290 / 2022-03-01 01:22:52

Redox processes on carbon nanomaterial surface proceeding in supercapacitors and Li batteries when potential is applied

Li batteries,supercapacitors,carbon nanomaterials,redox processes,oxygen-containing functional groups

（7）矿物与先进能源材料 > 3. 碳材料

Carbon nanomaterials are potential materials for electrodes of supercapacitors and Li-ion batteries due to their unique chemical and physical properties. The main advantages of these materials are mechanical stability, high specific surface area, good electrical conductivity, high thermal stability, chemical inertness, controlled hydrophilicity/hydrophobicity, wide possibility of surface fictionalization, etc. The basic principle of functioning of carbon nanomaterials in supercapacitors is the formation of a double electric layer on the electrode-electrolyte interface. Also, the surface of the carbon nanostructures can be functionalized or doped with heteroatoms which provide additional redox activity and enhancing the energy storage capability of the material. Reduced graphite oxide is a material with high surface area and aromatic or semi-aromatic network and can be decorated with oxygen-containing functional groups such as hydroxyl (carbinol) (−OH), epoxyl (−C −O −C −), carbonyl (C=O) and carboxyl (−COOH) which demonstrates high activity in electrochemical processes. Also, the quantity of oxygen-containing functional groups provides variation of important material characteristics as conductivity, wettability, and specific surface area. In this work we investigate the influence of thermal and chemical treatment of reduced graphite oxide on its functional composition and electrochemical performance. It is found that carboxyl, carbonyl, hydroxyl and epoxy groups present on the reduced graphite oxide surface, can be controllably modified. Electrochemical measurements over a wide range of pH values of the water buffer electrolytes for supercapacitors or organic electrolyte for Li-ion batteries allow to correlate the peaks in the cyclic voltammogram curves with the redox reactions of oxygen-containing functional groups as a function of applied potential. Also, contribution to capacity and stability parameters of investigated carbon nanomaterials is correlated with its functional composition.