Fabrication and characterization of Zn-ion-conducting solid polymer electrolyte films based on PVdF-HFP/Zn(Tf)2 complex system

Abstract

The present work is aimed at developing the Zn-ion-conducting solid polymer electrolyte (SPE) films based on PVdF-HFP/Zn(Tf)2 complex system via solution casting method. The structural and morphological characteristics of the as-prepared films are elucidated by X-ray diffraction and scanning electron microscopy. Further, impedance spectroscopy and cyclic voltammetry are performed to investigate their electrical and electrochemical properties. The structural analysis confirms that the PVdF-HFP is semi-crystalline and its amorphous domain increases with the addition of Zn(Tf)2 salt. The impedance results reveal that the ionic conductivity of the electrolyte film is raised up to a maximum value of 2.44 × 10–5 S cm−1 at room temperature when the mass ratio of Zn(Tf)2:PVdF-HFP is 0.4 (named as PE/Zn-4). However, further loading of salt degrades the overall properties of the film. Hence, the PE/Zn-4 system is regarded to be the optimal composition for efficient SPE films. Additionally, the PE/Zn-4 electrolyte exhibits sound thermal stability and mechanical properties. The electrochemical stability window of the PE/Zn-4 system is evaluated as approximately 3.45 V, being acceptable for energy storage applications. In addition, the present polymer electrolyte may well suppress the formation of Zn dendrites on Zn electrodes. Conclusively, the development of high-performance SPEs could be potentially very useful for the next-generation Zn-based devices.