Electrode structures may include an electronically conductive foam in contact with an electronically conductive substrate. In some embodiments, the foam may be formed by coating a porous precursor material in contact with a substrate with an electronically conductive material and subsequently removing the precursor material. In some embodiments, the foam may be formed by removing a non-conductive component of a composite material in contact with a substrate, leaving a conductive component in contact with the substrate. Electrode structures may be coated with electronically conductive materials or sintered at elevated temperature to improve durability and conductivity.