ION TRANSPORT AND ALL-SOLID-STATE BATTERY CHARACTERIZATION STUDIES ON Mg~(2+)-ION CONDUCTING NANO-COMPOSITE POLYMER ELECTROLYTE (NCPEs): (75PEO: 25MgSO_4) + x MgO

摘要

Characterization of ion transport property on Mg~(2+)-ion conducting Nano Composite Polymer Electrolytes (NCPEs): (75PEO: 25MgSO_4) + x MgO, where x = 0, 1, 2, 3, 4, 5, 6, 8, 10, 12 wt. (%) has been reported. Solid Polymer Electrolyte (SPE) composition: [75PEO: 25MgSO_4)], identified as the highest conducting film in an earlier study with room temperature conductivity σ ～ 3.38 × 10~(?7) S /cm, has been used as Ist-phase host matrix and active filler MgO particles (micro / nano-dimension) as IInd - phase dispersoid. NCPE films have been prepared by a novel hot-press technique in place of the traditional solution cast method. Hot-press technique is recently receiving wider acceptability to cast polymeric electrolyte films due to the fact that it is a completely dry/solvent free/rapid/inexpensive procedure as compared to solution cast method. The Optimum Conducting Composition (OCC) of NCPE film has been identified from the filler-dependent conductivity measurements. As a consequence of dispersal of nano-size particles, the room temperature conductivity (σ) in NCPE OCC film increased by an order of magnitude i.e. σ ～ 2.29 × 10~(?6) Scm~(?1). The quality of the film also improved substantially. The total ionic transference number (t_(ion)) and the cationic (Mg~(2+)) transport number (t_+) have been determined using dc polarization and a combined ac/dc technique respectively. A considerable increase in t_+ could be achieved with the dispersal of nanoparticles. The confirmation of the salt-complexation in PEO polymer was done by FTIR spectroscopic studies. The temperature dependent conductivity measurements were carried out in NCPE OCC film and the activation energy (Ea) has been computed from ‘log σ – 1/T’ Arrhenius plot. All-solid-state battery has been fabricated in the cell configuration: Mg (anode) // NCPE OCC film// MnO_2 + C + Electrolyte (cathode), in which both the cathode and anode were in the form of thin pellet. The Open Circuit Voltage (OCV) ～ 1.82 V was obtained. The cell performance has been studied by recording the cell potential discharge profiles at room temperature under different load conditions.