Modified surface effect of lithium-dispersed graphite and activated carbon at high-temperature conditions and their electrochemical properties for a lithium-ion capacitor

Abstract

Surface modification of graphene and activated carbon through heat treatment has been used to increase the materials' electrical and optical properties for lithium-ion capacitor (LIC) applications. The surface modification techniques employed in this study emphasize introduction of an acidic group and a small number of lactonic and phenolic groups on graphite and activated carbon to facilitate their dispersion in aqueous media. In this research, lithium dispersion at high temperatures, the surface properties of the materials, and their electrochemical and optical properties are assessed. These include lithium dispersion and covalent attachment of functional groups. The effects of these surface modifications on the performance characteristics of dispersed nanocomposites were evaluated through several techniques (XRD, SEM, TEM, cyclic voltammetry, Mott-Schottky, BET, BJH, T-plot, pore size distribution, Boehm titration, and chronoamperometry). Especially, the highest oxidation peak corresponding to current value appeared at 0.0056 mA/cm2 current density and the lowest reduction peak value marked at 0.0002 mA/cm2, when the Li-G sample used to the FTO surface. The electrochemical stability of cathode materials was tested by 10 recycling tests, which the peak current drop decreased the peak profile became stable. The Li-dispersed graphite and activated carbon had synergistically upgraded electrochemical activity and superior cycling stability that were demonstrated in LIC. This research presented herein offers a promising route for the rational design of Li amounts and stable electrochemical reaction in LIC working mechanism. Highlights Surface modification with the introduction of an acidic group and a small number of lactonic and phenolic groups on graphite and activated carbon Lithium dispersion at high temperatures for the lithium amounts expansion for the cyclic stability The electrochemical stability of cathode materials with stable peak profile The rational design of Li amounts and stable electrochemical reaction in LIC working mechanism