Eco-friendly biopolymer kappa carrageenan with NH4Br application in energy saving battery

•Application to energy saving devices.•This paper covers the recent developments in the field of biobased conducting materials.•Obtained a highest conducting biopolymer in the order of 10−3 S/cm.•The initial open circuit voltage of battery is 4.29v.•Very low glass transition temperature (32.08 °C) is obtained. Above this temperature it acts like rubbery materials.•The prepared biopolymer k-carrageenan with ammonium bromide membrane is Eco friendly. Preparation of biopolymer electrolyte based on kappa-Carrageenan with ammonium bromide (NH4Br) by means of solution casting manufacturing method using condensed back H2O as a solvent. Non crystalline characterization between the biopolymer (kappa-Carrageenan) and salt (NH4Br) has been investigated by XRD (X-ray diffraction) characterization. Glass transition temperature of the prepared sample is studied by DSC and its 32.08 °C for highest conducting biopolymer membrane. The conductivity value measured by the conductivity study for 1 gm kappa-Carrageenan with 300 mg NH4Br is 2.80 × 10−3 S/cm. The proton conducting battery has been fabricated and the measured output voltage is 4.29 V.