ABSTRACT
The performance of porous carbons as electrode in electrochemical capacitors is strongly dependent on a complex combination of properties which include carbon material properties, preparation method of the electrode and electrolyte characteristics. The proper selection of these properties will allow optimizing the electrochemical capacitor. Among the carbon material properties, the surface chemistry plays a key role, and it is essential to deepen into the mechanisms through which it participates when the carbon material is used as electrode. As electrodes in electrochemical capacitors, it is known that hetereoatoms have a strong influence in the performance of the material. They can affect to the wettability of the electrolyte and contribute through redox processes, being both of them positive contributions. However, they can also have a strong influence in the stability of the capacitor, either promoting the degradation of the material and the electrolyte, or reducing the degradation rate. This chapter describes the role of heteroatoms in the performance of porous carbons is discussed paying attention to oxygen and nitrogen functionalities and to the less frequently found heteroatoms, such as boron, phosphorus, sulfur and halogens. The chapter also explains the positive and negative effects of this kind of functional groups and emphasizes the need for this understanding from a technological point of view.
