Reserves of cobalt and nickel used in electric-vehicle cells will not meet future demand. Refocus research to find new electrodes based on common elements such as iron and silicon, urge Kostiantyn Turcheniuk and colleagues.
Interesting. I didn't know nickel was that uncommon. I know some batteries, like those in the Nissan Leaf don't use cobalt. Their anode is lithium nickel oxide. (edit) and their cathode is LiMn2O4...
Interesting. I didn't know nickel was that uncommon. I know some batteries, like those in the Nissan Leaf don't use cobalt. Their anode is lithium nickel oxide. (edit) and their cathode is LiMn2O4 (lithium... manganate?), and it looks like manganese is the 7th most common element on earth, so that's good.
Who knows, perhaps we'll be mining asteroids in ten years. That'd solve our nickel shortage in a pretty big way.
Could someone please explain this nomenclature to me? It has been a long long time since high school chemistry, but I learned that the subscript numbers after each element's symbol represents the...
LiNi0.8Co0.15Al0.05O2
LiNi0.6Co0.2Mn0.2O2
Could someone please explain this nomenclature to me? It has been a long long time since high school chemistry, but I learned that the subscript numbers after each element's symbol represents the number of atoms of that element in the molecule. In the famous molecule H2O, the sub-script "2" tells us that there are 2 atoms of hydrogen in this molecule (and 1 atom of oxygen, but the "1" isn't shown). So, in something like this, LiNi0.8Co0.15Al0.05O2, we're being told there are 0.8 atoms of nickel and 0.15 atoms of cobalt and 0.05 atoms of aluminium in this molecule - which just doesn't make sense to me.
These subscripts are normalized to molar proportions. If you'll remember back to high school chem, a mole is a measure of approx 6.022x1023 atoms. You will notice that all the subscripts together...
These subscripts are normalized to molar proportions. If you'll remember back to high school chem, a mole is a measure of approx 6.022x1023 atoms.
You will notice that all the subscripts together equal an integer, and all the decimals together are equal to 1. The compounds listed in the article are not bonded molecules, but rather metallic-oxide alloys. That is, metals melted and mixed together. In the context of molar proportions, we can simply think of the subscripts as 'parts' in a recipe.
For NCA (LiNi0.8Co0.15Al0.05O2) batteries, our cathode is an alloy comprised of Lithium, Nickel, Cobalt, and Aluminum: 1 part Lithium, 0.8 parts Nickel, 0.15 parts Cobalt, 0.05 parts Aluminum, and 2 parts of Oxygen between them all to form the oxides.
If we were to round to whole numbers, we'd get: 20 parts Lithium, 16 parts Nickel, 3 parts Cobalt, 1 part Aluminum, and 40 parts Oxygen — this is a less efficient way to communicate your 'recipe' given that this is more of a mixture, rather than a very large molecule.
The maths to find our quantities of ingredients for a 100kg cathode is far less painful to do with proportions, than it is to use whichever arbitrary numbers we get by rounding your smallest part to 1.
Thanks for the explanation! It mostly makes sense... But what if the proportions don't allow this? What if the "recipe" is 23 parts lithium, 17 parts nickel, 7 parts cobalt, 5 parts aluminium, and...
Thanks for the explanation!
It mostly makes sense...
and all the decimals together are equal to 1.
But what if the proportions don't allow this? What if the "recipe" is 23 parts lithium, 17 parts nickel, 7 parts cobalt, 5 parts aluminium, and 19 parts oxygen? There's no way to reduce those proportions in such a way as to get some of the decimals to add to 1 while keeping others as whole numbers.
If we were to round to whole numbers, we'd get: 20 parts Lithium, 16 parts Nickel, 3 parts Cobalt, 1 part Aluminum, and 40 parts Oxygen — this is a less efficient way to communicate your 'recipe'
Not necessarily. Given that we're counting atoms (even if in moles), it's easier to have a whole number of atoms to deal with.
The maths to find our quantities of ingredients for a 100kg cathode is far less painful to do with proportions
I don't dispute that. But your use of "100" makes me wonder whether it might not be even more efficient to simply use percentages: 25% lithium, 20% nickel, 3.75% cobalt, 1.25% aluminium, and 50% oxygen.
Oh well. Tradition is tradition. Chemists aren't likely to change this now. Thanks for explaining it.
In your example we could use a molar fraction: Li32.4Ni23.9Co9.9Al7.0O26.8 , in which the sum of the subscripts is 100%. Not necessarily :) Your percentages are in terms of moles (number of atoms)...
But what if the proportions don't allow this?
