Sodium Manganese Oxide Research Articles

Responsive agarose hydrogel incorporated with natural humic acid and MnO2 nanoparticles for effective relief of tumor hypoxia and enhanced photo-induced tumor therapy.

In spite of widespread applications of nano-photosensitizers, poor tumor penetration and severe hypoxia in the tumor microenvironment (TME) always result in an undesirable therapeutic outcome of photodynamic therapy (PDT). Herein, a biocompatible agarose-based hydrogel incorporated with sodium humate (SH), manganese oxide (MnO2) and chlorin e6 (Ce6) was synthesized as agarose@SH/MnO2/Ce6 through a "co-trapped" strategy during a sol-gel process and employed for combined photothermal therapy (PTT) and enhanced PDT. NIR-induced local hyperthermia is responsible for not only activating Ce6 release, but also triggering the catalytic decomposition of H2O2 mediated by MnO2 to relieve hypoxia. Such a hybrid hydrogel can realize deep tissue penetration through intratumoral injection, and exhibit remarkable tumor-site retention. Moreover, programmed laser irradiation led to an extremely high tumor growth inhibition rate of 93.8% in virtue of enhanced PTT/PDT. In addition, ultralow systemic toxicity caused by the hybrid hydrogel was further demonstrated in vivo. This reliable and eco-friendly hydrogel paves the way for the development of smart gel-based biomaterials, which respond to both exogenous and endogenous stimuli, towards the management of cancer and other major diseases.

Oxygen Redox Activity through a Reductive Coupling Mechanism in the P3-Type Nickel-Doped Sodium Manganese Oxide

Increasing dependence on rechargeable batteries for energy storage calls for the improvement of energy density of batteries. Toward this goal, introduction of positive electrode materials with high...

Highly-stable P2–Na0.67MnO2 electrode enabled by lattice tailoring and surface engineering

One of the key challenges of sodium ion batteries is to develop sustainable, low-cost and high capacity cathodes, and this is the reason that layered sodium manganese oxides have attracted so much attention. However, the undesired phase transitions and poor electrolyte-electrode interfacial stability facilitate their capacity decay and limit their practical applications. Herein, we design a novel Al2O3@Na0.67Zn0.1Mn0.9O2 electrode to mitigate these problems, by taking the advantages of both structural stabilization and surface passivation via Zn2+ substitution and Al2O3 atomic layered deposition (ALD) coating, respectively. Long-range and local structural analyses during charging/discharging processes indicate that P2–P2’ phase transformation can be suppressed by substituting proper amount of Mn3+ Jahn-Teller centers with Zn2+, whereas excessive Zn2+ leads to P2-OP4 structure transition at low sodium contents and facilitates the electrode degradations. Furthermore, the homogeneous and robust cathode electrolyte interphase (CEI) layers formed on the Al2O3-coated electrodes effectively hinder the organic electrolytes from further decomposition. Therefore, our synergetic strategy of Zn2+ substitution and ALD surface engineering remarkably boosts the cycling performance of P2–Na0.67MnO2 and provides some new insights into the designing of highly stable cathode electrodes for sustainable sodium ion batteries.

Layered Sodium Manganese Oxide Na2Mn3O7 as an Insertion Host for Aqueous Zinc-ion Batteries

ABSTRACTAqueous rechargeable batteries are attractive owing to their higher operational safety, high ionic conductivity, scalable and easy manufacturing. These aqueous batteries form an economic option for large-scale (grid) power storage. In the aqueous battery sector, Mn-based compounds are highly attractive with their non-toxic nature, low-cost, rich mineral chemistry and robust operational safety. Several Mn-based systems like LiMn2O4 spinel and LiNi1/3Mn1/3Co1/3O2 have seen successful commercialization. Pursuing Mn-based materials, we have shown layer structured Na2Mn3O7 as a versatile cathode material for non-aqueous systems like Li-, Na- and K-ion batteries. In the current work, we have exploited Na2Mn3O7 as a cathode material for aqueous Zn-ion battery for the first time. This Na-Mn-O ternary system was prepared using two-step emulsion-based synthesis. The phase-pure Na2Mn3O7 was formed in a triclinic structure with a space group of P-1. It exhibited versatile electrochemical insertion of different ions like Li-, Na- and K-ions involving phase transition. Na2Mn3O7 exhibited reversible Zn-ion intercalation delivering capacity of 245 mA h g-1 with a nominal voltage of 1.5 V. Upon discharge, it triggered phase transformation to an unknown phase. Layered Na2Mn3O7 oxide was found to act as an efficient cathode for Zn-ion batteries with good cycling stability.

