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Power

Sulfur Polymers Could Enable Long-Lasting, High-Capacity Batteries 131

Posted by Unknown Lamer
from the holding-out-for-an-atomic-cell-phone dept.
MTorrice writes "Lithium-sulfur batteries promise to store four to five times as much energy as today's best lithium-ion batteries. But their short lifetimes have stood in the way of their commercialization. Now researchers demonstrate that a sulfur-based polymer could be the solution for lightweight, inexpensive batteries that store large amounts of energy. Battery electrodes made from the material have one of the highest energy-storage capacities ever reported" Litihium Ion batteries should maintain capacity for about 1000 cycles, whereas Lithium-sulfur batteries traditionally went kaput after about 100. But it looks like they are getting pretty close to something feasible, from the article: "The best performing copolymer consisted of 90% sulfur by mass. Batteries using this copolymer had an initial storage capacity of 1,225 mAh per gram of material. After 100 charge-discharge cycles, the capacity dropped to 1,005 mAh/g, and after 500 cycles it fell to about 635 mAh/g. In comparison, a lithium-ion battery typically starts out with a storage capacity of 200 mAh/g but maintains it for the life of the battery, Pyun says."
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Sulfur Polymers Could Enable Long-Lasting, High-Capacity Batteries

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  • Still a ways to go (Score:3, Interesting)

    by mykepredko (40154) on Monday March 03, 2014 @10:08PM (#46393553) Homepage

    I saw an interesting graph in Aviation Week some time ago about the energy density of batteries versus the same mass of hydrocarbon fuel. The article was in relation to the idea of creating (plug-in) hybrid airliners.

    The batteries used in the 787 store four orders of magnitude less energy than the equivalent mass of jet fuel.

    I'm mentioning this because it looks like these batteries would bring the difference up to three orders of magnitude.

    Still a ways to go before batteries can compete against hydrocarbon/fossil fuels.

    myke

    • by Anonymous Coward on Monday March 03, 2014 @10:31PM (#46393667)

      I saw an interesting graph in Aviation Week some time ago about the energy density of batteries versus the same mass of hydrocarbon fuel. The article was in relation to the idea of creating (plug-in) hybrid airliners.

      The batteries used in the 787 store four orders of magnitude less energy than the equivalent mass of jet fuel.

      I'm mentioning this because it looks like these batteries would bring the difference up to three orders of magnitude.

      Still a ways to go before batteries can compete against hydrocarbon/fossil fuels.

      myke

      Based on a back-of-the-envelope calculation, that number seems wrong. Could you have misread Aviation Week?

      Jet fuel has an energy density close to 45 MJ/kg. A lithium-ion battery has an energy density of (approximately) 150 Wh/kg, which is 540 KJ/kg. That's about 1.2% of the energy density of the jet fuel, which is more like 2 orders of magnitude, not 4.

      4 orders of magnitude below jet fuel is more in the range of supercapacitors than batteries.

      • Dat envelope (Score:4, Interesting)

        by strack (1051390) on Tuesday March 04, 2014 @07:27AM (#46395289)
        Lets see what the range on a typical light aircraft would be if you ripped out the full fuel tanks and gasoline engine and stuffed it with a equivalent power electric engine and these new batteries to the same weight. So it says it will store 4-5 times as much energy as todays best lithium-ion batteries. the best li-ion today is lithium cobalt, at about 165 wh/kg. So x4 of that is 660 wh/kg.

        now, lets take a light plane for which I can find enough info to do this with, the jabiru j160D [jabiru.net.au] ok. so the fuel in it weighs (135L * 0.72kg/L) = 97.2kg. Now, the engine in it, the Jabiru 2200cc Aircraft Engine, weighs 62.8kg, and has a max power output of 60kw, and cruises at 75% power, so lets assume 50kw cruise power to account for takeoff and landing. So in total, engine and fuel weight 97.2 + 62.8 = 160kg

        so lets rip that 160kg out and replace it with a EMRAX228 Brushless AC electric Motor with a 100kw power output and weighing in at 11.9kg, leaving us 148.1 kg worth of batteries, with a energy storage capacity of 148.1 * 0.66 = 97.746 kwh. so, at the cruise speed of 100knots = 185.2km/h, your looking at a range of (97.746kwh / 50kw) * 185.2km/h = 362km in about 2 hours.

