One-step Solid-state Reaction Research Articles

Enhancing the activation of the Ni2+/Ni3+ redox couple by gradient-tantalum doping for high specific capacity and outstanding interfacial stability

P2-type transition metal layered oxides (TMOs) have gathered significant interest by virtue of their low-cost and excellent cycling stability. However, the extensive practical application of TMOs is constrained by inherent factors, such as inferior rate performance and deficient interfacial stability. Herein, the gradient Ta-doped Na0.78(Ni0.33Mn0.67)1-xTaxO2 (NMT) cathode material was synthesized via a one-step solid-state reaction method to overcome these obstacles. The Ta modification augments the Ni2+/Ni3+ redox couple activity, in accordance with the principle of charge conservation, thus bolstering the reversible capacity of the material. Furthermore, the gradient Ta-doping not only preserves the stability of the bulk phase of TMOs but also serves as a potent suppression against the emergence of deleterious interfacial side reactions. As a result, the NMT cathode delivers an improving initial discharge specific capacity of 105 mAh g−1 at 0.1 C and sustains an excellent capacity retention of 91.4 % after 500 cycles at 5 C within the voltage range of 2.0–4.0 V. Benefiting from the robust Ta–O bond, the highly reversible structure evolution of the gradient Ta-doped material during the Na+ extraction/insertion process is clearly elucidated through in-situ XRD. This research provides a straightforward and efficacious approach to elevate the electrochemical performance of TMOs for sodium-ion batteries (SIBs) in the future.

Mn-doped FeNCN as advance anode for potassium ion batteries

The development of anode materials with advanced structures to facilitate rapid charge transport and enhance potassium storage performance is urgently needed to propel the advancement of potassium ion batteries (PIBs). Transition metal carbodiimides have emerged as promising PIB electrode materials, but achieving high capacity and long-lasting cycling stability remains a challenging task. Here, Mn-doped FeNCN was synthesized by a one-step high-temperature solid-state reaction. Mn doping expands the lattice and boosts ionic conductivity, enabling favorable potassium ion storage and enhanced charging/discharging rates. In addition, density functional theory (DFT) calculations also prove that Mn-doped FeNCN facilitates the enhancement of potassium ions adsorption and promotes electron transfer. As a result, optimized Mn-FeNCN delivers high reversible capacity (402.6 mAh/g at 100 mA g−1) as PIBs anode. Even at high current density of 1000 mA g−1, it still delivers the reverse capacity of 301 mAh/g. This work provides a promising strategy to improve electrochemical performance of the transition metal carbodiimides.

The effects of Lu3+, Gd3+ and Ga3+ substitution on the photoluminescence of Y2.95-x-yLuxGdyAlzGa5-zO12:0.05Ce3+ phosphors for high-power white AC-LEDs.

Various yellowish-green persistent phosphors of Y2.95-x-yLuxGdyAl5-zGazO12:0.05Ce3+ (x = 0-1, y = 0-1, z = 1-4) were successfully synthesized by the one-step high-temperature solid-state reaction method in air. The effects of simultaneous doping of Lu3+, Gd3+ and Ga3+ on the luminescence properties of the phosphors were investigated in detail for the first time. Herein, the microstructure, morphology, afterglow performance, luminescence properties, thermoluminescence, thermal quenching and flicker index of the efficient blue-light-activated Y2.95-x-yLuxGdyAl5-zGazO12:0.05Ce3+ phosphors were tested. The τ90 and τ80 values of Y1.45LuGd0.5Al2.5Ga2.5O12:0.05Ce3+ are 10.8 ms and 33.2 ms, respectively. These parameters are important in terms of effectiveness in reducing flicker in alternating current (AC) LEDs. Compared with the conventional Y3Al2Ga3O12:Ce3+ phosphor, the Y1.45LuGd0.5Al2.5Ga2.5O12:0.05Ce3+ phosphor has a better luminescence performance, stronger afterglow performance, and lower flicker index. The quantum yield of the Y1.45LuGd0.5Al2.5Ga2.5O12:0.05Ce3+ phosphor was 86.42% and the luminous efficiency of the LED devices prepared with it reached 92.12 lm W-1 when operated at 100 mA. Integrating sphere and spectroradiometer tests as well as CIE chromaticity diagrams indicate that the AC-WLEDs assembled by mixing the Y1.45LuGd0.5Al2.5Ga2.5O12:0.05Ce3+ phosphor and a commercial red phosphor in an appropriate ratio could obtain ideal white light with a high color-rendering index (87.9) and the flickering index was successfully reduced from 100% to 61.4%.

