5 ms·

20% loss isn't too bad if you start out at double the capacity though.

by oofbaroomf 9mo ago

dyauspitr 9mo ago
But does it keep dropping? Is it 60% at 200 cycles
- hinkley 9mo ago
  I saw a video on the CATL sodium batteries the other day and the deal is that they’ve found a way to reinforce the material in a way that brings up the slope of the back half of the discharge curve so it’s almost as good as lithium down to about 20% state of charge before falling off the cliff. Lithium is more like 10% but that’s something you can manage with charge circuitry and overprovisioning. So yeah I’d like to know the answer to your question too.
cousinbryce 9mo ago
My first thought was put the new cells in aircraft, then cheap cars finally grid storage
- cogman10 9mo ago
  That actually could make sense especially with a good recycling program. Swap the packs every flight and recycle anything that falls below standards.
  - ryukoposting 9mo ago
    A good recycling program sounds like a tall order. I'm seeing Silver nanoparticles (heavy metal) and multiple things that react violently with water. I'm always skeptical of any idea that ends with a bespoke industrial-scale recycling process. People tend to massively underestimate the complexity of recycling, especially at scale.
    - gmueckl 9mo ago
      In general, bespoke recycling processes can make sense, especially if you manage to design the items to recycle with the recycling process in mind. There are several types of goods where this is put into practice (paper, compounds like TetraPak packages, various polymer plastics). Not sure about all the differrent types of batteries, though.
      - ryukoposting 9mo ago
        We struggle to recycle normal batteries without injuring or killing people. Lead-acid batteries contain literal plates of lead oxides, and we can't manage to keep that out of the water supply! I don't see how we'd do any better with silver nanoparticles. Nothing I'm saying is meant to condemn recycling as a concept, by the way. Only to condemn technologies where disposal is dismissed with a shrug and a "idk just recycle it."
        cogman10 9mo ago
        > we can't manage to keep that out of the water supply! AFAIK, the lead in the water supply doesn't come from batteries. It mostly comes from lead pipes. Lead acid battery recycling is one of the more efficient recycling programs out there.
        ryukoposting 9mo ago
        "efficient" and "clean" aren't the same thing, and they never have been. Recycling lead-acid batteries is extremely efficient. Nearly the entire battery by mass is recovered. But, it also causes severe lead pollution around recycling sites. Lead acid battery recycling is one of the leading causes of lead poisoning around the world [1]. Estimations vary, but all generally agree that millions of human-years of life have been lost due to lead pollution caused specifically by lead-acid battery recycling. [2] [1]: https://link.springer.com/chapter/10.1007/978-0-387-77030-7_4 https://link.springer.com/chapter/10.1007/978-0-387-77030-7_... [2]: https://pmc.ncbi.nlm.nih.gov/articles/PMC5990833/ https://pmc.ncbi.nlm.nih.gov/articles/PMC5990833/ Returning to the original point, recycling anything involving heavy metals is extremely difficult to do without poisoning people. If we can't avoid it with one of the simplest, dumbest battery technologies in regular use today, I don't see how we're going to avoid it with a battery technology involving heavy metal nanoparticles.
- specialist 9mo ago
  Surely there's a well trod progression, no? Something like military, space, drones, aircraft, IoT, consumer (phones, watches), vehicle, residential, grid?
maximus-decimus 9mo ago
Going down 10 times faster seems like a really bad trade off for 2 times the capacity. That means your battery will only lst 1/5 or 20% as long.
- Reason077 9mo ago
  Not if your application requires 2X the energy. Aircraft, drones, etc. There's always trade-offs in battery design. As an old saying goes: you can have high specific energy, low degradation, or low cost... pick two!
- TrainedMonkey 9mo ago
  Charge cycle capacity drops are generally not linear. If we start with 2x capacity and drop to 1.6x after 100 cycles, then we might end up with 1.2x after 1000 cycles. Some smartphone manufacturers would love that as you start with extremely superior energy density and then have a built-in obsolescence.
kazinator 9mo ago
That's only a valid concept in some embedded engineering case, where a certain capacity is required, and double that amount is provisioned to account for degradation. Few consumers think this way. Something doesn't have double the capacity that it has; the capacity is the capacity, and the decline looks bad.
- ryukoposting 9mo ago
  The whole idea of the embedded part is that you make the degredation invisible to the consumer for as long as possible. From the factory, only charge up to ~4.07 Volts or thereabouts. Every N cycles, add 0.01 V to the threshold. Your phone probably already does something like this. But yeah, 20% degredation in 100 cycles is atrocious. No amount of firmware shenanigans will be able to paper over that, not in any regular consumer product at least. I can still think of use cases, though. Reserve power sources that aren't meant to be cycled daily, where smallness is valuable. Those little car jumper packs, for example. If there was a UPS close to the size of a regular power strip, I'd buy a few.
  - hinkley 9mo ago
    Engineering is compromise though. If you can make a hybrid that loses 5% at 100 but still retains 500wh/l you’re in good shape. There was someone working on a membrane a while back that’s pretty good at diffusing the lithium transfer in a way that reduces dendrite formation substantially, for instance. That’ll drop your volumetric advantage and likely your max discharge and charge rate a bit but would fix a lot of other problems in the bargain. I’m not saying that the solution, but there is a palette of tools you can mix and match and that may be one of them.
  - joecool1029 9mo ago
    > Your phone probably already does something like this. It most certainly does not. Most devices track battery health % (last full capacity divided by design capacity) and the gauge just presents state of charge (current capacity/lastfull) The better phone charge threshold systems measure usage and keep the phone in the 30-80% soc range as often as possible. Voltage drops faster on old cells as they age so you need a coulomb counter. Only extremely shit designs guess soc based on voltage alone.

