## Results and Discussion
### Determination of the Optimal Deposition Mode of the BCGCuO Electrolyte Film (Test Deposition)  
EPD of BCGCuO films with a thickness of approximately 6 \(\upmu\)m on a model dense LBNO\({}_{\text{ss}}\) cathode in our earlier study [16] was carried out by multiple deposition/sintering cycles (12 cycles). The suspension in this case was subjected to ultrasonic treatment (UST), followed by centrifugation and removal of aggregates larger than 1 \(\upmu\)m. A BMA-5 modifier (a co-polymer of butyl methacrylate containing 5 mol.% of methacrylate acid) was added to the de-aggregated suspension (fractional composition of the suspension: aggregates of 323 (10) nm (81%) and individual particles of 60 (2) nm (19%)) to prevent coating cracking during drying, which is typical for submicron particles' layers. One of the objectives of this work was to reduce the number of deposition/sintering cycles. Therefore, the deposition of the BCGCuO powder in the present study was performed from the BCGCuO suspension after UST for 125 min (fractional composition in suspension: small aggregates 370 (11) nm in size--19% and large aggregates 1639 (49) nm--81%) without centrifuging and adding the BMA-5 modifier to avoid the insulating effect of the polymer adsorbed on the particles. The suspension without the centrifugation treatment was used for the EPD to maintain the suspension concentration at the given level and thus, increase the deposition rate and reduce the number of deposition/sintering cycles. Additionally, molecular iodine was used to increase the deposition efficiency. The optimal deposition mode was determined according to the results of the test deposition on the Ni-foil from a suspension with a concentration of 10 g/L of the BCGCuO micropowder in a mixed dispersion medium of isopropanol/acetylacetone (70/30 vol.%). Figure 2 shows the experimental time dependencies of the deposition weight during the EPD performed at a constant voltage of 80 V from the BCGCuO suspensions without (1) and with (2) the addition of molecular iodine in the amount of 0.4 g/L. It is seen that the addition of iodine significantly increases the deposition weight of the BCGCuO electrolyte and the dependence of the deposition weight on time when using a modified suspension has a pronounced nonlinear character. Time dependencies of the current strength at a constant voltage of 80 V during EPD from the base BCGCuO suspension and from that modified by the addition of iodine are shown in Figure 3a,b, respectively. For the base suspension without additive, there was a clear tendency for the current strength to decrease with time. In addition, the greatest rate of reduction was observed during the first minute of the deposition. For the modified suspension, there was no tendency to drop or increase current strength, but random fluctuations occurred around the average value and the current strength was much higher (approx. 1 order of magnitude) compared to that of the base suspension. The current dependence for the BCGCuO suspension with the addition of iodine demonstrated significant chaotic oscillations, the nature of which is probably associated with a change in the charge state of particles in suspensions. The I-V characteristic obtained for the modified suspension was characterized by insignificant nonlinearity and hysteresis when increasing and decreasing the cell voltage. Figure 3: Deposition kinetics of the BCGCuO film on the Ni-foil: Dependences of the current strength on time at a constant voltage of 80 V for the deposition from a suspension (10 g/L) in the mixed dispersion isopropanol/acetylacetone medium (70/30 vol.%) without J\({}_{2}\) (**a**) and with J\({}_{2}\) additive (0.4 g/L) (**b**); The current–voltage characteristic in the voltage range from 12 to 150 V obtained for the deposition from the BCGCuO suspension with J\({}_{2}\) additive (**c**).