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Power Science

New 'Water Batteries' Are Cheaper, Recyclable, And Won't Explode (sciencealert.com) 73

Posted by BeauHD from the new-and-shiny dept.
Clare Watson reports via ScienceAlert: By replacing the hazardous chemical electrolytes used in commercial batteries with water, scientists have developed a recyclable 'water battery' -- and solved key issues with the emerging technology, which could be a safer and greener alternative. 'Water batteries' are formally known as aqueous metal-ion batteries. These devices use metals such as magnesium or zinc, which are cheaper to assemble and less toxic than the materials currently used in other kinds of batteries.

Batteries store energy by creating a flow of electrons that move from the positive end of the battery (the cathode) to the negative end (the anode). They expend energy when electrons flow the opposite way. The fluid in the battery is there to shuttle electrons back and forth between both ends. In a water battery, the electrolytic fluid is water with a few added salts, instead of something like sulfuric acid or lithium salt. Crucially, the team behind this latest advancement came up with a way to prevent these water batteries from short-circuiting. This happens when tiny spiky metallic growths called dendrites form on the metal anode inside a battery, busting through battery compartments. [...]

To inhibit this, the researchers coated the zinc anode of the battery with bismuth metal, which oxidizes to form rust. This creates a protective layer that stops dendrites from forming. The feature also helps the prototype water batteries last longer, retaining more than 85 percent of their capacity after 500 cycles, the researchers' experiments showed. According to Royce Kurmelovs at The Guardian, the team has so far developed water-based prototypes of coin-sized batteries used in clocks, as well as cylindrical batteries similar to AA or AAA batteries. The team is working to improve the energy density of their water batteries, to make them comparable to the compact lithium-ion batteries found inside pocket-sized devices. Magnesium is their preferred material, lighter than zinc with a greater potential energy density. [I]f magnesium-ion batteries can be commercialized, the technology could replace bulky lead-acid batteries within a few years. The study has been published in the journal Advanced Materials.
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New 'Water Batteries' Are Cheaper, Recyclable, And Won't Explode More

New 'Water Batteries' Are Cheaper, Recyclable, And Won't Explode

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  • Repressed no longer! (Score:4, Funny)

    by JeremyWH ( 1354361 ) on Thursday March 07, 2024 @03:20AM (#64296580)
    Finally! Invented over 100 years ago, after being repressed by the oil companies, the water engine is back! Oh, wait..
  • Dumbass

  • Title: "New 'Water Batteries' Are Cheaper, Recyclable, And Won't Explode"

    What users look for in a battery is not if it's "cheaper, recyclable and won't explode" (well, maybe someone looks specifically for the last one), but instead they look for "rechargeable cycles, time to full recharge & capacity/durability time in use".

  • Batteries all used to have an aqueous electrolyte. After all, that is what "wet cells" are. And you can still buy NiMH cells - they last pretty well, and they have absolutely no fire risk. They are also expensive and have low energy density.

    Why would you want to go back to those days? It is nice that they got magnesium to work, which means slightly higher voltage and energy, but I just do not see these being competitive against LPF, LMFP or sodium batteries, which all have great fire safety.

    • Batteries all used to have an aqueous electrolyte. After all, that is what "wet cells" are.

      Right. That's why calling them "water batteries" is terrible. I've added a lot of water to a lot of batteries that won't work without it.

      And you can still buy NiMH cells - they last pretty well, and they have absolutely no fire risk. They are also expensive and have low energy density.

      NiMH has fairly decent energy density now, if you get good ones. They also have a lot of charge cycles, same caveat. Eneloop AAs of today have more energy capacity than the sub-C cells of yore, and 1000+ charge cycles. And if you totally deplete them it doesn't harm them.

  • Exploding WHAT? (Score:2, Informative)

    by smurfi ( 91140 )

    Could we please retire the "exploding batteries" nonsense?

    Batteries don't explode. They may go up in flames, esp. when shorted – more or less violently and more or less unstoppably, both depending on cell chemistry – "less" when using LiFePo4 – but *that's it*. (As opposed to petrol cars. The right mix of air and petrol vapor does go "foom" rather spectacularly, if not as nicely as in most movies.)

    • Lead-Acid batteries give off both hydrogen and oxygen. They can, in fact, go "foom" as many car mechanics can attest. No vigorous flames like the various lithium batteries; just a loud pop and acid flying everywhere.

      • Lead-acid batteries produce hydrogen during charge cycles because the charging voltage per cell is enough to break down the water in the electrolyte. This is a normal and expected part of operating these devices. These saltwater electrolyte batteries also use an aqueous electrolyte, and operate at an even higher voltage.

