For the successful utilisation of commercially available conventional graphite as a negative electrode in a lithium-ion capacitor (LIC), its intercalation rate capability needs to be improved or oversized to accommodate high charge rates. 1. Introduction
Ruan et al. decontaminated waste graphite and then composited it with silicon followed by an amorphous carbon layer coating, and the graphite/silicon@carbon coated composite material showed a specific capacity of 434.1 mAh/g and capacitance retention rate of 92.5 % after 300 cycles (Fig. 8 b).
Supercapacitors have gained e wide attention because of high power density, fast charging and discharging, as well as good cycle performance. Recently, expanded graphite (EG) has been widely investigated as an effective electrode material for supercapacitors owing to its excellent physical, chemical, electrical, and mechanical properties.
The amorphous carbon has small volume change during the charging and discharging process and can promote Li + transport due to its isotropic characteristics, so the carbon coating on the surface of waste graphite can well enhance the cycling stability and multiplicity performance of the material.
Hence, a LIC with graphite as a negative electrode and AC as a positive electrode will have substantially greater energy storage capacity than conventional EDLCs due to: (i) the higher capacity of the graphite electrode, (ii) the relatively constant voltage of the graphite electrode during discharge and (iii) the higher operating voltage (∼3 V).
Electrode material is vital in supercapacitors because it determines the capacitance, cycle, and rate performances of the supercapacitor [ 3 ]. Expanded graphite (EG) is obtained from expanded/split expandable graphite, which is the best prospective carbon anode material for different energy storage devices in recent years [ 25, 26, 27, 28, 29 ].