Safe and flexible chitosan-based polymer gel as an electrolyte for use in zinc-alkaline based chemistries

Abstract

A novel flexible, high performing chitosan-based gel electrolyte with poly (vinyl alcohol) (PVA) and potassium hydroxide (KOH) additives is prepared, using an optimized energy and time efficient method. Incorporation of a gel-based electrolyte in batteries aims to eliminate safety hazards present within conventional liquid-based electrolyte constructions. The ionic conductivity values obtained at room temperature are in the range of 5.32–105 mS/cm depending on composition. Optical, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectra studies are conducted to understand morphological and structural changes in the films with additives. Thermogravimetric analysis, manual bending and tensile tests, linear scan and cyclic voltammetry analysis are also conducted to study the physical and electrochemical stability of the films. Also, the prepared electrolytes are incorporated to form Zn-MnO₂ batteries and tested. Results reveal no physical damage of the films under continuous bending over 250 cycles. Mechanical properties for CPK0.3 suggest a strong and ductile material well suited for the intended application. Additionally, the novel electrolyte exhibits excellent physical stability up to 50°C, electrochemical stability until 2 V for zinc electrodes and prove to successfully accommodate redox reactions involved in the Zn-MnO₂ alkaline system.