Novel polymer gel electrolytes comprising montmorillonite embedded in sodium alginate and their electrochemical performance for future lead acid batteries

Abstract

The current work is motivated by the rising applications of value-regulated lead acid (VRLA) batteries. The performance of VRLA batteries depends on the type of electrolyte used. The gel electrolyte is an important factor that controls both the manufacturing process and the performance of VRLA batteries. We formulate polymer gel electrolytes composed of sodium alginate (NaAlg) with varying amounts of montmorillonite (MMT). The nature of gel electrolytes is analyzed by Fourier transform infrared (FTIR) spectroscopy, the ionic conductivity study and the water retention study. The gel electrolytes are subjected to electrochemical characterization methods like cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). 2 wt% MMT@NaAlg shows better electrochemical performances. Galvanostatic charge–discharge (GCD) tests are performed on optimized gel electrolytes, and display a maximum discharge capacity of 138 μA h cm⁻² at a current density of 0.55 mA cm⁻². The prototype battery shows a maximum discharge capacity of 2.8 × 10⁻⁶ A h at a current density of 35 μA cm⁻². After 500 cycles, the battery accomplishes 89% discharge capacity. NaAlg-based gel electrolytes with additives can be used for the manufacturing of VRLA batteries.