6 ms·

Edit: False assumption of atomic radius lead me to make an invalid conclusion On paper the top-level explanation of the technology makes sense by virtue of an

Edit: False assumption of atomic radius lead me to make an invalid conclusion On paper the top-level explanation of the technology makes sense by virtue of an Aluminum ion being able to transfer 3 electrons vs Lithium's single electron thereby achieving a faster discharge rate seems plausible. However when taking into account molecular weight it becomes a different story, at least as far as energy density is concerned. Lithium's molecular weight is 7 while Aluminum's is 27. So we'd be using 28.5% more mass to achieve the same energy density. And there is also the increased number of Aluminum's orbital shells to take into account so more volume would be require vs Lithium. How much this can be offset by the apparent lack of need for a heating/cooling system for vehicle tier applications remains to be seen. I'm guardedly cautious but hopeful.

virtue3 5y ago
Aluminum has 3x the thermal conductivity of lithium and half the thermal expansion, so this could result in a larger space savings. The weight is an issue but if we end up with less issues around dendrites etc, it might not matter? I imagine that larger cell sizes and lack of need for cooling might offset the perceived weight issues. I'd also be very curious about the longevity of the battery as well vs lithium-ion. I imagine for the automotive space (air running over the battery could be all it needs to cool) this could be huge, but maybe not so much for cellphones/aerospace!
- pengaru 5y ago
  > I imagine that larger cell sizes and lack of need for cooling might offset the perceived weight issues. Have you ever looked at Tesla's vehicle cooling system visualizations? It's not like by eliminating need for cooling in the battery you'd be able to omit the vehicle's cooling system. The coolant circulates through practically every active component of the vehicle, and regardless of battery requirements you'll still need sufficient thermal mass circulating to not overheat any of the other high-power components capable of producing a lot of heat like the motor and controller. Though maybe there could be some reduction in coolant volume by treating the less thermally sensitive battery as more of a heat sink, by continuing to circulate coolant through it. Still, I don't imagine it'd be a huge weight savings, but may help stabilize temperatures.
  - datameta 5y ago
    That's a fair point but nevertheless what the article meant by lack of need for cooling is twofold. The ability for the aluminum ion battery pack to function in a wider temperature range potentially does away with a heating system that is otherwise needed to help li-ion battery packs to function better (or even avoid early degradation) from a cold start. The implied lack of a need for a cooling system for the battery means the battery can function as a thermal mass, as you alluded, and a lower rate of circulation and total mass of coolant is necessary. That's on top of a simplified channel system that runs only through the motors, alternator, electronics that lie next to heat generating parts, etc.
andagainagain 5y ago
I just looked up the volume of aluminum vs lithium here: https://www.periodic-table.org/lithium-atomic-radius/ https://www.periodic-table.org/lithium-atomic-radius/ They have the same atomic radius of 121 pm. The length of bonds might change the calculation when you actually look at chemistry, but the increase in number of orbitals is not an issue. Also, no battery uses 100% of their electrons for storage. Your calculation of using the number of electrons on the outer orbital vs the atomic mass is completely misguided. their claims don't say aluminum ion holds more energy per unit mass, but simply looking at the ions available per unit of molecular mass also doesn't tell you this.
- datameta 5y ago
  You're correct - my assumption about atomic radius was off, which leads to an erroneous conclusion.

virtue3 5y ago

Aluminum has 3x the thermal conductivity of lithium and half the thermal expansion, so this could result in a larger space savings. The weight is an issue but if we end up with less issues around dendrites etc, it might not matter? I imagine that larger cell sizes and lack of need for cooling might offset the perceived weight issues. I'd also be very curious about the longevity of the battery as well vs lithium-ion. I imagine for the automotive space (air running over the battery could be all it needs to cool) this could be huge, but maybe not so much for cellphones/aerospace!

pengaru 5y ago
> I imagine that larger cell sizes and lack of need for cooling might offset the perceived weight issues. Have you ever looked at Tesla's vehicle cooling system visualizations? It's not like by eliminating need for cooling in the battery you'd be able to omit the vehicle's cooling system. The coolant circulates through practically every active component of the vehicle, and regardless of battery requirements you'll still need sufficient thermal mass circulating to not overheat any of the other high-power components capable of producing a lot of heat like the motor and controller. Though maybe there could be some reduction in coolant volume by treating the less thermally sensitive battery as more of a heat sink, by continuing to circulate coolant through it. Still, I don't imagine it'd be a huge weight savings, but may help stabilize temperatures.
- datameta 5y ago
  That's a fair point but nevertheless what the article meant by lack of need for cooling is twofold. The ability for the aluminum ion battery pack to function in a wider temperature range potentially does away with a heating system that is otherwise needed to help li-ion battery packs to function better (or even avoid early degradation) from a cold start. The implied lack of a need for a cooling system for the battery means the battery can function as a thermal mass, as you alluded, and a lower rate of circulation and total mass of coolant is necessary. That's on top of a simplified channel system that runs only through the motors, alternator, electronics that lie next to heat generating parts, etc.

andagainagain 5y ago

I just looked up the volume of aluminum vs lithium here: https://www.periodic-table.org/lithium-atomic-radius/ https://www.periodic-table.org/lithium-atomic-radius/ They have the same atomic radius of 121 pm. The length of bonds might change the calculation when you actually look at chemistry, but the increase in number of orbitals is not an issue. Also, no battery uses 100% of their electrons for storage. Your calculation of using the number of electrons on the outer orbital vs the atomic mass is completely misguided. their claims don't say aluminum ion holds more energy per unit mass, but simply looking at the ions available per unit of molecular mass also doesn't tell you this.

datameta 5y ago
You're correct - my assumption about atomic radius was off, which leads to an erroneous conclusion.