Papers by Keyword: Solid Electrolyte

Abstract: Solid oxide electrolysis cell (SOEC) and solid oxide fuel cell (SOFC) have been receiving significant attention for future energy storage and hydrogen production applications. This research focuses on the electrolyte material which can be used for both SOEC and SOFC particularly on 8 mol% yttria-stabilized zirconia (8YSZ) electrolyte material. YSZ has been used because of its high stability at elevated temperature, excellent mechanical and chemical properties and its excellent oxygen ion conductivity. This study aims to determine the effect of precursor’s grain size and sintering temperature on the properties of YSZ as electrolyte material for SOEC. Solid-state sintering was done to transform the ceramic powders into solid compacts. Pure cubic fluorite structure YSZ was achieved by both micrograined and nanograined YSZ sintered at 1200°C and 1500°C. It was observed that the micrograined YSZ sample sintered at 1500°C achieved the highest relative density at 99.48%. SEM images showed a smooth and compact microstructure for micrograined YSZ while small pores were still present in the micrographs of nanograined YSZ. However, interestingly, the nanograined YSZ has higher total conductivity as compared to the micrograined YSZ.

Abstract: Conductivity of sodium based solid electrolyte xNaI-(100 - x)NaN(CN)₂ with various compositions (0 ≤ x ≤ 70) were investigated by Electrochemical impedance spectroscopy (EIS) method in order to determine the conductivity value. Maximum conductivity of 10^-4 S cm^-1 was obtained for sample with 10 wt.% NaI. The improved conductivity could be due to presence of dicyanamide as an anionic-bridging ligand compound that provided conducting pathway for rapid Na⁺ ion conduction. The binary sodium solid electrolyte system was prepared by ball milling method with 200 rpm for 2 hours in order to promote ultra-fine size reduction and introducing defects in the crystal structure thus assisting rapid ionic mobility via hopping. Results obtained from Fourier transform infrared spectroscopy (FTIR) characterisation showed some changes in infrared spectrum peak appearance within wavenumber region of 2200 – 2500 cm^-1 that had proven some weak intermolecular interaction at the terminal N (nitrile) atoms of the dicyanamide.

Abstract: In this paper, Cu-doped lanthanum silicate electrolyte (La_9.33Si_6-xCu_xO_26-x) precursor was synthesized by urea-nitrate combustion method using La₂O₃, CuO and TEOS as raw materials. The as-prepared precursor was lighted at 600 °C and sintered at 800 °C. The sintered powder samples were grinded and mixed absolutely by ball milled. Finally, we preformed and sintered powder samples to synthesis Cu-doped lanthanum silicate ceramics. Ac impedance method and analysis was used to test conductivity of as-prepared electrolyte, investigated the influence of balling time, sintering temperature and doping content on conductivity property of LSO sintered product. The final result shows that best balling time is 3 h, secondary sintering temperature is 1500 °C and the doping content is 0.3. Under this condition, the conductivity of Cu-doped lanthanum silicate electrolyte could reach 7.28×10^-3 s/cm at 700 °C.

Abstract: Conventional solid-state synthesis of Li_7-3xGa_xLa₃Zr₂O₁₂ (LLZ) at x = 0.0 and 0.1 were performed in an attempt to investigate the microstructural and electrochemical properties of pure and Ga-doped LLZ as solid electrolyte material. The XRD patterns have shown that upon sintering at 1150°C the cubic-phased garnet LLZ were fully stabilized. Ga-doped LLZ exhibited a Li-ion conductivity up to 2.03 x 10^-4 Scm^-1 at 25°C. The relative densities of the pure and Ga-doped LLZ sintered at 1150°C for 15 h are 87.62% and 88.79%, respectively. This suggests that Ga dopant, even at small amount of x = 0.1, promotes densification. SEM-EDS confirmed the presence of Ga and homogenous distribution of elements in the synthesized material.

