5 ms·

That all makes sense about the weight, and it will likely matter for airplanes. But it doesn't matter enough for cars. LFP (lithium iron phosphate) batteries a

by eloff 4y ago

That all makes sense about the weight, and it will likely matter for airplanes. But it doesn't matter enough for cars. LFP (lithium iron phosphate) batteries are already used by Tesla and have a gravimetric energy density of 125 Wh/kg, much lower than Lithium-ion. CATL currently produces a sodium-ion battery at 160 Wh/kg, and they expect the next generation to reach 200 Wh/kg. Even if that doesn't come to fruition, it's already higher density than what's being used in electric cars! Now consider that sodium-ion is less flammable and doesn't have the risk of thermal runaway. You might be able to drop weight in hazard protection systems. Battery cycle times are competitive with Lithium chemistry. Contrary to your prediction that it doesn't pencil out, I expect sodium-ion to completely displace Lithium batteries for use in electric vehicles because it pencils out so much better. It will just be so much cheaper and doesn't bottleneck on any materials as you scale up.

DangitBobby 4y ago
As someone who occasionally walks and often cycles, I really hope batteries that are even heavier than lithium don't become commonplace.
- quonn 4y ago
  Why? compare the weight of SUVs or trucks. It's more than the battery weight, so better hope for smaller vehicles.
  - DangitBobby 4y ago
    I hope for smaller vehicles as well. It's hard to separate "big" and "heavy" statistically because they are highly correlated, but in general, heavier vehicles means higher likelihood of fatality in a crash 1. I suppose we will be doing a natural experiment to tease out the difference over the years as heavy EVs become more commonplace and pedestrian fatalities continue to increase. > It’s also about weight. Trucks today averaging around 5200 pounds -- that’s a jump of more than a half ton since 2000. And things get heavier as electric vehicles look to become our new normal. > On average electric vehicles are 10 percent heavier than gas powered cars. For instance, the new electric Hummer weighs in at a staggering 9,100 pounds or more than 4 and a half tons. All that weight can have deadly consequences. Researchers have found that for every 1,000 pounds a car puts on, a pedestrian is nearly 50 percent more likely to die if they’re hit and the more a truck weighs the longer it will take to stop. 1. https://www.clickondetroit.com/news/2022/08/08/size-does-matter-as-trucks-and-suvs-get-bigger-more-pedestrians-are-being-killed/ https://www.clickondetroit.com/news/2022/08/08/size-does-mat...
- solardev 4y ago
  I dunno that "lighter cars" is a realistic thing to hope for at this point. I do hope to see better bumper crush zone designs, more protected bike lanes, blinking crosswalks, better in-vehicle collision detection systems, etc. Even if a "lighter" car hits you, it's gonna be a bad day. Better to avoid the collision altogether, no? :)
  - DangitBobby 4y ago
    I "hope" for lighter cars in the same way I "hope" we start taking necessary drastic measures to combat climate change, which is by knowing that it won't happen and advocating for change anyway. On the other hand, I think maybe hoping that vehicles become no heavier than modern EVs is at least somewhat realistic.
scythe 4y ago
>LFP (lithium iron phosphate) batteries are already used by Tesla and have a gravimetric energy density of 125 Wh/kg, much lower than Lithium-ion. Tesla uses iron phosphate in its cheaper models, but the high end is still reliant on NMC. I'd be interested to know the maximum range available on LFP. BYD sells a lithium-iron-phosphate battery with an energy density of 150 Wh/kg. CATL's LFP is 125. Also, a lithium-iron-phosphate battery is a lithium-ion battery, in that the electrolyte works by lithium ionic conduction. The appropriate contrast would be "lithium-nickel". >CATL currently produces a sodium-ion battery at 160 Wh/kg, and they expect the next generation to reach 200 Wh/kg. This is reported as the "single-cell" energy density, and is not directly comparable to the battery pack density. >Now consider that sodium-ion is less flammable and doesn't have the risk of thermal runaway. Surely this isn't because of the stability of sodium, which anyone who watched that chemistry demonstration in high school knows, is significantly more reactive than lithium. I expect the risks to be similar; furthermore, the concept of a dense energy storage that has no risk of sudden release is physically unlikely.
- quonn 4y ago
  > Tesla uses iron phosphate in its cheaper models, but the high end is still reliant on NMC. I'd be interested to know the maximum range available on LFP. In theory 490 km, in practice, 380 km. Because they don't degrade as much, after a few years they are closer to what you call the high end models.
- samatman 4y ago
  > Also, a lithium-iron-phosphate battery is a lithium-ion battery, in that the electrolyte works by lithium ionic conduction. The appropriate contrast would be "lithium-nickel". Correct, I want to point out that John Goodenough was responsible for the basic research which lead to all lithium-ion batteries. I explicitly intended LiFePO to be included, and I hope for a variety of reasons that it's much more popular than cobalt-heavy formulas in ten years.
  - ben_w 4y ago
    Only now do I realise that "Goodenough" is a real person's name, and neither a placeholder name nor a case of Emphasis Via Capital Letters: https://en.wikipedia.org/wiki/John_B._Goodenough https://en.wikipedia.org/wiki/John_B._Goodenough

by eloff 4y ago

DangitBobby 4y ago

As someone who occasionally walks and often cycles, I really hope batteries that are even heavier than lithium don't become commonplace.