In your example we could use a molar fraction:
Li32.4Ni23.9Co9.9Al7.0O26.8
, in which the sum of the subscripts is 100%.
Given that we're counting atoms... makes me wonder whether it might not be even more efficient to simply use percentages
Not necessarily :) Your percentages are in terms of moles (number of atoms) yes, but a mole is 6.022x1023 atoms per gram. Mass is measured in grams, not moles.
To help show the difference, let's convert NCA to molar fraction:
A 100kg cathode made with your percentages (so 25kg of Lithium, and so forth) would give us, in molar fraction approx:
Li0.50180Ni0.04748Co0.00887Al0.00645O0.43540
Not exactly the recipe we're after.
Whereas if I knew I wanted to make a cathode of 100kg, I would take the Molar Proportions given in the article, multiply them by each elements Relative Atomic Mass, then take a sum of the mass I have. Then I would make a ratio of the desired Cathode Mass (C) and the sum I just took, and then I would multiply that by each of the numbers I found during the last step. This would give me the mass of each element I would need to combine to make an NCA Cathode. A simple calculator could be written to do this for us, or even an excel sheet (pardon any rounding errors):
Element
Atomic Mass
Molar Prop.
Li
6.94g/mol
x
1mol
=
6.94g
Ni
58.693g/mol
x
0.8mol
=
46.954g
Co
58.933g/mol
x
0.15mol
=
8.840g
Al
26.982g/mol
x
0.05mol
=
1.349g
O
15.999g/mol
x
2mol
=
31.998g
Total:
=
96.081
C = 100kg
Li
C/96.081g
x
6.94g
=
7.2kg
Ni
C/96.081g
x
46.954g
=
48.9kg
Co
C/96.081g
x
8.840g
=
9.2kg
Al
C/96.081g
x
1.349g
=
1.4kg
O
C/96.081g
x
31.998g
=
33.3kg
Total
=
100kg
In chemistry, most everything comes back to everybody's favorite subterranean mammal :)
@Algernon_Asimov, it's the stoichiometry of a layered bulk material. The proportions of each element in the given notation are the bulk proportions in the battery cathode material, not the...
@Algernon_Asimov, it's the stoichiometry of a layered bulk material. The proportions of each element in the given notation are the bulk proportions in the battery cathode material, not the components of single molecules.
If you visualise the material by positioning the atoms in three dimensions, you've got regularly arrayed quasi-molecular structures which have octohedral symmetry, with their various atoms packed in two-dimensional layers stacked on top of each other.
Hope that makes sense...my inorg chemistry is close to 30 years behind me as well, but it's easier to think of it as the "formula" for a ceramic, rather than typical whole-number stoichiometric proportions.
Correct me if I'm wrong, but I believe the explanation I was once told is that it refers to the relative concentrations of the atoms in the compound, especially if the compound is large or...
Correct me if I'm wrong, but I believe the explanation I was once told is that it refers to the relative concentrations of the atoms in the compound, especially if the compound is large or otherwise can be approximate.
But you're otherwise correct—in typical chemical nomenclature fractions are not valid values in chemical subscript notation.
If I could tell whether you were wrong, I wouldn't be asking the question! :) My best guess was something like you're suggesting: these numbers represent proportions rather than actual numbers....
Correct me if I'm wrong
If I could tell whether you were wrong, I wouldn't be asking the question! :)
My best guess was something like you're suggesting: these numbers represent proportions rather than actual numbers. Maybe the actual molecule is something like this: Li100Ni80Co15Al5O200. But I've seen molecular notation with large numbers in it, so I'm wondering why they wouldn't do the same thing here (assuming this is the reason).
Interesting. I didn't know nickel was that uncommon. I know some batteries, like those in the Nissan Leaf don't use cobalt. Their anode is lithium nickel oxide. (edit) and their cathode is LiMn2O4 (lithium... manganate?), and it looks like manganese is the 7th most common element on earth, so that's good.
Who knows, perhaps we'll be mining asteroids in ten years. That'd solve our nickel shortage in a pretty big way.
Could someone please explain this nomenclature to me? It has been a long long time since high school chemistry, but I learned that the subscript numbers after each element's symbol represents the number of atoms of that element in the molecule. In the famous molecule H2O, the sub-script "2" tells us that there are 2 atoms of hydrogen in this molecule (and 1 atom of oxygen, but the "1" isn't shown). So, in something like this, LiNi0.8Co0.15Al0.05O2, we're being told there are 0.8 atoms of nickel and 0.15 atoms of cobalt and 0.05 atoms of aluminium in this molecule - which just doesn't make sense to me.
