Studies of a plasticized PEO + NH4PF6 proton-conducting polymer electrolyte system and its application in a proton battery

Abstract

We have synthesized polyethylene oxide (PEO) + NH4PF6 polymer electrolyte films plasticized with ethylene carbonate (EC) and a mixture of ethylene carbonate and propylene carbonate (EC/PC) by using a solution cast technique. X-ray diffraction (XRD) results show a decrease in crystallinity from ∼67% in the unplasticized complex to 39% and 35% in the EC- and the EC/PC-plasticized complexes, respectively. Scanning electron microscopy (SEM) results show the formation of a fringed miscellar structure in the plasticized complexes. An increased coordination between dissociated ions and the ether oxygen of PEO on plasticization is established from the Fourier transform infrared (FTIR) studies. The ionic conductivity shows an enhancement of about two orders of magnitude on plasticization. The room-temperature ionic conductivities of the highest conducting compositions are obtained as ∼1.52 × 10−5 S cm−1 and ∼1.03 × 10−5 S cm−1 in the EC- and the EC/PC-plasticized complexes, respectively. The highest conducting compositions of plasticized polymer electrolyte films are used to fabricate proton batteries with the configuration Zn/ZnSO4.7H2O (anode) ‖Polymer electrolyte‖ PbO2/V2O5 (cathode), and different battery parameters are reported.