Synthesis and Characterization of Molybdenum- and Sulfur-Doped FeSe.

During the past decade, two-dimensional (2D) layered materials opened novel opportunities for the exploration of exciting new physics and devices owing to their physical and electronic properties. Among 2D materials, iron selenide has attracted much attention from several physicists as they provide a fruitful stage for developing new superconductors. Chemical doping offers a powerful approach to manipulate and optimize the electronic structure and physical properties of materials. Here, to reveal how doping affects the physical properties in FeSe, we report on complementary measurements of molybdenum- and sulfur-doped FeSe with theoretical calculations. Mo0.1Fe0.9Se0.9S0.1 was synthesized by a one-step solid-state reaction method. Crystal structure and morphology were studied using powder X-ray diffraction and scanning electron microscopy. Thermal stability and decomposition behavior in doped samples were studied by thermogravimetric analysis, and to understand the microscopic influence of doping, we performed Raman spectroscopy. First-principles calculations of the electronic structure illustrate distinct changes of electronic structures of the substituted FeSe systems, which can be responsible for their superconducting properties.

Fe-doped perovskite-like oxide KCuTa3O9 for photocatalytic hydrogen evolution under visible light irradiation

Tantalum-based perovskite-like metal oxides (PLMOs) are one of promising candidates for photocatalytic water splitting due to their high stability, structural tunability and excellent photocatalytic activity. However, the photocatalytic hydrogen production activity is often hampered by their narrow light absorption range and severe photo-generated carrier recombination. In this research, a series of Fe-doped KCuTa3O9 (FKCTO-x) oxides were synthesized for the first time via one-step high-temperature solid-state reaction. Based on the detailed characterization analysis, Fe atoms have been successfully incorporated into the lattice of KCuTa3O9. An extended visible light absorption range and enhanced separation of the photogenerated carriers have been achieved in Fe-doped KCTO. As a result, all the FKCTO-x samples exhibit enhanced photocatalytic hydrogen evolution activities, among which FKCTO-2 shows an optimal hydrogen production rate of 5.51 µmol h−1 under visible light irradiation, far exceeding that of the pure KCTO. This work provides a simple and effective strategy to design and prepare highly efficient visible-light-driven PLMOs for photocatalytic water splitting.

Evolving MXene species

<p>A Li-ion battery (LIB) with superior interior thermal management behavior to avoid thermal runaway is crucial for safe and long-lasting operation, especially at high temperatures or during fast discharging and charging. However, due to the lack of low-resistance electrode materials with comparatively low mid-infrared emission, such interior thermal management properties are usually achieved by focusing on the separator and electrolyte when overheating occurs. Herein, we developed a Se-terminated MXene free-standing electrode with superior electrical conductivity and low infrared emissivity to synergistically couple high-rate capacity with reduced heat radiation ability for safe, large and fast Li<sup>+</sup> storage, which was achieved through one-step organic Lewis acid-assisted solid-state reaction and vacuum filtration. Compared to conventional disordered O/OH/F-terminated materials, Se-terminated Nb<sub>2</sub>Se<sub>2</sub>C was found to enhance the Li<sup>+</sup>-storage capacity by approximately 1.5-folds in the fifth cycle (221 mAh��g<sup>?1</sup> at 1 A��g<sup>?1</sup>) and promote the mid-infrared adsorption with low thermal radiation. These effects are mainly induced by its superior electrical conductivity, excellent structural stability, and high permittivity in the infrared region. Further calculation by infrared spectra selectivity revealed that the increase in permittivity and the oriented enhancement of conductivity along the z-direction could reduce the heat radiation of electrodes. This work sheds light on a promising surface groups-terminated layered material-based free-standing flexible electrodes with novel self-thermal management ability and high-rate performance for safe and fast energy storage.</p>

Metal cobalt embedded N-doped carbon nanotube catalyst for catalytic ozonation

Through a one-step solid-state pyrolysis reaction, we construct a Co embedded N-doped carbon nanotube ([email protected]) catalyst for catalytic ozonation. The embedded Co and doped N effectively enhance the catalytic activity and stability of carbon nanotubes, and the core–shell structure effectively solves the problem of metal leaching. Experiment results showed that the [email protected] for catalytic ozonation could completely degrade 15 mg L-1 of methylene blue solution in 6 min, and the removal efficiency was about 35% higher than ozonation alone. Results of EPR experiments and quenching tests manifested that both.O2– and 1O2 were dominant ROS contributed to the improvement of degradation efficiency with [email protected]/O3 system.

