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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 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 Sodyum-iyon Pillerde Kullanılan MnFe-Bazlı Katotlarda Ni Etkisinin Araştırılması(2024) Ozgul, Metin; Altin, Serdar; Kalyoncuoglu, BurcuP2-NaMnO2 tabakalı metal oksit katot malzemeleri şarj edilebilir piller için yüksek kapasiteli ve ucuz bir pil malzemesi olarak bilinmektedir. Ancak Na+ iyonlarının interkalasyonu sırasında oluşan “Jahn-Teller bozulması” uygulamalarda kısıtlamalara neden olmaktadır. Yapılan çeşitli katkılamalarla bu bozulmaların baskılandığına dair çalışmalar mevcuttur. Bu çalışmada, x=0-0.5 mol% aralığında değişen oranlarda Ni katkılama ile katı hal sentezi yöntemi ile Na0.67Mn0.5-xNixFe0.43Al0.07O2 kompozisyonlarında katot malzemesi tozları üretildi. Üretilen örneklerin mikro yapı incelemeleri için SEM, kristal yapı tayini için XRD ve bağ türlerinin tespiti için FTIR analizleri ile yapısal karakterizasyonları gerçekleştirildi. İncelenen örnekler arasında en düşük BET yüzey alanı katkısız kompozisyonda gözlemlenmiştir. Üretilen katotların elektrokimyasal analizleri için Na0.67Mn0.5-xNixFe0.43Al0.07O2/sodyum metali ile hazırlanan CR2032 düğme pil hücreleri kullanıldı. Oluşturulan hücrelerin CV, EIS ve kapasite ölçümleri oda sıcaklığında gerçekleştirildi. Hücrelerin en yüksek kapasitesi katkısız örneklerde C/3 ve C/20 hızlarında sırasıyla 172 mAh/g ve 203 mAh/g olarak bulundu. Ni'in Na0.67Mn0.5Fe0.43Al0.07O2 içindeki içeriğinin artmasıyla Na tabakaları arasındaki mesafenin azaldığı görülmüştür. Bu durumun kristal yapıdaki Mn ve onunla yer değiştiren Ni iyonlarının iyonik yarıçaplarındaki farklılıktan kaynaklandığı söylenebilir.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.
