The electrodes do not corrode any time in the cell.
Corrosion is not what happens, to better understand and to properly discuss what is happening we need to try and use the proper terms the best we can to explain it.
Here we are not discussing corrosion. We are talking about Oxidation and reduction of the metals.
when we are dealing with metals or acids and bases, we are dealing with the atoms of the metals.
Oxidation (the loss of electrons or gain of oxygen). When metals are corroded they are oxidized, the corrosion is a salt of the metal, or metal dissolved into a salt solution, the atoms of the metal when they lose their electrons become ions of the metal (or the salt of that metal, the metal ions are called Cations they carry a positive charge (the missing electrons), in the silver cell the silver metal with all of its atoms is oxidized at the anode, in this case, the oxidation is forced by the power supply. with electrolysis, we can force reactions to occur that would not occur otherwise. (our example here silver will not oxidize or lose electrons in water or in silver nitrate salt, but with the electrical force of the power supply we can force this reaction to happen.
Anytime we have oxidation something has to be reduced, anytime something is reduced something else has to be oxidized. One gains electrons the other loses electrons.
Reduction is the gain of electrons, when ions (salts) gain electrons they are reduced back to elemental metal atoms with a full shell of electrons. (reduction of salts back into metal).
In the electrolytic cell, the metals are oxidized (the atoms loses electrons to become ions of that metal in solution) at the anode (positive of the power supply).
On the other side of the cell, at the cathode, the ions are reduced (gain electrons) to change from an ion to an elemental metal atom.
Our electrolyte is a salt (even if it is just water, a combination of Hydrogen H+and hydroxide OH-). In our discussion here we will use silver nitrate (salt) as an electrolyte, which consists of positive silver Cations Ag+, and negative nitrate Anions NO3-.
Note: the silver ions Ag+ are missing electrons, the nitrate has an excess of electrons when we made this silver salt for our electrolyte we used nitric acid to dissolve the silver metal, the silver was oxidized (the acid took its electrons) the silver atoms became positive ions (anions) in solution,at the same time the nitric acid was reduced (gain of electrons) to form a nitrate salt negative Ions (Cations) in solution.
silver metal was oxidized at the same time the acid was reduced. Basically movements of electrons in the chemical reaction...
In the cell the positive of our power supply is at the anode, the negative is at the cathode.
The metal we are oxidizing into solution is at the anode and the metal deposits on the cathode where the ions are reduced back to elemental metal.
The negative Cations migrate toward the anode (NO3-).
The positive metal Anions Ag+ migrate toward the cathode.
At the anode (positive pole of the power supply, the silver metal (Ag) atoms are losing electrons to become silver metal Ions (Cations) Ag+ which go into the soluton as the electrolyte.
At the cathode (negative of the power supply the silver ions (Ag+), gain electrons to be reduced back to silver metal (Ag).
This is a forced reaction using the power supply to force the movements of electrons.
The electrolyte is a salt (even if just water), it has positive Cations and negative Anions. To reduce silver at the cathode we must have silver ions around the cathode. The more Ag+) surrounding the cathode the more silver will gain electrons to become a metal deposit and free the NO3 Anions to move to the anode where the silver is oxidized to replenish the electrolyte of silver ions.
With pure water when we began we do not have silver ions in solution, we overcome resistance by bringing the anode and cathode to almost touching, to split the water to anions and cations, then the silver is oxidized putting some silver ions into the electrolyte, which can now be reduced at the cathode. freeing the Anion to migrate and gain more silver ions at the anode....
The simple answer to the question, the more salt (ions and cations in solution) the less resistance and the more oxidation, and reduction that will take place. (as you called it more "corrosion"). the electrolyte will need to contain silver ions, the more silver ions in solution (which would also mean the more positive Anions in Solution) the more you would see the anode oxidize.