        The gasoline version can fly at the same speed for 8.5 hours. So, sure, the range is a quarter of the gasoline one, but you could ditch a passenger, chuck another 100kg of batteries in there and get that up to about 3.5 hours and 630km of range. Pretty damn good for a few dollars of electricity, negligible maintainence costs on a electric engine vs gasoline engine. sure as hell beats the $100+ youll pay for fuel alone for that same 3.5 hour trip.

        • by strack (1051390)
          actually, i should probably lop off about 30km range to account for energy losses from the electric engine.
          • Electric motors are extremely efficient, over 99% in converting electricity to mechanical energy. So you don't have to lop off so much for the efficiency of the electric motor. But, how much of the energy in the battery can be actually extracted is the question. If the energy densities quoted were based on "available energy" you don't have to account for it. But if it is based on some theoretical value based on how much can be packed in, without worrying about how much of it will come out, then you need to
            • by strack (1051390)
              well its true, i dont know the conversion from mah/g to kwh/kg here, but im going on that 1005mah/g figure stated, and its comparison to the 200mah/g for a current lithium ion battery. and im being conservative, using the 4x multiplier instead of 5x. And since they say charge-discharge cycles, i presume they measured the energy coming out of the battery.
    • by Immerman (2627577) on Monday March 03, 2014 @10:36PM (#46393687)

      First off that's a bald-faced lie: Energy density of:
      Gasoline: ~46 MJ/kg
      Lithium-ion battery: 0.36-0.875 MJ/kg (1/127 - 1/52 times gasoline)
      Lead-acid battery: 0.17 MJ/kg (1/270 times gasoline)

      So even lead acid batteries are only two orders of magnitude less energy dense than gasoline.

      As for the suitability in vehicles - that depends entirely on the application. For aircraft the energy density per both unit mass and unit volume is very important, so I doubt we'll see electric jetliners any time soon. For automobiles and other short-range land vehicles on the other hand batteries are already adequate for a lot of applications, and cost is the primary limiting factor. A measly 5x increase in capacity could extend the range of the 85kWh Tesla Model S from 265 miles to 1325 miles - still not enough for a long road trip on a single charge, but a lot further than most people care to drive in a single day, and overnight charging in hotel parking lots could be extremely convenient.

      And for stationary applications the energy density per dollar is the only particularly important metric, and other battery technologies are probably more applicable to such applications.

      • by TubeSteak (669689)

        In comparison, a lithium-ion battery typically starts out with a storage capacity of 200 mAh/g but maintains it for the life of the battery, Pyun says."

        This is also a complete lie.
        AFAIK, all batteries have a certain rate of self-discharge.
        Lithium ion self-discharges at about 2%~3% per year, unless you keep it refrigerated.

      • by strack (1051390) on Monday March 03, 2014 @11:24PM (#46393893)
        Don't forget that gasoline engines typically turn only about 20-30% of the chemical energy into mechanical energy, whereas electric motors are about 90%. And you get rid of a heavy gasoline engine.
        • by Mashiki (184564)

          Ah, so we're throwing the aircraft through the air with the power of pixie dust and unicorn farts. Awesome!

          • You use a propeller. That is known to work.

            • by strack (1051390)
              I guess he doesn't know. I imagine there's a lot of things he doesn't know.
              • by Mashiki (184564)

                Don't worry, there's half a dozen replies that missed the sarcasm and humor in my post. You just happen to be one of them, so I have to ask what's the world like living in a state where there's no humor in it?

          • by skids (119237) on Tuesday March 04, 2014 @12:18AM (#46394127) Homepage

            Ah, so we're throwing the aircraft through the air with the power of pixie dust and unicorn farts.

            Aircraft engines are a red herring here, since the target of these batteries is automotive. But for what it's worth, jet turbines also only convert a portion of the fuel's chemical energy into kinetic energy. Combustion efficiency is 90%+, but cycle efficiency in turbojet and similar is nearer to 30%. [wikipedia.org]

            For automotive, in contrast to ICE+drivetrain at about 25%, shows average values of about 36% [wikipedia.org] and this is in part due to the efficiency of electric drive trains and in part due to the efficiency of the fuel cell process, but of course externals in the fuel production.

            Batteries win hands down against both of those options for efficiency, with externals excluded, so the same amount of energy in a battery is worth more miles than the equivalent amount of chemically stored energy in gasoline once it is onboard.

