Lithium-Sulfur Battery Project Aims To Double the Range of Electric Airplanes (ieee.org) 64
Oxis Energy, of Abingdon, UK, says it has a battery based on lithium-sulfur chemistry that can greatly increase the ratio of watt-hours per kilogram, and do so in a product that's safe enough for use even in an electric airplane. Specifically, a plane built by Bye Aerospace, in Englewood, Colo., whose founder, George Bye, described the project in this 2017 article for IEEE Spectrum. From a report: The two companies said in a statement that they were beginning a one-year joint project to demonstrate feasibility. They said the Oxis battery would provide "in excess" of 500 Wh/kg, a number which appears to apply to the individual cells, rather than the battery pack, with all its packaging, power electronics, and other paraphernalia. That per-cell figure may be compared directly to the "record-breaking energy density of 260 watt-hours per kilogram" that Bye cited for the batteries his planes were using in 2017.
This per-cell reduction will cut the total system weight in half, enough to extend flying range by 50 to 100 percent, at least in the small planes Bye Aerospace has specialized in so far. If lithium-sulfur wins the day, bigger planes may well follow. [...] One reason why lithium-sulfur batteries have been on the sidelines for so long is their short life, due to degradation of the cathode during the charge-discharge cycle. Oxis expects its batteries will be able to last for 500 such cycles within the next two years. That's about par for the course for today's lithium-ion batteries. Another reason is safety: Lithium-sulfur batteries have been prone to overheating. Oxis says its design incorporates a ceramic lithium sulfide as a "passivation layer," which blocks the flow of electricity -- both to prevent sudden discharge and the more insidious leakage that can cause a lithium-ion battery to slowly lose capacity even while just sitting on a shelf. Oxis also uses a non-flammable electrolyte.
This per-cell reduction will cut the total system weight in half, enough to extend flying range by 50 to 100 percent, at least in the small planes Bye Aerospace has specialized in so far. If lithium-sulfur wins the day, bigger planes may well follow. [...] One reason why lithium-sulfur batteries have been on the sidelines for so long is their short life, due to degradation of the cathode during the charge-discharge cycle. Oxis expects its batteries will be able to last for 500 such cycles within the next two years. That's about par for the course for today's lithium-ion batteries. Another reason is safety: Lithium-sulfur batteries have been prone to overheating. Oxis says its design incorporates a ceramic lithium sulfide as a "passivation layer," which blocks the flow of electricity -- both to prevent sudden discharge and the more insidious leakage that can cause a lithium-ion battery to slowly lose capacity even while just sitting on a shelf. Oxis also uses a non-flammable electrolyte.
Life (Score:3)
I don't think 500 cycles, quoted in the articles, is high enough. I'd like to see more longevity, along the lines of the LiFePO4 batteries. Still, I think this is impressive, and I wish them luck.
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I don't think 500 cycles, quoted in the articles, is high enough.
The 500 cycles means 100% charge to 0% discharge, and back again.
But nobody should actually use a lithium battery that way. It is best to keep it between 20% and 80%. If you do need to go over 80%, such as charging up for a long trip, then it is best to do it right before you are ready to leave. Likewise, if you run down below 20%, it is best to recharge as soon as possible. And when you are either over-charged or over-discharged, avoid heat. Don't park in the hot sun.
So with proper use and care, a "50
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The problem is that something like an airplane usually has a lifespan of decades. They are not something you toss out 3 or even 10 years after you've bought it. granted, I'm sure the cells from airplanes will be a lot easier to recover and recycle than many other devices like headphone and cell phones.
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But I could be wrong.
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This could be very cost-effective for GA Aircraft (Score:5, Informative)
There are roughly 210k General Aviation aircraft in use in the United States (http://download.aopa.org/hr/Report_on_General_Aviation_Trends.pdf)
Per year, there are approximately 8M take offs and landings per year by GA aircraft, which means each aircraft flies approximately 40 times per year. Total time in the air is approximately 25M hours per year or roughly 3 hours per flight.
If you had a Cessna 172, your time between overhauls (TBO) is 1,800 hours - or approximately 600 flights over over 15 years. Cost to overhaul the engine in a 172 is around $20k. Current average avgas price is $6.50/gallon and you can count on burning about 8.5 gallons/hour. So your total cost over 15 years would be around $32k over 15 years.
500 cycles (flights) is 16% or so less than the 600 you can expect for your 172 but "fuel" costs would be something approaching an insignificant fraction of the $12k of gas purchased over that time and while I would expect battery costs to be on the order of $15k for something like a 172 you would be seeing an overall fuel/overhaul cost being less than 60% of that of a gas powered aircraft over the same period of time.
I think saving a third of the major operating costs of an aircraft would make this battery technology very attractive for GA flyers.
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I said before,that I think there's definitely a future in electrically-powered flight. There are tremendous advantages if it can be done.
As you pointed out, fuel costs drop to almost nothing compared to using jet fuel. All of the infrastructure needed for handling a highly volatile liquid fuel also goes away, along with all the attendant safety issues.
