Cerium Chloride-Assisted Subcritical Water Carbonization for Fabrication of High-Performance Cathodes for Lithium-Ion Capacitors

Abstract

Lithium-ion capacitors are considered highly promising as a hybrid-type energy storage system and are suitable for largescale energy storage applications because of their superior power and energy density as well as prolonged cycle life. In this study, we developed an activated carbon (AC)-based electrode with excellent capacitive performance using salacca peel, a native Indonesian fruit, as the carbon precursor. The AC was synthesized via hydrothermal treatment of salacca peel with cerium (III) chloride (CeCl3) as the catalyst, followed by microwave-assisted chemical activation; the obtained sample was denoted as AC–S–CE. The addition of CeCl3 during the hydrothermal carbonization facilitated the formation of micropores in the AC; this resulted in a considerably greater surface area (1264.4 m²g‾¹) and a more defective graphitic structure than that of AC synthesized in the absence of CeCl3 (AC–S, 988.9 m²g‾¹) and of commercially available AC (742.8 m²g‾¹). In terms of being an LIC cathode, all the ACs exhibited a non-faradaic charge–discharge mechanism. AC–S–CE exhibited a higher capacitance of 90.6 F g‾¹ at 0.05 A g‾¹ and improved cycling performance compared with those of AC–S and commercially available AC.