            • by cbhacking (979169)

              Took me a moment to realize you were talking about fuel cells in the "36%" part; maybe you forgot a few words? Anyhow, no worry.

              Yeah, heat-based engines have pretty poor efficiency. We just can't get the "cold side" to be very low in practice. I'm not sure if we'll ever really beat this problem. There are lots of other systems out there, though...

              Mind you, electrics have their own host of inefficiencies. There's resistive losses (both within and outside the battery), losses to regulation circuitry, some of

        • On the other hand fuel weight is lost as the energy in the fuel is used battery weight stays with the plane for the entire flight.

      • by Anonymous Coward on Monday March 03, 2014 @11:24PM (#46393895)

        Energy density is more important here... not specific energy.

        the Tesla model S will be using new Panasonic batteries, quoted at 735wh/L, or 2.65 MJ/Liter
        Gasoline is ~36 MJ/Liter

        so that's an order of magnitude difference.

        BUT

        Electric cars are 3 to 4 times more efficient at taking electricity and converting it to forward motion that an internal combustion engine. This is basically due to the fact that 1) electric motors are about 90% efficient, with IC about 30%, and electric cars can get energy back when braking.

        So... instead of 36/2.65 = `3.6 times better for gas it's more like

        36/(3*2.65) = 4.52 times better for gas

        So yes... we are almost there.

        • Re: (Score:2, Informative)

          by Anonymous Coward

          that was supposed to be

            of 36/2.65 = 13.6

          little typo there...

        • by Joce640k (829181)

          So yes... we are almost there.

          Apart from the recharge time...

          If recharge time was a minute or two then a car with 200 miles range would probably be good enough, and we already have that.

          It's the "overnight" part that's keeping electric cars off the road right now.

          • by strack (1051390)
            If you get it to the point that you can drive the car all day on a full battery, the "overnight" part wont matter so much.
            • by Lumpy (12016)

              10 hour battery life no matter it's city driving or steady at 80mph on the highway tailgaiting people and road raging.

          • by beanpoppa (1305757) on Tuesday March 04, 2014 @08:05AM (#46395463)
            At the risk of sounding 'Applely', Think different. Right now, I have to stop to 'recharge' my ICE car for 5-10 minutes, once a week. That's, on average, about 6 hours a year I wait for my car to 'recharge'. If I had an electric car, I would be plugging it in every night. For most weeks of my commuting year, it would eliminate any time waiting at the gas pump.
            • That's, on average, about 6 hours a year I wait for my car to 'recharge'. If I had an electric car, I would be plugging it in every night.

              That's assuming you spend no time plugging your vehicle in at night, unplugging it in the morning, or otherwise managing the charge level. The breakeven point is only about 80 seconds per day.

          • by mattack2 (1165421)

            How often do you go to the gas station?

            Why not charge overnight at home, or during the day at work (if you happen to have EVSEs there)? There's PLENTY of time when your car isn't being used that it could be being charged.

            Even the lowest range electric cars have far more range than the average commute.. (I recently got one with one of the lowest ranges -- smart electric.)

        • by strack (1051390)
          Um, what? Specific energy is wh/kg, and is much more important than the amount of volume the battery takes up. Pushing extra battery weight around takes more energy, extra volume isnt that hard to deal with.
          • by Immerman (2627577)

            Actually AC is correct - for aircraft where you have to continuously fight gravity weight is pretty important, for cars... not so much. Especially with regenerative braking. More weight does reduce efficiency, but it's volume that the limits the number of batteries a standard-sized car can reasonably carry. If you can store 5x the energy in the same volume, but at 5x the mass, it's still a major win. The loss in efficiency means your range won't increase 5x, but 3x is probably easily attainable. And 5x

      • by riverat1 (1048260)

        ... so I doubt we'll see electric jetliners any time soon.

        You're right but electrically powered propeller airplanes already exist. They just need better batteries to have enough range to be practical.

      • "Only two orders of magnitude"?
        Well, that's the difference between flying and staying on the tarmac.

      • It doesn't even need to be that revolutionary in its deliverable form to be a game changer. Even a doubling would be huge. Ive looked at the nissan leaf (roughly 100 miles on a charge) and the chevy volt (35 on electric, then gas) but haven't bought (yet).

