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Öğe Challenges and recent advancements in MXene-based high-capacity electrodes for future generation rechargeable batteries(Elsevier, 2025) Ashfaq, Rughianah Gohar; Arshad, Muhammad; Siddique, Sofia; Abrar, Areebah; Shah, Saqlain A.; Bulut, Fatih; Altin, SerdarAn innovative family of 2-dimensional transition metal carbides, carbonitrides, and nitride multilayered materials, identified as MXenes, has attracted significant interest since the discovery of Ti3C2 in 2011. MXenes exhibit a broad surface area and excellent electronic conductivity and can be hydrophilic, hydrophobic, or a combination of both. It also possesses physical robustness, flexibility, and chemical and thermal resilience. Surface terminations such as hydroxyl (OH-), oxygen (O-), or fluorine (F-) groups impart hydrophilic properties to the surfaces of materials. Due to its outstanding conductive properties, large specific surface area, excellent mechanical characteristics, and distinctive multilayered structure, MXenes have extensive applications in energy storage devices, absorption processes, catalysis, and other fields. MXenes and related composite materials have gained significant traction in rechargeable batteries. While oxides, sulfides, and various other materials offer high capacities, they are also plagued by poor cyclability, limited conductivity, and volumetric expansion during reaction processes. Consequently, utilizing MXene-based composites can enhance the electronic conductivity, storage capacity, and overall electrochemical efficiency while mitigating volumetric expansion during charge/ discharge cycles. This comprehensive review article delves into the manufacturing process, structure, and characteristics of MXenes. We also explore the energy storage capabilities of these materials in future-generation rechargeable batteries, associated applications, and prospects for future research.Öğe Cobalt-substituted P2-Na0.67MnO2 and purple basil-derived hard carbon for high-performance sodium-ion battery full cells: insight to ex situ structural analysis(Springer Heidelberg, 2025) Whba, Rawdah; Dogan, Ebru; Altin, Emine; Benzaid, Abdelali; Arshad, Muhammad; Altin, SerdarThis study explores two energy storage materials: cobalt-doped P2-type Na0.67MnO2 (Na0.67Mn0.9Co0.1O2, NMCO) and hard carbon derived from purple basil (Ocimum basilicum L., HC-based PB) biomass. NMCO was synthesized via a solid-state method involving high-temperature quenching in liquid nitrogen (LN2). Analytical techniques confirmed a pure P2-type layered structure with reduced lattice volume due to Co3+ substitution. FTIR identified Na-O, Mn-O, and Co-O bonds, while XPS revealed reduced Mn3+ content, enhancing structural stability by mitigating the Jahn-Teller effect. Electrochemical tests of NMCO showed charge/discharge capacities of 184 mAhg(-1) and 185 mAhg(-1) with a coulombic efficiency of 99.5%. HC-based PB, exhibiting disordered graphitic structures, demonstrated higher charge and discharge capacities of 231 and 349 mAhg(-)(1), respectively, despite a relatively low efficiency of 66%. Long-term cycling demonstrated capacity fading for both materials after 100 cycles. Ex situ XRD confirmed NMCO's structural integrity, while HC's amorphous structure contributed to its stability. These findings provide valuable insights into these materials' electrochemical performance and durability for energy storage applications.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 symmetric supercapacitor enabled by MXene-based tungsten disulfide (V2CTx/WS2) composites(Elsevier, 2026) Iqbal, Muhammad Ahsan; Arshad, Muhammad; Zafar, Naveed; Amjad, Nouman; Sarwar, Sakhi Ghulam; Altin, Sardar; Haleem, Yasir A.The growing demand for high-performance and durable energy storage systems has intensified research into advanced electrode materials with high capacitance, rapid charge-discharge capability, and long cycle life. MXenes and transition metal dichalcogenides (TMDs) possess complementary electrochemical and structural properties, making their hybrid architectures highly promising for supercapacitor applications. This study focuses on the synthesis of a series of V2CTX/WS2 composites by employing an inexpensive ultrasonication technique for supercapacitor device. X-ray diffraction (XRD) confirmed that V2CTX, WS2 and V2CTX/WS2 composites have crystallized hexagonal structure within space group P63mmc. Field emission scanning electron microscopy (FE-SEM) combined with energy-dispersive spectroscopy (EDS) confirmed the embedding of WS2 sheets within the layers of V2CTX MXene and provides insight into their elemental composition. X-ray photoemission spectroscopy (XPS) analysis revealed the successful incorporation of WS2 filler into V2CTX MXene, confirming the surface chemistry and chemical interactions within the composite. The cyclic voltammetry (CV) curves were found perfectly rectangular and showed no distortion even at higher scan rates, confirming the non-faradic behavior. The galvanostatic charge-discharge profile of the V2CTX/WS2 (15 wt% WS2) composite showed a highest specific capacitance of 1216.34 F g-1 at 1 Ag-1 in 1 M KOH. The specific capacitance of composite is 4.07 folds the specific capacitance of pure V2CTx MXene in case of three-electrode-cell. The specific capacitance of fabricated symmetric supercapacitor device found 312.5 F g-1at 1 Ag-1 with capacity retention of 82.31 % and coulombic efficiency of 89.6 % after 6000 cycles. This study highlights the exceptional potential of V2CTX/WS2 composites for energy storage devices, making them well-suited to meet the requirements of high-power applications.