_Article_  
**Carbonate-Based Lanthanum Strontium Cobalt Ferrite (LSCF)-Samarium-Doped Ceria (SDC) Composite Cathode for Low-Temperature Solid Oxide Fuel Cells**  
**[PERSON] 1**, **[PERSON] 2**, **[PERSON] 3**, **[PERSON] 4**, **[PERSON] 1**, **[PERSON] 6**, **and [PERSON] 1**  
1 Fuel Cell Institute, Universit Kebangsaan Malaysia, UKM Bangi, Selangor 43600, Malaysia; [EMAIL_ADDRESS] (M.A.S.A.); [EMAIL_ADDRESS] (M.R.S.)  
2 Center of Materials Technology, Agency for the Assessment and Application of Technology (BPPT), Jl. M.H[PERSON] 8, Jakarta Pusat 10340, Indonesia; [EMAIL_ADDRESS]  
3U.S.-Pakistan Center for Advanced Studies in Energy, National University of Sciences and Technology, H-12, Islamabad 44000, Pakistan; [EMAIL_ADDRESS]  
4 Research Center for Physics, Indonesian Institute of Sciences (LIPI), Gd.440-442, Kawasan Puspiptek Serpong, Tangerang Selatan, Banten 15314, Indonesia; [EMAIL_ADDRESS]  
5 Department of Mechanical and Manufacturing Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, UKM Bangi, Selangor 43600, Malaysia  
6 Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Via G. Di Biasio 43, 03043 Cassino (FR), Italy  
7 Correspondence: [EMAIL_ADDRESS] (A.M.); [EMAIL_ADDRESS] (L.S.); Tel.: +60-389118379 (A.M.); rax: +089252699 (A.M.) check for updates  
Received: 2 May 2020; Accepted: 26 May 2020; Published: 28 May 2020  
**Featured Application: Lanthanum strontium cobalt ferrite oxide (LSCF) based composite materials were used as a cathode for low temperature solid oxide fuel cells. Many studies have been reported in literature concerning their performance in improving the oxygen ion conducting behavior at temperatures below 600 \({}^{\circ}\)C. However, studies concerning the effect of samarium doped ceria-carbonate (SDCC) composite electrolyte content on the electronic network over the LSCF cathode surface are still limited. Therefore, the present study aims to fill the research gap with respect to SDCC content and its effect on the in-plane electronic conducting behavior at the surface of the LSCF cathode at low operating temperatures (i.e., 400-650 \({}^{\circ}\)C). Composite cathode was prepared by mixing LSCF cathode and SDCC composite electrolyte powders at different weight percentages (i.e., 70:30 wt %, 60:40 wt %, and 50:50 wt %) to determine the effect on the overall electrochemical performance under real fuel cell operating conditions.**  
**Abstract:** Perovskite-based composite cathodes, La\({}_{0.6}\)Sr\({}_{0.4}\)Co\({}_{0.2}\)Fe\({}_{0.8}\)O\({}_{3-8}\) (LSCF)-Ce\({}_{0.8}\)Sm\({}_{0.2}\)O\({}_{1.9}\)-carbonate (SDCC), were investigated as cathode materials for low-temperature solid-oxide fuel cells. The LSCF was mixed with the SDC-carbonate (SDCC) composite electrolyte at different weight percentages (i.e., 30, 40, and 50 wt %) to prepare the LSCF-SDCC composite cathode. The effect of SDCC composite electrolyte content on the diffraction pattern, microstructure, specific surface area, and electrochemical performances of the LSCF-SDCC composite cathode were evaluated. The XRD pattern revealed that the SDCC phase diffraction peaks vary according to its increasing addition to the system. The introduction of SDCCs within the composite cathode did not change the LSCF phase structure and its specific surface area. However, the electrical performance of the realized cell drastically changed with the increase of the SDCC content in the LSCF microstructure. This drastic change can be ascribed to the poor in-plane electronic conduction at the surface of the LSCF cathode layer due to the presence of the insulating phase of SDC and molten carbonate. Among the cathodes investigated, LSCF-30 SDCC showed the best cell performance, exhibiting a power density value of 60.3-75.4 mW/cm\({}^{2}\) at 600 \({}^{\circ}\)C to 650 \({}^{\circ}\)C.  
**Keywords:** SOFC; perovskite; composites; cathode; electrical performance