        If I could get a leaf that went 200 miles on a charge, or a volt that went 80 miles on a charge and gasoline after that, I would be in the showroom tomorrow.
    • by Gravis Zero (934156) on Monday March 03, 2014 @10:51PM (#46393753)

      I saw an interesting graph in Aviation Week some time ago about the energy density of batteries versus the same mass of hydrocarbon fuel.

      the problem with that comparison is that it considers that the engines and motors will have the same efficiency which is not true at all. hypothetically, if your motor is four times as efficient as an engine but your battery has only half the energy storage of the engine's fuel, the motor is still going to run twice as long as the engine.

      it's systems, not components that matter.

      • by dutchwhizzman (817898) on Tuesday March 04, 2014 @12:53AM (#46394267)

        Airliner turbines are extremely efficient at transforming energy into air movement. Because of expanding gasses in the burn process inside the turbine, roughly 9 times the amount of air being used in the burn process is being "propelled" on the outside of the engine. The mix of these at the back of the engine is also very carefully engineered. This results in an extremely efficient transformation, compared to a combustion engine as used in cars.
        Getting the same amount of efficiency from an electrically driven turbine will be a challenge. Getting the same or better amount of efficiency from the system, including the primary generation of electricity, transporting it, battery losses and converting it in the electrical turbine doesn't sound very feasible at all. It's systems that matter, not components, right?
        • by Lumpy (12016)

          The small fact that air movement is a very very low efficiency way of making a plane fly. Actual thrust like from a jet engine is far more efficient.

          Turbofans are simply cheaper to make and operate.

    • by haruchai (17472) on Monday March 03, 2014 @11:52PM (#46394011)

      Have a look at molten-air batteries - http://phys.org/news/2013-09-m... [phys.org]

      With an iron anode, the energy content is roughly the same as petrol - ~ 10000 watt-hours per liter. But the most you can hope for an a straight gasoline ICE is about 30%, whereas a battery is likely to be 2.5x as efficient. A carbon anode, which is more likely to be developed is nearly double that of iron so if this tech pans out and it looks to be quite affordable, it'll kill the demand for fossil fuels in almost all light-duty vehicles and make it possible to have hybrid long-haul trucks.

      • by Rhywden (1940872)

        Definitely looks interesting, but highly unpractical for vehicles. After all, you have to keep the metal molten all the time. And that means some heavy-duty insulation, something akin to a Thermos bottle with a large volume. The problem then is the fact, that such bottles are not exactly great when it comes to vibrations, abrupt stops and crashes.

        • They achieve the high densities by using atmospheric air for oxygen. Basically they are rusting iron and reversing the rusting using electrolysis. Which means not only you need to keep the iron molten, you need to vent it to atmosphere too! Other molten metal batteries are sealed, allowing for better thermal insulation.
          • by haruchai (17472)

            There's also a carbon anode which I suspect would be the focus of development. It's not likely they'll put too much effort into vanadium boride in the short-term.

        • by haruchai (17472)

          There's already the ZEBRA battery, used in a few EVs since 2007. I think insulation isn't such a big problem when the batteries are large as there's a fair bit of thermal mass. The threshold for the ZEBRA is somewhere upwards of 20 kWh but that would depend on the shape.

          The Tesla Model S which used a flat, relatively thin pack on the floor of the vehicle would definitely be a challenge.

    • Aircraft are very sensitive to the weight. But ships are not. I wonder if it would be realistic to have a battery powered ship for cross ocean voyages. Especially for things like tankers and cargo ships. Pull into port and get hooked up with special massive power tx lines and fill up the battery.

      I seem to recall that large ships are a big source of CO2 emissions. If it is possible I wonder what the trade off is in terms of costs.
      • How big a part of the power requirement of a ship could be covered by solar panels on the deck?
        • by Calinous (985536)

          A supertanker has a deck about 300 by 30 meters, so 10,000 square meters. With an optimistic 100W from square meter, and 8 hours a day of full power, you'd get about 8 MWh (or some of 28,800 MJ) of energy a day. At 43 MJ/kg for diesel fuel, that's the equivalent to some 700 kg of diesel fuel a day.
          Now, ships use heavy fuel oil when outside territorial waters (which is much cheaper), so a full deck of solar panels wouldn't save you very much money. And those panels would be exposed to

