Iodine Electrode in Battery Cell - Can I2 be Used?

[pivoxa15]

In a battery cell, let iodine (I2) be the oxidant. In this half cell, what could the electrode be? Could it have an I2(solid) coating so when it accepts electrons, it will form iodide and fall into the solution? I recall I2 was a solid. But what physical form would iodide (I-) be? It will try to bind with positive charges very quickly which exists in the solution? Or it could be that the positive charge exists in the salt bridge and postive ions migrate towards this half cell and the newly formed I- will travel down the electrode to combine with the positive ion.

Or should the electrode be graphite and both iodine and iodide be in the solution? But I2 will form a precipitate? Does it matter?

 

[chemisttree]

The "iodine" electrode could be anything conductive that is compatible with water, iodide and iodine. At the anode, iodine would accept electrons from the cathode material (zinc?) via the conductor (electrode and wire) and would be reduced to iodide.

A reasonable form of iodine would be triiodide.

I2 + I- ----> I3- (brown)

 

[ravenprp]

Yes, I2 can be used as an oxidant in a battery cell. In this half cell, the electrode could potentially be a solid iodine (I2) coating, as you mentioned. When the electrode accepts electrons, the solid iodine will form iodide (I-) and fall into the solution. Iodide is typically in the form of an anion (negative ion) in solution.

It is important to note that the positive charge in the solution is not solely from the iodide ions. The salt bridge, as you mentioned, also plays a role in maintaining charge balance. The positive ions from the salt bridge will migrate towards the half cell with the solid iodine electrode, while the newly formed I- ions will travel down the electrode to combine with the positive ions.

Alternatively, the electrode could also be made of graphite and both iodine and iodide can be present in the solution. However, in this case, the iodine may form a precipitate which could potentially decrease the efficiency of the battery cell. It is important to carefully consider the materials and their interactions when designing a battery cell.