Does Tesla buying Maxwell Technologies signal to switch to solid state batteries?

I'll repeat the comment that I posted in response to your article, Domenick:

Googling the term “dry battery electrode”, it’s probably not a coincidence that the first hit is for a scientific article, “Electrochemical Performance of Dry Battery Electrode,” which includes the following in the abstract for the article:

…Maxwell Technologies unique heritage solvent-free dry electrode process used to commercialized Ultracapacitor electrodes can be adapted to existing lithium ion battery chemistries and advanced materials. Maxwell dry electrode manufacturing demonstrative benefits over conventional slurry wet coating process includes, (i)environmentally benign due to elimination of toxic solvent, (ii) lower cost by reducing capital and operating expenditures, resulting from elimination of solvent recovery and recycling system, (iii) improved energy and power density afforded by unique dense high loading electrode microstructures.

Maxwell Technologies has applied its proprietary dry electrode process to produced lithium ion battery cathode and anode electrode with unparalleled energy density and enhance cycle life over conventional wet coated electrodes. We have demonstrated dry robust process capability, incorporating current and advanced chemistries such as graphite, silicon, metal alloy, and nickel-rich layered transition metal oxides. In addition, we have demonstrated roll-to-roll dry process scalability using common and advanced battery material chemistries.
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Of course, this isn't at all proof that Tesla isn't moving toward solid-state batteries, but I think Occam's Razor shaves in the direction of merely improving the electrodes in the type of Panasonic batteries which Tesla is currently using.

Various comments by Elon and by JB Straubel over the past couple of years indicate that Tesla thinks usable solid state batteries are still several years off. Of course it's always best to take such comments with a few grains of salt, as both EV makers and battery cell makers like to play things close to the vest with proprietary battery tech and trade secrets. But my working assumption is that what both Elon and JB have said in those comments is correct.

It's possible that some new solid-state battery tech could be revealed tomorrow, or perhaps already has been revealed to Tesla in a private demo, which might cause Tesla to shift its strategy rather quickly. And Tesla might be able to keep that a secret until just before introducing it into their production cars, altho frankly I think the word would leak out sooner, during testing.

It's an exciting time to be an EV advocate!

 

Possibly. But Elon mentioned a few months back that Tesla was in the process of designing a new battery pack architecture for the Standard Range Model 3 battery pack; one that would reduce cost.

Perhaps that's the reason for the delay in switching the Model S/X packs over to using the 2170 cells. Probably doesn't make much sense to make the switch until they can take advantage of the new, presumably simpler and cheaper architecture.

This is, of course, all just speculation on my part; I could easily be wrong here. (I see I'm closely echoing what Domenick said above! )

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Batteries have two important characteristics:

• energy density - how many kWh they can carry around
• power density - how fast the kW can be drawn from the battery

These are frequently at odds. But if you use ultra capacitors combined with high energy cells, you get the best of both worlds. Peak power demands are fairly brief measured in 10s of seconds for acceleration and regeneration. The caps are great for this but they don't have the energy density to drive cross country. That is where the high energy density batteries come it to maintain the SOC on the caps.

The only technical problem are batteries are more 'constant voltage' whereas caps are 'variable voltage.' The power electronics are ... a mix.

Bob Wilson

 

Quite true; the voltage in a capacitor is a function of the energy level. As the electrical energy in a capacitor approaches zero, the voltage also approaches zero. Using a capacitor bank as the main "battery" for an EV would require a pretty hefty voltage converter, and one that could handle a wide range of voltages. I'm not sure that anything like that is made, or how difficult it would be to engineer if it's not already made.

On the other hand, capacitors can be cycled thousands of times without substantial loss of capacity, and can be recharged (and discharged) at electronic speeds without overheating, since they don't (as batteries do) depend on chemical reactions to store or discharge energy. So if anyone does ever produce a magic capacitor capable of holding that much energy in something not much bigger than today's li-ion battery pack, something like EEStor's fantasy of an "EESU", then it certainly would be worth the trouble to engineer a power electronics system that could use the magic capacitor to power an EV.

According to some who participated in discussions of the EESU and related topics on the old TheEEStory forum, those few who had degrees in physics (which I don't), it is theoretically possible to have a capacitor with the energy density EEStor claimed... it just isn't possible to do it the way EEStor claimed.