        The paper doesn't really address this. They talk about hydrogen-evolving reactions but seemingly only in the context of adverse chemical reactions. There's only one passing acknowledgement t

    • Re: (Score:2)

      by dargaud ( 518470 )
      I've always heard that cars in accidents don't explode like in american movies. And yet when we stopped in traffic on the highway and the guy behind us didn't, leading to being rear-ended at high speed, our car EXPLODED in a fireball that envelopped the car. I saw it IN FRONT OF ME (I was driving). Fortunately the backseat was packed to the ceiling (we were moving), so the flames were mostly outside. Total 8 cars burnt to the ground, minor injuries to us (glass cuts, burns) and the read-ender, total loss of

      • Ford Pinto?

      • Re: (Score:2)

        by Pascoea ( 968200 )

        I've always heard that cars in accidents don't explode like in american movies.

        That's the problem with generalities. They only apply the majority of the time. There's always outliers. And there's nothing magical about cars designed to not explode they just moved the gas tank more forward and made it less likely to rupture. With the right scenario, they can absolutely rupture, sometimes with spectacular results. Your car didn't "explode like in american movies" though, unless someone packed a bunch of TNT and detonators in your trunk.

        • Re: (Score:3)

          by dargaud ( 518470 )
          Yeah. It was extremely hot that day (105F?), so I don't know if it contributed to creating a volatile spray that went 'boom'. Anyway, it was impressive to see from the inside... while our tiny Fiat was catapulted over the 8 cars in front of us... When I later took the pictures for the insurance, our crushed car was 3 feet long... It seemed impossible that anyone could have gotten out alive.
  • I think you guys got cathode and anode wrong.

    • Re: (Score:2)

      by ls671 ( 1122017 )

      I think you guys got cathode and anode wrong.

      It depends if you look at it from inside or outside the battery. They are apparently looking at it from the outside. It should be kind of obvious since they mention electrons moving the opposite way. Inside a battery, we usually talk about anions and cations.

      • Re: (Score:2)

        by ls671 ( 1122017 )

        also note store/expend == charge/discharge

      • It doesn't, if it's an ion transfer surface, so on the inside, you call it 'cathode' or 'anode', but when it's an electron transfer surface, so on the outside, you call it 'terminal', negative or positive respectively. Exactly to prevent the ambiguity.

      • They are apparently looking at it from the outside.
        No, they are not.
        Outside the elecgtron flow is from kathode to anode. How else should it work?
        Inside it is ions.

        • Re: (Score:2)

          by ls671 ( 1122017 )

          Electrons have negative charge so they are attracted toward the cathode with a big "+" on it on the outside of the battery. Current flow in the opposite direction of electrons.

          Also two types on ions in batteries; cation and anion

          • Re: (Score:2)

            by ls671 ( 1122017 )

            *when battery is in normal use mode. When recharging a battery, everything (current and electrons flow) is inverted on the outside wire circuit

          • The Cathode does not have a big +.
            It has a big - ...

            Current flow in the opposite direction of electrons.
            Sure?
            If you mean the old physic laws as right hand rule for magnetic fields or Lorenz force: yes.

            But current is made from/buy electrons, the moving electrons are the current: and they move from - to +.

    • They also got this wrong:

      the researchers coated the zinc anode of the battery with bismuth metal, which oxidizes to form rust.

      Rust is IRON oxide, just because some process is oxidation or corrosion doesn't mean it is "rust"

  • Will reduce your body fat overnight, improve your sex life, and make you a millionaire! Doctors do not want you to know this one weird trick!

  • It retains 85% of capacity after a mere 500 cycles? Can you imagine losing 15% capacity after only a couple of years of ownership? This might be useful in an Uninterruptible Power Supply, where you just charge it to 100% and it mostly stays there.

    There's no mention of energy density either. So it's probably both too heavy and too large for EV usage.

    • Re: (Score:2)

      by etash ( 1907284 )
      do you drive 400km each day?

      • Re: (Score:2)

        by dgatwood ( 11270 )

        do you drive 400km each day?

        No, no, no. The legacy car companies long ago convinced governments to redefine the world "EV" to include plug-in hybrids. Because their batteries are designed to be as low-capacity as possible for cost reasons, drivers are likely to run down the battery in a plug-in hybrid approximately every weekday unless it's a parallel hybrid where the engine can move the car directly some of the time.

        There are about 260 work days per year, give or take. (This year has 262 because of leap year.) After eliminating p

    • Re: (Score:2)

      by Junta ( 36770 )

      There's no mention of energy density either.