Electric motors are much, much simpler than internal combustion (IC) engines or commercially-used jet engines. Very little maintenance is required for an elec
Re: This could be very cost-effective for GA Aircr (Score:1)
Actually no, electric motors are pound for pound more powerful than IC motors. IC motors only win in terms of the energy density of their fuel.
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Which means that ICE's win (at least for now). An electric motor or internal combustion engine develops zero power without fuel.
Re: This could be very cost-effective for GA Aircr (Score:2)
All of the infrastructure needed for handling a highly volatile liquid fuel also goes away,
And every tiny-ass, podunk airfield across the U.S. (there are approximately 15,000 of 'em) will have to replac replace a few tens of thousands of dollars of refueling infrastructure with charging equipment likely costing millions if you include the [all too likely] need to upgrade supply lines (most of these airfields aren't located near industry but rather fields and farms).
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And every tiny-ass, podunk airfield across the U.S. (there are approximately 15,000 of 'em) will have to replac replace a few tens of thousands of dollars of refueling infrastructure
Well boo hoo for the poor fuckers living in Podunk. Obviously we should not allow any advances in technology to be released until the backwoods goobers have caught up to 19th century technology. That's good news for the makers of buggy whips!
with charging equipment likely costing millions if you include the [all too likely] need to upgrade supply lines
Bullshit. Most airports have enough spare amps to recharge a battery or two.
Re: This could be very cost-effective for GA Airc (Score:2)
Most airports
As we're discussing General Aviation, "most airports" would be the 3/4's that are private airfields.
Boo hoo hoo
It is what it is (i.e. a numbers game); some might not like it but if you're imagining that I give a shit one way or the other, your "old man brain" has very much begun declining into "pseudo-child-brain state."
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As we're discussing General Aviation, "most airports" would be the 3/4's that are private airfields.
Yes, but will they also have to phase out their buggy whips and mustache wax vending machines?
but if you're imagining that I give a shit one way or the other,
I can't imagine anything about you, except that you probably have a lovingly-guarded collection of 5.25" floppies.
Re: This could be very cost-effective for GA Airc (Score:2)
Nonetheless, ignorance - and wishful thinking - abounds all around.
Re: This could be very cost-effective for GA Airc (Score:2)
Yes, but will they also have to phase out their buggy whips and mustache wax vending machines?
You're scraping the bottom of the barrel. That feeling that's gnawing away at you? It's an unbecoming emotion known as "desperation" and it smells.
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You're scraping the bottom of the barrel. That feeling that's gnawing away at you? It's an unbecoming emotion known as "desperation" and it smells.
I don't know what you mean, but regardless of your meandering, I think electric flight will be a thing. There are just soooooo many advantages that it's inevitable.
The fact is that no one gives a shit about podunk airports with cows wandering around on the runway, and if they can't modernize then they'll become obsolete.
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I fly out of "podunk" feilds almost exclusively. Very few of those podunk fields have "fueling infrastructure" more complex that me hauling 5gallon gas cans in the back of my car. If they do, it is an above ground tank, or possibly an old fuel truck that is just parked on the field.
Meanwhile, most of the fields have an electricity-free, open-faced pole barn (at most) for hangars. Most of the planes parked there are lucky to get flown once every few weeks. Meanwhile, for every flight hour, most get at le
Interesting. Sulfur may only fit medium-use (Score:3)
Those are interesting numbers, thanks.
It sounds like there are a lot of GA aircraft that don't get flown very often. They may not be good candidates for Li-S because the sulfur batteries self-discharge and permanently lose capacity in a few days. They can't be used the same way lead-acid are, frequently letting them sit for a few days between use.
On a plane used twice a day (a round-trip per day), the batteries would need to be replaced every six months or so.
Somewhere in between may be a good fit if all o
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500 W-h/kg of battery is still a lot for aviation. Cruise in something like a 172 is usually at about 60% power on a 160HP engine, so just round it out and call it 75kW. This means you'd need 150kg battery per hour of flight.
To put that in perspective, 150kg of avgas is about 55 gallons, which is coincidentally just about an entire full tank on a 172 (56 gal), a good 6 hours+ of flight.
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I don't think 500 cycles, quoted in the articles, is high enough.
It really depends on the cost of building the battery components and how easy they are to recycle. You have to remember that petrol is a single use product and 500 cycles is plenty in comparison.
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Gasoline is $4 a gallon. The battery needs to be less than $2000 a gallon to beat it in price.
Why not put them in cars? (Score:2)
If these work so well, why not put them in cars first?
The market for electric cars is way bigger than for electric aircraft.
Are they unsuitable for cars because of the cost? Longevity? Or what?
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Cars don't have as much of a problem with battery weight, because much the the energy expended upon moving a mass can be regained on deceleration by regenerative braking. This can't be achieved in aircraft. These batteries will be expensive, at least at first, and have limited life, in comparison with other battery technologies.
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Re: Why not put them in cars? (Score:2)
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If you haven't noticed, aircraft don't have "air-brakes", other than the dive brakes on a few WWII era bombers. All the energy expended to climb to altitude will necessarily be utilized in getting the airplane to the crash site. There is no stop and go traffic in the air.
