*2.3. Membrane Characterization*

Electrospun membranes have been characterized at first by scanning electron microscopy (SEM) using an EVO 50 apparatus (Zeiss, Oberkochen, Germany). The feasibility of the use of the electrospun mats as separators was evaluated by EIS. Swagelok-type cells with two stainless steel blocking electrodes (0.9 cm diameter), separated by the membranes (dried overnight before use at RT) soaked in

the different investigated electrolytes, were used. The EIS spectra were collected by a VSP multichannel potentiostat/galvanostat/FRA (BioLogic, Seyssinet-Pariset, France) within 500 kHz–100 mHz frequency range and 5 mV AC perturbation, acquiring 10 points per decade. The cells were thermostated at 30, 40 and 60 ◦C by a thermostatic oven. The bulk conductivity of the electrolytes without membranes were measured by a CDM 210 Conductivity Meter (MeterLab, Milano, Italy) with an Amel standard cell (platinum electrodes). The temperature was controlled by a DC50 K40 thermocryostat (Haake, Thermo Fisher Scientific, Karlsruhe, Germany) with an accuracy of 0.1 ◦C. Samples were thermostated for 1 h before every measurement.
