Regular Article

Preparation and property analysis of solid carbonate-oxide composite materials for an electrolyte used in low-temperature solid oxide fuel cell

College of Materials Science and Engineering, Guangdong University of Petrochemical Technology, 139 Guanduer Road, Maonan District, Maoming City 525000, Guangdong Province, PR China

^* Corresponding authors: 2032466104@qq.com; gyucao@gdupt.edu.cn

Received: 4 October 2021
Accepted: 4 February 2022

Abstract

The oxide-carbonate composite electrolyte material with high ionic conductivity at low temperature has been thought that it can be used to develop LT-SOFC. However, the carbonate composite electrolyte is not easy to make it dense, especially mixing and packing oxide and carbonate to fabricate the composite electrolyte simply. In this article, rare-earth-doped CeO₂ (RDC) (R = La, Sm, Gd, and Gd + Y) series samples were prepared by wet ball-milling, then sintered into fully dense and porous oxide bulk at 1500–1600 °C and 1000 °C. Melted carbonate LNCO, composed of Li₂CO₃ and Na₂CO₃ at a molar ratio of 1:1, was combined with porous oxide bulk materials using a bath method at 500 °C for 10 h to prepare a dense carbonate-oxide composite electrolyte. The dense oxide-carbonate composite electrolyte always obtains by this fabrication process. Boiling water was used to remove carbonate from these composites. Lattice parameters were obtained through Rietveld refinement, and a calculation procedure for quantifying the composite density was proposed. The quantified composite density results were verified through scanning electron microscopy microstructure observations. The Ce valence in the RDC oxides and RDC-carbonate composite was analyzed by X-ray absorption near edge structure spectroscopy to observe the effects of heat treatment temperature and carbonate on the Ce⁴⁺/Ce³⁺ mixed-valence state in doped CeO₂.