Effect of casting slurry composition on anode support microstructure and cell performance of MT-SOFCs by phase inversion method Cong Ren a , Tong Liu a , Yating Mao b , Panita Maturavongsadit c , Jittima Amie Luckanagul c , Qian Wang c , Fanglin Chen a, * a Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208, USA b Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208, USA c Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA A R T I C L E I N F O Article history: Received 13 August 2014 Received in revised form 25 September 2014 Accepted 13 October 2014 Available online 19 October 2014 Key words: Phase inversion Microstructure YSZ-NiO anode support Micro-tubular SOFCs A B S T R A C T Anode-supported micro-tubular solid oxide fuel cells (MT-SOFCs) have been fabricated by phase inversion method. The effect of the viscosity of the casting slurry on the microstructure of YSZ-NiO anode support has been investigated. The microstructure of the YSZ-NiO support can be effectively controlled by varying the slurry composition with different solvent and polymer binder content. Gas permeation and mechanical strength of the YSZ-NiO support have been measured and four YSZ-NiO anode supports have been chosen for subsequent cell fabrication. The effective conductivity of the different anode supports has been measured at room temperature. Anode-supported single cells with YSZ electrolyte and LSM/YSZ cathode are fabricated and tested. Maximum cell power densities of 606 mW/cm 2 , 449 mW/ cm 2 , 339 mW/cm 2 and 253 mW/cm 2 have been obtained respectively at 750  C with humidified hydrogen as fuel and ambient air as oxidant. The correlation between the cell electrochemical performance and anode microstructures has been discussed. ã 2014 Elsevier Ltd. All rights reserved. 1. Introduction Solid oxide fuel cells (SOFCs) have been regarded as promising next-generation power sources due to their high energy conver- sion efficiency and fuel flexibility [1–3]. Compared with planar SOFCs, tubular SOFCs, especially micro-tubular SOFCs (MT-SOFCs), exhibit faster start-up, better tolerance to thermal cycling and higher volumetric power density [4,5]. The traditional extrusion method has been the most commonly adopted technique for the fabrication of anode-supported MT-SOFCs [6]. Recently, the phase inversion method, which was initially developed for polymer membrane preparation [7], has been applied for anode-supported MT-SOFCs fabrications [8–13]. Comparing with the conventional extrusion method, phase inversion process can produce a unique asymmetrical microstructure that consists of a top layer with homogenously distributed small pores and a sub-layer with long finger-like pores. Othman et al. have concluded that the presence of finger-like pores in the anode in MT-SOFCs fabricated from the phase inversion method can function as microchannels for fuel gas transport and facilitate the fuel gas mixture inside the anode [14]. In such a case, the fuel oxidation reaction in the anode can be accelerated and the cell performance can be substantially improved. It has been reported that the anode microstructure can significantly affect the cell performance [15]. Therefore, it is crucial to study the correlation between the process parameters and the corresponding microstructure features for SOFC fabrica- tion through the phase inversion method. Although many efforts have been done for phase inversion process parameter optimiza- tion [16–18], there is still lack of systemic investigation to reveal the correlation between the casting slurry compositions and the final sample microstructure. In this study, YSZ-NiO anode supports have been prepared by phase inversion method and the microstructure was optimized by employing various casting slurry compositions. Four anode supports with different microstructure were selected for YSZ- NiO/YSZ/YSZ-LSM single cell fabrication. All of the prepared cells were tested at 750  C with humidified hydrogen (3% H 2 O) as fuel and ambient air as oxidant. The influence of solvent N-Methyl-2- pyrrolidone (NMP) and polymer binder polyethersulfone (PESf) content in the casting slurry on the microstructures was examined, and the correlation between microstructure and cell performance was discussed. * Corresponding author. Tel.: +1 803 777 4875. E-mail address: chenfa@cec.sc.edu (C. Ren). http://dx.doi.org/10.1016/j.electacta.2014.10.060 0013-4686/ ã 2014 Elsevier Ltd. All rights reserved. Electrochimica Acta 149 (2014) 159–166 Contents lists available at ScienceDirect Electrochimica Acta journa l home page : www.e lsevier.com/loca te/ele cta cta