      Well, there is:

      The team is working to improve the energy density of their water batteries,

      So, they don't want to say but want to assure anyone responsible for grants that they are "working on it".

      So good luck to them, and they may have some cool applications as-is, but some of the biggest applications may be out of reach. Maybe they succeed, but I've seen *way* too many revolutionary research have a "we just need to fix this one little deal breaker and we'll be set" that never gets resolved.

    • It retains 85% of capacity after a mere 500 cycles? Can you imagine losing 15% capacity after only a couple of years of ownership? This might be useful in an Uninterruptible Power Supply, where you just charge it to 100% and it mostly stays there.

      There's no mention of energy density either. So it's probably both too heavy and too large for EV usage.

      Well, TFA did say that they had worked their way up to coin-sized batteries currently, so progress will be made there hopefully toward larger form factors.

    • Re: (Score:2)

      by Pascoea ( 968200 )
      How many miles do you think you should get out of a battery pack? 500 tanks of gasoline in a normal car (using mine as an example) equates to 175,000 miles. I'd be ecstatic if got that many miles and still had 85% of my car's life left.

      • Re: (Score:2)

        by dgatwood ( 11270 )

        How many miles do you think you should get out of a battery pack? 500 tanks of gasoline in a normal car (using mine as an example) equates to 175,000 miles. I'd be ecstatic if got that many miles and still had 85% of my car's life left.

        To use an example on the opposite extreme, for a PHEV, a typical pack might have only a 14 kWh battery, which translates to O(50) miles. I'd be pretty pissed off if my car had only 85% of its battery capacity at 25,000 miles.

        Could be anywhere in between those extremes. :-)

        Having 85% of its capacity at 175k miles might be slightly on the low side for a true BEV, as opposed to a hybrid. Tesla says that theirs typically retain about 88% of their original capacity at 200k, and that number presumably includes

  • This creates a protective layer that stops dendrites from forming. The feature also helps the prototype water batteries last longer, retaining more than 85 percent of their capacity after 500 cycles

    500 cycles is 18-24 months in EV time. I promise your EV car loan is a hell of a lot longer than that, so before Mass Ignorance helps sell every Green water-battery headline on behalf of Greed, perhaps we ask why we assume this is a viable alternative to anything we need today.

    We expect better performance, out of our damn smartphone batteries. A car is expected to last a decade or more to sell the idea they’re “better” for us. Show me what your capacity statistics after half of that, so

    • Re:500 cycles, doesn’t Sell me anything. (Score:4, Informative)

      by flink ( 18449 ) on Thursday March 07, 2024 @09:14AM (#64296926)

      500 cycles is 18-24 months in EV time.

      Only if you completely discharge your battery every day. Most people drive < 50 miles/day. That's more like 8-10 years. After which the car does not explode, it just gradually loses 30-40 miles of range. It might still be good enough for you, or if not, sell it to someone for whom it is and buy a new one.

      • Re:500 cycles, doesn’t Sell me anything. (Score:4, Interesting)

        by Junta ( 36770 ) on Thursday March 07, 2024 @09:43AM (#64296990)

        NMC chemistry is already a source of reluctance, and that will typically get 1,000 to 2,300 cycles. LFP is widely considered a safer bet with 3-10k cycles.

        It's asking a *lot* for the industry to go back and declare '500 cycles is good enough'. It might be a slam dunk if a typical battery replacement job goes down to under $1,000 as a result, but I don't see if they'd expect it to be *that* much cheaper.

        Also, this depends on the range of the car with respect to a battery pack. If it's a PHEV, then every day would be a cycle in that average case.

        Also probably not well characterized, the lifespan under a variety of scenarios, temperatures and discharge/charging rate. If it lasts 500 cycles, but was tested at charge rate of 0.01C, then that would not tell us much of use, since a car would take 100H to charge. If it's 500 cycles at 10C, well that would be fantastic.

        The biggest skepticism for me is the energy density. I'll wager this will be the thing that makes it unrealistic for BEV/PHEV applications.

        • Re: (Score:3)

          by dfghjk ( 711126 )

          "It's asking a *lot* for the industry to go back and declare '500 cycles is good enough'. It might be a slam dunk if a typical battery replacement job goes down to under $1,000 as a result, but I don't see if they'd expect it to be *that* much cheaper."