Preparation and investigation of the structural properties of SmFeAsO0.7F0.3 compound

SmFeAsO0.7F0.3 polycrystalline bulk iron-based compound were prepared by one-step solid state reaction method at low sinter temperature. The aim was: to find the optimum preparing method for the compound and then to study its structural properties. The X-ray diffraction spectrum of the samples was analyzed using MAUD software. XRD measurements were used to characterize the crystal structure, phase purity, lattice parameters, ‎unit cell volume and bonding angles and intervals of the samples. The results were compared with JCPDS reference pattern and the reports in the literatures, to ensure the accuracy of the synthesis. The XRD analyses revealed an increase in the phase purity above 80%, by lowering the sinter temperature down to 900 ºC. Also, the samples have a tetragonal crystal structure with P4/nmm symmetry, at room temperature. The SEM images show the samples are almost homogeneous with some porosity. The porosity decrease and the grain size grow by decreasing the sinter temperature. These results show the preparation of good quality samples at low temperature of 900 ºC compared to 1200 ºC which usually is used for preparation of this family of compound.

Facile Synthesis of Sillén-Aurivillius Layered Oxide Bi7Fe2Ti2O17Cl with Efficient Photocatalytic Performance for Degradation of Tetracycline

The development of an efficient and environment-friendly photocatalyst for antibiotics degradation is of great significance and still remains a major challenge. Herein, a novel Sillén-Aurivillius layered oxide Bi7Fe2Ti2O17Cl is successfully synthesized via a one-step flux route (noted as F-BFTOC) and solid-state reaction (noted as S-BFTOC). The as-prepared F-BFTOC manifests the enhanced visible-light photocatalytic performance towards tetracycline (TC) degradation compared with Bi4NbO8Cl and its degradation efficiency reaches 90% within 90 min. Additionally, the proposed degradation pathway and photocatalytic mechanism are systematically investigated by liquid chromatography tandem-mass spectrometry (HPLC-MS), active species trapping test, electron spin resonance (ESR) and first-principles calculations. The superior degradation of antibiotics is primarily derived from the photo-generated h+, and radical ·O2− as the dominant active species. More importantly, the F-BFTOC exhibits excellent cycle stability and TC is ultimately transformed into non-toxic open-loop products. Simultaneously, Rhodamine B (RhB) as a typical organic pollutant is further employed to evaluate the photocatalytic activity of F-BFTOC, and 98% of the degradation efficiency is achieved. BFTOC as a multifunctional photocatalyst for pollutant degradation offers a new insight for Sillén-Aurivillius photocatalytic in the field of water purification.

Green-emitting carbon quantum dots as a dual-mode fluorescent and colorimetric sensor for hypochlorite.

In this work, green-emitting carbon quantum dots were successfully prepared through a facile one-step solid-state reaction method. The obtained green-emitting carbon dots (G-CDs) showed good fluorescence stability in NaCl aqueous solution and different pH values. Moreover, the G-CDs showed high sensitivity and selectivity for detecting hypochlorite by both fluorometry and colorimetry. Under the optimized condition, a highly sensitive detection of hypochlorite was established in the range of 0.2-100μM and 10-150μM for fluorescent and colorimetric methods, respectively. The corresponding limits of detection (LOD) were 0.0781μM and 1.82μM, respectively. Therefore, the G-CDs were successfully applied to determinate hypochlorite in actual water samples. In addition, a paper-based sensor loading with the G-CDs was also developed for rapid visual detection of hypochlorite. The results suggested that the G-CDs could be a promising candidate to detect hypochlorite.

