7 ms·

A bit of inaccuracy in the article: > a typical Li-ion battery retains only 80 percent of its charge capacity after 300 to 500 cycles That's off by 10x at lea

A bit of inaccuracy in the article: > a typical Li-ion battery retains only 80 percent of its charge capacity after 300 to 500 cycles That's off by 10x at least. Typical LFP batteries that are widely used now have thousands of cycles. Over 5K in some cases. Some of the solid state batteries that are coming to production in the next few years might do better. 300 to 500 is more typical of some older chemistries. Even NMC batteries used in e.g. Teslas have cycle life spans of at least 1500 or so cycles. And for reference, if you charge and full de-charge your car that would be 1 cycle. A decade is only 3653 or so cycles (there might be 2 or 3 leap years). Most car vehicle owners don't charge nearly as often or so completely. A typical Tesla that is partially charged maybe once a week or so is not going to need a battery replacement until the 2040s or so. Anyway, the article carefully avoids talking about energy density. Which is of course the key thing here. Together with other things like charging speeds. Operational temperatures, etc. These all matter. This is a university study, not a plan to get this to production. Promising and interesting but probably well over a decade away from any serious applications. By that time we might have all sorts of other battery tech that is sitting a bit higher on the technological readiness scale on the market.

radlad 2y ago
I find it interesting that my 2021 MBP's "health" was down to about 85% after the first year, but has only decreased to 82% after two additional years. I have 653 cycles now. Assuming that's accurate, and batteries spend a majority of their usable lifetime around this capacity, perhaps battery estimates should be based off of the 80% capacity mark.
- peer2pay 2y ago
  80% SoH is the de-facto industry standard for EoL/replacement. Mostly because after that you will eventually get a "knee-point" in your degradation curve at which operation is risky and largely inefficient. Without knowing specifics, your MBP might have had issues with an individual cell such that initial capacity dropped significantly until the cell was disconnected.
  - deleted 2y ago
    [deleted]
  - formerly_proven 2y ago
    I've seen several laptops start out in the 90-95% SoH range, drop off quickly to the mid-80s and stay there for a very long time. Similarly for iPhone batteries, they go below 90% pretty fast, then each % off takes longer and longer until they actually start dying. Maybe that's due to different baselines though, BMS of laptop batteries normally refer last-full energy to the design energy, which is probably just a fixed value in an EEPROM and might not ever be reached due to a more conservative charge cutoff and tolerances.
  - vasco 2y ago
    Enough cycles and you get a free pillow so the risk comes with rewards sometimes!
- thefourthchime 2y ago
  I use https://apphousekitchen.com https://apphousekitchen.com to only charge to 80%
  - ffsm8 2y ago
    Apple added a feature that only charges to 80% if you're only using it while plugged in (and discharges to 80% if not disconnected). That made me uninstall aldente again.
  - radlad 2y ago
    I struggle a bit with this concept. It feels silly to me to only use 80% of my laptop's battery capacity in order to... avoid my usage bringing my battery's capacity down to 80%. OK, so it can go below 80%, but if it takes 3-4+ years, I'm not sure I care. (Don't get me wrong - I do of course use the built-in intelligent charging on Apple and Android devices. No reason to charge a battery to 100% when I'm going to plug it in for bedtime in a few hours anyway.)
    - nicoburns 2y ago
      It might make sense if you occasionally use the full 100%. But for most people I expect it makes more sense to just use 100% of the capacity and then replace the battery if/when it degrades. For some reason, many people seem to have an aversion to replacing the battery in phones. Yes, it's expensive, but those same people will often replace the entire phone which is much more expensive!
      - deleted 2y ago
        [deleted]
    - Tagbert 2y ago
