Stable Seamless Interfaces and Rapid Ionic Conductivity of Ca–CeO2/LiTFSI/PEO Composite Electrolyte for High‐Rate and High‐Voltage All‐Solid‐State Battery

Stable and seamless interfaces among solid components in all‐solid‐state batteries (ASSBs) are crucial for high ionic conductivity and high rate performance. This can be achieved by the combination of functional inorganic material and flexible polymer solid electrolyte. In this work, a flexible all‐solid‐state composite electrolyte is synthesized based on oxygen‐vacancy‐rich Ca‐doped CeO₂ (Ca–CeO₂) nanotube, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and poly(ethylene oxide) (PEO), namely Ca–CeO₂/LiTFSI/PEO. Ca–CeO₂ nanotubes play a key role in enhancing the ionic conductivity and mechanical strength while the PEO offers flexibility and assures the stable seamless contact between the solid electrolyte and the electrodes in ASSBs. The as‐prepared electrolyte exhibits high ionic conductivity of 1.3 × 10^?4 S cm^?1 at 60 °C, a high lithium ion transference number of 0.453, and high‐voltage stability. More importantly, various electrochemical characterizations and density functional theory (DFT) calculations reveal that Ca–CeO₂ helps dissociate LiTFSI, produce free Li ions, and therefore enhance ionic conductivity. The ASSBs based on the as‐prepared Ca–CeO₂/LiTFSI/PEO composite electrolyte deliver high‐rate capability and high‐voltage stability.     

Study of trivalent samarium ion embedded lithium‐based borate glass for high‐density optical memory devices

Sm³⁺ ions doped strontium lithium lead borate glasses (SLLB:Sm) were prepared using a conventional melt‐quenching technique. The glasses were analyzed using X‐ray diffractometry and Fourier transform infrared spectroscopy, optical absorption, fluorescence spectral analysis, and fluorescence lifetime decay. The Judd–Ofelt (J–O) parameters and radiative parameters of the SLLB:Sm10 glass (1.0 mol% Sm³⁺ ion‐doped glass) were calculated using J–O theory. From the emission spectra, among all the synthesized glass, SLLB:Sm10 glass had the highest emission intensity for ⁴G_5/2→⁶H_11/2 transition (610 nm). Emission parameters, such as stimulated emission cross‐section and optical gain bandwidth, were calculated. For all concentrations of Sm³⁺ ions, the decay profile showed an exponential nature and decreased when the Sm³⁺ ion concentration was increased due to a concentration quenching effect. This result suggests that the synthesized SLLB:Sm10 glass could be used for application in high‐density optical memory devices.     

Intense green‐, red‐emitting Tb3+, Tb3+/Bi3+‐doped and Sm3+, Sm3+/La3+‐doped Ca2Al2SiO7 phosphors

This paper focuses on an optical study of a Tb³⁺/Bi³⁺‐doped and Sm³⁺/La³⁺‐ doped Ca₂Al₂SiO₇ phosphor synthesized using combustion methods. Here, Ca₂Al₂SiO₇:Sm³⁺ showed a red emission band under visible light excitation but, when it co‐doped with La³⁺ ions, the emission intensity was further enhanced. Ca₂Al₂SiO₇:Tb³⁺ shows the characteristic green emission band under near‐ultraviolet light excitation wavelengths, co‐doping with Bi³⁺ ions produced enhanced photoluminescence intensity with better colour tunable properties. The phosphor exhibited better phase purity and crystallinity, confirmed by X‐ray diffraction. Binding energies of Ca(2p), Al(2p), Si(2p), O(1s) were studied using X‐ray photoelectron spectroscopy. The reported phosphor may be a promising visible light excited red phosphor for light‐emitting diodes and energy conversion devices.     

Enhanced photoluminescence properties of electrospun Dy3+‐doped ZnO nanofibres for white lighting devices

Dy³⁺‐doped ZnO nanofibres with diameters from 200 to 500 nm were made using an electrospinning technique. The as‐fabricated amorphous nanofibres resulted in good crystalline continuous nanofibres through calcination. Dy³⁺‐doped ZnO nanofibres were characterized using scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDX), X‐ray diffraction (XRD), ultraviolet–visible (UV–vis) light spectroscopy, Fourier transform infrared spectroscopy (FTIR), and photoluminescence (PL). XRD showed the well defined peaks of ZnO. UV–vis spectra showed a good absorption band at 360 nm. FTIR spectra showed a Zn–O stretching vibration confirming the presence of ZnO. Photoluminescence spectra of Dy³⁺‐doped ZnO nanofibres showed an emission peak in the visible region that was free from any ZnO defect emission. Emissions at 480 nm and 575 nm in the Dy³⁺‐doped ZnO nanofibres were the characteristic peaks of dopant Dy³⁺ and implied efficient energy transfer from host to dopant. Luminescence intensity was found to be increased with increasing doping concentration and reduction in nanofibre diameter. Colour coordinates were calculated from photometric characterizations, which resembled the properties for warm white lighting devices.     

Binary Indium–Zinc Oxide Photoanodes for Efficient Dye‐Sensitized Solar Cells

The benefits of incorporating binary metal‐oxide electrodes en route toward efficient dye‐sensitized solar cells (DSSCs) have recently emerged. The current work aims at realizing efficient indium‐doped zinc oxide based DSSCs by means of enhancing charge transport processes and reducing recombination rates. Electrochemical impedance spectroscopic assays corroborate that low amounts of indium reduce charge transport resistances and increase electron recombination resistances. The latter are in concert with a remarkable enhancement of the charge collection efficiency from 33% to 83% for devices with ZnO and In₁₅Zn₈₅O photoanodes, respectively. Going beyond 15 mol% of indium, an effective electron trapping increases the charge transport resistance and, in turn, dramatically reduces charge collection efficiency. Upon implementing In₁₅Zn₈₅O into an electron cascade photoanode architecture featuring an In₁₅Zn₈₅O bottom layer and a ZnO top layer, a device efficiency of 5.77% and a significantly high current density of 20.4 mA cm^?2 in binary ZnO DSSCs are achieved.     

