Anode current flows into "the device" (i.e. the battery cell). This inward current is carried externally by electrons moving outwards, negative charge flowing in one direction being electrically equivalent to positive charge flowing in the opposite direction. In a recharging battery, or an electrolytic cell, the anode is the positive terminal, which receives current from an external generator. The current through a recharging battery is opposite to the direction of current during discharge; in other words, the electrode which was the cathode during battery discharge becomes the anode while the battery is recharging. In a diode, the anode is the positive
Electrolytic capacitor are therefore smaller than aluminium electrolytic capacitors. In practice different safety margins to reach reliable components makes a comparison difficult. The anodically generated insulating oxide layer is destroyed if the polarity of the applied voltage changes. Electrolytic capacitors are based on the principle of a "plate capacitor" whose capacitance increases with larger electrode area A, higher dielectric permittivity ε, and thinner dielectric (d). The dielectric thickness of electrolytic capacitors is very small, in the range of nanometers per volt. On the other hand, the voltage strengths of these oxide layers are quite high. With this very thin dielectric oxide layer