Polyelectrolyte complex membranes for zinc-ion cathode by polymerization of polyaniline

Although lithium batteries dominate the rechargeable battery market, concern over safety and material supply have motivated scientists to develop non-lithium-based alternative such as zinc-ion batteries (ZIBs). This work focuses on the development of polyelectrolyte complex-based cathode for ZIBs using a mild aqueous electrolyte such as ZnCl₂ instead of KOH and to be further developed into wearable electronics. Composite polyelectrolyte complex electrodes with carbon black and polyaniline (PANI), or manganese oxide (MnO₂) as active materials were prepared. The membranes were then further modified by electropolymerization of PANI to enhance the battery performance. Results show that electropolymerization leads to a threefold increase in ZIB performance with increased current density, power density, and specific energy capacity. Zinc chloride (ZnCl₂; 1 m) was used as a mild electrolyte instead of potassium chloride (KOH; 6 m) leading to a reduced performance yet allowing for potential use in skin contact and wearable electronics. All the membranes were assembled into ZIB and tested using the battery testing machine. Scanning electron microscopy was used to observe the morphology of the electropolymerized PANI while attenuated total reflection Fourier transform infrared spectroscopy was used to confirm the chemical nature of PANI.