Preparation of YSZ electrolyte coating on conducting porous NieYSZ cermet by DC and pulsed constant voltage electrophoretic deposition process for SOFCs applications Omid Ekhlasi Oskouyi a , Amir Maghsoudipour b, * , Mohammad Shahmiri a , Masood Hasheminiasari a a School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran, Iran b Materials and Energy Research Center, Karaj, Iran article info Article history: Received 17 March 2019 Received in revised form 29 April 2019 Accepted 30 April 2019 Available online 4 May 2019 Keywords: Solid oxide fuel cell Pulse width Electrophoretic deposition YSZ abstract In this article, electrolyte coating of solid oxide fuel cells (SOFCs) based on yttria stabilized zirconia (YSZ) on Ni-YSZ cermet fuel cells anode in ethanol was investigated using pulsed constant voltage and DC electrophoretic deposition (EPD). The NiO-YSZ substrate was prepared by hydraulic pressing of mixed YSZ, NiO and starch powders following pre-sintering at 1200  C for 3 h. The NiO-YSZ composite was reduced in hydrogen atmosphere in order to produce Ni-YSZ cermet. The suspension properties and EPD process parameters were investigated. The YSZ electrolyte was sintered at 1350  C for 4 h. The morphology of sintered YSZ electrolyte coating was investigated by scanning electron microscope (SEM) and optical microscopy (OM). Results showed that dense and uniform coatings were deposited in ethanol with solid concentration of 10 g/L of YSZ, 0.5 g/L of iodine at distance of anode to cathode being 5 mm. The thickness of YSZ electrolyte after 6 min of deposition with pulsed constant voltage and DC elec- trophoretic deposition were 20 and 88 ± 1 mm, respectively. © 2019 Published by Elsevier B.V. 1. Introduction Fuel cells directly convert chemical energy from gas into elec- trical and thermal energy through an electrochemical reaction between the fuel and the oxidizing agent [1e5]. Reliable power generation, quietness, etc are considered as main advantages of SOFCs [6e8]. SOFCs consist of the oxidizing electrode, an electro- lyte, and a reductive electrode as three major components. It is necessary for the electrodes to be porous, while the YSZ electrolyte layer must be dense to prevent the gas from spreading between the electrodes [9]. YSZ electrolyte in SOFCs gained much attention due to its chemical properties, excellent thermal properties, stability and ionic conductivity [1 , 10e12]. Reducing the operating temper- ature of the SOFCs decreases the degradation of the cell compo- nents, increases flexibility in the design of the cell and reduces the cost of construction due to the use of ferrite steels as an inner connector [13, 14]. By decreasing the SOFCs operating temperature, the electrolyte conductivity and kinetics of the electrode are significantly reduced. This problem can be overcome by reducing the thickness of the YSZ electrolyte or by replacing high ionic conductivity materials at low temperatures [15, 16]. There are many ways to deposit thin films such as physical vapor deposition (PVD), chemical vapor deposition (CVD) or electrochemical vapor depo- sition (EVD), which complex and expensive equipment are often required [17 , 18]. There are cheaper colloid methods, such as im- mersion, tape-casting, which are difficult to have control over sedimentation [19,20]. Electrophoretic deposition (EPD) process is a suitable method to be used in SOFCs due to the production of thin and dense coating on porous electrode [21 ,22]. The EPD process is attractive while it is a quick and simple method with less complexity of equipment, higher adhesion with the ability to coat on multifaceted shapes (flat and cylindrical surfaces) [23]. The EPD process consists of two steps: in the first step the electric field is applied between the anode and cathode, which causes the sus- pended particles being transferred to the opposite electrode. In the second step charged particles lose their electrical charge and form a relatively dense and uniform layer on the electrode [16]. In elec- trophoretic deposition, parameters related to the suspension and process behavior such as particle size [24], dielectric constant of * Corresponding author. E-mail address: am.maghsoudipour@gmail.com (A. Maghsoudipour). Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: http://www.elsevier.com/locate/jalcom https://doi.org/10.1016/j.jallcom.2019.04.334 0925-8388/© 2019 Published by Elsevier B.V. Journal of Alloys and Compounds 795 (2019) 361e369