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Don't ask too many questions. My guess is they are looking for some free government money or VC money.
Re: Why not put them in cars? (Score:2)
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I would say it's because they're new and not getting the crazy economies of scale standard Li chemistries are.
Sell to a less price sensitive, highly performance (wh/kg) sensitive market to build capacity and bring down the price before tackling the automotive market.
Also: longevity is less of an issue in aerospace vs automotive applications. For instance, a Rotax 912 needs a full rebuild at 1200 hours. That would be like ~80k miles of 70 mph driving. A modern car engine will easily triple that.
Re: Why not put them in cars? (Score:2)
You cannot compare a car engine to an aircraft engine, aircraft engines are rebuilt way before any failure can occur..because , well........gravity.
If a car engine is running rough, it will still get you from A to B safely, not so much for an aircraft engine..
Re: Why not put them in cars? (Score:2)
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Cutting edge electric aviation batteries tend to be halo projects. They're not intended to be useful, they're intended to continue the progress toward that order magnitude plus that current battery density per weight needs to be anywhere close to being viable in aviation. That means things like unit cost, toxicity, safety and other pragmatic problems that you get to work on AFTER you have a product that theoretically can meet the needs is made. Right now, they're about fifty times too low in terms of energy
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> If these work so well, why not put them in cars first?
TFS: "its batteries will be able to last for 500 such cycles"
We know a guy who owns a short-haul airline and this is fine. He spends a lot on fuel and nearly as much replacing engines. He's already building out solar systems to charge some prototype electric airplanes on loan and plans to convert to all-electric as soon as the range is there. 500W/Kg is about that point.
Almost nobody wants an electric car with incredible range and very high maint
Re: Why not put them in cars? (Score:2)
For what it's worth: (Score:5, Informative)
* Lithium-sulphur is a very real tech with great energy density. There's even (small-scale) commercial suppliers out there today
* Its main drawback is its very poor cycle life.
* You can increase the cycle life by increasing the amount of a mesoporous carbon scaffolding you use on the cathode end, but then you increase the cathode mass, lowering energy density and defeating part of the purpose of going with Li-S in the first place.
* Despite what's claimed in the article, 500 cycles is not "on par" with today's li-ion EV batteries by any stretch. But probably good enough for electric aircraft. With electric aircraft, you're more energy density limited (Wh/kg), while for electric cars, you're more budget limited ($/kWh). Replacing the battery pack at regular intervals can go into the maintenance schedule.
Hopefully they'll achieve their goals (I wouldn't bet the house on it... but it's not as improbable as many battery claims). That could push a next-generation version of a passenger plane like the Eviation Alice to ~2100km range
Still a long ways to go (Score:3)
260 Wh/kg = 0.936 MJ/kg.
Jet fuel = 43 MJ/kg [wikipedia.org]. Even if you factor in the ~50% efficiency of a jet turbine, it's still about 23x more energy per kg than batteries. Electric planes may work for short-haul trips. But the long-range transcontinental and intercontinental flights (where about 40% of the plane's takeoff weight is fuel) are going to continue to be fuel-powered for the foreseeable future.
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Why would you do that when you can just synthesize jet fuel? It doesn't matter if the plane emits CO2 when that CO2 was pulled out of the air in the first place to make the fuel.
An electrically-driven plane will also be flying much slower due to the lower efficiency of propellers at high speeds.
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Fuel volume and weight also affects efficiency in an airplane.
Re: Still a long ways to go (Score:2)
Re: Still a long ways to go (Score:2)
Re: Still a long ways to go (Score:2)
Add a touch KNO3... (Score:2)
...and a dash of activated charcoal... cracker. Take that Branston... this may even get into real space...
Oh... you can remove the Lithium too; though a hull built from it would be [an] interesting [puddle].
Again? Please stop now (Score:3)
Odd application choice (Score:2)
Airplanes seem a strange place to use a new high energy density battery technology. I'd think portable electronics would be a win since it can tolerate more $/KW and doesn't tend to kill people when the batteries fail
Re: Odd application choice (Score:1)
Density by mass, not volume.
Re: Odd application choice (Score:2)
I would
Lithium Sulfer? (Score:2)
Can set your watch (Score:3)
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This must be the third time someone invented Li-S batteries.
Re: Can set your watch (Score:2)
just the thing for ion drive airplanes (Score:1)
MIT developed a small prototype of an airplane with no moving parts, that ionizes nitrogen to generate lift. https://www.youtube.com/watch?... [youtube.com]
Obviously it needs a lot of power and this could be just the ticket. Even sci-fi has not speculated much about advanced atmospheric flight in this way. I for one can't wait for the day where commuter planes are silent!
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While a very cool concept, they'll only remain silent if they continue to fly at 20 mph. I doubt many people would want to travel across the continent at that speed. Also, ionized nitrogen may be more polluting than burnt jet fuel.
The Aircraft is interesting. (Score:2)