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Switching power supplies are quite flexible but you need a dual ... on for charging and one for discharging. Equally challenging is keeping the cap voltages for series strings at same voltages. But these are things Maxwell has been working on for as long as they've been in business.

I may have mentioned it elsewhere but a mix of high energy storage batteries with caps for short duration, high power would be great. Tesla by now has an extensive database of the power and energy needed to optimize the mix.

Bob Wilson

 

I don't understand. If they are connected in series (or connected in parallel, for that matter), wouldn't the energy/ voltage automatically balance out between them?

Not at all suggesting you're wrong; I'm not an electrical engineer and don't understand why it's not as simple as, say, connecting a bunch of water tanks with some pipes at the bottom, which would result in water running downhill to automatically keep the water level the same in all tanks, assuming they're all at the same height.

As I said in a comment above, I think Tesla's acquisition of Maxwell indicates an interest in the improved tech for battery electrode coating, not anything else... neither Maxwell's unproven solid state battery tech, nor capacitors. I have no doubt that someday we'll see solid-state batteries in Tesla cars, but from various comments by Elon and JB Straubel, I doubt that will happen in the next 2-3 years, and perhaps not the next 4-5 years.

Of course it's not impossible that Tesla will start including a bank of capacitors in its energy storage systems, but there's a reason that even stationary energy storage systems (where the use of much larger capacitors wouldn't be as much a limitation) use banks of electrochemical batteries rather than banks of capacitors. I don't see that Maxwell's tech is going to change that.

 

In parallel, the voltage remains constant. But in series, minor part differences will lead to different voltages, not a lot but measurable. Over time, it can lead a marginal part to a bad place. Fortunately when I looked a Maxwell many years ago, they had a solution.

Bob Wilson

 

Light in technical details, more of a high-level review:


The 'dry battery' paper:
http://www.powersourcesconference.com/Power Sources 2018 Digest/docs/3-1.pdf

The separator has to pass ions but not electrons. The only thing that springs to my mind are carbon nanotubes. Apparently they can behave as a semiconductor (source: https://en.wikipedia.org/wiki/Carbon_nanotube.) So oriented as a porous field in a polymer carrier, ions could flow through the nanotubes and no electrolyte is needed. A very nice solution.

Bob Wilson

ps. Perhaps this Tesla-Maxwell technology thread should be relocated into the Tesla forum? I'm 50/50 on this but the term "proprietary" suggests Tesla-Maxwell are going where others won't be able to follow.

 

Tesla have been loosely talking about a 20% jump in capacity for some time now. See the semi range comments (500 to 600 miles). This aligns with Maxwells claim of increasing power density from 250w to 300w per kg.

 

No. Dry coating electrodes (anodes and cathodes), is not the same as solid electrolyte (solid state).

 

Regardless of electrode separator, it must pass ions and not electrons.

Bob Wilson

 

well speculated sir but my concern is if there is any solution on how to deal with dead batteries without causing more harm to the earth,are there any new ways of tackling this that i should know about?

 

I did find it odd that Domenick (our forum moderator) placed this thread in "General" rather than under "Tesla"... but I guess this is where he thinks it belongs. Maybe that's because the subject of solid-state batteries, and/or using capacitors in EVs, has ramifications beyond just Tesla?

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Indeed, not everything has to be done instantly. <GRINS>

Bob Wilson

 

But... but... but.. as an American, I've been "educated" by advertising and mass media to expect instant gratification in everything!

 

Jack Rickard videos are long but with a lot of technical content:

(Reminds me of Mark Twain's Simon Wheeler.) Youtube playback can be sped up but not as entertaining.

Bob Wilson

 

Can someone explain to me how this works. Tesla offers $4.75/share. Maxwell share price goes up, $4.74 Friday closing. Maxwell shares were about $3.60 before the offer. If I was a Maxwell share holder I would sell now and take my profit. This has to be approved by SEC and ratified by a Maxwell shareholder vote that will happen in about 3 months.
1. Why 3 months? Is this to give time for another competitive offer by someone else like GM or VAG?
2. Why are investors willing to offer $4.74 now? Doesn’t make sense for 1 cent in 3 months. Are they expecting higher offers?
3. What are the odds of this going through?