Polypyrrole as a Novel Chloride‐Storage Electrode for Seawater Desalination

The desalination battery is regarded as a promising high‐efficiency technology for seawater desalination on account of the reversible salt‐ion storage in the bulk of the battery electrodes. Herein, polypyrrole is used as a new electrode to store chloride ions in seawater desalination. The as‐prepared polypyrrole composite electrode shows good electrochemical reversibility in chloride‐ion storage and removal in the aqueous NaCl electrolyte. When this chloride electrode is incorporated with a sodium electrode of sodium manganese oxide, a desalination battery that can capture chloride and sodium ions from the electrolyte through the electrochemical redox reactions is obtained. A stable and reversible capacity of 40 mAh g−1 of the desalination battery is achieved after 200 cycles.

Structure and electrochemical properties of layered sodium manganese oxide NaxMnO2

Layered Na0.808MnO2-δ were prepared by solid state method under oxygen environment. The Rietveld refinement result showed that lattice parameters are a = 2.8653 Å, c = 11.0987 Å with space group P63/mmc. There were some vacancies in Na site and O site, and the Na vacancy is more easily formed in the Na1(2b) site by first-principles calculation. The electrochemical measurement shows reversible de/intercalation of about 0.4Na ion so as to deliver a discharge capacity of 103 mAhg−1 in the potential range of 2.0–3.6 V. By comparison of theory and experiment, some Na vacancies is favor to improving the cycle performance of sodium ion battery.

Performance Modulation through Synergetic Effect of Interstitial Water with Ti-substitution for Sodium Ion Battery Cathode

In this study, a novel P2-type sodium manganese oxide is presented using a facile preparation method. With the help of titanium doping, and introduction of interstitial water, the electrochemical p...

Scale Formation on Na4Mn9O18 Insertion Electrodes in Electrochemical Deionization

Several sodium insertion materials have been used as cathode materials in electrochemical deionization. [1][2][3][4]In this work, we evaluate the performance of sodium manganese oxide (Na4Mn9O18/ NMO), a layered insertion compound in separating sodium ions from a mixed cation (Na+/Ca2+) system (figure1). We observe that the specific capacity of a composite Na4Mn9O18/C electrode in 1M NaCl solution is 54 mAh/g, and is reduced to 23 mAh/g in 0.2 M CaCl2+ 1 M NaCl. We also observe that the capacity is not fully recovered when the electrode cycled in mixed ion solution is electrochemically cycled again in 1M NaCl. The X-ray diffractograms of the electrodes cycled in the mixed ion solutions reveals that in addition to the Na4Mn9O18 phase there is a second phase comprising primarily of calcite CaCO3. The presence of calcite on the NMO electrode is confirmed using SEM/EDX and XPS. It is expected that calcite is formed during the oxidation of carbon particles in close contact with NMO particles in the composite electrodes, and the capacity loss occurs due to the calcite layers that hinder ion transport to the NMO particles. [5] Reference [1] M.E. Suss, V. Presser, Water Desalination with Energy Storage Electrode Materials, Joule. 2 (2018) 25–35. doi:10.1016/j.joule.2017.12.010. [2] S. Shanbhag, Y. Bootwala, J.F. Whitacre, M.S. Mauter, Ion Transport and Competition Effects on NaTi2(PO4)3and Na4Mn9O18Selective Insertion Electrode Performance, Langmuir. 33 (2017) 12580–12591. doi:10.1021/acs.langmuir.7b02861. [3] J.F. Whitacre, A. Tevar, S. Sharma, Na4Mn9O18as a positive electrode material for an aqueous electrolyte sodium-ion energy storage device, Electrochem. Commun. 12 (2010) 463–466. doi:10.1016/j.elecom.2010.01.020. [4] F. Sauvage, L. Laffont, J.M. Tarascon, E. Baudrin, Study of the insertion/deinsertion mechanism of sodium into Na 0.44MnO2, Inorg. Chem. 46 (2007) 3289–3294. doi:10.1021/ic0700250. [5] C. Zhang, D. He, J. Ma, W. Tang, T.D. Waite, Faradaic reactions in capacitive deionization (CDI) - problems and possibilities: A review, Water Res. 128 (2018) 314–330. doi:10.1016/j.watres.2017.10.024. Figure 1

Fluorine anion doped Na0.44MnO2 with layer-tunnel hybrid structure as advanced cathode for sodium ion batteries

