Electrodes with Unique Graphite Sheet-Supported Zn–Co–S Nanoparticles for Hybrid Supercapacitors with High Performance

Zinc–cobalt double-metal sulfides (ZCSs) with kinds of structures as electrode materials play an essential role in supercapacitors (SCs). However, their poor electronic transfer efficiency and irreversible structural damage greatly affect their practical applications. The idea of high structural stability and bimetal synergy (Zn-Co) is introduced to prepare high-performance electrodes and construct hybrid supercapacitors. A unique graphite sheet-supported ZCS nanoparticle is grown on porous Ni foam (GZCS/NF) by a facile hydrothermal and ion-exchange reaction. The unique nanosheet structure with a nanosheet of about 80 nm exhibits a specific capacity of 1293.5 C g–1 at 1 A g–1, a relatively low charge-transfer resistance of 0.16 Ω, and superior cycling stability, which can be attributed to the excellent pseudocapacitive capacity of ZCS nanoparticles and the good chemical stability of the graphite sheet. A hybrid supercapacitor in KOH solution is assembled with GZCS/NF as the cathode and AC as the anode. The assembled GZCS/NF//AC HSC delivers a wide working voltage of 1.7 V and a specific capacity of 196.4 C g–1 at 1 A g–1. Its ability to light up eight red LEDs for about 7 min proves its good prospects in energy storage devices.