Crystallographic engineering to reduce diffusion barrier for enhanced intercalation pseudocapacitance of TiNb2O7 in fast-charging batteries

Improving the ion/electron transport of TiNb2O7 composite is of great significance for achieving fast-charging lithium-ion batteries. Herein, we firstly report a rare-earth element engineering to tailor the bandgap and crystallographic structure for the dual function of electronic and ionic conductivity. Tb-doped TiNb2O7 (denoted as Tbx-TNO, x=0, 0.005, 0.010, 0.015) are successfully fabricated through a one-step solid-state reaction strategy. The Rietveld refinement technology of X-ray diffraction (XRD) demonstrates an effective substitution of Tb in the central sites of Nb-O octahedral. Significantly, in-situ XRD and ex-situ TEM techniques reveal the positive influence of Tb doping on the underlying ion transport behavior, which is verified by the increased unit cell volume, decreased mechanic effects, and promoted Li+-diffusion kinetics. DFT calculations demonstrate a narrow down of bandgap (from insulators to semiconductors) and reduction of ion-diffusion barrier in various migration modes, which lead to substantially enhanced ion/electron conductivities of Tb-TiNb2O7 microrod. Benefiting from the structural merits, the Tb0.01-TiNb2O7 presented outstanding rate capability (a reversible capacity of 192.8 mA h g−1 at 50 C) and an impressive cycle lifespan, corresponding to an ultra-high retention ratio of 98.9% (203.2 mA h g−1) over 1000 cycles. A pouch cell based on LiNi0.8Co0.1Mn0.1O2 cathodes and the Tb0.01-TiNb2O7 anodes exhibits potential application with superior rate capability and cycling stability. This work provides a simple strategy to enhance the rate-performance of TiNb2O7, making a guideline to construct fast-charging batteries with long cycling life.

Thermoelectric properties of Sb-doped tin oxide by a one-step solid-state reaction

Recently, oxide-based materials have proven to be potential thermoelectric materials at high temperatures. In this work, the thermoelectric properties of one-step solid-state sintered Sn1-xSbxO2 (x = 0, 0.005, 0.01, 0.02, 0.03, 0.04) ceramic pellets were investigated in detail. It was confirmed that the addition of Sb significantly alters the thermoelectric properties of SnO2 due to the increase in the carrier concentration, which increases the electrical conductivity. The Seebeck coefficient values of all the solid solutions were negative, which indicates that these samples have n-type conduction. The thermoelectric performance of the material was evaluated by determining the zT value and the best composition was Sn0·98Sb0·02O2 with zT ∼0.06 at 1073 K.

Photoluminescence properties of Eu-doped WO3-Eu2(WO4)3 composites and single-phase Eu2(WO4)3 powders

The development of highly stable and efficient oxide-based red phosphors is urgently required for next-generation lighting devices. Herein, we report the micro/crystal structures and luminescent properties of single-phase Eu2(WO4)3 and Eu3+-doped WO3-Eu2(WO4)3 composite phosphors prepared by a one-step conventional solid-state reaction method in air atmosphere. As increasing Eu contents in the mixtures of WO3 and Eu2O3, the intensities of the X-ray diffraction peaks of Eu2(WO4)3 increased while that of WO3 decreased. The photoluminescence intensity of the synthesized phosphors increased with increase in the Eu content when calcined at 900 °C, while it degraded at a higher temperature. Red-emitting single-phase Eu2(WO4)3 powders were successfully obtained when the WO3 and Eu2O3 powders were calcined in the ratio of 3:1. The intensity of the red emission spectra of the Eu2(WO4)3 phosphor was higher than those of the 6, 12, and 24 at.% Eu-added WO3 composites at excitation wavelengths of 394 and 465 nm. On the other hand, the intensity of emission from the single-phase phosphor was lower than that of the Eu-doped WO3-Eu2(WO4)3 composites under excitation of UV light at 254 nm. Thus, we propose two prospective phosphors for application as red phosphors at various wavelengths.

One-step low-temperature solid-state synthesis of lead-free cesium copper halide Cs3Cu2Br5 phosphors with bright blue emissions

The development of new efficient and environmental-friendly inorganic phosphors is highly important for phosphor-converted white light-emitting diodes and optoelectronic displays. In this paper, we report a novel and simple one-step solid-state reaction to synthesize lead-free cesium copper halide Cs3Cu2Br5 powders with bright blue emission around 460 nm. The preparation process is performed at low calcination temperatures (290–320 °C) and requires no complex apparatus, reagents, or techniques, and thus it holds great potential for mass production of halide emitters. The Cs3Cu2Br5 powder phosphors are characterized by X-ray diffraction, field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, photoluminescence excitation and emission spectroscopy, CIE color coordinates, color purity, photoluminescence quantum yield, and temperature-dependent emission spectra. The effect of calcination temperature on the photoluminescence properties of the as-prepared Cs3Cu2Br5 blue phosphors has been investigated and the air-stability property has also been discussed. Impressively, Cs3Cu2Br5 blue phosphors show outstanding stability toward air exposure exceeding one month (30 days). Our work will open a new and simple approach to obtain excellent halide emitters for future solid-state lighting and displays.