Abstract: Researchon thepreparation of ceria based materialfor electrolyteof solid oxide fuelcellhasbeen conducted. The Sm_0.2Ce_0.8O_1.9(SDC) was prepared by sol-gel method and the layered composites of SDC with Y_0.08Zr_0.92O_3-δwerepreparedbyscreenprintingmethod.This research aims to studythecrystal structure and its conductivitycharacter. XRDmeasurementequippedwithLeBailrefinementshowsthatSDCiscrystallizedin cubic structure with space group of Fm3m.Theaddition ofYSZ into SDC does not changeitscrystal structure. However, the cell parameter of SDC is reduced from 5.434036(2) Å to 5.433(0) Å. At 600 °C, SDC has electronic conductivity that indicates the presence of electrons migration that can promotes short circuit during fuel cell operation. The combination of SDC with YSZ forming a layered composite of SDC-YSZ-SDC could reduce the electronicconductivity,eventhoughitsionicconductivityisalsobecomelowerthansingleSDCatthe same temperature.

Abstract: One of the promising material for proton-conducting solid electrolyte operating at intermediate temperature range (400-600 °C) is the Yttrium-doped BaZrO₃ (BZY) due to its high conductivity and chemical stability. In this study, a modified citrate-nitrate combustion method (Pechini method) has been employed for BZY powder preparation. A stoichiometric amounts of starting nitrates and oxide raw materials with nitric acid, citric acid and ethylene glycol for the synthesis of 20 mol% Y-doped BaZrO₃ (BZY20) were prepared, then calcined and sintered at 1000 °C for two heat treatment durations of 24 hours and 48 hours. The obtained BZY20 powder samples have been fully characterized for its structure, morphology, and thermal properties. From the X-ray diffraction (XRD) results, the sample sintered for 48 hours showed a cubic phase of BZY20 which can be indexed to a Pm3m cubic structure which is also supported by Raman analysis. The calculated lattice parameter is 4.2067 Å which is higher than the reported lattice parameter of a pure BaZrO₃ (BZ) of 4.1930 Å which indicates a successful doping due to higher ionic radius of Y³⁺ dopant as compared to Zr⁴⁺ in the B-site ABO₃ perovskite sub-lattice. In addition, SEM-EDX analyses of the sintered pellet revealed a uniform distribution of Yttrium dopant in the BZY20 prepared solid electrolyte.

Abstract: The development trend of all solid state lithium ion battery and the importance of lithium ion solid electrolyte in all solid state lithium ion batteries is introduced in this paper. The application of rare earth doping in solid electrolyte of lithium ion battery is summarized. We suggest that rare earth doping is favorable for the increase of the lithium ion battery electrolyte conductivity, thus it is beneficial to further improve the overall performance of all solid state lithium ion battery. The development prospect of rare earth doping in solid electrolyte of all solid state lithium ion battery is looked forward. In addition, we deem that the above mentioned technology is an important research aspect of solid state electrolyte.

Abstract: Ceramics based on Y-doped BaCeO₃ were prepared by citrate process. The X-ray fluorescence shows that barium stoichiometry deviation is established during calcination step. Through the SEM analysis of fracture surface of sintered samples it was possible to infer that powder highly deficient of barium shows higher diffusion coefficient during sintering than stoichiometric powder promoting grain growth and, consequently, trapping pores into the grains.

Abstract: High performance Al-doped Li₇La₃Zr₂O₁₂ (LLZO) solid electrolytes were successfully prepared by plasma activated sintering method. The effect of Al₂O₃ concentration on the microstructure and ionic conductivity of Li₇La₃Zr₂O₁₂ was investigated. Without addition of Al₂O₃, only tetragonal phase was obtained at temperature range of 1000-1200 °C. Pure cubic phase of LLZO was obtained with the addition of 1.2-1.8 wt.% Al₂O₃. The pellet sintered at 1150 °C with 1.5 wt.% content of Al₂O₃ had a maximum relative density of 99.8 % with total ionic conductivity of 5.7×10⁻⁴ S/cm at room temperature. Al₂O₃ can stabilize the cubic LLZO phase which promotes the transformation of LLZO from tetragonal to cubic phase.

Abstract: Hydroxide ion conductors containing KOH were prepared for application in an all-solid-state Fe–air battery. ZrO₂ and Mg–Al layered double hydroxide (LDH) were employed as the matrix materials. The ionic conductivity and conducting ion species were evaluated by impedance and electromotive force measurements. Repeated charge and discharge were achieved by using negative electrodes composed of the solid electrolyte and iron oxide-supported carbon.