Role of the voltage window on the capacity retention of P2-Na2/3[Fe1/2Mn1/2]O2 cathode material for rechargeable sodium-ion batteries (original) (raw)
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Science and Technology Development Journal, 2021
Introduction: Localized high concentration electrolytes (LHCE) have been intensively studied due to their unique properties, especially in suppressing the Na dendrite formation and long-term cycling. Therefore, the low electrochemical performance of the P2-type cathode can be overcome by using LHCE. Methods: P2-type sodium layered oxides Na2=3Mn2=3M1=3O2 (M = Fe, Co, Ni) cathode materials were synthesized via a simple co-precipitation following a supported solid-state reaction. XRD and Rietveld method analyzed the phase composition and lattice parameters. SEM images observed the morphology of materials. The half-cell of three cathode were performed in LHCE consisting of 2.1 M sodium bis(fluorosulfonyl)imide (NaFSI) dissolved in 1,2-dimethoxyethane (DME) and bis(2,2,2-trifluoroethyl) ether (BTFE) (solvent molar ratio 1:2). The galvanostatic charge-discharge, striping-plating, and linear sweep voltage tests were carried out to investigate the electrochemical behaviors. Results: As-pre...
Materials, 2021
Herein, we formulated a new O3-type layered Na0.80[Fe0.40Co0.40Ti0.20]O2 (NFCTO) cathode material for sodium-ion batteries (SIBs) using a double-substitution concept of Co in the parent NaFe0.5Co0.5O2, having the general formula Na1-x[Fe0.5–x/2Co0.5–x/2M4+x]O2 (M4+ = tetravalent ions). The NFCTO electrode delivers a first discharge capacity of 108 mAhg−1 with 80% discharge capacity retention after 50 cycles. Notably, the first charge–discharge profile shows asymmetric yet reversible redox reactions. Such asymmetric redox reactions and electrochemical properties of the NFCTO electrode were correlated with the phase transition behavior and charge compensation reaction using synchrotron-based in situ XRD and ex situ X-ray absorption spectroscopy. This study provides an exciting opportunity to explore the interplay between the rich chemistry of Na1–x[Fe0.5–x/2Co0.5–x/2M4+x]O2 and sodium storage properties, which may lead to the development of new cathode materials for SIBs.
Ionics, 2019
A series of different Na content P2-and O3-type Na x (Fe 0.35 Mn 0.35 Co 0.3)O 2 (x = 0.5, 0.6, 0.7, 0.8, 0.9) were successfully synthesized by sol-gel method. The newly prepared materials were examined by means of X-ray diffraction. They were characterized by scanning electron microscopy (SEM-EDS) and inductively coupled plasma mass spectrometry (ICP-OES). The electrochemical performances of these materials were studied to understand the effect of the Na content. The initial discharge capacities of P2-type Na 0.5 (Fe 0.35 Mn 0.35 Co 0.3)O 2 is 122.5 mAh g −1 , Na 0.6 (Fe 0.35 Mn 0.35 Co 0.3)O 2 is 114.7 mAh g −1 , and Na 0.7 (Fe 0.35 Mn 0.35 Co 0.3)O 2 is 136.5 mAh g −1 at 0.05 C. After 110 cycles of these materials, the discharge capacities dropped to 55.6 mAh g −1 , 71.2 mAh g −1 , and 89.0 mAh g −1 at 0.05 C, respectively. The initial discharge capacities of O3-type Na 0.8 (Fe 0.35 Mn 0.35 Co 0.3)O 2 and Na 0.9 (Fe 0.35 Mn 0.35 Co 0.3)O 2 are 145.6 mAh g −1 and 120.2 mAh g −1 at 0.05 C, respectively. After 110 cycles of these materials, the discharge capacities dropped to 94.2 mAh g −1 and 24.95 mAh g −1 at 0.05 C, respectively. Given these results, P2-type Na x (Fe 0.35 Mn 0.35 Co 0.3)O 2 (x = 0.5, 0.6, and 0.7) have higher cycling stability than the O3-type Na x (Fe 0.35 Mn 0.35 Co 0.3)O 2 (x = 0.8 and 0.9).
Journal of the American Chemical Society, 2017
Large-scale electric energy storage is fundamental to the use of renewable energy. Recently, research and development efforts on room-temperature sodium-ion batteries (NIBs) have been revitalized, as NIBs are considered promising, low-cost alternatives to the current Li-ion battery technology for large-scale applications. Herein, we introduce a novel layered oxide cathode material, Na0.78Ni0.23Mn0.69O2. This new compound provides a high reversible capacity of 138 mAh g(-1) and an average potential of 3.25 V vs Na(+)/Na with a single smooth voltage profile. Its remarkable rate and cycling performances are attributed to the elimination of the P2-O2 phase transition upon cycling to 4.5 V. The first charge process yields an abnormally excess capacity, which has yet to be observed in other P2 layered oxides. Metal K-edge XANES results show that the major charge compensation at the metal site during Na-ion deintercalation is achieved via the oxidation of nickel (Ni(2+)) ions, whereas, to ...