Enhanced crystallinity and photoluminescence properties of Yb2+ doped SrSi2O2N2 phosphor for image storage applications

A series of Yb2+ and Dy3+ doped SrSi2O2N2 phosphors with enhanced crystallinity and photoluminescence properties have been successfully synthesized by two-step method using Sr2SiO4 as precursor. It is clearly indicated from XRD results that Yb2+ ions can substitute Sr sites in SrSi2O2N2 crystal and exhibit pure phase and well-crystalline in comparison with the samples prepared by traditional solid-state reaction. The excessive amount of Si3N4 in the reactants promoted the formation of pure SrSi2O2N2 phosphors phase. SrSi2O2N2: Yb2+ phosphors show emission band at 583 nm and the broad excitation peaks located at 308 nm, 384 nm and 447 nm, covering the emission wavelength of NUV and blue chips. Compared with the sample prepared by traditional one-step solid-state reaction method, a dramatic enhancement of photoluminescence emission intensity (∼1.75 times) can be observed for SrSi2O2N2: 0.01 Yb2+ phosphor synthesized by two-step method. Due to the concentration quenching, the luminescence intensity reaches the maximum when doping concentration of Yb2+ ions is 1 mol%, which is identified as the electric dipole-electric dipole interaction. Notably, Yb2+ and Dy3+ co-doped SrSi2O2N2 phosphors with pure phase exhibit a unique thermal-stimulated luminescence property under NUV excitation, indicating the potential application in optical information storage. Furthermore, the mechanism of thermal-stimulated luminescence has been proposed.

Electronic transport of ZnSnSb2 for thermoelectric application

Thermoelectric (TE) devices convert heat energy directly into electricity, which requires highly efficient, eco-friendly, and reliable materials. The chalcopyrite compound zinc tin antimonide (ZnSnSb2) is a promising thermoelectric material that has high electrical conductivity, non-toxic, low cost, and plenty in nature. The ZnSnSb2was synthesized by simple one-step Solid-State Reaction (SSR) and studied their microstructural and electronic transport properties. The X-Ray Diffraction (XRD) pattern of the ZnSnSb2 exhibited a tetragonal crystal structure with ca ratio of 2 that indicates the valance band was degenerate, which was the reason for the low electrical resistivity of ZnSnSb2 (0.32 mΩ-cm at 325 K). Furthermore, the thermopower exhibited p-type behaviour and the maximum power factor ZnSnSb2 was found 39 µW/m-K2 at 542 K.

Stabilizing P2-Type Ni-Mn Oxides as High-Voltage Cathodes by a Doping-Integrated Coating Strategy Based on Zinc for Sodium-Ion Batteries.

The key to development of high-voltage P2-type Na0.66Ni0.33Mn0.67O2 is the modification methods that can effectively improve its electrochemical reversibility. Herein, a doping-integrated coating strategy based on zinc element is proposed to modify P2-type Na0.66Ni0.33Mn0.67O2, which can be achieved by a facile one-step solid-state reaction. The formation mechanism of Na0.66Ni0.26Zn0.07Mn0.67O2@0.06ZnO (NNZM@0.06ZnO) is investigated, revealing that the spinel and P3 intermediate phases appear prior to the formation of the P2 phase. Ni2+ can be preferentially incorporated into the P2 structure in competition with Zn2+ at high temperature, resulting in a uniform enrichment of ZnO on the surface. A small amount of Zn2+ doping significantly suppresses the Na+/vacancy ordering effect and improves the structural reversibility. Furthermore, the electrolyte decomposition is effectively reduced because of the presence of the ZnO coating layer, leading to the formation of a thin cathode electrolyte interphase film that is favorable to fast Na+ diffusion. In virtue of the Zn2+ doping and in situ formed ZnO coating, NNZM@0.06ZnO exhibits excellent cycling stability with a capacity retention of 83.7% after 100 cycles at 100 mA g-1 and rate performance with a discharge capacity of 56.4 mAh g-1 at 2000 mA g-1, which significantly outperforms the uncoated Na0.66Ni0.26Zn0.07Mn0.67O2 and the Na0.66Ni0.26Zn0.07Mn0.67O2/0.06ZnO with the coating layer introduced by mechanical milling. This work provides a new strategy to design high-performance cathode materials for sodium-ion batteries.

