Guest–host interaction in energy storage systems Original Research Article

Charge transfer reactions are the most frequent processes met during the conversion of chemical energy into electrical one. Intercalation/insertion processes are the best examples of these phenomena. The type of interaction/binding between guest species and host material decides about the reversibility of the processes. The important drawback of the carbon anode in Li-ion cells is often its irreversible capacity. It correlates with the active surface area and it can be significantly diminished through pyrolytic carbon coating. In situ7Li-NMR measurement is a perfect method for monitoring the type of Li–C bonding during the insertion/deinsertion process. Supercapacitor is the second category of attractive energy storage system. The main operation of a capacitor is based on an electrostatic attraction; however, very often pseudocapacitance effects take place. Intensive research is devoted to electrochemical hydrogen storage where the type of C–hydrogen bonding is crucial for practical application of this process. The reversibility of hydrogen insertion into the carbon network is ensured by a weak chemical bonding. Carbon materials with electrosorbed hydrogen play a perfect role of negative electrode in supercapacitor. Attractive host–guest interactions take place during the performance of various supercapacitor electrode materials, e.g. nitrogen-doped carbons with modified electronic structure, layered double hydroxides, conducting polymers, etc.