
Research Development on K-Ion Batteries - rustoo
http://dx.doi.org/10.1021/acs.chemrev.9b00463
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MayeulC
Density is listed page "X" (24) together with cycing performance, as far as I
saw. up to 131 mAh.g⁻¹ is listed (theoretical capacity). That is, if I do not
misunderstand the article; it is a bit too long and in-depth for a non-chemist
like me.

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fnord77
lithium has an electronegativity of 0.98

potassium's is 0.82.

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cagenut
would you be so kind as to explain more about what that means? particularly
w/r/t this line in the abstract

    
    
      the low standard electrode potentials of K/K+ electrodes
      lead to high operation voltages competitive to those 
      observed in LIBs
    

I think what i'm hearing is that this is a tradeoff of density for power?
(separate from the source materials concerns)

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rckoepke
Along with atomic mass (7 for lithium, 19 for potassium)

This means that for a given number of atoms, a K battery will store less
energy and be significantly heavier than an Li battery.

So maybe if it's cheaper that's okay for fine for stationary power (backup
generators etc)

But for mobile uses (cars, boats, planes) lithium is much better.

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labawi
Random article[1] says:

> our guideline real-world figure of 1.4 kg of Li2CO3 per kWh

> 73 grams of Lithium metal .. equates to 385 grams of Li2CO3.

Adjusting for atomic mass difference, by data from an article[1], a 100kWh
battery would be about 100 * 1.4kg * 73g/385g = 27 kg of Lithium, or 27 kg *
19/7 = 73 kg of potassium for a 46kg difference, if all else were equal. If
that were the only difference, it would not even register for the usual
1000-2000 kg car.

Electronegativity difference 0.98-0.82 = 0.16 should (I'm just guessing)
change a 3.7V nominal battery to a 3.55V nominal. This a notable decrease, as
you would need about 5% more batteries for the same capacity. 5% of a 500kg
battery pack is additional 25 kg.

All else being equal, it would be an irrelevant change for stationary, marine
and road use. For planes it would be a notable factor, though not immediately
disqualifying.

Since a 1:1 substitution wont work, all the other changes can make a material
difference, in either direction. Comments about research batteries still
apply.

[1] [http://www.meridian-int-
res.com/Projects/How_Much_Lithium_Pe...](http://www.meridian-int-
res.com/Projects/How_Much_Lithium_Per_Battery.pdf)

EDIT: Fix calculation.

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rckoepke
Thank you so much for putting in this work . Helped me a lot .

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labawi
I really hope we wean ourselves off of Cobalt and Lithium in batteries.

