Ag, N and O co-doped carbon cloth as high-capacitance electrodes for high-energy capacitors

Abstract

Binder-free carbon cloth supported activated carbon electrode has become one of the most promising electrodes in electrochemical capacitors due to its advantages of large specific capacity and long cycle stability, but its application is limited by its inherent low electric double layer capacitance and low electrical conductivity. In this study, a nitrogen-doped carbon layer with Ag particles is formed on the carbon cloth via carbonizing polydopamine layer, which is formed via polymerization reaction, and introducing Ag particles into the obtained carbon layer can improve the electrical conductivity. Subsequently, oxygen-containing functional groups were introduced on the surface of the carbon layer by means of electro-oxidation to provide additional pseudo capacitance to the carbon layer. The obtained electrode exhibits a high area specific capacitance of 2740 mF cm−2 at a current density of 1 mA cm−2, and the capacitance retention rate is 69.1 % when the current density is increased by 15-fold. The symmetric capacitor assembled by this electrode maintains a specific capacity of 87.7 % after 20,000 cycling cycles. The electrode's high specific capacity and long-cycle stability make it as a promising candidate for practical application in energy storage.