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Öğe High-Performance Ag-Doped Na0.67MnO2 Cathode: Operando XRD Study and Full-Cell Performance Analysis with Presodiated Anode(Amer Chemical Soc, 2023) Kalyoncuoglu, Burcu; Ozgul, Metin; Altundag, Sebahat; Altin, Emine; Moeez, Iqra; Chung, Kyung Yoon; Arshad, MuhammadThe key challenges of Na-ion batteries are to design structurally stable electrodes and reach high-enough capacities with full-cells. In this study, we report the positive effects of Ag substitution/addition to Na0.67MnO2. We determined that some of the intended Ag was incorporated into the structure, while the rest remained in metallic form. Ag substitution/addition increases the capacity (208 mA h/g at C/3 rate) and improves the cycle life of Na0.67MnO2 (42% capacity fade with 100 cycles) in half-cells. We attribute these results to an enlarged interlayer spacing due to the large ionic radius of Ag, a suppressed Jahn-Teller effect due to the reduced number of Mn3+ ions, and an increased electrical conductivity due to the presence of metallic Ag. We also produced full-cells with an electrochemically presodiated hard carbon anode. We reached a very high initial capacity of 190 mA h/g at the C/3 rate, showing that Ag substituted/added Na0.67MnO2 is a promising candidate for commercialization of Na-ion batteries.Öğe High-Performance Full Sodium Cells Based on MgO-Treated P2-Type Na0.67(Mn0.5Fe0.5)1-xCoxO2 Cathodes(Mdpi, 2023) Taskiran, Nermin; Altundag, Sebahat; Koleva, Violeta; Altin, Emine; Arshad, Muhammad; Avci, Sevda; Ates, Mehmet NurullahHerein, we design a cathode material based on layered Na-2/3(Mn1/2Fe1/2)O-2 for practical application by combining the Co substitution and MgO treatment strategies. The oxides are prepared via solid-state reactions at 900 degrees C. The structure, morphology, and oxidation state of transition metal ions for Co-substituted and MgO-treated oxides are carefully examined via X-ray diffraction, IR and Raman spectroscopies, FESEM with EDX, specific surface area measurement, and XPS spectroscopy. The ability of oxides to store sodium reversibly is analyzed within a temperature range of 10 to 50 degrees C via CV experiments, galvanostatic measurements, and EIS, using half and full sodium ion cells. The changes in the local structure and oxidation state of transition metal ions during Na+ intercalation are monitored via operando XAS experiments. It is found that the Co substituents have a positive impact on the rate capability of layered oxides, while Mg additives lead to a strong increase in the capacity and an enhancement of the cycling stability. Thus, the highest capacity is obtained for 2 at.%-MgO-treated Na-2/3(Mn1/2Fe1/2)(0.9)Co0.1O2 (175 mAh/g, with a capacity fade of 28% after 100 cycles). In comparison with Co substituents, the Mg treatment has a crucial role in the improvement of the lattice stability during the cycling process. The best electrode materials, with a chemical formula of 2 at.%-MgO treated Na-2/3(Mn1/2Fe1/2)(0.9)Co0.1O2, were also used for the full cells design, with hard carbon as an anode. In the voltage window of 2-4 V, the capacity of the cells was obtained as 78 mAh/g and 51 mAh/g for applied current densities of 12 mA/g and 60 mA/g, respectively.Öğe High-performance Na-ion full-cells with P2-type Na0.67Mn0.5-xNixFe0.43Al0.07O2 cathodes: Cost analysis for stationary battery storage systems(Elsevier, 2024) Kalyoncuoglu, Burcu; Ozgul, Metin; Altundag, Sebahat; Bulut, Fatih; Oz, Erdinc; Sahinbay, Sevda; Altin, SerdarNa -ion batteries are viable alternatives to Li-ion batteries especially for stationary applications. Developing suitable electrode materials, half-cell and full-cell studies and cost analysis are major steps and challenges for their commercialization. In this study, we report the synthesis of a promising cathode material, Na0.67Mn0.5- xNixFe0.43Al0.07O2 (x = 0.02-0.10 with Delta x = 0.02), using a modified solid-state synthesis technique. The materials were heated at high temperature for 6 h in air and quenched in liquid N-2. We determined the solubility limit of Ni in Na0.67Mn0.5Fe0.43Al0.07O2 as x <= 0.06. The interlayer separation increases with increasing Ni content due to the ionic radii difference between Mn and Ni. X-ray photoelectron spectroscopy (XPS) measurements evidence the valance state of Ni in the x = 0.06 sample as 2+ and 3+. Cyclic voltammetry (CV) analysis of the half-cells were performed at 10 