Co-Free P2–Na0.67Mn0.6Fe0.25Al0.15O2 as Promising Cathode Material for Sodium-Ion Batteries
ACS Applied Energy Materials, 2018
P2-Na 0.67 Mn 0.6 Fe 0.25 Al 0.15 O 2 (NaMFA) was developed as cheaper and lesstoxic cathode material for sodium-ion batteries than the Co analogous, P2-Na 0.67 Mn 0.6 Fe 0.25 Co 0.15 O 2 (NaMFC). Despite cobalt being considered to stabilize layered structures upon cycling, NaMFA proved to have not only a higher specific charge 163 mAh•g-1 compared to 141 mAh•g-1 at 0.1C rate, but also a better cycling stability and rate capability than NaMFC. The structural transitions occurring during sodiation/desodiation in the layered frames were characterized by operando X-ray
Layered P2-Na2/3Co1/2Ti1/2O2 as a high-performance cathode material for sodium-ion batteries
Journal of Power Sources, 2017
A positive electrode material based on Co and Ti for Na-ion batteries was prepared. Na 2/3 Co 1/2 Ti 1/2 O 2 crystallizes in P2type structure with P6 3 /mmc space group. A specific discharge capacity of 100 mAh g À1 was obtained. Na 2/3 Co 1/2 Ti 1/2 O 2 shows better stability than Na 2/3 CoO 2 (Cap. Ret. 98%). Ex-situ XRD confirms the structural stability of the studied material upon cycling.
Energy Technology, 2022
The full commercialization of sodium‐ion batteries (SIBs) is still hindered by their lower electrochemical performance and higher cost ($ W−1 h−1) with respect to lithium‐ion batteries. Understanding the electrode–electrolyte interphase formation in both electrodes (anode and cathode) is crucial to increase the cell performance and, ultimately, reduce the cost. Herein, a step forward regarding the study of the cathode–electrolyte interphase (CEI) by means of X‐ray photoelectron spectroscopy (XPS) has been carried out by correlating the formation of the CEI on the P2‐Na0.67Mn0.8Ti0.2O2 layered oxide cathode with the cycling rate. The results reveal that the applied current density affects the concentration of the formed interphase species, as well as the thickness of CEI, but not its chemistry, indicating that the electrode–electrolyte interfacial reactivity is mainly driven by thermodynamic factors.
Investigating Na-ion battery (SIB) materials is complicated by the absence of a well-performing (reference) electrode material since sodium metal cannot be considered as a quasi-reference electrode. Taking advantage of the activity of both Ni and Mn, herein, the P2-type and Mn-rich Na 0.6 Ni 0.22 Al 0.11 Mn 0.66 O 2 (NAM) material, known to be an excellent positive electrode, is investigated as a negative electrode. To prove NAM stability as both positive and negative electrode, symmetric cells have been assembled without pre-sodiation, which showed a reversible capacity of 73 mA h g À 1 and a remarkable capacity retention of 82.6 % after 500 cycles. The outstanding cycling performance is ascribed to the high stability of the active material at both the highest and lowest Na-ion storage plateaus and the rather limited electrolyte decomposition and solidelectrolyte-interphase (SEI) formation occurring. The long-term stability of NAM at both electrodes enables its use as a "reference" electrode for the investigation of other positive and negative electrode materials for SIBs, resembling the role played by lithium titanate (LTO) and lithium iron phosphate (LFP) in LIBs.
Sodium-ion battery cathodes Na2FeP2O7 and Na2MnP2O7: diffusion behaviour for high rate performance
Journal of materials chemistry. A, Materials for energy and sustainability, 2014
Na-ion batteries are currently the focus of significant research interest due to the relative abundance of sodium and its consequent cost advantages. Recently, the pyrophosphate family of cathodes has attracted considerable attention, particularly Li2FeP2O7 due to its high operating voltage and enhanced safety properties; in addition the sodium-based pyrophosphates Na2FeP2O7 and Na2MnP2O7 are also generating interest. Herein, we present defect chemistry and ion migration results, determined via atomistic simulation techniques, for Na 2MP2O7 (where M = Fe, Mn) as well as findings for Li2FeP2O7 for direct comparison. Within the pyrophosphate framework the most favourable intrinsic defect type is found to be the antisite defect, in which alkali-cations (Na/Li) and M ions exchange positions. Low activation energies are found for long-range diffusion in all crystallographic directions in Na2MP2O7 suggesting three-dimensional (3D) Na-ion diffusion. In contrast Li2FeP2O7 supports 2D Li-ion diffusion. The 2D or 3D nature of the alkali-ion migration pathways within these pyrophosphate materials means that antisite defects are much less likely to impede their transport properties, and hence important for high rate performance.