The anode in aluminium electrometallurgy is graphite, and the cathode iron is graphite lined.

Electrolysis liberates O₂, which combines with the graphite anode to produce CO₂ and CO. If it hadn’t been graphite, the oxygen would have interacted with the aluminium to generate Al₂O₃ during the electrolysis. This would have resulted in aluminium being wasted, so graphite being less expensive than aluminium, it is dispensable.

This is the function of graphite rod in aluminium electrometallurgy.