C-degrees, room temperature, and 50 degrees C to observe the effect of environmental temperature on redox mechanism. The highest half-cell capacity of the cells was determined as 181 mAh/g for x = 0.06 at C/3-rate. Artificial solid electrolyte interface (SEI) formation was performed on the hard carbon anode by presodiation technique and the full-cells of Na0.67Mn0.44Ni0.06- Fe0.43Al0.07O2/hard carbon were assembled in CR2032 coin cells. The capacity values of the cells at C/2, C, and 2C-rate were determined as 131.4 mAh/g, 116 mAh/g and 100.8 mAh/g for the 1 cycle and 33 mAh/g, 40.6 mAh/g and 49.9 mAh/g for the 500th cycle, respectively. The cost analysis for the commercial package for stationary energy storage system was performed by BatPac program and results are discussed.Öğe High-performance P2-Na0.67Mn0.85Cu0.15O2/Hard carbon full cell Na-ion battery: Pre-Sodiation of anode, p/n ratio optimizations, and Operando XAS studies(Pergamon-Elsevier Science Ltd, 2023) Altundag, Sebahat; Altin, Emine; Altin, Serdar; Ates, Mehmet Nurullah; Ji, Xiaobo; Sahinbay, SevdaNa-ion batteries have gained significant attention as a cost-effective and efficient energy storage option for large scale applications, serving as an alternative to the Li-ion batteries. However, commercialization of these batteries is still many steps away since most cathode materials suffer from significant capacity loss and more full-cell studies are required. In this work, we report the electrochemical properties of half-and full-cells of P2-type Na0.67Mn0.85Cu0.15O2 synthesized by solid state technique. X-ray diffraction, FT-IR, and Raman spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy techniques are used to determine the structural properties. Surface properties are studied by X-ray photoelectron spectroscopy and Bru-nauer-Emmett-Teller techniques. Half cells and full cells were constructed with Na-metal and hard carbon, respectively. Na-ion diffusion kinetics at 10 degrees C, room temperature, and 50 degrees C were determined experimentally. Galvanostatic cycling tests on half-cells show capacity values of 165/124 mAh/g for the 1./100. cycles with 24.8 % capacity fade. Operando x-ray absorption spectroscopy measurements were utilized to study local structural modification around transition metal ions during charge/discharge. In the full-cell studies, electrode mass ratio (p/n) and parameters for presodiation of hard carbon were optimized. Using 30 mA/g current density, the un-processed and the pre-sodiated full-cells reach capacity values of 48 mAh/g (p/n = 2.5) and 150 mAh/g (p/n = 0.75 and 1.15), respectively.Öğe Investigation of electrochemical performance of Na-ion batteries by hard carbon anodes produced by biomass of Prunusarmeniaca seeds(Springer, 2023) Oktay, Zeynep Melek; Onal, Yunus; Depci, Tolga; Altundag, Sebahat; Altin, Serdar; Yasar, Sedat; Altin, EmineHard carbon is successfully fabricated using biomass of Prunusarmeniaca seed shells, and its structural properties are examined by different spectroscopic techniques. For using as an anode electrode in Na-ion batteries, the material is subjected to further pyrolysis at varying temperatures for achieving the necessary levels of conductivity and surface area which are important features for electrode materials. Distinguish properties of the hard carbon in the XRD study appeared as broad peaks at 2 & theta; = 23 & DEG; and 43 & DEG;. The purity of produced hard carbons was approved by EDX to analyze that the purity of hard carbon is greater than 99.9%, making it suitable for industrial use. It was found that the CV curves of the cells created in this work utilizing hard carbon were quite comparable to the CV curves of commercially produced hard carbon cells. According to charge/discharge cycling measurements for constant current at rt, the highest capacity of 210.2 mAh/g using 0.1 A/g is obtained for the material pyrolyzed at 1200 & DEG;C and the capacity fade was found as 0.11. From these promising results, it is thought that the produced hard carbon can be easily used in the production of anode electrodes in commercial Na-ion batteries and technological applications. So it is summarized that P. armeniaca seed shells is one of the main sources for the production of the hard carbon and it can be used as an anode materials in battery cells.