While a battery is discharged, the mass of the cathode/anode increases or decreases?

Anode decrease , cathode  increase. Anode is the Pol where oxidation takes place. In this case the negative one.
In an electrolytical cell its the same, but Anode and cathode are exchanged. The positive one is Anode now. Plus and minus dont change but current direction does.

Quote from: prasamb@yahoo.com on April 22, 2023, 10:05:15 PM
While a battery is discharged, the mass of the cathode/anode increases or decreases?

Cathode is the one where reduction is taking place and solid is getting deposited on the surface of cathode. So mass increases.
Anode is the one where oxidation is taking place and solid is coming out in solution as ions. So mass decreases.