          • 700 kg of fuel equals about an hour of usage. However, if the ship is all electric one can assume a 3x as efficient powertrain, so 3 hours. If we combine the solar panels with a skysail [skysails.info] which provides around 2000 kW continuously we would get an additional 48 MWh or 172,800 MJ (depending on shipping routes). This equals to approx 4000 kg/day without efficiency improvements or 5.7 hours. With a powertrain efficiency improvement of a factor 3 (doable when using electric power) this would equal to 17 hours of b
    • by manu144x (3377615)
      Why is everybody forgetting about how much of that energy an ICE Gas engine converts into motion? Roughly 15% ? A diesel goes up to 25% if i remember correctly. An electric engine is easily over 90% even 95%. I agree, the electric solution is still far from being better right now, but the fight is NOT only about energy/kg it's also about energy/actual useful movement too. It's a balance of both these things, makes no point to have 100 gallons of gas if you're gonna throw out 85% of it out.
  • by cold fjord (826450) on Monday March 03, 2014 @10:09PM (#46393557)

    There have been a lot of materials developments in battery designs over the last year or two. Some of them are providing 10x or better power storage with varying lifetimes. I'm really looking forward to seeing some of this make it into production. It would be better if they could couple improved batteries with some minimalist portable computer designs. People comfortable with Unix would get by with something with much lower specks than is typical today (assuming a minimalist interface), and the battery could probably last for hundreds of hours. I wouldn't mind that a bit.

    Some of the other battery tech could be very useful for emergency situations.

    This might be one to keep an eye on: A Battery That Runs On Sugar Could Soon Be Powering Your Electronics [businessinsider.com]

  • FTA: 'The best performing copolymer consisted of 90% sulfur by mass. Batteries using this copolymer had an initial storage capacity of 1,225 mAh per gram of material. After 100 charge-discharge cycles, the capacity dropped to 1,005 mAh/g, and after 500 cycles it fell to about 635 mAh/g. In comparison, a lithium-ion battery typically starts out with a storage capacity of 200 mAh/g but maintains it for the life of the battery, Pyun says.' So, situations in which a massive blast of current is required could be

    • by Nemyst (1383049)
      Huh? mAh is a unit of charge, not current. It's a bit like kWh that's generally used for electricity costs.
      • by skids (119237)

        This. And the goal of this line of battery research isn't to provide "blasts of current" as we've already got that covered with ultracaps and Li-ion for burst needs. The goal is to provide slightly more current than is required to propel a vehical at highway speeds, and do so for a long time between charges, and to do so for many charges.

  • where's my flying car?
    • First, you have to prove that you deserve a flying car.

      Then you have to prove that you can be trusted to dive/pilot a flying car.

      Given how the vast majority of people drive, almost no one passes the second test.

      I'm not claiming that I do either. I also know that I should not ride a motorcycle because I don't have the right kind of attention for it.

      • by causality (777677)

        First, you have to prove that you deserve a flying car.

        Then you have to prove that you can be trusted to dive/pilot a flying car.

        Given how the vast majority of people drive, almost no one passes the second test.

        I'm not claiming that I do either. I also know that I should not ride a motorcycle because I don't have the right kind of attention for it.

        With a motorcycle your main problem is the other drivers.

        What you would discover (or be reminded of) is that average people don't put any thought or attention energy into anything that isn't directly in their selfish interests. George Carlin called it stupidity and consumerism, Erich Fromm called it alienation, I call it spiritual infancy. Regardless, that's the deal. The SUV driver doesn't see your little motorcycle as a threat and isn't likely to spend much time looking out for you (meanwhile they c

    • by Lumpy (12016)

      at the airport, go get your recreational pilots license and then get ready to pony up $250,000 for it, or less if you will accept used, but only poor people would buy used.

      Cessna and other companies have several choices for you.

  • 1) are these expensive to make?
    2) can they be scaled up to be used as batteries in an electric car?
    3) where are my keys?

    • 3) Behind the third cushion on the right in your couch /NSA //You're welcome

    • 1) are these expensive to make?

      This is what I came here looking for. 100 cycles is perfectly acceptable if the battery costs 25 cents. But I guess I'll die wondering...

  • by no-body (127863)

    Some kind of modular system where a standarized batterypack is used which can be refurbisched with material (sulfur) reused?

  • by Anonymous Coward

    Smells fishy to me.

