3D-printed polyacrylamide-based hydrogel polymer electrolytes for flexible zinc-ion battery

Zinc ion batteries (ZIBs) are a highly cost-effective and safe option for electrochemical energy storage, particularly suited for flexible wearable devices. However, the development of hydrogel polymer electrolytes (HPEs) for ZIBs using 3D printing technology presents challenges in terms of performance, stability, and durability. The purpose of this study is to address these challenges by creating 3D-printed flexible HPEs with varying porosity from polyacrylamide (PAM) using digital light processing (DLP) 3D printing. The electrochemical properties of the 3D-printed HPEs were compared to conventional casted HPEs. The 3D printed HPEs exhibited improved electrochemical performance, especially in ionic conductivity (28.10 mS cm-1, equivalent to the current conventional HPEs). Higher porosity in the 3D printed HPEs enhanced electrolyte absorption and facilitated Zn2+ ions diffusion, as confirmed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) results. Furthermore, galvanostatic charge-discharge (GCD) measurements demonstrated that the 3D-printed PAM hydrogel electrolyte with 40% porosity achieved a specific capacity of 161.4 mAh g-1 at 0.1 A g-1. The findings validate the potential of the 3D-printed PAM hydrogel as a flexible HPE for ZIBs. The customized design structure of the 3D-printed HPEs enabled improved electrochemical properties, surpassing the limitations of conventional casted HPEs.