Design and synthesis of mixed-ligand architectured Zn-based coordination polymers for energy storage

Abstract

In this work, a Zn-based 1D coordination polymer [Zn(H₂O)(C₁₀H₈N₂)(C₉H₄O₆)]·2H₂O, denoted as Zn–CP, has been designed and synthesized by a slow diffusion mediated multi-ligand approach at room temperature. The Zn–CP material is characterized by single crystal analysis and other spectroscopic methods. A heteronanocomposite (Zn–CP/rGO) is prepared by mixing Zn–CP with conductive rGO nanosheets through ultrasonication and is used as a battery-type material for supercapacitor application. The Zn–CP/rGO hybrid nanostructure material delivers a specific capacity of 188.5 C g⁻¹ (377 F g⁻¹) at a current density of 1 A g⁻¹ with good cycling stability (85% capacity retention upon 6000 charge–discharge cycles at 6 A g⁻¹) and a high coulombic efficiency of 97% while a pure Zn–CP electrode delivers only 135.5 C g⁻¹ (261 F g⁻¹) at the same current density. Furthermore, a hybrid supercapacitor device (Zn–CP/rGO∥AC) is fabricated, which delivers a maximum energy density of 13.3 W h kg⁻¹ and a power density of 7446 W kg⁻¹. The suitable power density and long standing endurance of the hybrid device show promising potential for battery-type supercapacitor application.