Stable LSM/LSTM bi-layer interconnect for flat-tubular solid oxide fuel cells

• Published in: International journal of hydrogen energy Vol. 43; no. 1; pp. 363 - 372
• Main Authors: Yoon, Heechul, Kim, Taewook, Park, Sungtae, Sammes, Nigel Mark, Chung, Jong-Shik
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 04.01.2018
• Subjects: Bi-layer; Ceramic interconnect; Flat-tubular solid oxide fuel cell; Perovskite; Titanate; Perovskite; Ceramic interconnect; Titanate; Flat-tubular solid oxide fuel cell; Bi-layer
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2017.11.024

A bi-layer interconnect with La0.8Sr0.2MnO3 and La0.4Sr0.6Ti0.6Mn0.4O3 (LSM/LSTM) is applied to anode-supported button cells and flat-tubular cells. Using a button cell, SEM images and gas permeation tests confirm that the bi-layer possesses a dense microstructure. The area specific resistance (ASR) of the LSM/LSTM remains nearly constant under oxidizing/reducing atmospheres with varying gas concentrations. For comparison, an LSM/LST with the same thickness is prepared; an increase in the ASR is observed as the concentration of H2 feed to the LST side decreases. The difference in the ASR of LSM/LST can be explained by exposure to a relatively high oxygen partial pressure and partial destruction of the interfacial LST layer region where oxygen diffuses from the LSM layer. Flat-tubular cells with the LSM/LSTM bi-layer interconnect achieve a maximum power density (MPD) of 463 mW cm−2 using humidified H2 fuel and air at 800 °C. With decreasing H2 concentration in the fuel, the polarization resistance increases rather than the ohmic resistance, implying that the LSM/LSTM interconnect provides stable conduction property. In comparison with the conventional LSM/LST interconnect cell, it shows improved stability and performance as the concentration of H2 in the fuel decreases. •We fabricated LSM/LSTM bi-layer interconnect with a dense microstructure.•ASR of the bi-layer was investigated under oxidizing/reducing atmospheres.•A flat-tubular SOFC with an LSM/LSTM bi-layer interconnect was investigated.