Additive manufacturing and characterization of AgI and AgI–Al2O3 composite electrolytes for resistive switching devices

Abstract

This work investigates the electrochemical dynamics and performance of additively manufactured composite electrolytes for resistive switching. Devices are comprised of a Ag/AgI–Al2O3/Pt stack, where the solid state electrolyte is additively manufactured using extrusion techniques. AgI–Al2O3 composite electrolytes are characterized by x-ray diffraction and electrochemical impedance spectroscopy. The ionic conductivities of the electrolytes were measured for different concentrations of Al2O3, observing a maximum conductivity of 4.5 times the conductivity of pure AgI for composites with 20 mol. % Al2O3. There was little change in activation energy with the addition of Al2O3. Setting the Ag layer as the positive electrode and the Pt layer as the negative electrode, a high conductivity state was achieved by applying a voltage to electrochemically establish an electrically conducting Ag filament within the solid state AgI–Al2O3 electrolyte. The low conductivity state was restored by reversing this applied voltage to electrochemically etch the newly grown Ag filament. Pure AgI devices switch between specific electrical resistivity states that are separated by five orders of magnitude in electrical conductivity. Endurance tests find that the AgI resistive switches can transition between a low and high electrical conductivity state over 8500 times. Composite AgI–Al2O3 resistive switches formed initial Ag filaments significantly faster and also demonstrated two orders of magnitude separation in resistivity when cycling for 1600 cycles.