These subscripts are normalized to molar proportions. If you'll remember back to high school chem, a mole is a measure of approx 6.022x1023 atoms.
You will notice that all the subscripts together equal an integer, and all the decimals together are equal to 1. The compounds listed in the article are not bonded molecules, but rather metallic-oxide alloys. That is, metals melted and mixed together. In the context of molar proportions, we can simply think of the subscripts as 'parts' in a recipe.
For NCA (LiNi0.8Co0.15Al0.05O2) batteries, our cathode is an alloy comprised of Lithium, Nickel, Cobalt, and Aluminum: 1 part Lithium, 0.8 parts Nickel, 0.15 parts Cobalt, 0.05 parts Aluminum, and 2 parts of Oxygen between them all to form the oxides.
If we were to round to whole numbers, we'd get: 20 parts Lithium, 16 parts Nickel, 3 parts Cobalt, 1 part Aluminum, and 40 parts Oxygen — this is a less efficient way to communicate your 'recipe' given that this is more of a mixture, rather than a very large molecule.
The maths to find our quantities of ingredients for a 100kg cathode is far less painful to do with proportions, than it is to use whichever arbitrary numbers we get by rounding your smallest part to 1.
Thanks for the explanation!
It mostly makes sense...
But what if the proportions don't allow this? What if the "recipe" is 23 parts lithium, 17 parts nickel, 7 parts cobalt, 5 parts aluminium, and 19 parts oxygen? There's no way to reduce those proportions in such a way as to get some of the decimals to add to 1 while keeping others as whole numbers.
Not necessarily. Given that we're counting atoms (even if in moles), it's easier to have a whole number of atoms to deal with.
I don't dispute that. But your use of "100" makes me wonder whether it might not be even more efficient to simply use percentages: 25% lithium, 20% nickel, 3.75% cobalt, 1.25% aluminium, and 50% oxygen.
Oh well. Tradition is tradition. Chemists aren't likely to change this now. Thanks for explaining it.
In your example we could use a molar fraction:
Li32.4Ni23.9Co9.9Al7.0O26.8
, in which the sum of the subscripts is 100%.
Not necessarily :) Your percentages are in terms of moles (number of atoms) yes, but a mole is 6.022x1023 atoms per gram. Mass is measured in grams, not moles.
To help show the difference, let's convert NCA to molar fraction:
Molar Proportion - LiNi0.8Co0.15Al0.05O2
Molar Fraction - Li0.25Ni0.20Co0.0375Al0.0125O0.5
A 100kg cathode made with your percentages (so 25kg of Lithium, and so forth) would give us, in molar fraction approx:
Li0.50180Ni0.04748Co0.00887Al0.00645O0.43540
Not exactly the recipe we're after.
Whereas if I knew I wanted to make a cathode of 100kg, I would take the Molar Proportions given in the article, multiply them by each elements Relative Atomic Mass, then take a sum of the mass I have. Then I would make a ratio of the desired Cathode Mass (C) and the sum I just took, and then I would multiply that by each of the numbers I found during the last step. This would give me the mass of each element I would need to combine to make an NCA Cathode. A simple calculator could be written to do this for us, or even an excel sheet (pardon any rounding errors):
In chemistry, most everything comes back to everybody's favorite subterranean mammal :)
I surrender! I'm in way over my head. Sure, I was a top student in high-school chemistry, but it was only high school and it was three decades ago. :)
@Algernon_Asimov, it's the stoichiometry of a layered bulk material. The proportions of each element in the given notation are the bulk proportions in the battery cathode material, not the components of single molecules.
If you visualise the material by positioning the atoms in three dimensions, you've got regularly arrayed quasi-molecular structures which have octohedral symmetry, with their various atoms packed in two-dimensional layers stacked on top of each other.
www.ehcar.net/library/rapport/rapport069.pdf
Hope that makes sense...my inorg chemistry is close to 30 years behind me as well, but it's easier to think of it as the "formula" for a ceramic, rather than typical whole-number stoichiometric proportions.
Correct me if I'm wrong, but I believe the explanation I was once told is that it refers to the relative concentrations of the atoms in the compound, especially if the compound is large or otherwise can be approximate.
But you're otherwise correct—in typical chemical nomenclature fractions are not valid values in chemical subscript notation.
If I could tell whether you were wrong, I wouldn't be asking the question! :)
My best guess was something like you're suggesting: these numbers represent proportions rather than actual numbers. Maybe the actual molecule is something like this: Li100Ni80Co15Al5O200. But I've seen molecular notation with large numbers in it, so I'm wondering why they wouldn't do the same thing here (assuming this is the reason).
Fixed, thank you.