      For most people they are not using 100% of capacity every day. In fact large numbers of laptops are primarily used plugged in and just move from desk to desk. In that scenario charging to 80% has no downside. The upside is that your battery may last longer. If you are keeping your laptop for longer than 2-3 years that might be worthwhile.
- codemiscreant 2y ago
  The number is, I believe, simply peak voltage. And personally I find the measure grossly misleading: an iPhone with an 80% battery has an almost useless runtime. It definitely isn’t 80% of the original runtime.
  - ruszki 2y ago
    My iPhone could handle about 2 days with heavy usage. It was reduced to a day after 1 year. Now after 2 and half years, the battery dies in about 12 hours with the same usage. The battery health is 83% according to iOS. So it’s definitely not a good indicator for real life usage.
- ksec 2y ago
  600 cycles in 4 years is pretty high IMO. Do you carry it around all the time without it being plugged into socket ?
  - deleted 2y ago
    [deleted]
kccqzy 2y ago
> Typical LFP batteries that are widely used It depends on the use case. I believe LCO batteries are still more widely used since they are popular in small electronic devices rather than electric vehicles. These do not achieve the thousands of cycles you mention. In general I don't like articles that simply talk about specs of Li-ion batteries as a whole without specifying the exact chemistry. Apple has different incentives when they choose a battery as compared to say Ford.
hnuser123456 2y ago
High discharge rate + high energy/mass density optimized chemistries usually have the worst charge cycle degradation. LFP doesn't have top discharge rate or energy/mass density, it trades some of that off for improved long term stability.
morserer 2y ago
Li-ion != LFP. LFP is incredible, but LFP batteries are 5x larger than li-ion. The two aren't comparable. You won't find LFP batteries in cars nor smartphones.
- hnuser123456 2y ago
  It would appear LFPs are making their way into EVs, despite having about half the energy/mass density. https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery
  - Reason077 2y ago
    LFP has made huge energy density improvements in recent years, so the difference is much less than that today. If you compare a standard range Tesla Model Y with LFP pack, the newest LFP pack stores around 62 kWh, vs. around 80 kWh for the long range (NMC) variant. And the LR pack actually weighs more than the LFP one, putting the difference in energy density at <30%. Further more, typically with an NMC pack it's recommended to only charge to 80% for day-to-day use, to reduce long-term degradation. But with an LFP pack you can routinely charge to 100%. So the effective difference in range for day-to-day driving if you follow that recommendation is small.
- dgacmu 2y ago
  There are a lot of LFP model 3's on the road, and my understanding is it was only canceled because of manufacturing location effects on tax rebates. A lot of BYDs cars use LFP. And they sell a -lot- of cars. The 2024 Mach-E is LFP. The Kia EV5. And so on. I think you have an outdated model of lfp tradeoffs. Many of the extended range models still use higher-density chemistries. But LFP is making amazing strides.
  - rstuart4133 2y ago
    LFP Tesla 3's is what they ship from China. Australia gets Chinese made Model 3's, so they are all LFP. The US doesn't get Chinese made Tesla's, so no LFP for you. It doesn't seem to effect things much. The cars still have the same range. I guess they must be heavier. Australian drive their cars around 13,000 km's per year. If the LFP battery got 3,000 cycles that's 90 years. I guess they must hit some other limit long before then.
dragontamer 2y ago
LFP is 3000 cycles last time I checked. NCA, a very common LiIon chemistry, is only 500 cycles as the article rightfully claims The article is anywhere from 'correct' to off by 600% depending on which LiIon chemistry. But that's the nature of such a wide chemistry, there's so many LiIon out there it's hard to generalize. NCA / NMC is common for phone and even EV applications though. So it's not necessarily wrong and both have similar endurance specs. > Anyway, the article carefully avoids talking about energy density. Which is of course the key thing here. No one cares about density in utility scale applications. It can be heavy as all heck but as long as it's cheap it will be an effective solar or wind battery.
