Cathodic safety is a well known method to manage the corrosion of any metal surface in a fashion by getting it to work within the form of a cathode of the electrochemical cell. In a tube by which the filament itself was the cathode, the alternating electric field from the filament surface would affect the motion of the electrons and introduce hum into the tube output. Most NiMH rechargeable batteries merely use two metals strips, the latter being a destructive cathode, wrapped in plastic foil to carry their cost.
An anode is an electrode by way of which the conventional present enters into a polarized electrical system. The cathode gets its optimistic charge from the chemical reaction that occurs inside the battery, not from an external supply...