A medical electrical lead and body implantable electrode suitable for a variety of medical applications are disclosed. In general, the electrode includes a composite material having particles of pseudo-capacitive material, such as iridium oxide, dispersed within a polymer matrix including a polyelectrolyte. The polymer matrix can also include a conductive polymer doped with an excess of the polyelectrolyte. The composite may used to form the electrode itself or an electrode coating. The presence of a pseudo-capacitive material within the composite may increase the charge-storage capacity of the electrode and may allow for safe deliveries of charge densities within an electrochemical window suitable for pacing a patient's heart.