumetric energy density (per L) increase of 25% and a specific energy density (per kg) increase of 20% over conventional lithium-ion cells.

They don't specifically cover cost, but it probably isn't that different.

 

[MC3OZ]

I read that as the lithium-metal mode capacity is reduced to ~80% after 160 full charges of the battery. (Full trip mode.):



The graphite mode portion of the hybrid cell only lost ~3% of its capacity after 500 cycles. (Traditional cells lose ~2% after 500 cycles.)

Hybrid cell @ 100%: 890Wh/L (20% more than traditional)
Hybrid cell in lithium-ion only mode: 530 Wh/L (25% less than traditional)

Those numbers don't all make sense, because the full hybrid numbers says the traditional cell is 741 Wh/L while the lithium-ion only mode portion says that a traditional cell would be 706 Wh/L. (I guess you can split the difference and say a traditional cell is 723 Wh/L.)



Remember that a normal lithium-ion battery is charged to 4.2v when it is considered full, in the hybrid you are only charging to 4.0v in lithium-ion mode, which should result is less degradation. For the same size of battery in normal daily mode you have ~25% less range, but for trip mode you have 20% more range. Most people don't need as much range daily, but the extra trip range would be useful. They say they actually weigh less:



They don't specifically cover cost, but it probably isn't that different.

Thanks I'm starting to see a case for this being useful in "trip mode".

 

[MP3Mike]

Thanks I'm starting to see a case for this being useful in "trip mode".

Especially if it allows you to charge to 100% of non-trip mode faster, and that that would be enough of a charge to get you between most Superchargers. And who knows if/how this could be combined with dry electrode technology...

 

[MC3OZ]

Yet another patent:- Tesla Gained Another Battery Cell Patent: Cell With A Tabless Electrode

 

[Buckminster]

Yet another patent:- Tesla Gained Another Battery Cell Patent: Cell With A Tabless Electrode

He discusses faster supercharging as a likely outcome - another huge expectation for battery day!

 

[willow_hiller]

Saw this discussed briefly in the main thread, but I'm interested to hear thoughts here as well: Tesla partners with US' biggest solar installer to deploy Powerwalls - Electrek

Tesla partnering with Sunrun to provide them with Powerwalls. Is it possible many of the Battery Day innovations have quietly been put into place already? Selling Powerwalls to a third-party solar installer doesn't sound like something a battery constrained company would do.

 

[Mo City]

If you haven't already, watch these two short videos from The Limiting Factor done earlier this year. One on Jeff Dahn and the other on Shirley Meng.

If you are like me and the term "Battery Day" comes to your mind every time "Tesla" does, it's more fuel to the fire.

 

[Buckminster]

Munro is hopeful that Tesla are developing solid state batteries - Maxwell were working on them.

Seems a stretch. All the other pieces of the jigsaw / patents suggest not.

 

[MC3OZ]

Munro is hopeful that Tesla are developing solid state batteries - Maxwell were working on them.

Seems a stretch. All the other pieces of the jigsaw / patents suggest not.

Battery Day should reveal a big leap forward, solid state may eventually be even better, but questions around sold state are the manufacturing process and the cost.

No one has revealed a proven formula for mass producing solid state batteries for a competitive price, that may need another 5-10 years of R&D.

 

[JRP3]

Just because Maxwell talked about solid state as a future goal in their press release doesn't mean it's a near term reality.

 

[Doggydogworld]

He discusses faster supercharging as a likely outcome - another huge expectation for battery day!

I can't imagine Supercharging is in any way limited by the distance electrons travel on the substrate foil.

 

[willow_hiller]

I can't imagine Supercharging is in any way limited by the distance electrons travel on the substrate foil.

Is it possible the limiting factor is the ability to keep the battery cool? At which point the lowered resistance would help?