Öğe Investigation of hybrid-capacitor properties of ruthenium complexes(Wiley-Hindawi, 2019) Altin, Serdar; Oz, Erdinc; Altundag, Sebahat; Bayri, Ali; Roisnel, Thierty; Dorcet, Vincent; Bruneau, ChristianRu complexes were successfully produced, and their structural properties were investigated using FTIR, Raman, and single crystal XRD patterns. The HOMO, LUMO, Eg, and electronic surface potential (ESP) values of the molecules were calculated by a Gaussian program. The complexes were used for producing hybrid capacitor cells as electrode materials. According to electrochemical analysis, complex 2 showed the best CV graph between -1 V and +1 V and had the highest current value and hysteresis area when compared with the other complexes. The performance analysis and the capacity fade of the cells were investigated. The first capacity values of the complexes were 57.5, 22.1, 16.9, and 0.0021 F/g for complexes 1, 2, 3, and 4, respectively. The capacitive mechanism of the cells as relates to molecular interactions was also investigated. We suggested that the ESP values of the molecules were directly related to the capacitive performance of the cells. In addition to this, the best cycling performance was obtained for complex 2, which has the lowest Eg value among the complexes. We speculate that the charged regions on the complex materials have a crucial role in the increasing the capacitance of the cells.Öğe Investigation of structural and electrochemical performance of Ru-substituted LiFePO4 cathode material: an improvement of the capacity and rate performance(Springer, 2022) Yolun, Abdurrahman; Altin, Emine; Altundag, Sebahat; Arshad, Muhammad; Abbas, Syed Mustansar; Altin, SerdarLiRuxFe1-xPO4 (where x = 0.01-0.12) samples are successfully fabricated by conventional solid-state reaction technique and the structural properties are analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and fourier transform infrared spectroscopy (FTIR) measurements. The XRD analysis shows that the minor impurity phases of RuO2 and LiRuO2 are observed for x >= 0.05 samples. Furthermore, the lattice volume is decreased with increasing Ru-content in the structure. The Ru-substituted battery cells exhibit similar cycling voltammetry (CV) data with the unsubstituted LiFePO4 battery cells. According to the charging/discharging cycles measurements for C/3-rate, the best capacity (147.58 mAh g(-1)) is obtained for LiFe0.93Ru0.07PO4 with a capacity fade of 0.0084 per cycle. It is found that Ru-substituted LiFePO4 has maximum C-rate when we analogize with the pristine LiFePO4 and the battery cycling performance is investigated for 4 C-rate up to 100 cycles and 3 and 4 C-rate up to 1000 cycles and it is found that Ru-substituted LiFePO4 exhibits excellent electrochemical performance such as 122, 84.5, and 53.1 mAh g(-1) for 1st, 500th, and 1000th cycles at 4 C-rate.Öğe Investigation of Ti-substitution effects on structural and electrochemical properties of Na0.67Mn0.5Fe0.5O2batterycells(Wiley-Hindawi, 2020) Altin, Serdar; Altundag, Sebahat; Altin, Emine; Oz, Erdinc; Harfouche, Messaoud; Bayri, AliTi-substituted Na(0.67)Mn(0.5)Fe(0.5)O(2)powders were fabricated by quenching at high temperatures, and the structural properties were investigated by Fourier transform infrared (FTIR), Scanning Electron Microscope (SEM), X-ray powder diffraction (XRD), and X-ray absorption spectroscopy (XAS) measurements. According to XRD analysis, it was not observed any impurity phases and it was found that the lattice constants of the powders were slightly increased by Ti content. The change in the valence state of both Mn and Fe ions was investigated by X-ray absorption near edge structure (XANES), and it was found that Ti-substitution caused a decrease in the valance state of Fe in Na0.67Mn0.5Fe0.5O2. Fourier transform (FT) of XANES showed that the local structure around the metal ions changed with the addition of Ti ions. The cycling voltammetry (CV) graphs of Ti-substituted cells were almost the same as the pure sample, which may not change the cycling mechanism in the cells. According to galvanostatic cycling measurements at room temperature, the best performance was obtained with Ti-substitution of 0.06 to 0.09 in the structure. The effect of environmental temperature in the battery cells was investigated at 10 degrees C to 50 degrees C, and it was found that the battery performance depends on the environmental temperatures.