Optimizing Nickel Doping in La_0.7Sr_0.3Ti_0.15Fe_{0.85- x}Ni_xO_3-δ Perovskite as a Potential Cathode Material for LT-SOFC

¹ Department of Physics, Faculty of Mathematics and Natural Science, Universitas Negeri Malang, Jl. Semarang 5, Malang 65145, Indonesia.
² Center of Advanced Materials for Renewable Energy, Universitas Negeri Malang, Jl. Semarang 5, Malang 65145, Indonesia.
³ Integrated Science and Innovation, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, Thailand

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

Solid Oxide Fuel Cells (SOFCs) are among the most efficient and environmentally friendly technologies. The cathode is a crucial component of SOFC system, a high-performance cathode material must exhibit high conductivity, good catalytic activity and structural stability toward the oxygen reduction reaction (ORR). In this study, the sol-gel method was used to prepare La_0.7Sr_0.3Ti_0.15Fe_0.85-xNi_xO_3-δ (x=0, 0.1, 0.2, 0.3) powders and investigated for its potential as a cathode material for LT-SOFC. The phase, crystal structure, microstructure, morphology, and conductivity were characterized with varying Ni compositions. X-ray diffraction characterization reveals orthorhombic perovskite structure with space group Pnma. With increasing Ni content, the unit cell volume initially expanded but slightly contracted at x = 0.3, attributed to the smaller ionic radius of Ni³⁺ compared to Fe²⁺. The LSTFN powders exhibit an interconnected network-like morphology consisting of fine particles and pores. All samples showed good homogeneity, uniform particle distribution, and high porosity. Electrical conductivity increased with Ni doping, reaching a maximum value of 8.97 S∙m^-1 at room temperature for x = 0.2, more than twice that of the undoped sample. Further Ni content at x = 0.3, conductivity decreased may due to unit cell contraction. Therefore, the Ni composition of x = 0.2 is identified as the optimal concentration for enhancing performance. These results suggest that LSTFN is a potential cathode material for LT-SOFC.