- megaman821 2y ago
  Also for utility uses, why is 80% the benchmark? It seems likely that batteries will be used down to 60% capacity; so double the number of cycles for a reduced capacity.
  - deleted 2y ago
    [deleted]
  - nine_k 2y ago
    Also, in a utility-scale battery with literally millions of cells there will always be gradual but constant replacement of a small amount of cells, while the remaining cells continue to bear the load. This is something you can't do in a phone, and what may be too costly in a EV.
    - bcrl 2y ago
      It doesn't quite work out for a centralized utility scale battery unless it gets built gradually over the expected lifetime of the component batteries, as most existing infrastructure projects tend to get financed and built all at once, so all the batteries are the same age and are likely to require replacement around the same time. On a small scale that is quite visible with UPS batteries in data centers that all fail at once. The easiest way to avoid that is to slow things down and build up a decentralized grid scale battery over time through incentives.
hinkley 2y ago
The last aluminum battery discussed here only had about 40% of the volumetric density of Lion and did not mention wh/kg, just w/kg. Which sounds a lot like lying with statistics.
moron4hire 2y ago
Oh, but they should be able to get that time down to a few months if they just use an LLM.
Melatonic 2y ago
When people say Li-ion they typically are talking about Lipo batteries (unfortunately). LFP obviously are much better longevity wise.
- jillesvangurp 2y ago
  No they are not, they are talking about batteries that contain a lot of lithium. Aside from battery nerds, the finer points of most chemistries are lost the vast majority of people and I doubt even experts would agree with your very narrow definition. In any case, my point was that the car industry and the storage industry is dominated by a wide variety of batteries (most of them lithium based of course; some might say lithium ion even) that have way better longevity than the article suggests is the key selling point of this new battery chemistry. I think it's a bit misleading or sloppy. I'd expect better from IEEE.
  - tim333 2y ago
    I've been guilty of thinking of lithium polymer. Most people have no idea of battery chemistry beyond thinking of the thing that comes with their phone.
ikigai_sign 2y ago
I got so burned on QuantumScape stock I haven't been able to think about solid state batteries since then.
- toss1 2y ago
  You are not alone, sadly.
amatecha 2y ago
LFP !== Li-ion. If you "full de-charge" your car battery that battery is toast, so that's not a useful comparison.
- gnabgib 2y ago
  LFP is certainly a Li-ion battery chemistry (and also a Lithium Iron chemistry). https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery
  - amatecha 2y ago
    Sure, and I'm no expert on the subject, but when someone writes "a typical Li-ion battery" they mean the common rechargeable lithium battery with lithium cobalt oxide, not lithium iron phosphate. LiFePo4 is not a "typical" Li-ion chemistry yet, unfortunately.
kvakerok 2y ago
Came here to ask about energy density, but it seems the article answered it without answering it.
lightedman 2y ago
"300 to 500 is more typical of some older chemistries." And this is almost purely a function of the very first charge cycle the battery receives. If the initial charge cycle is fairly aggressive, you can actually pull something like 1500 cycles out of those older chemistries, at the cost of actual capacity. We're running tests on this right now in a lab in San Diego. Almost all non-solid-state Li chemistry batteries are similarly affected.
jve 2y ago
And there is such thing as DoD (Depth of Discharge) - Doing 4x 25% charges (1 cycle) is much much much better than 1x100% cycle. You'd lose 27% of capacity vs 8% capacity over a cycle test that lasted 2,5 years. https://youtu.be/i31x5JW361k?si=93KYNqKFVJRgSbKs&t=1216 https://youtu.be/i31x5JW361k?si=93KYNqKFVJRgSbKs&t=1216
deleted 2y ago
[deleted]
hilbert42 2y ago
