Featured Toyota’s Redesigned Aqua uses a new Bipolar Nickel-Hydrogen Battery

Discussion in 'Prius, Hybrid, EV and Alt-Fuel News' started by drash, Jul 21, 2021.

  1. drash

    drash Senior Member

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    Toyota to Launch All-New Aqua | Toyota | Global Newsroom | Toyota Motor Corporation Official Global Website

    The world named Prius C (as known in the US) has a better 1.5L engine and a new bipolar NiH2 battery. Unusual to call it Nickel Hydrogen and not NiMH. Makes me think it’s actually using gaseous hydrogen like the NiH2 batteries I worked on in the 90’s. The brunt of the story is they can make a Bipolar Nickel Hydrogen battery in a smaller denser space as well as lower the internal resistance (read: less heat generation while charging and especially discharging) than the current NiMH battery. Maybe the current hybrids using Nickel based batteries have some life left in them.

    Just wondering if Toyota has started calling all their NiMH batteries Nickel Hydrogen? Or is this a plan to test using bipolar design for their eventual solid state batteries to get more current out of them?


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  2. ChapmanF

    ChapmanF Senior Member

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    1,500 watts of "PriUPS" or "plug-out" capacity, with an emergency power supply mode, included in all trims! :)

    Coat each electrode with anode material on one side and cathode material on the other and stack 'em to make a battery, rather than stringing together individual anode-cathode modules:

    [​IMG]
     
    #2 ChapmanF, Jul 21, 2021
    Last edited: Jul 21, 2021
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  3. PriusCamper

    PriusCamper Senior Member

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    Who cares about the new battery design how about that new "comfort pedal" (patent pending) lol...

    Mostly I'm just glad Toyota is using the term "bi-polar" when it comes to their marketing strategy. Makes a lot of sense to me based on how they've been operating of late.
     
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  4. ChapmanF

    ChapmanF Senior Member

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    The "comfort pedal" seems to be essentially a one-pedal drive mode, where backing off the go pedal gives strong slowing.

    That can be a nice effect. I sometimes arrange something like it in my Gen 3 just by setting the cruise for 25 mph and then driving my desired higher speed using the go pedal.
     
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  5. Trollbait

    Trollbait It's a D&D thing

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    Just how different is this from the Yaris hybrid? There are the tech improvements, but those are things that will filter out to all Toyota hybrids in time. Is it mostly cosmetic differences, like the Rav4 and Venza? Will it actually get sold outside of Japan?

    Seems bipolar lead-acid batteries have been available for at least a few years.
    The highs and lows of bipolar batteries | www.bestmag.co.uk.

    The Comfort Pedal is as close to one pedal driving as a hybrid without a plug can get. Think I'd rather control regen braking levels through something like paddle shifters than drive modes though.
    I can see them doing that for messaging purposes.

    edit: A likely downside to the new battery is that refurbishing them will be harder, if not impossible for small companies to do.
     
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  6. ChapmanF

    ChapmanF Senior Member

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    At the same time, replacement batteries may be smaller and possibly cheaper (losing most of those bus bars and nut connections and the assembly labor to fuss with them).
     
  7. Trollbait

    Trollbait It's a D&D thing

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    The per cell cost will be lower for those reasons, once equal levels of production are reached. The pack in the new car has 1.4 times the number of cells as the previous Aqua pack had though.

    Regardless of how that effects the pack price, the price of a stack, module, or whatever the smallest subassembly is called, will be higher than that of a single one of the old cells. Which can be replaced individually currently.
     
  8. bisco

    bisco cookie crumbler

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    one pedal driving sounds horrible to me. i actually appreciate having to move my foor/leg a bit to brake.

    i like the idea of paddle control as well.
     
  9. austingreen

    austingreen Senior Member

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    I can't see any advantages of this battery versus toyota's lion hybrid battery. Are there any?
     
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  10. drash

    drash Senior Member

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    Yep since Toyota will definitely make a module of bipolar cells similar in size to the modules they have now with the same number of cells and probably keep the 6.5Ah since they already have BMS for modules of that size.

    The more I think about, I believe Toyota is using hydrogen as a gas. Easier than storing hydrogen at the anode when charging (recharging) as a hydride. They were coming out with bipolar NiH2 cells back in the 90s. What’s old is new again.


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  11. drash

    drash Senior Member

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    They don’t have to compete for Lithium and already have sizeable tooling for nickel based batteries. Keep the Lithium for Toyota Primes and Lexus +. Seems they got rid of the metal hydride anode used to store hydrogen and are just using a pure metal anode they developed.


