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

In this work, a Zn-based 1D coordination polymer [Zn(H 2 O)(C 10 H 8 N 2 )(C 9 H 4 O 6 )]·2H 2 O, 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.