Magnesium ion conducting solid polymer blend electrolyte based on biodegradable polymers and application in solid-state batteries

Magnesium ion conducting solid polymer blend electrolyte based on biodegradable polymers polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) mixed with different molecular weight percentages (wt.%) of magnesium nitrate (Mg(NO3)2) was prepared by using solution casting technique. X-ray diffraction studies lead the reduction of crystalline nature by the addition of magnesium nitrate to the polymeric matrix. The complex formation between polymer and salt confirmed by Fourier transform infrared spectroscopy studies. Differential scanning calorimetry shows that the glass transition temperature decreases with increase in magnesium salt concentration and the thermal stability of PVA–PVP–Mg(NO3)2 complexes. The maximum ionic conductivity σ ~ 3.78 × 10−5 S cm−1 was obtained for 50PVA–50PVP–30 wt.% of Mg(NO3)2 polymer blend electrolyte at room temperature (303 K). The conductivity–temperature plot is found to follow the Arrhenius behavior, which showed the decrease in activation energy with the increasing salt concentration. The transference number data indicated the dominance of ion-type charge transport in these polymer blend electrolytes. The solid-state electrochemical cells were fabricated, and their discharge profiles were studied for this polymer blend electrolyte system under a constant load of 100 kΩ.