Innovative method to avoid the reduction of silver ions to silver nanoparticles (Ag+ → Ag°) in silver ion conducting based polymer electrolytes

In this research work an innovative method is used to prevent the silver ion reduction in solid polymer electrolytes. The x-ray diffraction (XRD) results reveal the disruption of the crystalline nature of chitosan (CS) and formation of silver nanoparticles upon addition of silver triflate (AgTf) salt. The UV-vis measurement confirms the existence of silver nanoparticles via the broad surface plasmon resonance (SPR) peak. Upon the addition of Al2O3 nanoparticles the SPR peak intensity is greatly reduced. The amorphous domain of the CS: silver triflate (CS: AgTf) system increases with the addition of Al2O3 nanoparticles up to 4 wt.%. Deconvolution of the XRD results reveals that a larger crystallite size is obtained for higher Al2O3 concentrations and the peaks due to silver nanoparticles almost disappear. Scanning electron microscope (SEM) analyses show that Al2O3 nanoparticles are well dispersed at low concentrations and the leakage of chains of silver nanoparticles to the membrane surface almost disappear. The XRD, UV-vis, SEM and energy-dispersive x-ray (EDX) results strongly support that the reduction of silver ions to silver nanoparticles (Ag+ -> Ag degrees) in the CS: silver triflate system is significantly avoided upon the addition of an Al2O3 filler.