quonn 4y ago
Why? compare the weight of SUVs or trucks. It's more than the battery weight, so better hope for smaller vehicles.
- DangitBobby 4y ago
  I hope for smaller vehicles as well. It's hard to separate "big" and "heavy" statistically because they are highly correlated, but in general, heavier vehicles means higher likelihood of fatality in a crash 1. I suppose we will be doing a natural experiment to tease out the difference over the years as heavy EVs become more commonplace and pedestrian fatalities continue to increase. > It’s also about weight. Trucks today averaging around 5200 pounds -- that’s a jump of more than a half ton since 2000. And things get heavier as electric vehicles look to become our new normal. > On average electric vehicles are 10 percent heavier than gas powered cars. For instance, the new electric Hummer weighs in at a staggering 9,100 pounds or more than 4 and a half tons. All that weight can have deadly consequences. Researchers have found that for every 1,000 pounds a car puts on, a pedestrian is nearly 50 percent more likely to die if they’re hit and the more a truck weighs the longer it will take to stop. 1. https://www.clickondetroit.com/news/2022/08/08/size-does-matter-as-trucks-and-suvs-get-bigger-more-pedestrians-are-being-killed/ https://www.clickondetroit.com/news/2022/08/08/size-does-mat...
solardev 4y ago
I dunno that "lighter cars" is a realistic thing to hope for at this point. I do hope to see better bumper crush zone designs, more protected bike lanes, blinking crosswalks, better in-vehicle collision detection systems, etc. Even if a "lighter" car hits you, it's gonna be a bad day. Better to avoid the collision altogether, no? :)
- DangitBobby 4y ago
  I "hope" for lighter cars in the same way I "hope" we start taking necessary drastic measures to combat climate change, which is by knowing that it won't happen and advocating for change anyway. On the other hand, I think maybe hoping that vehicles become no heavier than modern EVs is at least somewhat realistic.

scythe 4y ago

>LFP (lithium iron phosphate) batteries are already used by Tesla and have a gravimetric energy density of 125 Wh/kg, much lower than Lithium-ion. Tesla uses iron phosphate in its cheaper models, but the high end is still reliant on NMC. I'd be interested to know the maximum range available on LFP. BYD sells a lithium-iron-phosphate battery with an energy density of 150 Wh/kg. CATL's LFP is 125. Also, a lithium-iron-phosphate battery is a lithium-ion battery, in that the electrolyte works by lithium ionic conduction. The appropriate contrast would be "lithium-nickel". >CATL currently produces a sodium-ion battery at 160 Wh/kg, and they expect the next generation to reach 200 Wh/kg. This is reported as the "single-cell" energy density, and is not directly comparable to the battery pack density. >Now consider that sodium-ion is less flammable and doesn't have the risk of thermal runaway. Surely this isn't because of the stability of sodium, which anyone who watched that chemistry demonstration in high school knows, is significantly more reactive than lithium. I expect the risks to be similar; furthermore, the concept of a dense energy storage that has no risk of sudden release is physically unlikely.

quonn 4y ago
> Tesla uses iron phosphate in its cheaper models, but the high end is still reliant on NMC. I'd be interested to know the maximum range available on LFP. In theory 490 km, in practice, 380 km. Because they don't degrade as much, after a few years they are closer to what you call the high end models.
samatman 4y ago
> Also, a lithium-iron-phosphate battery is a lithium-ion battery, in that the electrolyte works by lithium ionic conduction. The appropriate contrast would be "lithium-nickel". Correct, I want to point out that John Goodenough was responsible for the basic research which lead to all lithium-ion batteries. I explicitly intended LiFePO to be included, and I hope for a variety of reasons that it's much more popular than cobalt-heavy formulas in ten years.
- ben_w 4y ago
  Only now do I realise that "Goodenough" is a real person's name, and neither a placeholder name nor a case of Emphasis Via Capital Letters: https://en.wikipedia.org/wiki/John_B._Goodenough https://en.wikipedia.org/wiki/John_B._Goodenough