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  12. Trollbait

    Trollbait It's a D&D thing

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    I don't either, and neither did the press release mention any. Still will have the same limitations as any NiMH chemistry in terms buffer zones for life span. Then Li-ion could be likely made bipolar, as lead-acid has already been done.

    It is better than single cell NiMH in performance, and Toyota will likely being using that for some time, until they get their Li-ion supplies up.

    The stacks will actually have less cells. The construction reduces internal losses. A footnote claims 1.5 times the current of a traditional cell.

    Volta's voltiac pile was using hydrogen according to the article I posted.

    This is just how NiMH batteries work. The press release used nickel hydrogen in reference to the traditional NiMH design. This is Toyota trying to keep hydrogen in the public's mind as a fuel.
     
  13. ChapmanF

    ChapmanF Senior Member

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    I think they mean to increase both current and number of cells. The write-up mentions about a factor of two increase in available power, achieved with roughly √2 times the current through about √2 times the cells.
     
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  14. Richard2005

    Richard2005 Member

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    The way it's described in the press release, it's Nickel Hydrogen (NiH2) and that is different to Nickel Hydride (NiMH). Whatever it actually is, they say they have achieved 1.5 times the output (I'm assuming they mean power) and 1.4 times increase in density .. so basically the bi-polar pack is 2.1 times the power of a similar sized NiMH pack. That is a substantial improvement and as its being released in a production car, it means it's market ready and not vapour ware. In typical Toyota style, you could easily miss this as their was nothing before or after ... just a description in the press release for a new model.

    In my view this is a substantial step forward and looks like it will underpin their future hybrid roll out ... currently forecast at 2.7 million for 2021. It may also be used for their PHEV's. Maybe they are proposing to use these batteries in their hybrid utilities/trucks. I would imagine solid state will be for BEV's and PHEV's but not hybrids.
     
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  15. bwilson4web

    bwilson4web BMW i3 and Model 3

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    From my earlier experiments:
    • NiMH needs better terminal seals to prevent the loss of electrolyzed gas - over time with heat and high usage, part of the water in the electrolyte becomes H{2} and O{2}. As some of the gas, particularly hydrogen, leaks out it gradually dehydrates the electrolyte leading to a hot spot that melts part of the plastic separator. However, rehydration returns the battery to like-new (and even better) capacity.
    • Lower internal resistance - by using both sides of the anode and cathode, the electrical path is shorter and lower resistance.
    • Fewer parts - no external current carry wires are needed making the parts count smaller and more affordable.
    As for Toyota's LiON battery ... I am NOT impressed. For example, our former 2017 Prius Prime had a 25 mi EV battery built from prismatic cells, a square peg located in the spare tire round hole. Had Toyota used cylindrical cells, a spare tire shaped, battery could have fit in the spare tire recess: (1) more Ahr capacity, and; (2) lower the floor for usable cabin space. It was an opportunity missed.

    Bob Wilson
     
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  16. Skylis A

    Skylis A Senior Member

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    So, Ni-H, how well can you regen in the cold with it compared to Lion?
     
  17. Richard2005

    Richard2005 Member

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    So BOB .. do you think the Aqua battery is actually NiH2 or a bi polar NiMH ?
     
  18. john1701a

    john1701a Prius Guru

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    There were multiple mutually exclusive opportunities. Lots of people want to cast Toyota's intent as maximizing sales. It was not. Since the goal was to take advantage of a proven design, leveraging the low cost and robust design, it simply didn't make sense pursuing a shape change at that time.

    Looking back, now knowing Toyota's goal was to confirm the prismatic cells were indeed an excellent PHEV choice, the decision should be obvious. We got RAV4 Prime as a result.
     
  19. drash

    drash Senior Member

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    Loaded question, because it depends on the electrolyte and concentration. Better question for Toyota engineers, but the potassium hydroxide electrolyte in older NiH2 freezes at about -42C, however, diffusion will fail long before then. Regen produces hydrogen, which is diffused into the anode. Compared to Lion batteries, you’re comparing lithium versus hydrogen, so you could assume hydrogen would perform better at lower temperatures.

    A more interesting question is how the heck does Toyota get rid of the heat in a bipolar cell because recombination of oxygen and hydrogen can produce a lot of heat.


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  20. wjtracy

    wjtracy Senior Member

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    Europeans dislike gasoline autos because they are accustomed to the higher power/pep of diesel cars. If a hybrid gaso ICE can be made more peppy, then that potentially expands the hybrid space globally. However, in USA it somewhat falls on deaf ears because liberals want 100% Li batt BEVs and conservatives reject hybrids like COVID shots. Culture wars.
     
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