  • Sulphur Batteries?!!!? The exhaust is gonna smell like rotten eggs!
  • ... they're taking out of gasoline for them.

  • Well, if Moore got his own law, I'm going to go ahead and call it erroneus's law. "batteries will get better."

    I made it more simple and easier not to fail in the future too. So is it me or are they creating batteries out of just about everything?

    • "So is it me or are they creating batteries out of just about everything?"

      It's not just you. http://hilaroad.com/camp/proje... [hilaroad.com]

    • by mjwx (966435)

      Well, if Moore got his own law, I'm going to go ahead and call it erroneus's law. "batteries will get better."

      I made it more simple and easier not to fail in the future too. So is it me or are they creating batteries out of just about everything?

      I'm going to counter this with the Grandpa Simpson principal which states "everything gets worse as you get older and you will complain about it".

  • We need devices that consume less power and batteries that last longer (retain the same charge across multiple cycles).

    Any other formula will lead to devices that waste power and burn through batteries with increasing speed. I'm not looking forward to garbage lots filled to the sky with used batteries.

    • You recycle batteries. The elements are not wasted, usually they lost their specific shape or a not intended molecule is being formed once in a while, and that molecule does not release electric energy. All these things are reversible.
      In fact, never ever throw a battery in a landfill. Most are quite bad for the environment when not recycled properly.
    • by Joce640k (829181)

      I'm not looking forward to garbage lots filled to the sky with used batteries.

      Is it as bad is the air being filled to the sky with CO2?

      • We need something to displace all the nitrogen. That stuff is dangerous!
      • One is proven by science. The other is "proven" by Al Gore :)

        What I resent about the latter is that there was plenty of scientific evidence before/after Al Gore's stupid movie, but that bit of "science" only got momentum because of the movie. We shouldn't make decisions based on what's popular. We should make decision based on scientific fact.

        So to reiterate: I'm not arguing whether Global Warning exists or not, but rather that it's stupid that people only began saying it exists because that movie came out

        • by romanval (556418)

          The scientific consensus for AGW/climate change was pretty darn clear even before Al Gore's movie: He just made it more popular. The only people making it controversial are the old school energy companies and everyone associated with it.

        • ...

          So to reiterate: I'm not arguing whether Global Warning exists or not, but rather that it's stupid that people only began saying it exists because that movie came out.

          ...

          I am tempted to say something is indeed stupid here, but it is not what you are claiming is stupid.

          Three dates:

          • 1992: Due to the growing scientific consensus on the reality of anthropogenic global warming the UN establishes the Framework Convention on Climate Change, which leads five years later to:
          • 1997: the Kyoto Protocol on limiting greenhouse gas emissions being negotiated;
          • 2006: An Inconvenient Truth, narrated by Al Gore comes out.

          "People began saying it exists" well more than 15 years before "that mov

  • by imsabbel (611519) on Tuesday March 04, 2014 @02:17AM (#46394529)

    What matters, in the end, is the amount of energy a battery can store.

    With Lithium Sulfur cells, the voltage is a little more than half as high as for Lithium Ion batteries, so the initial advantage is not as large as it might seem from the mAh numbers.

    • by Donwulff (27374)

      Well, amount of energy per mass. But amount of energy per volume will come a close second, and unless they have unlimited charge cycles with no degradation, energy per dollar will be sharing that close second position. Charge efficiency is probably around third most important, and whether it's prone to exploding randomly in a fiery conflagration is up high there as well. In short, almost anything else than what was actually provided in the summary :)

    • by Twinbee (767046)
      Are you saying..... wow... we should (god forbid) measure, energy capacity in....... watt hours (or joules)? How dare you recommend such a statement!

      Honestly it amazes me the number of people who think volts or amps alone constitute energy. It also saddens me that watts and watt-hours are not more commonly stated in products such as on battery labels.
      • by wvmarle (1070040)

        When looking at electronics recently, specifically little ICs, they always specified the power usage in units of current.

        It seems that the reason is that semiconductor ICs can handle a broad range of voltages, like 3V-15V, and use roughly the same current at the whole range. As long as your supply voltage is in that range, the components are happy. The same when powering LEDs, they need a certain current, and any supply voltage will do as long as it is high enough (you always have to add a resistor to regul

    • Compressed air has volumetric energy density similar to lead acid (about half lithium ion) but extremely high power density. Energy density by weight is dependent on scale - bigger is better - because the weight scales as the surface area of the container while the energy scales with volume. But

      If you are looking for a power boost on take off, compressed air is totally viable. Doubly so because it would naturally drive a propeller with an air motor which is more efficient at low speeds. Fix the expansio

  • Batteries using this copolymer had an initial storage capacity of 1,225 mAh per gram of material.

