Trying to understand the chemistry in an iron carbon battery I am trying to understand the chemistry that occurs in an iron carbon battery during charging. 

The negative electrode is iron, the positive electrode is carbon. The electrolyte is iron(II) chloride. I understand that ferrous chloride dissociates in water to $\ce{Fe^2+}$ and $\ce{Cl-}$ ions. During charge the $\ce{Fe^2+}$ ions are attracted to to the negative iron electrode and the $\ce{Cl-}$ ions are attracted to the positive carbon electrode. The $\ce{Fe^2+}$ ions combine with electrons from the power supply to form metallic iron that plates on to the iron electrode.

My problem is understanding what happens at the positive carbon electrode. I'm told that iron(II) chloride loses electrons to the positive electrode and becomes iron(III) chloride. Fine, but how does this happen if all the $\ce{Fe^2+}$ ions are at the negative electrode? How does this happen if the iron(II) chloride has dissociated in to ions, there is no iron(II) chloride anymore? 

If the power supply drives all the $\ce{Fe^2+}$ ions to the negative electrode and $\ce{Cl-}$ ions to the positive electrode how can any $\ce{Fe^2+}$ ions even be at the positive electrode to somehow recombine with $\ce{Cl-}$ ions back into iron(II) chloride that then loses electrons to the positive electrode and becomes iron(III) chloride?
Ions in solution


  [OP] I understand that ferrous chloride dissociates in water to $\ce{Fe^2+}$ and $\ce{Cl-}$ ions.


Yes. The same goes for the iron(III) species.


  [OP] I'm told that iron(II) chloride loses electrons to the positive electrode and becomes iron(III) chloride.


No, iron(II) loses electrons and becomes iron(III). The chloride is less relevant, and could be exchanged for a different ion.


  [OP]  How does this happen if the iron(II) chloride has dissociated in to ions, there is no iron(II) chloride anymore?


The reactant is $\ce{Fe^2+(aq)}$, not $\ce{FeCl2(s)}$.

Ion movement


  [OP] During charge the $\ce{Fe^2+}$ ions are attracted to to the negative iron electrode and the $\ce{Cl-}$ ions are attracted to the positive carbon electrode. 


Yes, but a small fraction, only. Otherwise the repulsion between like ions would be too great.


  [OP] My problem is understanding what happens at the positive carbon electrode. I'm told that iron(II) chloride loses electrons to the positive electrode and becomes iron(III) chloride. 


Just $\ce{Fe^3+(aq)}$. There might be a double layer, but no solid iron(III) chloride.


  [OP] Fine, but how does this happen if all the $\ce{Fe^2+}$ ions are at the negative electrode?


There are plenty of cations in the bulk of the solution, and plenty near either electrode.