Charge transport and discharge mechanism in [PVA+PVP+ Mg (NO3)2] polymer electrolyte films

In answer to the growing demand for compact, high energy density power sources and micro-power sources, one exciting avenue to be explored is the use of multivalent ion batteries. One such system would be a Mg2+ ion system, in which the Mg2+ cation would replace the monovalent Li+ cation in common lithium ion batteries. Although such a system would operate at a lower voltage (3.3 V for Mg vs 4.0 V for Li), the higher valence of the Mg ion could significantly increase the capacity and current output of such a battery [1]. Most studies in this field are devoted to poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) based polymer electrolytes [2-3]. In the present work, we prepared the polyblend electrolyte based on polyvinyl alcohol + polyvinyl pyrrolidone complexed with Mg(NO3)2 by solution casting technique. Several experimental techniques such as X-ray diffraction, composition – dependent conductivity, temperature-dependent conductivity in the temperature range 303-373 K and discharge characteristic studies at the load 100 KΩ are employed to characterize these polyblend electrolyte films.. Fig. 1 represents the X-ray diffraction of pure PVA/PVP (50/50) blend and PVA/PVP blends filled with different concentrations of Mg(NO3)2. It can be seen that, the peak intensity at 2θ=19.7 ° decreased and the band width increased with increasing the concentrations of Mg(NO3)2, which implied that, decrease of the degree of crystallization and causes increase in the amorphous region, which causes increasing the conductivity. The temperature dependent ionic conductivity plots are shown in fig. 2. The Arrhenius plots show non-linearity which suggests that the ion transport in polymer electrolytes depends on the polymer segmental motion [4]. The discharge characteristics of the cel