Developing Redox Stability of Ceramic Anode Supported Intermediate Temperature Solid Oxide Fuel Cells
Authors: Kim Youdong , Jo Su Yeon , Park Jun-Young 
Published: February 2020

Solid oxide fuel cells (SOFCs) are eco-friendly and promising electrochemical devices which can convert chemical energy of fuel to electrical energy. They have many advantages including high conversion efficiency (45~65%) and fuel flexibility [1]. However they have to stand under harsh condition such as frequent load cycles, operational temperature fluctuations, and pump malfunctions. They should also operate over 40,000h on combined head and power (CHP) plants for commercial uses [2].

Mixed ionic and electronic conductors (MIEC) normally (particularly, Ni-YSZ cermets) use for the anode material of SOFCs, because of their good electrical conductivity and high catalytic activity for hydrogen oxidation. However Ni is likely to agglomerate at high temperature, thus resulting in reducing electrical conductivity with the significant loss of Ni-Ni contacts [3]. In addition, when SOFCs are exposed on the fuel starvation condition in the anode side, it can occur mechanical failure of anode substrates with the significant chemical expansion due to oxidation of Ni to NiO [4]. Furthermore Ni is not albe to use hydrocarbon fuel because of carbon deposition and has low tolerance to Sulphur.[4]

In order to solve those issues, ceramic anode materials, La0.75Sr0.25Cr0.5Mn0.5O3-
δ(LSCM), have been considered as a candidate material for the SOFC anode due to high chemical stability and good electrical conductivity. Furthermore, LSCM anode materials are fabricated with the highly conductive Nd0.1Ce0.9O2(NDC) electrolytes to investigate the practicability of SOFCs at the intermediate temperature (IT), since decreasing the operating temperature of SOFCs is one of possible solutions to enhance operational stability and long-term durability.

In this work, LSCM anode-supoorted cells are fabricate by the using uniaxial pressing and drop-coating methods. For the electrical characterizations of LSCM-based cells electrochemical impedance spectra (EIS) and I-V (current-voltage) polarization curves are measured by using the Potentiostat/Galvanostatntequipped with impedance spectroscopy (Biologic) field emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD) spectroscopy are used for the physicochemical analysis of LSCM anode-cells.

[1] Steele, Brian CH, and Angelika Heinzel. "Materials for fuel-cell technologies." Nature 414.6861 (2001): 345-352.

[2] Wachsman, Eric D., and Kang Taek Lee. "Lowering the temperature of solid oxide fuel cells." Science 334.6058 (2011): 935-939.

[3] Simwonis, D., F. Tietz, and D. Stöver. "Nickel coarsening in annealed Ni/8YSZ anode substrates for solid oxide fuel cells." Solid State Ionics 132.3 (2000): 241-251.

[4] Sarantaridis, D., and A. Atkinson. "Redox Cycling of Ni‐Based Solid Oxide Fuel Cell Anodes: A Review." Fuel cells 7.3 (2007): 246-258.

[5] Yokokawa, Harumi, et al. "Fundamental mechanisms limiting solid oxide fuel cell durability." Journal of Power Sources 182.2 (2008): 400-412.

[6] Tao, Shanwen, and John TS Irvine. "A redox-stable efficient anode for solid-oxide fuel cells." Nature materials 2.5 (2003): 320-323.

* Corresponding author: jyoung@sejong.ac.kr (J.-Y. Park).

Keywords
: solid oxide fuel cells, ceramic anode, La0.75Sr0.25Cr0.5Mn0.5O3-
δ, electrochemical performances, durability.