Layered P2-Na2/3Co1/2Ti1/2O2 as a high-performance cathode material for sodium-ion batteries (original) (raw)
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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
Scientific reports, 2017
Rechargeable lithium batteries have been well-known and indispensable for portable electronic devices, and have the potential to be used in electric vehicles and smart grids. However, the growing concerns about the availability of lithium resources for large-scale applications have revived interest in sodium ion batteries. Of many obstacles to commercialization of Na-ion batteries, achieving simultaneously a large reversible capacity and good cycling capability of electrode materials remains a major challenge. Here, we report a new cathode material, Na-rich layered oxide Na2Ti0.94Cr0.06O2.97, that delivers high reversible capacity of 336 mAh g(-1) at current density of 18.9 mA g(-1) along with promising cycling capability of 74% capacity retention over 1000 cycles at current of 378 mA g(-1). The high capacity is associated to the redox reaction of oxygen, which is confirmed here by a combined experimental and theoretical study. The present work therefore shows that materials beyond ...
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...
Layered Na0.71CoO2: a powerful candidate for viable and high performance Na-batteries
Physical Chemistry Chemical Physics, 2012
The present study reports on the synthesis and the electrochemical behavior of Na 0.71 CoO 2 , a promising candidate as cathode for Na-based batteries. The material was obtained in two different morphologies by a double-step route, which is cheap and easy to scale up: the hydrothermal synthesis to produce Co 3 O 4 with tailored and nanometric morphology, followed by the solid-state reaction with NaOH, or alternatively with Na 2 CO 3 , to promote Na intercalation. Both products are highly crystalline and have the P2-Na 0.71 CoO 2 crystal phase, but differ in the respective morphologies. The material obtained from Na 2 CO 3 have a narrow particle length (edge to edge) distribution and 2D platelet morphology, while those from NaOH exhibit large microcrystals, irregular in shape, with broad particle length distribution and undefined exposed surfaces. Electrochemical analysis shows the good performances of these materials as a positive electrode for Na-ion half cells. In particular, Na 0.71 CoO 2 thin microplatelets exhibit the best behavior with stable discharge specific capacities of 120 and 80 mAh g À1 at 5 and 40 mA g À1 , respectively, in the range 2.0-3.9 V vs. Na + /Na. These outstanding properties make this material a promising candidate to construct viable and high-performance Na-based batteries.
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.
Cubic Sodium Cobalt Metaphosphate [NaCo(PO3)3] as a Cathode Material for Sodium Ion Batteries
Inorganic Chemistry, 2018
Cubic-framework sodium cobalt-based metaphosphate NaCo-(PO 3) 3 was recently demonstrated to be an attractive Na + cationic conductor. It can be potentially used in the next-generation rechargeable Na ion batteries. The crystal structure and electrical conductivity were studied and found to have a three-dimensional framework with interconnecting tunnels for Na + migration (J. Solid State Electrochem., 2016, 20, 1241). This inspired us to study the electrochemical (de)intercalation behavior of Na + in the NaCo(PO 3) 3 assuming a cubic Pa3̅ framework. Herein, synergizing experimental and computational tools, we present the first report on the electrochemical activity and Na + diffusion pathway analysis of cubic NaCo(PO 3) 3 prepared via conventional solid-state route. The electrochemical analyses reveal NaCo(PO 3) 3 to be an active sodium insertion material with well-defined reversible Co 3+ /Co 2+ redox activity centered at 3.3 V (vs Na/ Na +). Involving a solid-solution redox mechanism, close to 0.7 Na + per formula unit can be reversibly extracted. This experimental finding is augmented with bond valence site energy (BVSE) modeling to clarify Na + migration in cubic NaCo(PO 3) 3. BVSE analyses suggest feasible Na + migration with moderate energy barrier of 0.68 eV. Cubic NaCo(PO 3) 3 forms a 3.3 V sodium insertion material.
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.
Chemistry of Materials, 2017
Sodium ion battery technology is gradually advancing and can be viewed as a viable alternative to lithium ion batteries in niche applications. One of the promising positive electrode candidates is P2 type layered sodium transition metal oxide, which offers attractive sodium ion conductivity. However, the reversible capacity of P2 phases is limited by the inability to directly synthesize stoichiometric compounds with sodium to transition metal ratio equals to 1. To alleviate this issue, we report herein the in-situ synthesis of P2-NaxMO2 (x≤ 0.7, M= transition metal ions)-Na2CO3 composites. We find that sodium carbonate acts as a sacrificial salt, providing Na + ion to increase the reversible capacity of the P2 phase in sodium ion full cells, and also as a useful additive that stabilizes the formation of P2 over competing P3 phases. We offer a new phase diagram for tuning the synthesis of the P2 phase under various experimental conditions and demonstrate, by in-situ XRD analysis, the role of Na2CO3 as a sodium reservoir in full sodium ion cells. These results provide insights into the practical use of P2 layered materials and can be extended to a variety of other layered phases.