Anion-doping strategy represents one efficient route to adjust the structure of electrode material for advanced reversible batteries. The work herein obtains an optimized F-doping sodium manganese oxide Na0.44MnO1.93F0.07 with a layer-tunnel hybrid structure, and the essential factors such as synthesis temperature and crystal structure which determine the electrochemical behavior for the F-doping cathode materials are systematically explored and investigated. The optimized cathode Na0.44MnO1.93F0.07 prepared at 900 °C for 3 h, among various Na0.44MnO2−xFx samples, delivers an extraordinary discharge capacity of 149 mA h g−1 and 138 mA h g−1 at 0.5 C and 1 C, respectively. In addition, the electrode displays an impressive cycling stability with a superb capacity retention rate of approximately 79% over 400 cycles at 5 C. And thus, it shows enhanced reversible capacity over the tunnel phase Na0.44MnO2. Therefore, this work provides a new avenue for designing and optimizing the advanced cathode materials with superior electrochemical performance for sodium-ion batteries by introducing halogen anions to modify the structure.

Understanding on the structural and electrochemical performance of orthorhombic sodium manganese oxides

Sodium manganese oxide with divalent Ni in prismatic sites, represented as o-Na0.67[Ni0.05Mn0.95]O2, shows high capacity with excellent cyclability.

High-Capacity P2-Type NaxLi0.25Mn0.75O2 Cathode Enabled by Anionic Oxygen Redox

Sodium-ion battery technology has attracted significant attention due to its substantial cost advantage and similar operating mechanism to Li-ion batteries. P2-type sodium manganese oxide cathode is one of the most promising candidates, demonstrating both high capacity and good cycling stability. Here, we explore the lattice oxygen activity in layered sodium transition metal oxides. We synthesize a series of sodium lithium manganese oxides, NaxLi0.25Mn0.75O2 (x = 0.75 – 0.833), to optimize Na content. We further investigate the charge compensation mechanism for the best performing Na0.75Li0.25Mn0.75O2 over an extensive electrochemical cycling window. The large charge and discharge capacity is enabled by reversible lattice oxygen redox in the high voltage region (≥2.5 V), along with Mn redox at the voltages below 2.5 V. Additionally, we reveal a small amount of oxygen gas evolution, 0.04% of the total oxygen in Na0.25Li0.25Mn0.75O2. This initial study will trigger an interest in the lattice oxygen activity in layered sodium metal oxide cathode, therefore, leading to better understanding of its correlation with crystal structure and electrochemical performance.

Different crystallographic sodium manganese oxides for capacitive deionization: performance comparison and the associated mechanism

The influence of the crystal structure of NMO on its desalination performance was investigated in the capacitive deionization system.

In Situ Tracking of Partial Sodium Desolvation of Materials with Capacitive, Pseudocapacitive, and Battery-like Charge/Discharge Behavior in Aqueous Electrolytes.

Aqueous electrolytes can be used for electrical double-layer capacitors, pseudocapacitors, and intercalation-type batteries. These technologies may employ different electrode materials, most importantly high-surface-area nanoporous carbon, two-dimensional materials, and metal oxides. All of these materials also find more and more applications in electrochemical desalination devices. During the electrochemical operation of such electrode materials, charge storage and ion immobilization are accomplished by non-Faradaic ion electrosorption, Faradaic ion intercalation at specific crystallographic sites, or ion insertion between layers of two-dimensional materials. These processes may or may not be associated with a (partial) loss of the aqueous solvation shell around the ions. Our work showcases the electrochemical quartz crystal microbalance as an excellent tool for quantifying the change in effective solvation. We chose sodium as an important cation for energy storage materials (sodium-based aqueous electrolytes) and electrochemical desalination (saline media). Our data show that a major amount of water uptake occurs during ion electrosorption in nanoporous carbon, while battery-like ion insertion between layers of titanium disulfide is associated with an 80% loss of the initially present solvation molecules. Sodiation of MXene is accomplished by a loss of 90% of the number of solvent molecules, but nanoconfined water in-between the MXene layers may compensate for this large degree of desolvation. In the case of sodium manganese oxide, we were able to demonstrate the full loss of the solvation shell.

