The state of understanding of the electrochemical behaviours of a valve-regulated lead–acid battery comprising manganese dioxide-impregnated gel polymer electrolyte

Gel electrolyte plays a vital role in the valve-regulated lead acid battery. To address this, we formulate a gel polymer electrolyte containing poly(vinyl alcohol) as the base matrix and manganese dioxide as an additive. The addition of manganese dioxide into poly(vinyl alcohol) increases the ionic conductivity of the gel. Chemical interaction between poly(vinyl alcohol) and manganese dioxide is confirmed by Fourier transform infrared spectroscopy. Electrochemical characterisations such as cyclic voltammetry, electrochemical impedance spectroscopy and potentiodynamic polarisation suggest that 3 wt% manganese dioxide in the poly(vinyl alcohol) gel system displays better electrochemical performance. The galvanostatic charge–discharge technique reveals that the battery device with an optimised gel system showed the highest discharge capacity of 9.080 μA h at a current density of 87.5 μA cm−2 and 81% discharge capacity after 500 steady cycles.