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New sodium-ion battery skips mechanical cooling with 97.9% efficiency (interestingengineering.com)
submitted 3 months ago by to c/technology@lemmy.world
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I've been hearing about these for a few years now. Huge if they work out at a large scale.

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[–] 26 points 3 months ago (14 children)

According to Wikipedia:

Looks like power to weight it much higher, while energy per volume and energy per mass is comparable to existing lithium ion batteries.

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  • [–] 40 points 3 months ago (11 children)

    idk about that, the regularly cited reason Na-ion batteries are mainly being looked at for grid storage rather than vehicle applications is their bad Wh/l and W/kg numbers compared to Li-ion. the table in the Na-ion article seems to use "1000W/kg" without a source, and it shows lithium as being about a third of that even though the Li-ion article quotes figures up to 10kW/kg.

    seems the editors of the two articles aren't cross-checking eachother.

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  • [–] 13 points 3 months ago (5 children)

    The "1000W/kg" figure appears to be from Wikipedia, which claims https://www.idtechex.com/en/research-article/sodium-ion-batteries-will-diversify-the-energy-storage-industry/30405 as a source. Wikipedia has the information in a table flagged as "Needs update".

    Anyway, most of the lithium-ion chemistry variations drop off relatively fast in capacity over repeated charge cycles (the exception being LiFePo4). If the sodium-ion chemistry is better that way, and drops off less in the cold, it's still worth exploring for vehicle use even if the energy density is a little lower.

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  • [–] 4 points 3 months ago (3 children)

    from other comments it seems the energy density of batteries currently on the market is about 2/3rds that of lithium cells.

    there's also the asymmetry to worry about: with a max discharge rate of 8C but a charge rate of 3C there could potentially be limits on regen braking. if i'm understanding it correctly, sodium cells degrade quickly at higher charge rates.

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  • [–] 2 points 3 months ago* (last edited 3 months ago)

    Interesting, but from what I understand limited charging would only be a problem if you do not have large enough battery capacity. So for heavier vehicles with larger capacity this might not matter much.

    PS: This video about the CATL NaFePO4 battery also mentions a "half sodium half lithium" battery pack for cars to combine the best of both.

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  • [–] 1 point 3 months ago (2 children)

    W/kilo? Isn't there a h missing or something?

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