Potassium-ion Intercalation Mechanism in Layered Na2Mn3O7

Potassium-ion batteries (KIBs) are emerging as promising candidates for large scale applications due to their low cost, elemental abundance, and smaller Stokes radius of K+ relative to Li+ and Na+ ions. However, the large size of K+ ion remains the bottleneck for the development of KIBs. Herein, layered sodium manganese oxide Na2Mn3O7 is demonstrated as a promising intercalation host for K ion for the first time. Prepared by facile one-step solid-state synthesis, Na2Mn3O7 compound crystallized in a triclinic structure (space group P1). An initial discharge capacity of 152 mA h g–1 at a current rate of C/20 was realized with a nominal voltage of 2.1 V vs K/K+. The mechanistic aspects of K+ ion (de)intercalation was investigated using X-ray photoelectron spectroscopy (XPS), ex situ X-ray diffraction (XRD), and potentiostatic intermittent titration technique (PITT). Similar to the Na+-ion insertion, the K+-ion insertion into Na2Mn3O7 involves a two-phase redox mechanism. The layered Na2Mn3O7 forms a potenti...

P2/O3 phase-integrated Na0.7MnO2 cathode materials for sodium-ion rechargeable batteries

We describe a phase-integrated P2-Na0.7MnO2/O3-NaMnO2 sodium manganese oxide (Na0.7MnO2) cathode material for sodium-ion rechargeable batteries. By changing the crystallization cooling rate after the calcination of P2/O3-Na0.7MnO2, the ratio between the two different (P2-Na0.7MnO2 and O3-NaMnO2) phases (and the Mn4+/Mn3+ ratio) in the Na0.7MnO2 material could be controlled. The P2/O3-Na0.7MnO2 sample prepared by fast cooling contains the optimum content of the two principal phases and showed excellent electrochemical performance because of the synergy between the fast kinetics of the P2-Na0.7MnO2 phase and high capacity of the O3-NaMnO2 phase. The stability of the layered crystal structure of Na0.7MnO2 was also improved by increasing the portion of the P2-Na0.7MnO2 phase, which has a higher average oxidation state of Mn compared to that in O3-NaMnO2; this suppressed the Jahn–Teller distortion during cycling.

(Invited) In Operando NMR/EPR Studies of High-Performance Transition Metal Oxides for Electrochemical Energy Storage

High-voltage cathodes made of transition metal oxides have been the leading candidates for rechargeable Li and Na ion batteries. Continuous effort for further improvement in the energy density and stability of available oxides and for discovering new materials is ongoing. Understanding the Li extraction and insertion dynamics, the involved anionic redox chemistry and its coupling with transition metal redox, and the role that Li plays in stabilizing Na transition metal oxides, is important for making the effort more efficient and effective. Li in Li-rich cathodes mostly resides at octahedral sites in both Li layers (LiLi) and transition metal layers (LiTM). Extraction and insertion of LiLi and LiTM are strongly influenced by surrounding transition metals. pjMATPASS and operando Li nuclear magnetic resonance are combined to achieve both high spectral and temporal resolution for quantitative real time monitoring of lithiation and delithiation at LiLi and LiTM sites in Li2MnO3, Li1.2Ni0.2Mn0.6O2, and Li1.2Ni0.13Mn0.54Co0.13O2cathodes. The results have revealed that LiTM are preferentially extracted for the first 20% of charge and then LiLi and LiTM are removed at the same rate. No preferential insertion or extraction of LiLi and LiTM is observed beyond the first charge. Ni and Co promote faster and more complete removal of LiTM. The recovery of the removed Li is <60% for LiTM and >80% for LiLi upon first discharge. The study sheds light on the activity of LiLi and LiTM during electrochemical processes as well as their respective contributions to cathode capacity. Anionic redox chemistry offers a transformative approach for significantly increasing specific energy capacities of cathodes for rechargeable Li-ion batteries. This study employs operando electron paramagnetic resonance (EPR) to simultaneously monitor the evolution of both transition metal and oxygen redox reactions, as well as their intertwined couplings in Li2MnO3, Li1.2Ni0.2Mn0.6O2, and Li1.2Ni0.13Mn0.54Co0.13O2 cathodes. Reversible O2–/O2 n – redox takes place above 3.0 V, which is clearly distinguished from transition metal redox in the operando EPR on Li2MnO3 cathodes. O2–/O2 n – redox is also observed in Li1.2Ni0.2Mn0.6O2, and Li1.2Ni0.13Mn0.54Co0.13O2 cathodes, albeit its overlapping potential ranges with Ni redox. This study further reveals the stabilization of the reversible O redox by Mn and e– hole delocalization within the Mn–O complex. The interactions within the cation–anion pairs are essential for preventing O2 n – from recombination into gaseous O2 and prove to activate Mn for its increasing participation in redox reactions. Operando EPR helps to establish a fundamental understanding of reversible anionic redox chemistry. The gained insights will support the search for structural factors that promote desirable O redox reactions. Further efforts have been invested on monitoring the evolution of O species in Li-rich transition metal oxides using both ex and in situ 17O solid-state NMR spectroscopy. Sodium manganese oxides with different compositions and crystal structures have attracted much attention because of their high capacity and low cost. We have investigated a group of promising lithium doped sodium manganese oxide cathode materials with exceptionally high initial capacity of ∼223 mAh g−1 and excellent capacity retentions, attributed primarily to the absence of phase transformation in a wide potential range of electrochemical cycling. Solid-state 7Li and 23Na NMR characterizations have been employed to follow the evolution of these active ions, in order to understand the roles that they play in stabilizing the structures over electrochemical cycling. The systematic study of structural evolution and the correlation with the electrochemical behavior of the doped cathode materials provides new insights into rational design of high-performance intercalation compounds. Figure 1

