4 ms·

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 h

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.

Merrill 7y ago
I wonder what fraction of a battery's mass is the ions that move from plate to plate, versus the plates, separator, electrolyte, casing, terminals and any other inactive parts?
- mrfusion 7y ago
  I always thought the ion wasn’t a big portion of the battery. Maybe someone can cofnrim?
labawi 7y ago
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_Per_Battery.pdf http://www.meridian-int-res.com/Projects/How_Much_Lithium_Pe... EDIT: Fix calculation.
- rckoepke 7y ago
  Thank you so much for putting in this work . Helped me a lot .

Merrill 7y ago

I wonder what fraction of a battery's mass is the ions that move from plate to plate, versus the plates, separator, electrolyte, casing, terminals and any other inactive parts?

mrfusion 7y ago
I always thought the ion wasn’t a big portion of the battery. Maybe someone can cofnrim?

labawi 7y ago

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_Per_Battery.pdf http://www.meridian-int-res.com/Projects/How_Much_Lithium_Pe... EDIT: Fix calculation.

rckoepke 7y ago
Thank you so much for putting in this work . Helped me a lot .