Development of a Solid Bio‐Electrolyte from a Seaweed Extract – Polyvinyl Alcohol Blend for Primary Mg‐Ion Conducting Batteries

Abstract

A novel solid bio‐electrolyte from seaweed acts as a potential candidate for electrolytes in batteries by solution casting technique. The ethanol extract of seaweed Sargassum Muticum (SME) is blended with PVA to prepare the bio‐membrane and along with MgCl2 as the ionic provider, a solid bio‐electrolyte is produced. The ionic conductivity of the prepared bio‐membrane, 1 g SME+0.8 g PVA is 1.57×10−6 S cm−1. XRD analysis affirms the amorphous nature of the prepared bio‐electrolytes and the highest degree of amorphous nature is apparent for the composition of 1 g SME+0.8 g PVA+0.7 wt% MgCl2. Complex formation between the SME, polyvinyl alcohol, and the added charge carrier has been made evident from the FTIR technique. Thermal properties of the bio‐electrolytes by differential scanning calorimetry (DSC) are supported by the low Tg. Electrochemical impedance analysis for the prepared bio‐electrolytes and the maximum ionic conductivity of 2.22×10−3 S cm−1 is exhibited by 1 g SME+0.8 g PVA+0.7 wt% MgCl2 membrane. A primary magnesium‐ion conducting battery has been constructed with the highest conducting bio‐electrolyte membrane and an open circuit voltage of 2.18 V validates the application of this bio‐membrane as a promising solid electrolyte for energy storage devices.