Öğe Magnetic Properties and Environmental Temperature Effects on Battery Performance of Na0.67Mn0.5Fe0.5O2(Wiley-V C H Verlag Gmbh, 2021) Altin, Serdar; Bayri, Ali; Altin, Emine; Oz, Erdinc; Yasar, Sedat; Altundag, Sebahat; Harfouche, MessaoudHerein, a modified solid state synthesis of Na0.67Mn0.5Fe0.5O2 and the results of a detailed investigation of the structural and magnetic properties via Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis are reported. The magnetic properties of Na0.67Mn0.5Fe0.5O2 do not fit the Curie-Weiss law and a model regarding the spin configuration of the Mn and Fe ions and a possible ferrimagnetic order is suggested. Electrochemical measurements and ex situ structural analysis of the cathode material confirm the reversible structural transitions for the cells charged up to 4.0 V. Environmental temperature-dependent electrochemical measurements reveal a strong temperature dependence of both, the initial capacity and the capacity retention. Ex situ SEM, FTIR, and XRD studies on the battery membrane verify the formation of a Na2CO3 phase on the membrane, which blocks the Na ion diffusion through membrane pores and is responsible for the capacity fade for this compound.Öğe Optimization of Electrochemical Presodiation Parameters of Na-Ion Full Cells for Stable Solid-Electrolyte Interface Formation: Hard Carbon Rods from Waste Firefighter Suits(Wiley-V C H Verlag Gmbh, 2023) Yalman, Emine; Altundag, Sebahat; Aydin, Mustafa Goktan; Onal, Yunus; Depci, Tolga; Tekbas, Hasan; Bulut, FatihUtilizing the synthetic waste of firefighter costumes, rod-shaped hard carbon materials are effectively produced for the first time with over 99% purity, and their structural properties are evaluated using the appropriate spectroscopic techniques. The galvanostatic cycling tests are performed at different temperatures and the result shows that the capacity and capacity fade values are directly affected by the temperature. The high-rate consumption of sodium ions during the evolution of the solid-electrolyte interface in the first cycle of the cells is observed and the highest capacity of the half cells is obtained as 410 and 233 mAh g(-1) for the first and second cycles, respectively. To compensate for the sodium-ion loss, an electrochemical treatment presodiation technique is implemented, which is an effective means of compensating for the initial inefficiency. The optimum presodiation condition of electrochemical treatment of anode electrode for the production of Na0.67Mn0.5Fe0.45Ti0.07O2/presodiated hard carbon full cells is investigated. The highest capacity values for C/10 are obtained at 114.9 mAh g(-1) for the full cells using the voltage window of 2-4 V. The cost analysis of the battery pack for 90 kW electric-powered cars is calculated by the BatPaC software and the results are evaluated for possible commercialization.Öğe P2-type Na0.67Mn0.5-xVxFe0.43Ti0.07O2 powders for Na-ion cathodes: Ex-situ structural analysis and full-cell study(Pergamon-Elsevier Science Ltd, 2024) Dogan, Ebru; Altundag, Sebahat; Altin, Emine; Oz, Erdinc; Altin, SerdarThis study used a modified solid-state synthesis technique to synthesize Na0.67Mn0.5-xVxFe0.43Ti0.07O2 (x = 0.02 0.1) cathode materials. The XRD pattern shows that there are no impurity phases in the samples for x <= 0.06. The granular grain formation was observed in each sample and the largest surface area was obtained for x = 0.06 Vdoped composition. According to XPS analysis of the x = 0.06 sample, the V and Ti ions have three different valence states in the structure and the ratio of V3+/V4+/V5+ ions in the powders was calculated as 13 %/36 %/51 % and the spin splitting binding energy gaps were found as 7.1 eV for each V-ions and they affected by cycling process. The redox mechanism of the half cells was investigated at 10 degrees C and room temperature. The diffusion coefficient values of Na+ were calculated by cycling voltammetry (CV) and GITT techniques for the x = 0.06. Although the highest capacity of the half cells for the V-substituted samples was found to be 188.3 mAh/g for x = 0.02 V-doping in the cells for C/3-rate, the best capacity fade among the cells was obtained for x = 0.06 as 36.9 %. The ex-situ analysis of the electrodes after 100 cycles at the environmental temperatures of 10 degrees C, 50 degrees C, and 60 degrees C was investigated and it was found that the valence state of the elements changed by the cycling process. The artificial solid electrolyte interface (SEI) formation on the anode surface was performed by presodiation technique and the full cells were assembled using Na0.67Mn0.44V0.06Fe0.43Ti0.07O2/hard carbon architecture and the obtained first capacity values for C/3-rate were 90.1 mAh/g and 66.6 mAh/g, respectively, and the capacity value decreased with the cycling process up to 60 cycles and then gave a plateau with increasing cycle numbers up to 500 cycles.