Low-Temperature Anode-Supported SOFC with Ultra-Thin Ceria-Based Electrolytes Prepared by Modified Sol-Gel Route

Abstract

The utilization of anode-supported electrolytes is a very promising strategy to improve the electrical performance in solid oxide fuel cells (SOFCs) application, because it is possible to decrease considerably the electrolytes thickness. In this paper, ultra-thin ceria-based electrolyte films were successfully prepared on porous NiO/GDC anode support. The electrolyte films with thickness of 0.5-1 µm were deposited by a novel citrate sol-gel route combined with a suspension spray coating technique. The characterization and microstructure of the ultra-thin films were investigated by DTA/TGA, XRD and FE-SEM. The results showed that ceria-based films prepared were pure fluorite type nanocrystalline, homogenous and almost fully dense. Electrochemical performance of single cells based on the ultra-thin electrolyte films was also tested. The single cell with electrolyte thickness of 1 µm provided an OCV of 0.832 V at 500 o C which was close to that of the reported single cell with thicker ceria-based electrolyte film of 10 µm, and maximum power densities of 59.6, 121.9 and 133.8 mW/cm 2 at 500, 600, and 700 o C, respectively. These ultra-thin electrolyte films showed good combination with the porous NiO/GDC anode supports, and good insulating ability for inactive electron migration at temperatures less than 600 o C.

Solid Oxide Fuel Cells with Magnetron Sputtered Single-Layer SDC and Multilayer SDC/YSZ/SDC Electrolytes

“…OCV of the SOFC with the single-layer electrolyte (5.5 µm thick) does not surpass 0.85 V at 500 °C and gradually lowers to 0.77 V as operating temperature increases up to 700 °C. For comparison, this figure shows OCV values of SOFCs with the single-layer SDC electrolyte having thicknesses of 0.5 µm [ 35 ], 10 µm [ 44 ], and 400 µm [ 45 ]. OCV depends not only on temperature, but also thickness of the SDC electrolyte, although OCV of anode-supported fuel cells with the electrolyte having 0.5 to 10 µm thickness does not strongly depend on the thickness.…”

“… Temperature dependences of OCV of SOFCs with single-layer SDC electrolyte, reproduced from [ 35 , 44 , 45 ], and multilayer SDC/YSZ/SDC electrolyte with different thickness of YSZ layer. …”

“…SOFCs with 1 µm thick SDC electrolyte, prepared in [ 35 ] by modified sol–gel route, were characterized by 0.83 OCV at 500 °C and maximum power densities of 59.6, 121.9, and 133.8 mW/cm 2 at 500, 600, and 700 °C, respectively. Yoo et al [ 36 ] fabricated an SDC electrolyte 30 µm thick by using suspension plasma spray for tubular SOFCs with metal base.…”