          This is all complete nonsense. First, no one is "asking" for some garbage straw man. Second, what does "go back and declare" mean? Go back to what? Third, what does 500 cycles even mean? Do you know? What is the lifetime range of a vehicle? And how muc

          • Re: (Score:2)

            by Junta ( 36770 )

            "cycles" is a pretty well understood term in battery world, a mostly full discharge/charge cycle. If a battery pack gets you 50 miles on a charge (ballpark of a PHEV), then 500 cycles would be 25,000 miles. If one charge gets you 500 miles, then 250,000 miles. There are games to be played to maybe be more optimistic, like going from 65-70 percent 20 times might be less rough than one cycle, but still get the same miles, but broadly speaking charge/discharge cycles are extremely well recognized indicators

      • Re: (Score:2)

        by AmiMoJo ( 196126 )

        It is in fact impossible to do a full cycle on most EV batteries. As far as I know, all manufacturers have a significant buffer built in, i.e. the full capacity of the battery is not available to the user. Therefore a full cycle is more like 90-95%.

        Additionally, many cars have a charge limited that you can set to say 80%. Battery degradation accelerates rapidly above 80% charge, so using this feature greatly prolongs the lifetime of EV batteries.

        • Re: (Score:2)

          by dfghjk ( 711126 )

          Yes, and PHEVs heavily exploit this. "Full cycle" means something objective in characterizing batteries but it doesn't translate well to what a driver does with his car. It is useful in making bad faith arguments on /. though.

        • Re: (Score:3)

          by dgatwood ( 11270 )

          Battery degradation accelerates rapidly above 80% charge, so using this feature greatly prolongs the lifetime of EV batteries.

          Battery degradation accelerates rapidly as you get close to 100% charge for some battery chemistries. For example, Tesla recommends not charging most of their cars to more than 90% for longevity reasons. But the only time they recommend stopping at 80% is when you're supercharging.

          The 80% recommendation, in turn, has nothing to do with battery lifetime and everything to do with charge time while you and other people are waiting. By the time you're at 80%, you're only adding about three miles per minute,

    • Re: (Score:2)

      by dfghjk ( 711126 )

      "500 cycles is 18-24 months in EV time."

      Citation please.

      "I promise your EV car loan is a hell of a lot longer than that..."

      There has never in history been an EV car loan "longer" than 500 cycles.

  • So were back to lead-acid battery technology isn't all that bad. LOL.

  • How different is this from the "salt water battery" that Aquion Energy was selling a few years ago?
    https://en.wikipedia.org/wiki/... [wikipedia.org]
    Saw these units actually listed for sale in some stores before Aquion went belly-up.

  • The PLATES are a much bigger problem than the electrolyte. Look at a car battery... LEAD plates and sulfuric acid. The acid isn't the environmental problem, the lead is. It's the plates you need to be looking at, not the electrolyte. Also,

    the technology could replace bulky lead-acid batteries within a few years.

    Lead-acid plates are almost always used in cars right now, where you need rugged and high current batteries. Two things that these "water batteries" perform very poorly at.

  • Nuclear? (Score:4, Funny)

    by bill_mcgonigle ( 4333 ) * on Thursday March 07, 2024 @10:05AM (#64297028) Homepage Journal

    > zinc anode of the battery with bismuth metal, which oxidizes to form rust

    So they're popping four protons off Zn to get Fe?

    Sounds spicy.

  • Batteries store energy by creating a flow of electrons that move from the positive end of the battery (the cathode) to the negative end (the anode).
    Oh Really?

  • Anyone that's been paying attention to battery tech knows that Sodium-ion batteries [wikipedia.org] have been around for a while. The actual breakthrough here is they have found a way to suppress dendrite growth [wiley.com] by introducing bismuth to the zinc anode.

    This diagram illustrates it pretty well: https://onlinelibrary.wiley.co... [wiley.com]

    Zinc is not used as an anode for existing sodium-ion batteries, likely due to the dendrite growth problem. So the question of why you would want to use a zinc anode. It could be economics in which case

    • Re: (Score:2)

      by dgatwood ( 11270 )

      Zinc is not used as an anode for existing sodium-ion batteries, likely due to the dendrite growth problem. So the question of why you would want to use a zinc anode. It could be economics in which case this would be great.

      Probably economics, yeah. Zinc is so cheap that it literally costs pennies. :-D

  • Just like the last 100 of them seen over the past 20 years. Where are they?

  • a month or so ago, Beau?

  • "Batteries store energy by creating a flow of electrons that move from the positive end of the battery (the cathode) to the negative end (the anode)."

    Which would mean negative side has electrons that flow to the positive, destroying the charge imbalance. Filling the little holes...

  • Crustal abundance [wikimedia.org] of magnesium is higher than zinc, but bismuth is as rare as silver. But perhaps the process does not need a lot of it.
  • The reporter's credibility was instantly destroyed when she said: "electrons that move from the positive end of the battery (the cathode) to the negative end (the anode). " and i saw no need to read further!

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