The thermoelectric and mechanical properties of Mg2(Si0.3Sn0.7)0.99Sb0.01 prepared by one-step solid state reaction combined with hot-pressing

Achieving high-performance by an effective and convenient preparation method is of great significance to the application of thermoelectric materials. Herein, we propose a facile method combined one-step solid state reaction (SSR) with hot pressing (HP) to fabricate Mg2(Si0.3Sn0.7)0.99Sb0.01. Although the main products after the SSR are Mg2Si and Mg2Sn compounds as well as various Mg2Si1−xSnx phases, the compact bulk sample with anti-fluorite structure is obtained in 2 h of HP process by controlling HP temperature. The obtained Mg2(Si0.3Sn0.7)0.99Sb0.01 exhibits a decent figure of merit of 1.37 at 673 K associated with a flexural strength of 74 MPa, which is fully comparable with the samples prepared by the method of two-step SSR combined with sintering technique, but the process of our method is obviously simplified.

High-capacity and high-rate Ni-Fe batteries based on mesostructured quaternary carbon/Fe/FeO/Fe3O4 hybrid material

SummaryThe Ni-Fe battery is a promising alternative to lithium ion batteries due to its long life, high reliability, and eco-friendly characteristics. However, passivation and self-discharge of the iron anode are the two main issues. Here, we demonstrate that controlling the valence state of the iron and coupling with carbon can solve these problems. We develop a mesostructured carbon/Fe/FeO/Fe3O4 hybrid by a one-step solid-state reaction. Experimental evidence reveals that the optimized system with three valence states of iron facilitates the redox kinetics, while the carbon layers can effectively enhance the charge transfer and suppress self-discharge. The hybrid anode exhibits high specific capacity of 604 mAh⋅g−1 at 1 A⋅g−1 and high cyclic stability. A Ni-Fe button battery is fabricated using the hybrid anode exhibits specific device energy of 127 Wh⋅kg−1 at a power density of 0.58 kW⋅kg−1 and maintains good capacity retention (90%) and coulombic efficiency (98.5%).

High-Capacity and High-Rate Ni-Fe Batteries Based on Mesostructured Quaternary Carbon/Fe/Feo/Fe <sub>3</sub>O <sub>4</sub> Hybrid Material

There is now an increasing demand for green, long-lasting and sustainable battery technology, due to the rapid development of photovoltaic and other renewable energy power systems. The Ni-Fe battery is a promising alternative to lithium ion batteries due to its long life, high reliability and eco-friendly characteristics. However, passivation and self-discharge of the iron anode are currently two of the main issues with Ni-Fe batteries, which lead to low specific energy (20-30 Wh·kg-1) and poor cycle efficiency (~65%). Here, we demonstrate that controlling the valence state of the iron and coupling with carbon can solve these problems. We develop a novel mesostructured quaternary carbon/Fe/FeO/Fe3O4 hybrid, containing iron oxides wrapped with a few atomic layers of carbon synthesized by a one-step solid state reaction. Experimental evidence reveals that the optimized system with three valence states of iron facilitates the redox kinetics, while the carbon layers can effectively enhance the charge transfer and suppress self-discharge. The hybrid anode exhibits high specific capacity of 604 and 528 mAh · g-1 at 1 and 10 A·g-1, respectively and high cyclic stability. A Ni-Fe button battery is fabricated using the carbon/Fe/FeO/Fe3O4 hybrid, delivering specific device energy of 127 and 110 Wh·kg-1 at a power density of 0.58 and 5.07 kW·kg-1, respectively. ~98.5 % Coulombic efficiency and ~90 % capacity retention have been achieved after 2500 cycles at 300 mA ·g-1. These features suggest that the Ni-Fe battery holds promise to become an important alternative in stationary energy storage.