Can Metal-Bromine Batteries Be the Next Big Thing in Energy Storage?

[Stanley514]

Currently there exist Zinc/Bromine batteries which could be recharged many times.
What about such pairs as Calcium/Bromine or Magnesium/Bromine?
Could somebody predict their properties such as energy density or rechargeability?

 

[Borek]

Maximum theoretical energy density is trivial (basic thermodynamics and a molar mass), rechargeability is where the problem is.

 

[Stanley514]

Maximum theoretical energy density is trivial (basic thermodynamics and a molar mass), rechargeability is where the problem is.

Calcium Bromide enthalpy of formation = 647.9 kJ/mol http://en.wikipedia.org/wiki/Calcium_bromide
Magnesium Bromide enthalpy of formation = 524.3 kJ/mol
http://en.wikipedia.org/wiki/Magnesium_bromide

In comparison:
Zinc Bromide 328 kJ/mol
Sodium Sulfide 364 Kj/mol

Looks like very good energy density.

Rechargeability:
Calcium Bromide soluble in water (143 g/100 ml (20°C)), alcohol, acetone.
Magnesium Bromide soluble in water (102 g/100 mL (anhydrous)), ethanol: 6.9 g/100 mL, methanol: 21.8 g/100 mL.

Problems?

 

[Borek]

Because of a high reactivity it is not that easy to store metallic calcium (or magnesium) safely and not reacting with whatever is present in the battery.

I am not saying it can't be done, just it will be definitely tricky.

 

[Stanley514]

Because of a high reactivity it is not that easy to store metallic calcium (or magnesium) safely and not reacting with whatever is present in the battery.

But certainly much easier than metallic Sodium in Sodium-Sulfur batteries or metallic lithium in Lithium-air cells. Currently many researchers work on Magnesium-Sulfur battery. They do not report any problems with metallic Magnesium. There are Aluminum-air fuel cells. Is Aluminum less reactive than Calcium?
I think Bromine based batteries could be used in some stand alone applications such as renewable energy or power plants, where toxicity of Bromine is a lesser issue.

 

[Neale]

IND LLC is working on solving some of the problems you discuss.. It should be possible to make two types of batteries - one is a flow battery like zinc - bromine battery where the bromine is stored externally ; the other one can compete with lithium ion batteries. I also noticed a hydrogen - bromine battery concept from MIT.
Neale