    At what voltage? mA*h isn't a unit of energy. V*mA*h is.

  • Article says "In comparison, a lithium-ion battery typically starts out with a storage capacity of 200 mAh/g but maintains it for the life of the battery, Pyun says."

    Hmm. I have lithium ion batteries that can't hold a charge at all.

    And it's only partially to do with how they're used. Lithium ion batteries lose capacity while in storage. Which is why you should never buy a used, or a new-old-stock one.

    • by afidel (530433)

      Look into low self discharge batteries, the Eneloop second generation batteries maintain 75% of their charge after 3 years without use and can be fully charged for 1500 cycles. The third generation cells go to 90% after 1 year and 70% after 5 years but they're enough more expensive at this point that they're not worth the extra cost for most applications, they've also increased the stability a bit to 1800 cycles.

  • They'll have to use some pretty strong casing on these things if they want to use them in cars because if they leaked in a crash things could get really nasty as free sulphur burns quite easily and creates SO2 which would kill or severely cripple anyone trapped nearby quite quickly.

  • The total amount of energy stored is much larger per cycle - about five times as much. So 200 recharges for a LiS battery would give as much play time on your phone as 1,000 recharges on a Li-ion battery (the typical lifetime of such a battery). With the loss of capacity that may be 250 recharges for the LiS battery, with it still going strong after all that time.

    So what're they waiting for? Life time is more than good enough already! I want one of these batteries! Much better than having to recharge my pho

  • I wonder if people are working on charged liquid electrolytes based batteries. If I could drain the electrolyte from the discharged battery, refill it will charged electrolyte much like filling gasoline into a tank. Must be a dumb idea because I have not seen any excited posts about it. May be the energy density is so very poor for these charged electrolytes.
  • by Anonymous Coward

    It should be possible to group 2 for these together with an advertised capacity of ~1200mAh and then add some smart discharge circuitry to keep the total capacity at ~1200mAh. e.g as the first cell nears half capacity, take it off-line and put a fresh one on-line; after that one degrades (you've already gone 1000 cycles now) put the two "half capacity" cells on-line and run them into the ground (maybe get another 500 cycles). You'd need 6 standard Lion cells to get the same capacity; so still a 3x improvem

  • "Batteries using this copolymer had an initial storage capacity of 1,225 mAh per gram of material. After 100 charge-discharge cycles, the capacity dropped to 1,005 mAh/g, and after 500 cycles it fell to about 635 mAh/g. In comparison, a lithium-ion battery typically starts out with a storage capacity of 200 mAh/g but maintains it for the life of the battery, Pyun says."
    So, the lithium sulfur battery, after a mere half as many cycles as a lithium ion battery can substain, only has THREE TIMES the charge of a

  • Telsa and others have shown the interesting kind of electric vehicles you can build. Batteries still limit cost and distance. Another factor of 2-5 performance cost will clinch it.
  • Technically we could easily make a high powered battery pack using Lithium Polymer batteries due to their high energy densities. The downside of course is your car turns into a bomb if the battery pack malfunctions or is punctured. I wonder if these high density Sulphur batteries are as stable as some of the Lithium Phosphate Manganese batteries that are used in modern electric cars? Otherwise we'll never see them in large applications because they would be considered to be unsafe.

  • even with just a 100 charges a battery that has 1.2 A per gram sounds awesome for RC flying.

  • In the 1960s there was research into sulfur-based polymers but apparently ran into some problems:

    "Recently we found ourselves with an odour problem beyond our worst expectations. During early experiments, a stopper jumped from a bottle of residues, and, although replaced at once, resulted in an immediate complaint of nausea and sickness from colleagues working in a building two hundred yards away. Two of our chemists who had done no more than investigate the cracking of minute amounts of trithioacetone found themselves the object of hostile stares in a restaurant and suffered the humiliation of having a waitress spray the area around them with a deodorant."

    http://pipeline.corante.com/archives/2009/06/11/things_i_wont_work_with_thioacetone.php [corante.com]

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