Öğe Production of Pb-doped LiFePO4 and analysis of their electrochemical performance(Springer, 2023) Gultek, Ezgi; Altundag, Sebahat; Altin, Serdar; Altin, EmineIn this study, LiFe1-xPbxPO4 (x = 0-0.12) powders were successfully produced by solid-state technique. The XRD patterns of the samples exhibit that the main phase is LiFePO4 with minor impurity phases of PbO and Fe2O3 in the structure, in which the phase ratio of PbO increases with increasing doping content. Four probe electrical resistance measurements showed that resistance decreases from 111 kO to 37 kO when increasing Pb-content; however, CV measurement indicated that redox peak wideness increased for x = 0.09, unwanted behavior for the battery cells. The galvanostatic cycles at C/2-rate yielded the highest capacity value of 121.6 mAh/g at room conditions with 1.06% capacity fade over 100 cycles when using x = 0 0.06 sample-better than undoped cells-while C-rate tests confirmed promising results for LiFePO4 cells using same sample concentration level.Öğe Production of V-Doped P2-type Na0.67Mn0.5Fe0.43Al0.07O2 Cathodes and Investigation of Na-Ion Full Cells Performance(Wiley-V C H Verlag Gmbh, 2024) Dogan, Ebru; Altundag, Sebahat; Altin, Serdar; Arshad, Muhammad; Balci, Esra; Altin, EmineThe Na0.67Mn0.5Fe0.43Al0.07O2(x = 0-0.1) samples are successfully produced and their structural properties are investigated by common techniques. The highest surface area is found as 4.94 m(2) g(-1) for x = 0.04 V by the Brunauer-Elmet-Teller analysis. According to X-ray photoelectron spectroscopy of x = 0.04 V-doped sample,V4+, and V5+ ions are formed in the structure. The main phase is observed as P63/mmc symmetry with an impurity phase of V6O13 for x >= 0.06 . According to the CV analysis, while the redox voltage decreases for the Mn3+/Mn4+ , the intensity of the peaks of Fe2+/Fe3+ redox reaction decreases. While the best capacity value of the half cells at C/3-rate is obtained as 171 mAh g(-1) for x = 0.04, the lowest capacity fade is found for x = 0.08 . It is mentioned the V6O13 may contribute to the electrochemical process . The galvanostatic tests are investigated for the voltage windows of 3.5-1.5, 4-1.5, 4-2.5, 4-2, and 4-2.5 V and it is seen that the battery cells for 3.5-1.5 V have the best capacity fade (6%) among the others. The Na0.67Mn0.5Fe0.43Al0.07O2/ hard carbon is used for the full cells with presodiated anode and the first capacity value of the full cell is obtained as 80.2 mAh g(-1) for C/2-rate.Öğe Unveiling the outstanding full-cell performance of P2-type Na0.67(Mn0.44Ni0.06Fe0.43Ti0.07)O2 cathode active material for Na-ion batteries(Elsevier, 2024) Kalyoncuoglu, Burcu; Ozgul, Metin; Altundag, Sebahat; Harfouche, Messaoud; Oz, Erdinc; Avci, Sevda; Ji, XiaoboIn this study, we unravel the effect of Ni doping on the half-cell and full-cell performances of the Na0.67Mn0.5-xNixFe0.43Ti0.07O2 cathode materials where x varies between 0.02 and 0.1. The cyclic voltammetry (CV) analysis of the half-cells is performed at 10 degrees C, room temperature (RT), and 50 degrees C to elucidate the redox reaction mechanisms at different temperatures. Among the studied cathodes, the highest specific capacity is obtained fox = 0.06 which delivered a specific capacity of 186 mAh g-1 at C/3-rate. The full cell of Na0.67Mn0.44Ni0.06-Fe0.43Ti0.07O2/hard carbon couple is assembled in coin cell format and the specific capacity of the cell at C/2, 1C, and 2C rates are found as 153 mAh g- 1, 125 mAh g-1 and 120 mAh g-1, respectively. At the C/2-rate, the excellent capacity retention of the full cell is around 70% after 500 cycles delivering a specific capacity of 103 mAh g- 1. Along with the conventional physicochemical characterization methods such as X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Raman and Fourier-transform Infrared Spectroscopies (FTIR), we also utilize X-ray photoelectron spectroscopy (XPS) to bridge the nexus between the performance and the structure properties of the studied materials. Furthermore, we also employ synchrotron-based X-ray Absorption (XAS) to understand the local geometry of the optimized cathode materials in operando.
