High Electrochemical Performances Resulted from the Metamorphic Differentiation of Amorphous Carbons

Abstract

© 2015 The Electrochemical Society. All rights reserved.Without well balanced electric conductivity and transmission of electrolyte in structures, amorphous carbons suffer from their declined electrochemical performances at increasing charge-discharge rates or current densities. A metamorphic differentiation of amorphous carbons has been carried out by annealing activated carbon fibers (ACFs) in gaseous sodium metal at 950°C, resulting in a multifold structural transformations from the unique amorphous style in ACFs to multilayer graphene, turbulent and amorphous carbons in the matrix of restructured activated carbon fibers (RACFs). RACFs display the specific surface area and mesoporous volume ratio of 1651 m 2 g -1 and 83%, respectively, and show the specific capacitance of RACFs about 125 F g -1, which is 2.5 times larger than that of ACFs at 20 A g -1. The metamorphic differentiation of amorphous carbons is caused by the graded distribution of sodium metal in the matrix of carbons, leading to the porous and crystalline character of carbons to be effectively combined in RACFs. This greatly improves the transmission abilities both of electron and electrolyte at a large flux and results in their high electrochemical performance at large charge-discharge rates and current densities.