Spectrum: "…its energy density will need to be improved, the researchers say." "Anyway, the article carefully avoids talking about energy density. Which is of course the key thing here." I agree. And as you say, there's a bit of inaccuracy in the article. In fact, it's more than just a little—not to mention the omissions. What's so annoying about this article is that it's from the IEEE's magazine Spectrum where one expects the best—the most authorative, factual and most current—technical information available at publication time but it's often not the case. Unfortunately, in recent years, the IEEE has been unduely influenced by commercial interests which has affected or slanted the accuracy of its reporting of science and engineering news. As Spectrum is the main face of the organization and its principal news outlet this is where the policy shift has been most obvious. I could give other instances of bad or overly enthusiastic reporting of new tech where known downsides were either not reported and or downplayed but I'll refrain here as I don't have the issues of Spectrum immediately to hand to give specific references. Suffice to say, I became so disillusioned with stuff I was reading in Spectrum† that I terminated my 20-year-plus IEEE membership some while back. My main criticism of this story is—as you correctly point out—carefully avoids talking about energy density, which has to be a crucial aspect of any story about new battery tech that's posited as a potential competitor and or replacement for Li-ion. That's damn obvious. If the researchers did not provide numerical comparisons (experimental and or theoretical) of the energy densities between their Al-ion prototypes and Li-ion in their paper/press release then Spectrum's editor should have provided a side/footnote on the matter. Most of us already know that Li has a larger electrode potential‡ than Al, so Al is already coming from behind Li in this regard, but of course that's far from the end of the story as there are many other factors involved in addition to those benefits as promulgated by the researchers, namely recharge cycles, safety and cost. For example, how does Al stack up against Li as far as electrode surface area (spongy metal surfaces, etc.)? We know from long experience with electrolytic capacitors that Al can be treated to have very large effective surface areas, in fact they can be enormous. If Al has the potential to be much better than Li in this regard then this new tech could certainly be a winner. As this is an obvious factor, Spectrum's editor should have mentioned it amongst others even if not mentioned in the original paper (in fact, Spectrum should have criticized its omission if the case). In summary, one would hope this research leads to much better and safer batteries but the IEEE—as the premier representative for electrical and electronic engineering/engineers—has done precious little in providing us with information that actually matters. __ † Whilst I've strong criticisms of the IEEE not all are negative, many of its specialist publications are quite excellent including Proceedings of the IEEE. ‡ From Wiki: Standard electrode potentials: Li: Li+ + e− ⇌ Li(s) -3.0401V Al: Al3+ + 3e− ⇌ Al(s) -1.662V Edit: It was only after I'd written this comment that I was able access the original ACS research paper (initially I'd difficulty downloading it). I've since skimmed it several times and I need to read it thoroughly to get a proper understanding but it's pretty short on the issues I've raised. Thus, my point that Spectrum should have mentioned these shortfalls still stands.
ErigmolCt 2y ago
I think by the time it's commercially ready (if ever), the battery landscape could look very different
DoctorOetker 2y ago
> Anyway, the article carefully avoids talking about energy density. Which is of course the key thing here. But it's right there in the article: https://pubs.acs.org/doi/pdf/10.1021/acscentsci.4c01615?download=true https://pubs.acs.org/doi/pdf/10.1021/acscentsci.4c01615?down... > The cell with F-SSAF electrolyte and pyrolytic graphite (PG) cathode show reversible capacities of 83, 81, 79, 77, and 75 mA h g−1 at the current densities of 20, 40, 60, 80, and 100 mA g−1 (Figure 2a). so 83 Ah/kg (at 20 A/kg), and at a cell voltage of ~ 2V thats ~166 Wh/kg.
baranul 2y ago
Clarity is very much needed. There are so many stories about "battery technology breakthroughs", but then they never come to market or are x number of years away from production. The general public is often way more interested in when they are going to actually sell the new battery technology, and getting their hands on them to put to use.

