5 ms·

No, these are room-temperature NaS batteries. They use some special electrolyte, but I have no idea how this really works. Their main drawback so far was longev

by deng 4y ago

No, these are room-temperature NaS batteries. They use some special electrolyte, but I have no idea how this really works. Their main drawback so far was longevity, but this battery has a capacity fade of 0.05% per cycle, which is on par at least with a poor Li-Ion battery. LiFePo4 is still superior in that regard, but the much higher capacity and hopefully lower cost (if they can be manufactured efficiently) might make up for that, hard to tell.

ksec 4y ago
> but this battery has a capacity fade of 0.05% per cycle, which is on par at least with a poor Li-Ion battery. 20% lost at 400 cycles. This isn't so bad if it really offers 4x the capacity. In terms of usage it will last 1600 cycles comparatively speaking. Which is still far better than Li-Ion.
- onlyrealcuzzo 4y ago
  Can they be recycled to get back close to 100% capacity?
- deng 4y ago
  No, Li-Ion batteries can be twice as good: "In 2003 it was reported the typical range of capacity loss in lithium-ion batteries after 500 charging and discharging cycles varied from 12.4% to 24.1%, giving an average capacity loss per cycle range of 0.025–0.048% per cycle." (https://en.wikipedia.org/wiki/Capacity_loss https://en.wikipedia.org/wiki/Capacity_loss) And that was twenty years ago, things probably have improved. I think you have a wrong impression what is meant with "a battery lasts X cycles". That does not mean that it will be at zero capacity after 'X' cycles, but usually that it is down to ~70% of the initial capacity. EDIT: Sorry, I missed the "comparatively speaking", so you mean when including the 4x capacity. You are right, of course.
  - deleted 4y ago
    [deleted]
  - nwiswell 4y ago
    I'd happily trade 2x capacity for 0.5x life in my cell phone battery, provided that the cell phone manufacturer just makes it easy to swap batteries. Something that baffles me is how hard it's become to replace the battery. I had the original generation Galaxy S -- I loved that thing, because there was a little latch mechanism on the back-side. With a firm tug, the rear cover popped right off, allowing you to pop the battery out. It took less than 10 seconds to do a battery swap, which I used to great advantage while traveling (carried a second battery with me). Of course, back in those days, the typical battery capacity was not nearly as good. In any event, I wish I could still do that with my current phone. It would be super slick if there was a tiny auxillary battery or 60-second hold-up capacitor too, so you wouldn't even have to shut the phone off.
    - midoridensha 4y ago
      >Something that baffles me is how hard it's become to replace the battery. Why is this baffling? It makes perfect sense for batteries to be non-replaceable: you can make the phone slightly thinner, and you can charge owners a small fortune to replace them, which will usually result in them simply throwing the device away after a while and buying a new one. Just look at Apple: they pushed non-replaceable batteries (and also removed headphone jacks in favor of expensive airPods), and people love iPhones and can't wait to get the next version, even if it costs $1399 and they have to sell their kidney to buy it.
      - kemiller 4y ago
