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Metal-Bromine batteries

  1. Sep 15, 2014 #1
    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?
     
  2. jcsd
  3. Sep 15, 2014 #2

    Borek

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    Staff: Mentor

    Maximum theoretical energy density is trivial (basic thermodynamics and a molar mass), rechargeability is where the problem is.
     
  4. Sep 16, 2014 #3
    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?
     
  5. Sep 16, 2014 #4

    Borek

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    Staff: Mentor

    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.
     
  6. Sep 16, 2014 #5
    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.
     
    Last edited: Sep 16, 2014
  7. Dec 9, 2014 #6
    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
     
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