radlad 2y ago

I find it interesting that my 2021 MBP's "health" was down to about 85% after the first year, but has only decreased to 82% after two additional years. I have 653 cycles now. Assuming that's accurate, and batteries spend a majority of their usable lifetime around this capacity, perhaps battery estimates should be based off of the 80% capacity mark.

peer2pay 2y ago
80% SoH is the de-facto industry standard for EoL/replacement. Mostly because after that you will eventually get a "knee-point" in your degradation curve at which operation is risky and largely inefficient. Without knowing specifics, your MBP might have had issues with an individual cell such that initial capacity dropped significantly until the cell was disconnected.
- deleted 2y ago
  [deleted]
- formerly_proven 2y ago
  I've seen several laptops start out in the 90-95% SoH range, drop off quickly to the mid-80s and stay there for a very long time. Similarly for iPhone batteries, they go below 90% pretty fast, then each % off takes longer and longer until they actually start dying. Maybe that's due to different baselines though, BMS of laptop batteries normally refer last-full energy to the design energy, which is probably just a fixed value in an EEPROM and might not ever be reached due to a more conservative charge cutoff and tolerances.
- vasco 2y ago
  Enough cycles and you get a free pillow so the risk comes with rewards sometimes!
thefourthchime 2y ago
I use https://apphousekitchen.com https://apphousekitchen.com to only charge to 80%
- ffsm8 2y ago
  Apple added a feature that only charges to 80% if you're only using it while plugged in (and discharges to 80% if not disconnected). That made me uninstall aldente again.
- radlad 2y ago
  I struggle a bit with this concept. It feels silly to me to only use 80% of my laptop's battery capacity in order to... avoid my usage bringing my battery's capacity down to 80%. OK, so it can go below 80%, but if it takes 3-4+ years, I'm not sure I care. (Don't get me wrong - I do of course use the built-in intelligent charging on Apple and Android devices. No reason to charge a battery to 100% when I'm going to plug it in for bedtime in a few hours anyway.)
  - nicoburns 2y ago
    It might make sense if you occasionally use the full 100%. But for most people I expect it makes more sense to just use 100% of the capacity and then replace the battery if/when it degrades. For some reason, many people seem to have an aversion to replacing the battery in phones. Yes, it's expensive, but those same people will often replace the entire phone which is much more expensive!
    - deleted 2y ago
      [deleted]
  - Tagbert 2y ago
    For most people they are not using 100% of capacity every day. In fact large numbers of laptops are primarily used plugged in and just move from desk to desk. In that scenario charging to 80% has no downside. The upside is that your battery may last longer. If you are keeping your laptop for longer than 2-3 years that might be worthwhile.
codemiscreant 2y ago
The number is, I believe, simply peak voltage. And personally I find the measure grossly misleading: an iPhone with an 80% battery has an almost useless runtime. It definitely isn’t 80% of the original runtime.
- ruszki 2y ago
  My iPhone could handle about 2 days with heavy usage. It was reduced to a day after 1 year. Now after 2 and half years, the battery dies in about 12 hours with the same usage. The battery health is 83% according to iOS. So it’s definitely not a good indicator for real life usage.
ksec 2y ago
600 cycles in 4 years is pretty high IMO. Do you carry it around all the time without it being plugged into socket ?
- deleted 2y ago
  [deleted]

kccqzy 2y ago

> Typical LFP batteries that are widely used It depends on the use case. I believe LCO batteries are still more widely used since they are popular in small electronic devices rather than electric vehicles. These do not achieve the thousands of cycles you mention. In general I don't like articles that simply talk about specs of Li-ion batteries as a whole without specifying the exact chemistry. Apple has different incentives when they choose a battery as compared to say Ford.

hnuser123456 2y ago

High discharge rate + high energy/mass density optimized chemistries usually have the worst charge cycle degradation. LFP doesn't have top discharge rate or energy/mass density, it trades some of that off for improved long term stability.

morserer 2y ago

Li-ion != LFP. LFP is incredible, but LFP batteries are 5x larger than li-ion. The two aren't comparable. You won't find LFP batteries in cars nor smartphones.

hnuser123456 2y ago
It would appear LFPs are making their way into EVs, despite having about half the energy/mass density. https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery
- Reason077 2y ago
  LFP has made huge energy density improvements in recent years, so the difference is much less than that today. If you compare a standard range Tesla Model Y with LFP pack, the newest LFP pack stores around 62 kWh, vs. around 80 kWh for the long range (NMC) variant. And the LR pack actually weighs more than the LFP one, putting the difference in energy density at <30%. Further more, typically with an NMC pack it's recommended to only charge to 80% for day-to-day use, to reduce long-term degradation. But with an LFP pack you can routinely charge to 100%. So the effective difference in range for day-to-day driving if you follow that recommendation is small.
dgacmu 2y ago
There are a lot of LFP model 3's on the road, and my understanding is it was only canceled because of manufacturing location effects on tax rebates. A lot of BYDs cars use LFP. And they sell a -lot- of cars. The 2024 Mach-E is LFP. The Kia EV5. And so on. I think you have an outdated model of lfp tradeoffs. Many of the extended range models still use higher-density chemistries. But LFP is making amazing strides.
- rstuart4133 2y ago
  LFP Tesla 3's is what they ship from China. Australia gets Chinese made Model 3's, so they are all LFP. The US doesn't get Chinese made Tesla's, so no LFP for you. It doesn't seem to effect things much. The cars still have the same range. I guess they must be heavier. Australian drive their cars around 13,000 km's per year. If the LFP battery got 3,000 cycles that's 90 years. I guess they must hit some other limit long before then.

