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A room temperature Li2O-based lithium-air battery enabled by a solid electrolyte

science.org

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Re: A room temperature Li2O-based lithium-air battery enabled by a solid electrolyte

#21

Post by adrian_b »

TOMDM wrote: post #11
andy_ppp wrote: post #9

Earlier quoted context omitted.

Does the engine and drive train weight make these calculations even better for electric vehicles?

I feel like a good like to like comparison would be the density of battery + motors compared to the density of fuel tank, engine and drive train.

Even more like to like would be to compare the battery with a fuel tank + a turbo-generator.

For any kind of battery, there will be a power threshold over which a fuel tank + a turbo-generator will be smaller and lighter.

So a useful comparison would determine those power thresholds.

Re: A room temperature Li2O-based lithium-air battery enabled by a solid electrolyte

#22

Post by sroussey »

adrian_b wrote: post #14
aetherspawn wrote: post #10

Does it use external air? Would this technically make it a fuel cell and not a battery, since some of the reactants are discarded :)

Not really. In a fuel cell the reaction products are discarded (the reactants cannot be discarded, as they are needed for the reaction to take place). In a metal-air battery, air from the atmosphere is taken into the battery and the oxygen from it becomes bound to the metal, in a metal oxide. So unlike for a fuel cell, where the vehicle becomes lighter after the fuel is consumed and the reaction products are discarde…

How would an aluminum-ion battery work out as for as theoretical charge per weight or volume?

I know that is decades out, of course.

Re: A room temperature Li2O-based lithium-air battery enabled by a solid electrolyte

#23

Post by sroussey »

Xamayon wrote: post #7

If it can be made small enough for use in mobile devices, I wonder whether the need for air/oxygen might require compromising on water-tightness. Would an oxygen permeable waterproof membrane allow enough through for operation? It would be interesting if instead of just for cooling, future high powered devices might also need a fan to feed the battery!

So probably not for water tight devices, but perhaps for laptops.

Re: A room temperature Li2O-based lithium-air battery enabled by a solid electrolyte

#24

Post by grapesodaaaaa »

adrian_b wrote: post #18
norrsson wrote: post #5

Earlier quoted context omitted.

Usual disclaimer regarding the energy density of gasoline: current gasoline engines have an efficiency of 10-30% while EVs are around 90%. So to reach similar kWh/g we're looking at ~3k Wh/kg

A lithium-air battery (in general all metal-air batteries) is likely to have lower efficiencies for a complete cycle than other lithium-based batteries, perhaps not much above 80%, if not even less. The lower efficiency is caused by one of the reactants being a gas, which causes certain thermodynamic constraints. A fuel cell with hydrocarbons would have a slightly better efficiency than the best mobile thermal engine…

> The claim from the parent article is wrong and it is based on an incorrect method for computing the ideal energy per mass ratio for lithium-air batteries.

Can you elaborate for laypersons such as myself?

Re: A room temperature Li2O-based lithium-air battery enabled by a solid electrolyte

#26

Post by giantg2 »

I'm a bit excited but also a bit tired of hearing about all these batteries. I just want someone to wake me up when we have a commercially available 1kwh+/kg with decent durability, decent price, and good safety.

Maybe this is a good idea for an ammoseek website but for batteries that can send alerts. I'm honestly surprised a quick search didn't turn one up.

Re: A room temperature Li2O-based lithium-air battery enabled by a solid electrolyte

#27

Post by cyberax »

grapesodaaaaa wrote: post #24
adrian_b wrote: post #18

Earlier quoted context omitted.

A lithium-air battery (in general all metal-air batteries) is likely to have lower efficiencies for a complete cycle than other lithium-based batteries, perhaps not much above 80%, if not even less. The lower efficiency is caused by one of the reactants being a gas, which causes certain thermodynamic constraints. A fuel cell with hydrocarbons would have a slightly better efficiency than the best mobile thermal engine…

> The claim from the parent article is wrong and it is based on an incorrect method for computing the ideal energy per mass ratio for lithium-air batteries. Can you elaborate for laypersons such as myself?

Basically, Li-Air elements are wasting the energy from the phase change of oxygen. When a Li-Ion battery is discharged, you get the gaseous oxygen and bind it into a solid state molecule.

To do that, you need to expend roughly the same amount of energy that is needed to first liquify and then solidify the oxygen.

In fancy chemistry-speak it's called "entropic loss". You do gain some of that energy back when the battery is charged, as oxygen goes from a well-ordered solid state into the gaseous state. But it's not 100%.

Re: A room temperature Li2O-based lithium-air battery enabled by a solid electrolyte

#28

Post by fuzzfactor »

Xamayon wrote: post #7

If it can be made small enough for use in mobile devices, I wonder whether the need for air/oxygen might require compromising on water-tightness. Would an oxygen permeable waterproof membrane allow enough through for operation? It would be interesting if instead of just for cooling, future high powered devices might also need a fan to feed the battery!

If this comes through it may boost performance to have a turbocharger for better forced air intake.

Or with a tank of pure oxygen, have the EV act like it was gasoline engine on nitrous oxide.

Somebody should calculate a ballpark figure for the number of grams or kilos of oxygen that would be needed per mile for an average vehicle.

Re: A room temperature Li2O-based lithium-air battery enabled by a solid electrolyte

#29

Post by gpm »

adrian_b wrote: post #18
norrsson wrote: post #5

Earlier quoted context omitted.

Usual disclaimer regarding the energy density of gasoline: current gasoline engines have an efficiency of 10-30% while EVs are around 90%. So to reach similar kWh/g we're looking at ~3k Wh/kg

A lithium-air battery (in general all metal-air batteries) is likely to have lower efficiencies for a complete cycle than other lithium-based batteries, perhaps not much above 80%, if not even less. The lower efficiency is caused by one of the reactants being a gas, which causes certain thermodynamic constraints. A fuel cell with hydrocarbons would have a slightly better efficiency than the best mobile thermal engine…

> A lithium-air battery (in general all metal-air batteries) is likely to have lower efficiencies for a complete cycle than other lithium-based batteries, perhaps not much above 80%, if not even less.

This paper directly contradicts this claim with actual measurements of efficiency.

> The energy efficiency of the first cycle was 92.7%, and it gradually dropped to 87.7% after 1000 cycles.

Which is centered just above the 90% mark the person you are replying to gave.

Re: A room temperature Li2O-based lithium-air battery enabled by a solid electrolyte

#30

Post by cyberax »

Matterless wrote: post #12

/Up to 1000 charge cycles/ is a big damper on the excitement, for me. Does anyone know if a limitation like that is inherent to the chemistry here or is this something that they could potentially (hopefully, vastly) surpass?

If an EV goes 400 miles on a single charge, then you're looking at 400000 miles of total range! That's absolutely acceptable.
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