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    Structure and ionic conductivity of NASICON-type LATP solid electrolyte synthesized by the solid-state method
    (Elsevier Sci Ltd, 2024) Oksuzoglu, Fatih; Ates, Sule; Ozkendir, Osman Murat; Celik, Gultekin; Eker, Yasin Ramazan; Baveghar, Hadi
    The area of commercial battery innovation to replace safer batteries in widely used secondary batteries offers promising research into solid-state electrolytes (SSEs). Compared to lithium-ion electrolytes, solid-state electrolytes are inherently safer because they replace solvents with non-flammable materials. One of the promising materials for electrolytes today is based on inorganic materials, especially ceramics. Ceramics with superior mechanical, chemical and electrochemical stability and stability against high temperatures are of great interest. NASICON structured Li1.3 Al0.3 Ti1.7 (PO4)3 (LATP) is the most studied type of solid electrolyte due to its stability against air and humidity and high ionic conductivity. In this study, LATP samples were synthesized by solid-state synthesis method. The structural, morphological and charge transport properties (ionic conductivities) of the synthesized samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Since the modifications applied during the sample preparation process can change the crystal structure and size of the target material, in this study, in order to minimize the formation of impurity phases and to achieve high ionic conductivity it was applied the different synthesis steps (temperature, time, grinding speed, etc.) from the literature. While the ionic conductivity value obtained is among the best values obtained by LATP synthesis methods in the literature, it is the best ionic conductivity value (1.3 x 10-3 S cm-1) obtained by the solid state synthesis method.
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    Öğe
    The Effect of CrFe2O4 Addition on the Ionic Conductivity Properties of Manganese-Substituted LiFeO2 Material
    (Springer, 2024) Gunaydin, Selen; Miyazaki, Hidetoshi; Saran, Sevda; Baveghar, Hadi; Celik, Gultekin; Harfouche, Messaoud; Abdellatief, Mahmoud
    The influence of Mn substitution on the iron lattice sites in LiFeO2 material was investigated with respect to the electronic, crystalline, and electrochemical properties of the material, using the LiFe1-xMnxO2 (x = 0.0, 0.05, and 0.10) series. The electronic structure study was conducted with the acquisition of x-ray absorption fine structure spectroscopy data, while the crystal structure properties of the studied materials were investigated using x-ray diffraction patterns. The data collected for the ionic conductivity properties of the samples by electrochemical impedance spectroscopy under increasing temperature conditions around and above room temperature aided the crystal and electronic structure studies on cathode materials. Furthermore, studies were conducted with the addition of CrFe2O4 material in varying molar concentrations into LiFeO2 material, as CrFe2O4 is known to have thermoelectric properties well above the room temperature of 400 K (127 degrees C). Encouraging results for next-generation battery cathodes were obtained.
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    Öğe
    The effect of Ti to the crystal structure of Li7-3xMxLa3Zr1.8Ti0.2O12 (M= Ga, In) garnet-type solid electrolytes as a second dopant
    (Sage Publications Inc, 2022) Saran, Sevda; Eker, Yasin Ramazan; Ates, Sule; Celik, Gultekin; Baveghar, Hadi; Ozkendir, Osman Murat; Atav, Ulfet
    Garnet-type solid-state electrolytes are promising candidates for solid-state lithium batteries, nevertheless their ionic conductivity is still not enough for commercial applications. On the other hand, doping still is the common way to improve the ionic conductivities of these solid electrolytes. In this study, mono and dual-doped garnet-type solid electrolytes were synthesised by substituting indium (In), gallium (Ga), indium-titanium (In-Ti) and gallium-titanium (Ga-Ti) to the Li7La3Zr2O12 structure by a solid-state reaction method. The contribution of substitutions to the formation of crystal phases was investigated by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). On the other hand, morphological analyses were done by scanning electron microscope (SEM) and the ionic conductivities of the solid electrolytes were determined by electrochemical impedance spectroscopy (EIS). The study showed that while Li7-3xInxLa3Zr2O12 (for x = 0.05, 0.10, 0.15, 0.20) and Li7-3xGaxLa3Zr2O12 (for x = 0.05) samples were formed in tetragonal phase with a space group of I41/acd:2, dual substituted Li7-3xInxLa3Zr1.8Ti0.2O12 and Li7-3xGaxLa3Zr1.8Ti0.2O12 solid electrolytes for all x values were formed in cubic phase with a space group of I-43d. The highest conductivity is reached for Li6.85Ga0.05La3Zr1.8Ti0.2O12. The radial distribution function studies showed that when more In and Ga atoms take place in the sites of Li atoms, more O atoms take place in the vicinity of both substituted In and Ga atoms within the Li7La3Zr1.8Ti0.2O12 (LLZTO) crystal framework which can eventuate in a change in the conduction mechanism.
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    Öğe
    The Impact of Boron Compounds on the Structure and Ionic Conductivity of LATP Solid Electrolytes
    (Mdpi, 2024) Oksuzoglu, Fatih; Ates, Sule; Ozkendir, Osman Murat; Celik, Gueltekin; Eker, Yasin Ramazan; Baveghar, Hadi; Basyooni-M. Kabatas, Mohamed A.
    The increasing demand for safe and high-energy-density battery systems has led to intense research into solid electrolytes for rechargeable batteries. One of these solid electrolytes is the NASICON-type Li1+xAlxTi2-x(PO4)3 (LATP) material. In this study, different boron compounds (10% B2O3 doped, 10% H3BO3 doped, and 5% B2O3 + 5% H3BO3 doped) were doped at total 10 wt.% into the Ti4+ sites of an LATP solid electrolyte to investigate the structural properties and ionic conductivity of solid electrolytes using the solid-state synthesis method. Characterization of the synthesized samples was conducted using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). The XRD patterns of the boron-doped LATP (LABTP) samples show that the samples have a rhombohedral phase with space group R3c together and low amounts of impurity phases. While all the LABTP samples exhibited similar ionic conductivity values of around 10-4 S cm-1, the LABTP2 sample doped with 10 wt.% H3BO3 demonstrated the highest ionic conductivity. These findings suggest that varying B3+ ion doping strategies in LATP can significantly advance the development of solid electrolytes for all-solid-state lithium-ion batteries.