dragontamer 2y ago

LFP is 3000 cycles last time I checked. NCA, a very common LiIon chemistry, is only 500 cycles as the article rightfully claims The article is anywhere from 'correct' to off by 600% depending on which LiIon chemistry. But that's the nature of such a wide chemistry, there's so many LiIon out there it's hard to generalize. NCA / NMC is common for phone and even EV applications though. So it's not necessarily wrong and both have similar endurance specs. > Anyway, the article carefully avoids talking about energy density. Which is of course the key thing here. No one cares about density in utility scale applications. It can be heavy as all heck but as long as it's cheap it will be an effective solar or wind battery.

megaman821 2y ago
Also for utility uses, why is 80% the benchmark? It seems likely that batteries will be used down to 60% capacity; so double the number of cycles for a reduced capacity.
- deleted 2y ago
  [deleted]
- nine_k 2y ago
  Also, in a utility-scale battery with literally millions of cells there will always be gradual but constant replacement of a small amount of cells, while the remaining cells continue to bear the load. This is something you can't do in a phone, and what may be too costly in a EV.
  - bcrl 2y ago
    It doesn't quite work out for a centralized utility scale battery unless it gets built gradually over the expected lifetime of the component batteries, as most existing infrastructure projects tend to get financed and built all at once, so all the batteries are the same age and are likely to require replacement around the same time. On a small scale that is quite visible with UPS batteries in data centers that all fail at once. The easiest way to avoid that is to slow things down and build up a decentralized grid scale battery over time through incentives.

hinkley 2y ago

The last aluminum battery discussed here only had about 40% of the volumetric density of Lion and did not mention wh/kg, just w/kg. Which sounds a lot like lying with statistics.

moron4hire 2y ago

Oh, but they should be able to get that time down to a few months if they just use an LLM.

Melatonic 2y ago

When people say Li-ion they typically are talking about Lipo batteries (unfortunately). LFP obviously are much better longevity wise.

jillesvangurp 2y ago
No they are not, they are talking about batteries that contain a lot of lithium. Aside from battery nerds, the finer points of most chemistries are lost the vast majority of people and I doubt even experts would agree with your very narrow definition. In any case, my point was that the car industry and the storage industry is dominated by a wide variety of batteries (most of them lithium based of course; some might say lithium ion even) that have way better longevity than the article suggests is the key selling point of this new battery chemistry. I think it's a bit misleading or sloppy. I'd expect better from IEEE.
- tim333 2y ago
  I've been guilty of thinking of lithium polymer. Most people have no idea of battery chemistry beyond thinking of the thing that comes with their phone.

ikigai_sign 2y ago

I got so burned on QuantumScape stock I haven't been able to think about solid state batteries since then.

toss1 2y ago
You are not alone, sadly.

amatecha 2y ago

LFP !== Li-ion. If you "full de-charge" your car battery that battery is toast, so that's not a useful comparison.

gnabgib 2y ago
LFP is certainly a Li-ion battery chemistry (and also a Lithium Iron chemistry). https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery
- amatecha 2y ago
  Sure, and I'm no expert on the subject, but when someone writes "a typical Li-ion battery" they mean the common rechargeable lithium battery with lithium cobalt oxide, not lithium iron phosphate. LiFePo4 is not a "typical" Li-ion chemistry yet, unfortunately.

kvakerok 2y ago

Came here to ask about energy density, but it seems the article answered it without answering it.

lightedman 2y ago

"300 to 500 is more typical of some older chemistries." And this is almost purely a function of the very first charge cycle the battery receives. If the initial charge cycle is fairly aggressive, you can actually pull something like 1500 cycles out of those older chemistries, at the cost of actual capacity. We're running tests on this right now in a lab in San Diego. Almost all non-solid-state Li chemistry batteries are similarly affected.

