_Applied_  
_sciences_  
_Article_  
**Features of Electrophoretic Deposition of a Ba-Containing Thin-Film Proton-Conducting Electrolyte on a Porous Cathode Substrate**  
**[PERSON] 1,2,*, [PERSON] 3,4, [PERSON] 5, [PERSON] 3,4 and [PERSON] 3,6,*()**  
1 Laboratory of Complex Electrophysic Investigations, Institute of Electrophysics, Ural Branch of the Russian Academy of Sciences, Yekaterinburg 620016, Russia  
2 Department of Physical and Inorganic Chemistry, Institute of Natural Sciences and Mathematics, Ural Federal University, Yekaterinburg 620002, Russia  
3 Laboratory of Solid Oxide Fuel Cells, Institute of High Temperature Electrochemistry, Ural Branch of the Russian Academy of Sciences, Yekaterinburg 620137, Russia; [EMAIL_ADDRESS] (A.K.); [EMAIL_ADDRESS] (A.F.)  
4 Laboratory of Chemical Design of New Multifunctional Materials, Institute of Natural Sciences and Mathematics, Ural Federal University, Yekaterinburg 620002, Russia  
5 Laboratory of Cross-Cutting Technologies in Distributed Power Generation (InEnergy), Institute of High Temperature Electrochemistry, Ural Branch of the Russian Academy of Sciences, Yekaterinburg 620137, Russia; [EMAIL_ADDRESS]  
6 Department of Environmental Economics, Graduate School of Economics and Management, Ural Federal University, Yekaterinburg 620002, Russia  
* Correspondence: [EMAIL_ADDRESS] (E.K.); [EMAIL_ADDRESS] (E.P.); Tel.: +7-343-267-87-82 (E.K.); +7-343-362-31-94 (E.P.)  
Received: 18 July 2020; Accepted: 16 September 2020; Published: 18 September 2020  
**Featured Application: The results of the study can be used for the development of the production technology of cathode-supported SOFCs with a thin-film electrolyte using the electrophoretic deposition method.**  
**Abstract: This paper presents the study of electrophoretic deposition (EPD) of a proton-conducting electrolyte of BaCe\({}_{0.89}\)Gd\({}_{0.1}\)Cu\({}_{0.01}\)O\({}_{3-8}\) (BCGCuO) on porous cathode substrates of LaNi\({}_{0.6}\)Fe\({}_{0.4}\)O\({}_{3-8}\) (LNFO) and La\({}_{1.7}\)Ba\({}_{0.3}\)NiO\({}_{4+8}\) (LBNO). EPD kinetics was studied in the process of deposition of both a LBNO sublayer on the porous LNFO substrate and a BCGCuO electrolyte layer. Addition of iodine was shown to significantly increase the deposited film weight and decrease the number of EPD cycles. During the deposition on the LNFO cathode, Ba preservation in the electrolyte layer after sintering at 1450 \({}^{\circ}\)C was achieved only with a film thickness greater than 20 \(\upmu\)m. The presence of a thin LBNO sublayer (10 \(\upmu\)m) did not have a pronounced effect on the preservation of Ba in the electrolyte layer. When using the bulk LBNO cathode substrate as a Ba source, Ba was retained in a nominal amount in the BCGCuO film with a thickness of 10 \(\upmu\)m. The film obtained on the bulk LBNO substrate, being in composition close to the nominal composition of the BCGCuO electrolyte, possessed the highest electrical conductivity among the films deposited on the various cathode substrates. The technology developed is a base step in the adaptation of the EPD method for fabrication of cathode-supported Solid Oxide Fuel Cells (SOFCs) with dense barium-containing electrolyte films while maintaining their nominal composition and functional characteristics.**  
**Keywords: solid oxide fuel cell; proton-conducting electrolyte; barium cerate; thin film; cathode-supported cell; electrophoretic deposition; deposition kinetics; microstructure; conductivity**