Öğe Influence of precursor selection on the structural integrity and electrochemical performance of α-NaMnO2 cathode(Wiley, 2025) Dogan, Ebru; Whba, Rawdah; Canbay, Canan Aksu; Arshad, Muhammad; Sahinbay, Sevda; Altin, SerdarIn this study, the alpha-NaMnO2 phase was successfully synthesized using three different combinations of starting materials: Na2O2/Mn2O3, Na2O2/MnO2, and Na2CO3/Mn2O3. A one-step heat treatment at 900 degrees C for 5 h under air with quenching was applied. X-ray diffraction analysis confirmed the formation of pure alpha-NaMnO2 phase in all three samples, with only slight variations in lattice parameters. Elemental and oxidation state analyses were conducted using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy with energy-dispersive X-ray spectroscopy, and inductively coupled plasma measurements. XPS results revealed noticeable differences in Mn ion valence states, suggesting variations in oxygen stoichiometry and the presence of oxygen-excess structures. Electrochemical evaluations were performed in both half-cell and full-cell configurations. The samples exhibited distinct performance characteristics, with capacity fade over 100 cycles at C/3 between 1.5 and 4.3 V measured at 83.6%, 73.9%, and 83.1%, respectively. These differences correlated with the average oxidation state of Mn and O content. Full-cells, paired with presodiated commercial hard carbon anodes, showed the highest capacity for the Na2O2/MnO2 system and the best retention for the Na2CO3/Mn2O3 sample. Overall, this work demonstrates how even small variations in starting materials can significantly influence the structural and electrochemical behavior of alpha-NaMnO2.Öğe Interfacial Evaluation in ZnO-Coated NaxMn0.5Fe0.5O2 Cathodes and Hard Carbon Anodes Induced by Sodium Azide: Operando EIS and Structural Insights(Wiley-V C H Verlag Gmbh, 2025) Whba, Rawdah; Dogan, Ebru; Duygulu, Ozgur; Alanazi, Abdullah K.; Arshad, Muhammad; Stoyanova, Radostina; Koleva, VioletaThis article explores the synthesis and electrochemical properties of NaxMn0.5Fe0.5O2 powders, prepared via a conventional solid-state reaction. Subsequently, the powders are functionalized with a ZnO protective coating through a wet-chemical approach employing zinc acetate in ethanol. Structural characterization confirmed that the ZnO layer maintained the P2-type (P6 3 /mmc) structure, while energy-dispersive X-ray spectrometry mapping verified the successful coating. Electrochemical analyses, including electrochemical impedance spectroscopy (EIS) and cyclic voltammetry, revealed that although the redox reaction mechanism remained unchanged, the charge-transfer resistance (R ct) depended on the coating thickness. ZnO-coated NMFO electrodes exhibited initial discharge capacities of 159.3, 153.6, and 124.8 mAh g- 1 with respective capacity retentions of 48.9%, 41.9%, and 52.0% after 100 cycles for ZnO contents of 0.2, 0.4, and 0.6 wt.%. The galvanostatic intermittent titration technique results indicated that the diffusion coefficients varied with the coating conditions. Operando EIS from 1.5 to 4.3 V showed stable bulk resistance (R b) but voltage-dependent variations in solid electrolyte interface resistance (R SEI) and R ct. Additionally, sodium azide is used to presodiate the hard carbon (HC) anode to enhance the full-cell performance. The ZnO-coated cathode paired with NaN3 presodiated HC delivered a capacity of over 120 mAh g- 1 at C/10. Ex situ analysis after 500 cycles confirmed structural stability, demonstrating that ZnO coating and NaN3 presodiation collectively improve sodium-ion battery performance.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 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 Revealing the Role of Ruthenium on the Performance of P2-Type Na0.67Mn1-xRuxO2 Cathodes for Na-Ion Full-Cells(Wiley-V C H Verlag Gmbh, 2024) Altin, Emine; Moeez, Iqra; Kwon, Eunji; Bhatti, Ali Hussain Umar; Yu, Seungho; Chung, Kyung Yoon; Arshad, MuhammadHerein, P2-type layered manganese and ruthenium oxide is synthesized as an outstanding intercalation cathode material for high-energy density Na-ion batteries (NIBs). P2-type sodium deficient transition metal oxide structure, Na0.67Mn1-xRuxO2 cathodes where x varied between 0.05 and 0.5 are fabricated. The partially substituted main phase where x = 0.4 exhibits the best electrochemical performance with a discharge capacity of approximate to 170 mAh g(-1). The in situ X-ray Absorption Spectroscopy (XAS) and time-resolved X-ray Diffraction (TR-XRD) measurements are performed to elucidate the neighborhood