jve 2y ago

And there is such thing as DoD (Depth of Discharge) - Doing 4x 25% charges (1 cycle) is much much much better than 1x100% cycle. You'd lose 27% of capacity vs 8% capacity over a cycle test that lasted 2,5 years. https://youtu.be/i31x5JW361k?si=93KYNqKFVJRgSbKs&t=1216 https://youtu.be/i31x5JW361k?si=93KYNqKFVJRgSbKs&t=1216

deleted 2y ago

[deleted]

hilbert42 2y ago

Spectrum: "…its energy density will need to be improved, the researchers say." "Anyway, the article carefully avoids talking about energy density. Which is of course the key thing here." I agree. And as you say, there's a bit of inaccuracy in the article. In fact, it's more than just a little—not to mention the omissions. What's so annoying about this article is that it's from the IEEE's magazine Spectrum where one expects the best—the most authorative, factual and most current—technical information available at publication time but it's often not the case. Unfortunately, in recent years, the IEEE has been unduely influenced by commercial interests which has affected or slanted the accuracy of its reporting of science and engineering news. As Spectrum is the main face of the organization and its principal news outlet this is where the policy shift has been most obvious. I could give other instances of bad or overly enthusiastic reporting of new tech where known downsides were either not reported and or downplayed but I'll refrain here as I don't have the issues of Spectrum immediately to hand to give specific references. Suffice to say, I became so disillusioned with stuff I was reading in Spectrum† that I terminated my 20-year-plus IEEE membership some while back. My main criticism of this story is—as you correctly point out—carefully avoids talking about energy density, which has to be a crucial aspect of any story about new battery tech that's posited as a potential competitor and or replacement for Li-ion. That's damn obvious. If the researchers did not provide numerical comparisons (experimental and or theoretical) of the energy densities between their Al-ion prototypes and Li-ion in their paper/press release then Spectrum's editor should have provided a side/footnote on the matter. Most of us already know that Li has a larger electrode potential‡ than Al, so Al is already coming from behind Li in this regard, but of course that's far from the end of the story as there are many other factors involved in addition to those benefits as promulgated by the researchers, namely recharge cycles, safety and cost. For example, how does Al stack up against Li as far as electrode surface area (spongy metal surfaces, etc.)? We know from long experience with electrolytic capacitors that Al can be treated to have very large effective surface areas, in fact they can be enormous. If Al has the potential to be much better than Li in this regard then this new tech could certainly be a winner. As this is an obvious factor, Spectrum's editor should have mentioned it amongst others even if not mentioned in the original paper (in fact, Spectrum should have criticized its omission if the case). In summary, one would hope this research leads to much better and safer batteries but the IEEE—as the premier representative for electrical and electronic engineering/engineers—has done precious little in providing us with information that actually matters. __ † Whilst I've strong criticisms of the IEEE not all are negative, many of its specialist publications are quite excellent including Proceedings of the IEEE. ‡ From Wiki: Standard electrode potentials: Li: Li+ + e− ⇌ Li(s) -3.0401V Al: Al3+ + 3e− ⇌ Al(s) -1.662V Edit: It was only after I'd written this comment that I was able access the original ACS research paper (initially I'd difficulty downloading it). I've since skimmed it several times and I need to read it thoroughly to get a proper understanding but it's pretty short on the issues I've raised. Thus, my point that Spectrum should have mentioned these shortfalls still stands.

ErigmolCt 2y ago

I think by the time it's commercially ready (if ever), the battery landscape could look very different

DoctorOetker 2y ago

> Anyway, the article carefully avoids talking about energy density. Which is of course the key thing here. But it's right there in the article: https://pubs.acs.org/doi/pdf/10.1021/acscentsci.4c01615?download=true https://pubs.acs.org/doi/pdf/10.1021/acscentsci.4c01615?down... > The cell with F-SSAF electrolyte and pyrolytic graphite (PG) cathode show reversible capacities of 83, 81, 79, 77, and 75 mA h g−1 at the current densities of 20, 40, 60, 80, and 100 mA g−1 (Figure 2a). so 83 Ah/kg (at 20 A/kg), and at a cell voltage of ~ 2V thats ~166 Wh/kg.

baranul 2y ago

Clarity is very much needed. There are so many stories about "battery technology breakthroughs", but then they never come to market or are x number of years away from production. The general public is often way more interested in when they are going to actually sell the new battery technology, and getting their hands on them to put to use.