An Aluminum Chloride battery?

[Moreno]

Can somebody predict if it's possible to create a rechargeable battery based on the following chemistry:

At discharge: Al + SCl2 = AlCl3 + S

At recharge: AlCl2 + S = Al + SCl2

 

[John Cuthber]

I don't think it would work, or, at best, it would work badly because none of the species involved is ionic.

[Moreno]

5 hours ago, John Cuthber said:

I don't think it would work, or, at best, it would work badly because none of the species involved is ionic.

Why does it have to be ionic?

[Moreno]

Boiling point temperature of Chlorine (-31C) is similar to that of propane. Does it mean Chlorine can be stored in liquid form at relatively low pressures or in some adsorbent? AlCl3 is very well soluble in different liquids including water. Does it imply good reversibility if we make a battery?

[TheRadiochemist]

What's the electrolyte? 

[Moreno]

9 hours ago, TheRadiochemist said:

What's the electrolyte? 

There are plenty of electrolytes which are capable to conduct aluminum ions such as salt water, alkaline, molten aluminum chloride-sodium chloride electrolyte (which was tested in aluminum chlorine batteries) http://www.dtic.mil/dtic/tr/fulltext/u2/747775.pdf

and recently - ionic liquids.

The aluminum- chlorine batteries tested by nasa in 1970-th required elevated temperatures to be operational (around 175 C). It seems related to molten electrolyte but there should be plenty of other electrolytes which stay conducting at room temperature. Ionic liquids may be perspective.

Edited September 12, 2017 by Moreno

[TheRadiochemist]

A good electrolyte might be Manganese dioxide, but that is usually used with an ionic fuel such as lithium ions. I think the entire mixture is simply too safe and inert to do much at all. Designing and speculating a more efficient and safe battery is a very noble and fun thing to do, but sadly there is a barrier. A perfectly safe battery would never work. The whole purpose is to be slightly dangerous, and while I commend your work here I think that the reaction would be rather messy and the battery hard to produce. But keep working! Battery technology is improved every day, and you might just be the one to find the right combo of efficiency and safety.

On 9/12/2017 at 6:06 PM, Moreno said:

There are plenty of electrolytes which are capable to conduct aluminum ions such as salt water, alkaline, molten aluminum chloride-sodium chloride electrolyte (which was tested in aluminum chlorine batteries) http://www.dtic.mil/dtic/tr/fulltext/u2/747775.pdf

and recently - ionic liquids.

The aluminum- chlorine batteries tested by nasa in 1970-th required elevated temperatures to be operational (around 175 C). It seems related to molten electrolyte but there should be plenty of other electrolytes which stay conducting at room temperature. Ionic liquids may be perspective.

 

[Moreno]

On 2017-09-14 at 10:02 PM, TheRadiochemist said:

A good electrolyte might be Manganese dioxide, but that is usually used with an ionic fuel such as lithium ions. I think the entire mixture is simply too safe and inert to do much at all. Designing and speculating a more efficient and safe battery is a very noble and fun thing to do, but sadly there is a barrier. A perfectly safe battery would never work. The whole purpose is to be slightly dangerous, and while I commend your work here I think that the reaction would be rather messy and the battery hard to produce. But keep working! Battery technology is improved every day, and you might just be the one to find the right combo of efficiency and safety.

 

Messy reaction and hard to produce? Why exactly? More problems than with Lithium-Sulfur or Sodium-Sulfur? 

 

[TheRadiochemist]

19 hours ago, Moreno said:

Messy reaction and hard to produce? Why exactly? More problems than with Lithium-Sulfur or Sodium-Sulfur? 

 

Well all that I mean is that inside the battery it might be a rather clumsy setup and would be very hard to hook up the contacts without an internal short. If the reaction does do much at all, you would have to have a very clever internal setup. If the battery punctured or suffered even a tiny blow then all hell would break loose and the battery would likely stop working and would be impossible to fix.

[Moreno]

To TheRadiochemist: Why would it be clumsy? Sodium-Sulfur looks messy too, at first sight, yet it is one of the most successful batteries with 89% efficiency and 4.000-7.000 cyclelife. In Lithium-Sulfur and Sodium-Sulfur Sulfur is stored in a sorbent. So is Chlorine in Aluminum-Chlorine. What is the difference?

 

 

Edited September 26, 2017 by Moreno

[Moreno]

Can someone calculate approximate energy density of Al-Cl battery by VOLUME? Taking in account that There should be 3 times more Clorine atoms than Aluminum atoms to form AlCl3 and density of Chlorine stored in adsorbant may not be too big, I think there could be a problems with volumetric energy density of a whole battery.