Design of high-performance cathode materials with single-phase pathway for sodium ion batteries: A study on P2-Nax(LiyMn1-y)O2 compounds

Sodium-ion batteries (SIBs) are an emerging electrochemical energy storage technology that has high promise for electrical grid level energy storage. High capacity, long cycle life, and low cost cathode materials are very much desired for the development of high performance SIB systems. Sodium manganese oxides with different compositions and crystal structures have attracted much attention because of their high capacity and low cost. Here we report our investigations into a group of promising lithium doped sodium manganese oxide cathode materials with exceptionally high initial capacity of ∼223 mAh g−1 and excellent capacity retentions, attributed primarily to the absence of phase transformation in a wide potential range of electrochemical cycling, as confirmed by in-operando X-ray diffraction (XRD), Rietveld refinement, and high-resolution 7Li solid-state NMR characterizations. The systematic study of structural evolution and the correlation with the electrochemical behavior of the doped cathode materials provides new insights into rational design of high-performance intercalation compounds by tailoring the composition and the crystal structure evolution in electrochemical cycling.

Efficient Capacitive Deionization Using Thin Film Sodium Manganese Oxide

More energy efficient desalination methods are needed to address global water scarcity. Capacitive deionization (CDI) is an emerging electrochemical desalination technology that could outperform other desalination technologies if new electrode materials were developed with high salt sorption capacity and efficiency. In this paper, we report on the desalination performance of thin-film sodium manganese oxide (NMO). We deposit thin-film MnO via atomic layer deposition (ALD), and electrochemically convert the MnO to NMO in NaCl(aq). Charge storage capacity is tuned with NMO thickness, and the relationship between charge storage capacity and reversible salt sorption is probed. NMO coated electrodes exhibit increases in charge storage capacity up to 170 times higher than uncoated electrodes. Electrochemical quartz crystal microbalance (EQCM) measurements reveal that thin-film NMO leads to the efficient electrochemical removal of Na+ ions. A hybrid CDI (HCDI) cell comprised of NMO-coated carbon nanotube (CNT) cathode and Ag nanoparticle-decorated CNT anode yields a ∼20-fold improvement in charge storage over bare CNT electrodes. The HCDI cell has an anomalously high reversible charging efficiency, which we study using ab initio modeling and EQCM. This is the first CDI report using thin film NMO, and the high desalination efficiency we identify promises to facilitate the development of HCDI devices with enhanced performance.

Revisit of layered sodium manganese oxides: achievement of high energy by Ni incorporation

Ni incorporation into Na2/3MnO2 suppresses the cooperative Jahn–Teller distortion and leads to a P2–O2 phase transition with about 13% of volume change.

Energy extraction and water treatment in one system: The idea of using a desalination battery in a cooling tower

The use of sodium manganese oxide as an intercalation electrode for water treatment was recently explored, and referred to as a “desalination battery” and “hybrid capacitive deionization”. Here, we examine the feasibility of using such a desalination battery, comprising crystalline Na4Mn9O18 as the cathode and Ag/AgCl/Cl− electrode as the anode, to extract energy from low-grade waste heat sources. Sodium manganese oxide electrode's material was produced via a solid-state synthesis. Electrodes were produced by spray-coated onto graphite foils, and showed a temperature dependence of the electrode potential, namely, ∂E/∂T, of −0.63 mV/K (whereas, the Ag/AgCl/Cl− mesh electrode showed much lower temperature dependence, < 0.1 mV/K). In order to demonstrate ion-removal capabilities together with the feasibility of thermal-energy conversion, a flow battery system was constructed. Thermally regenerative electrochemical cycles (TREC) were constructed for the flow battery cell. The thermal energy conversion, in this particular system, was shown to be feasible at relatively low C-rate (C/19) with temperatures varying between 30 °C and 70 °C.