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

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 1.57x10(-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 2.22x10(-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.