of the local structure and lattice parameters during cycling. X-ray photoelectron spectroscopy (XPS) revealed the oxygen-rich structure when Ru is introduced. Density of States (DOS) calculations revealed the Fermi-Level bandgap increases when Ru is doped, which enhances the electronic conductivity of the cathode. Furthermore, magnetization calculations revealed the presence of stronger Ru & horbar;O bonds and the stabilizing effect of Ru-doping on MnO6 octahedra. The results of Time-of-flight secondary-ion mass spectroscopy (TOF-SIMS) revealed that the Ru-doped sample has more sodium and oxygenated-based species on the surface, while the inner layers mainly contain Ru-O and Mn-O species. The full cell study demonstrated the outstanding capacity retention where the cell maintained 70% of its initial capacity at 1 C-rate after 500 cycles.Öğe The ion-exchange study by LiMn2O4 for Na-ion cathodes: an investigation of structural and electrochemical performance(Springer, 2025) Dogan, Ebru; Arshad, Muhammad; Altin, Emine; Altundag, Sebahat; Altin, SerdarThe sodium manganese oxide phase was synthesized by an ion-exchange process in the glovebox using LiMn2O4 electrodes. For this process, LiMn2O4 cathodes were discharged at specific voltage values that correspond to the redox reaction values in cycling voltammetry measurements and then the cell was disassembled, and the cathode was used for Na-ion cell by Na metal. The newly assembled cell was discharged to 1.5 V for the ion-exchange process. To understand the mechanism during the ion-exchange process, the cells were disassembled in each redox voltage during the charging and discharging of the cell for structural analysis. The XRD patterns of each electrode were analyzed by Rietveld refinement and the possible reaction mechanism for the ion-exchange process was investigated. It was found that there are lambda-MnO2, Li2MnO3, and NaMn2O4 phases in the electrodes which formed at different cut of voltages. According to Fourier Transform Infrared Spectroscopy measurements, the presence of Na-O bands was confirmed the successful ion-exchange within the materials. Structural properties were further examined using Scanning Electron Microscopy combined with Energy Dispersive X-ray analysis dot mapping and X-ray photoelectron spectroscopy analysis, supported by X-ray diffraction experimental results. The electrochemical performance of the ion-exchanged electrodes was investigated by cyclic voltammetry, electrochemical impedance spectroscopy, galvanostatic cycling, and C-rate measurements. The results showed that there was a significant change in the redox reaction mechanism by the ion-exchange process. According to galvanostatic measurements, the ion-exchanged electrodes showed better performance up to 50 cycles, but a phase change in the electrodes during the cycling caused a sharp decrease in capacity. Ex-situ XRD analysis after 100 cycles revealed the formation of the Na2Mn3O7 phase which is electrochemically inactive, and it has Mn4+ ions in the structure. The results suggest that the ion-exchange mechanism is a successful method, but the crystal structure has a crucial role in the cycling process of the cells.Öğe Validating superior electrochemical properties of Ti3C2 MXene for supercapacitor applications through first-principles calculations(Royal Soc Chemistry, 2024) Irfan, Sheheera; Haleem, Yasir A.; Usman, Muhammad; Ahmad, Naseeb; Arshad, Muhammad; Irshad, Muhammad Imran; Saleem, Muhammad FarooqThis work explores the characteristics of two-dimensional (2D) titanium carbide (Ti3C2 MXene) and utilizes first-principles study to weigh its potential for supercapacitor applications. Scanning electron microscopy images confirm the layered morphology of the MXene, and energy-dispersive X-ray spectroscopy (EDX) analysis supports the extraction of aluminum from the MAX phase. Fourier-transform infrared (FTIR) spectroscopy confirms the presence of oxygen-based functional groups on the surface of the MXene and X-ray diffraction (XRD) patterns validate its hexagonal crystalline structure. Cyclic voltammetry (CV) analysis reveals the presence of redox peaks, indicating the pseudocapacitive behaviour of the fabricated electrode. Additionally, galvanostatic charge-discharge (GCD) measurements yield a calculated specific capacitance of 370 F g(-1). Electrochemical impedance spectroscopy (EIS) substantiates the low impedance resulting from the layered structure via the adequate adsorption/desorption of cations. The utilization of first-principles density functional theory (DFT) calculations reveals the merging of conduction and valence bands, signifying effective conductivity. Both the total and partial density of states cross the Fermi level, indicating a highly efficient charge mobility process. The combination of prominent surface redox reactions and excellent conductivity contributes to the superior specific capacitance of the fabricated electrode. Overall, these results highlight the excellent electrochemical properties of the Ti3C2 MXene electrode, declaring it as a promising candidate for supercapacitor applications.
