IONIC CONDUCTIVITY AND ACTIVATION ENERGY OF Ce0,7Gd(0,3-x)NdxO1,9SOLID ELECTROLYTE FOR THE APPLICATION OF INTERMEDIATE TEMPERATURE SOLID OXIDE FUEL CELL

• Main Author: BAQIR (NIM : 12513046), FATTAAH
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/27222
• Institution: Institut Teknologi Bandung

Energy consumption is increasing by the years, resulting in the need of efficient power conversion technology. Solid Oxide Fuel Cell (SOFC) is a technology that can directly and efficiently converts chemical energy into electrical energy. Commercial SOFC still has some drawbacks such as high operating temperature, long start-up time, and also the aging effect on its solid electrolyte. Gadoliniumdoped Ceria (GDC) is a type of solid electrolyte for SOFC that has shown promising <br /> <br /> ionic conductivity at lower operating temperature. Addition of co-dopant into GDC can further increase its ionic conductivity, and the main elements and co-dopants <br /> <br /> needed to make solid electrolyte are available in Indonesia. For these reasons, it is promising to conduct a research about Gadolinium-Neodymium-doped Ceria (GNDC) solid electrolyte. <br /> <br /> <br /> In this experiment, GNDC solid electrolytes were made with Nd moles percentage variations of 0%, 10%, 15%, and 20%. Powder preparation was conducted using solid state mixing method, the powders are compacted at 40 kN to make pelletshaped samples with a diameter of 0,8 cm. The samples were sintered at 1400°C with sintering time variations of 3, 4, and 5 hours. Dimension and mass of the samples were measured before and after sintering to discover the linear shrinkage mechanism and densification. Impedance datas of the samples were measured using LCR meter at the operating temperature of 600°C to 350 °C with a temperature difference of 50 °C for each measurement. Impedance datas were analyzed using Electrochemical Impedance Spectroscopy (EIS). Resistance data from EIS analysis were converted into ionic conductivity and activation energy. SEM-EDS and XRD analysis were also conducted to the sintered samples. <br /> <br /> <br /> GDC and GNDC samples were successfully synthesized and CeO2 phase with cubic crystal structure is identified within the samples. The linear shrinkage mechanism is observed to be diffusion at grain boundary for samples with Nd moles percentage of 0% and 15%, but for samples with Nd moles percentage of 10% and 20% the linear shrinkage mechanism is diffusion at grain boundary lattice. EIS analysis showed contribution of grain boundary and grain bulk to sample resistance. Ionic <br /> <br /> conductivity and relative density increased with higher sintering time. The highest ionic conductivity (2,1×10-2 S/cm) and relative density (77,31%) are obtained respectively by GNDC510 and GDC5 sample. The ionic conductivity increased to the optimum value at 10% moles Nd but starts to decrease with further increase of <br /> <br /> Nd moles percentage. It is also observed that samples with high ionic conductivity have a lower activation energy, for example the GNDC510 sample with activation energy of 0,68 eV. <br />