        This is such a cynical take. By ditching removable bits they save on internal room which allows bigger batteries. I would take 25% better main battery life over removable any day. If you don’t mind carrying an extra item (because that’s what swappable batteries means — by the way how do you keep the spare charged?) then get an external. Even easier to swap and use, often supports pass-through charging, and doesn’t create yet another aperture that needs waterproofing.
        midoridensha 4y ago
        You're missing the real reason for replaceable batteries: they need replacement after a few years because their capacity decreases with age.
- dachryn 4y ago
  My LifePo4 battery has a 6000 cycle guarantee at 60% capacity. So its not even close yet
  - deng 4y ago
    > So its not even close yet Yes, if you compare just capacity fade, that's true. But the longevity of LiFePo4 comes with a lower charge density than Li-Ion, about 170 mAh/g. This NaS battery currently has 1017 mAh/g, so almost a factor of 6. If the capacity is higher, you don't have to cycle as often, but of course, mileage depends on the use case.
    - cogman10 4y ago
      That lower capacity comes at a cost cut and a huge materials advantage. LFPs are made of highly available materials. (Lithium, iron and phosphate). The higher capacity NMC batteries are constrained on nickel production.
  - Retric 4y ago
    The question is more how many kWh can you store and extract over a lifetime at a given cost rather than how many cycles can it take. If the 5999th charge is only holding appropriately 60% of a LifePo4 battery you don’t get 6,000 cycles * full battery capacity.
    - jacquesm 4y ago
      True, but you probably will get more before the battery becomes unusable in total. It would be very nice if batteries were super predictable as in 'perfect until the 6 thousandth cycle and then dead', instead you get this gradual drop-off to the point where a battery is no longer usable for its intended purpose. Whether or not that is at 60% of the original capacity or not is moot if it doesn't make it to the 60% in the first place (lots of batteries get murdered well before the end of their design life), on the other hand if that means that the drop-off itself slows down then you might be able to get much more life out of them when treated carefully. The big ones - in my experience, which is obviously not the final word on this - is to ensure that you don't charge batteries when they're very cold, that you don't use currents in excess of what they're made for (and preferably a bit below that) and that you don't subject them to mechanical stress. If you live by those rules you can make them stretch for a very long time, enough for technology itself, rather than that battery, to make your battery obsolete. Witness the old lead-acid batteries used in cars, telephone switch boards and submarines. In cars they would last a couple of years at best, in telephone switch boards and submarines they would routinely outlast the rest of the installation.
- abdulmuhaimin 4y ago
  The faster battery life deterioration might even be desirable for those manufacturers with planned obsolescence in mind, especially phone manufacturers
- splitstud 4y ago
analog31 4y ago
A somewhat shorter lifespan might be a decent trade if the materials are much more recyclable and if mining is produces less pollution.
- marcus_holmes 4y ago
  also if the batteries are cheap enough they can be considered "partially rechargeable" and swapped out when the capacity fades too much
  - analog31 4y ago
    I suppose partially worn out batteries can also find new uses, such as stationary power reserves, where they're not being cycled a lot.
davrosthedalek 4y ago
Is it 0.05% of the remaining capacity, or of the initial capacity?