20% loss isn't too bad if you start out at double the capacity though.

dyauspitr 9mo ago

But does it keep dropping? Is it 60% at 200 cycles

hinkley 9mo ago
I saw a video on the CATL sodium batteries the other day and the deal is that they’ve found a way to reinforce the material in a way that brings up the slope of the back half of the discharge curve so it’s almost as good as lithium down to about 20% state of charge before falling off the cliff. Lithium is more like 10% but that’s something you can manage with charge circuitry and overprovisioning. So yeah I’d like to know the answer to your question too.

cousinbryce 9mo ago

My first thought was put the new cells in aircraft, then cheap cars finally grid storage

cogman10 9mo ago
That actually could make sense especially with a good recycling program. Swap the packs every flight and recycle anything that falls below standards.
- ryukoposting 9mo ago
  A good recycling program sounds like a tall order. I'm seeing Silver nanoparticles (heavy metal) and multiple things that react violently with water. I'm always skeptical of any idea that ends with a bespoke industrial-scale recycling process. People tend to massively underestimate the complexity of recycling, especially at scale.
  - gmueckl 9mo ago
    In general, bespoke recycling processes can make sense, especially if you manage to design the items to recycle with the recycling process in mind. There are several types of goods where this is put into practice (paper, compounds like TetraPak packages, various polymer plastics). Not sure about all the differrent types of batteries, though.
    - ryukoposting 9mo ago
      We struggle to recycle normal batteries without injuring or killing people. Lead-acid batteries contain literal plates of lead oxides, and we can't manage to keep that out of the water supply! I don't see how we'd do any better with silver nanoparticles. Nothing I'm saying is meant to condemn recycling as a concept, by the way. Only to condemn technologies where disposal is dismissed with a shrug and a "idk just recycle it."
      - cogman10 9mo ago
        > we can't manage to keep that out of the water supply! AFAIK, the lead in the water supply doesn't come from batteries. It mostly comes from lead pipes. Lead acid battery recycling is one of the more efficient recycling programs out there.
        ryukoposting 9mo ago
        "efficient" and "clean" aren't the same thing, and they never have been. Recycling lead-acid batteries is extremely efficient. Nearly the entire battery by mass is recovered. But, it also causes severe lead pollution around recycling sites. Lead acid battery recycling is one of the leading causes of lead poisoning around the world [1]. Estimations vary, but all generally agree that millions of human-years of life have been lost due to lead pollution caused specifically by lead-acid battery recycling. [2] [1]: https://link.springer.com/chapter/10.1007/978-0-387-77030-7_4 https://link.springer.com/chapter/10.1007/978-0-387-77030-7_... [2]: https://pmc.ncbi.nlm.nih.gov/articles/PMC5990833/ https://pmc.ncbi.nlm.nih.gov/articles/PMC5990833/ Returning to the original point, recycling anything involving heavy metals is extremely difficult to do without poisoning people. If we can't avoid it with one of the simplest, dumbest battery technologies in regular use today, I don't see how we're going to avoid it with a battery technology involving heavy metal nanoparticles.
specialist 9mo ago
Surely there's a well trod progression, no? Something like military, space, drones, aircraft, IoT, consumer (phones, watches), vehicle, residential, grid?

maximus-decimus 9mo ago

Going down 10 times faster seems like a really bad trade off for 2 times the capacity. That means your battery will only lst 1/5 or 20% as long.

Reason077 9mo ago
Not if your application requires 2X the energy. Aircraft, drones, etc. There's always trade-offs in battery design. As an old saying goes: you can have high specific energy, low degradation, or low cost... pick two!
TrainedMonkey 9mo ago
Charge cycle capacity drops are generally not linear. If we start with 2x capacity and drop to 1.6x after 100 cycles, then we might end up with 1.2x after 1000 cycles. Some smartphone manufacturers would love that as you start with extremely superior energy density and then have a built-in obsolescence.

kazinator 9mo ago

That's only a valid concept in some embedded engineering case, where a certain capacity is required, and double that amount is provisioned to account for degradation. Few consumers think this way. Something doesn't have double the capacity that it has; the capacity is the capacity, and the decline looks bad.

ryukoposting 9mo ago
The whole idea of the embedded part is that you make the degredation invisible to the consumer for as long as possible. From the factory, only charge up to ~4.07 Volts or thereabouts. Every N cycles, add 0.01 V to the threshold. Your phone probably already does something like this. But yeah, 20% degredation in 100 cycles is atrocious. No amount of firmware shenanigans will be able to paper over that, not in any regular consumer product at least. I can still think of use cases, though. Reserve power sources that aren't meant to be cycled daily, where smallness is valuable. Those little car jumper packs, for example. If there was a UPS close to the size of a regular power strip, I'd buy a few.
- hinkley 9mo ago
  Engineering is compromise though. If you can make a hybrid that loses 5% at 100 but still retains 500wh/l you’re in good shape. There was someone working on a membrane a while back that’s pretty good at diffusing the lithium transfer in a way that reduces dendrite formation substantially, for instance. That’ll drop your volumetric advantage and likely your max discharge and charge rate a bit but would fix a lot of other problems in the bargain. I’m not saying that the solution, but there is a palette of tools you can mix and match and that may be one of them.
- joecool1029 9mo ago
  > Your phone probably already does something like this. It most certainly does not. Most devices track battery health % (last full capacity divided by design capacity) and the gauge just presents state of charge (current capacity/lastfull) The better phone charge threshold systems measure usage and keep the phone in the 30-80% soc range as often as possible. Voltage drops faster on old cells as they age so you need a coulomb counter. Only extremely shit designs guess soc based on voltage alone.