by deng 4y ago

ksec 4y ago

> but this battery has a capacity fade of 0.05% per cycle, which is on par at least with a poor Li-Ion battery. 20% lost at 400 cycles. This isn't so bad if it really offers 4x the capacity. In terms of usage it will last 1600 cycles comparatively speaking. Which is still far better than Li-Ion.

onlyrealcuzzo 4y ago
Can they be recycled to get back close to 100% capacity?
deng 4y ago
No, Li-Ion batteries can be twice as good: "In 2003 it was reported the typical range of capacity loss in lithium-ion batteries after 500 charging and discharging cycles varied from 12.4% to 24.1%, giving an average capacity loss per cycle range of 0.025–0.048% per cycle." (https://en.wikipedia.org/wiki/Capacity_loss https://en.wikipedia.org/wiki/Capacity_loss) And that was twenty years ago, things probably have improved. I think you have a wrong impression what is meant with "a battery lasts X cycles". That does not mean that it will be at zero capacity after 'X' cycles, but usually that it is down to ~70% of the initial capacity. EDIT: Sorry, I missed the "comparatively speaking", so you mean when including the 4x capacity. You are right, of course.
- deleted 4y ago
  [deleted]
- nwiswell 4y ago
  I'd happily trade 2x capacity for 0.5x life in my cell phone battery, provided that the cell phone manufacturer just makes it easy to swap batteries. Something that baffles me is how hard it's become to replace the battery. I had the original generation Galaxy S -- I loved that thing, because there was a little latch mechanism on the back-side. With a firm tug, the rear cover popped right off, allowing you to pop the battery out. It took less than 10 seconds to do a battery swap, which I used to great advantage while traveling (carried a second battery with me). Of course, back in those days, the typical battery capacity was not nearly as good. In any event, I wish I could still do that with my current phone. It would be super slick if there was a tiny auxillary battery or 60-second hold-up capacitor too, so you wouldn't even have to shut the phone off.
  - midoridensha 4y ago
    >Something that baffles me is how hard it's become to replace the battery. Why is this baffling? It makes perfect sense for batteries to be non-replaceable: you can make the phone slightly thinner, and you can charge owners a small fortune to replace them, which will usually result in them simply throwing the device away after a while and buying a new one. Just look at Apple: they pushed non-replaceable batteries (and also removed headphone jacks in favor of expensive airPods), and people love iPhones and can't wait to get the next version, even if it costs $1399 and they have to sell their kidney to buy it.
    - kemiller 4y ago
      This is such a cynical take. By ditching removable bits they save on internal room which allows bigger batteries. I would take 25% better main battery life over removable any day. If you don’t mind carrying an extra item (because that’s what swappable batteries means — by the way how do you keep the spare charged?) then get an external. Even easier to swap and use, often supports pass-through charging, and doesn’t create yet another aperture that needs waterproofing.
      - midoridensha 4y ago
        You're missing the real reason for replaceable batteries: they need replacement after a few years because their capacity decreases with age.
dachryn 4y ago
My LifePo4 battery has a 6000 cycle guarantee at 60% capacity. So its not even close yet
- deng 4y ago
  > So its not even close yet Yes, if you compare just capacity fade, that's true. But the longevity of LiFePo4 comes with a lower charge density than Li-Ion, about 170 mAh/g. This NaS battery currently has 1017 mAh/g, so almost a factor of 6. If the capacity is higher, you don't have to cycle as often, but of course, mileage depends on the use case.
  - cogman10 4y ago
    That lower capacity comes at a cost cut and a huge materials advantage. LFPs are made of highly available materials. (Lithium, iron and phosphate). The higher capacity NMC batteries are constrained on nickel production.
- Retric 4y ago
  The question is more how many kWh can you store and extract over a lifetime at a given cost rather than how many cycles can it take. If the 5999th charge is only holding appropriately 60% of a LifePo4 battery you don’t get 6,000 cycles * full battery capacity.
  - jacquesm 4y ago
    True, but you probably will get more before the battery becomes unusable in total. It would be very nice if batteries were super predictable as in 'perfect until the 6 thousandth cycle and then dead', instead you get this gradual drop-off to the point where a battery is no longer usable for its intended purpose. Whether or not that is at 60% of the original capacity or not is moot if it doesn't make it to the 60% in the first place (lots of batteries get murdered well before the end of their design life), on the other hand if that means that the drop-off itself slows down then you might be able to get much more life out of them when treated carefully. The big ones - in my experience, which is obviously not the final word on this - is to ensure that you don't charge batteries when they're very cold, that you don't use currents in excess of what they're made for (and preferably a bit below that) and that you don't subject them to mechanical stress. If you live by those rules you can make them stretch for a very long time, enough for technology itself, rather than that battery, to make your battery obsolete. Witness the old lead-acid batteries used in cars, telephone switch boards and submarines. In cars they would last a couple of years at best, in telephone switch boards and submarines they would routinely outlast the rest of the installation.
abdulmuhaimin 4y ago
The faster battery life deterioration might even be desirable for those manufacturers with planned obsolescence in mind, especially phone manufacturers
splitstud 4y ago

analog31 4y ago

A somewhat shorter lifespan might be a decent trade if the materials are much more recyclable and if mining is produces less pollution.

marcus_holmes 4y ago
also if the batteries are cheap enough they can be considered "partially rechargeable" and swapped out when the capacity fades too much
- analog31 4y ago
  I suppose partially worn out batteries can also find new uses, such as stationary power reserves, where they're not being cycled a lot.

davrosthedalek 4y ago

Is it 0.05% of the remaining capacity, or of the initial capacity?