LiTFSI‐Free Spiro‐OMeTAD‐Based Perovskite Solar Cells with Power Conversion Efficiencies Exceeding 19%

To date, the most efficient perovskite solar cells (PSCs) employ an n–i–p device architecture that uses a 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenyl‐amine)‐9,9′‐spirobifluorene (spiro‐OMeTAD) hole‐transporting material (HTM), which achieves optimum conductivity with the addition of lithium bis(trifluoromethane)sulfonimide (LiTFSI) and air exposure. However, this additive along with its oxidation process leads to poor reproducibility and is detrimental to stability. Herein, a dicationic salt spiro‐OMeTAD(TFSI)₂, is employed as an effective p‐dopant to achieve power conversion efficiencies of 19.3% and 18.3% (apertures of 0.16 and 1.00 cm²) with excellent reproducibility in the absence of LiTFSI and air exposure. As far as it is known, these are the highest‐performing n–i–p PSCs without LiTFSI or air exposure. Comprehensive analysis demonstrates that precise control of the proportion of [spiro‐OMeTAD]⁺ directly provides high conductivity in HTM films with low series resistance, fast hole extraction, and lower interfacial charge recombination. Moreover, the spiro‐OMeTAD(TFSI)₂‐doped devices show improved stability, benefitting from well‐retained HTM morphology without forming aggregates or voids when tested under an ambient atmosphere. A facile approach is presented to fabricate highly efficient PSCs by replacing LiTFSI with spiro‐OMeTAD(TFSI)₂. Furthermore, this study provides an insight into the relationship between device performance and the HTM doping level.     

Fatigue‐Free and Bending‐Endurable Flexible Mn‐Doped Na0.5Bi0.5TiO3‐BaTiO3‐BiFeO3 Film Capacitor with an Ultrahigh Energy Storage Performance

As the rapid development of intelligent systems moves toward flexible electronics, capacitors with extraordinary flexibility and an outstanding energy storage performance will open up broad prospects for powering portable/wearable electronics and pulsed power applications. This work presents a simple one‐step process to fabricate a flexible Mn‐doped 0.97(0.93Na_0.5Bi_0.5TiO₃‐0.07BaTiO₃)‐0.03BiFeO₃ (Mn:NBT‐BT‐BFO) inorganic thin film capacitor with the assistance of a 2D fluorophlogopite mica substrate. The film element, which has a high breakdown strength, great relaxor dispersion, and the coexistence of ferroelectric and antiferroelectric phases, has a high recoverable energy storage density (W_rec ≈81.9 J cm^?3), high efficiency (η ≈64.4%), superior frequency stability (500 Hz–20 kHz), excellent antifatigue property (1 × 10⁹ cycles), and a broad operating temperature window (25–200 °C). The all‐inorganic Mn:NBT‐BT‐BFO/Pt/mica capacitor has a prominent mechanical‐bending resistance without obvious deterioration in its corresponding energy storage capability when it is subjected to a bending radius of 2 mm or repeated bending for 10³ cycles. This work is the first demonstration of an all‐inorganic flexible film capacitor and sheds light on dielectric energy storage devices for portable/wearable applications.     

Dual‐Functional N Dopants in Edges and Basal Plane of MoS2 Nanosheets Toward Efficient and Durable Hydrogen Evolution

Herein, the authors explicitly reveal the dual‐functions of N dopants in molybdenum disulfide (MoS₂) catalyst through a combined experimental and first‐principles approach. The authors achieve an economical, ecofriendly, and most efficient MoS₂‐based hydrogen evolution reaction (HER) catalyst of N‐doped MoS₂ nanosheets, exhibiting an onset overpotential of 35 mV, an overpotential of 121 mV at 100 mA cm^?2 and a Tafel slope of 41 mV dec^?1. The dual‐functions of N dopants are (1) activating the HER catalytic activity of MoS₂ S‐edge and (2) enhancing the conductivity of MoS₂ basal plane to promote rapid charge transfer. Comprehensive electrochemical measurements prove that both the amount of active HER sites and the conductivity of N‐doped MoS₂ increase as a result of doping N. Systematic first‐principles calculations identify the active HER sites in N‐doped MoS₂ edges and also illustrate the conducting charges spreading over N‐doped basal plane induced by strong Mo 3d –S 2p –N 2p hybridizations at Fermi level. The experimental and theoretical research on the efficient HER catalysis of N‐doped MoS₂ nanosheets possesses great potential for future sustainable hydrogen production via water electrolysis and will stimulate further development on nonmetal‐doped MoS₂ systems to bring about novel high‐performance HER catalysts.     

Mn‐Rich P′2‐Na0.67[Ni0.1Fe0.1Mn0.8]O2 as High‐Energy‐Density and Long‐Life Cathode Material for Sodium‐Ion Batteries

Herein, P′2‐type Na_0.67[Ni_0.1Fe_0.1Mn_0.8]O₂ is introduced as a promising new cathode material for sodium‐ion batteries (SIBs) that exhibits remarkable structural stability during repetitive Na⁺ de/intercalation. The O? Ni? O? Mn? O? Fe? O bond in the octahedra of transition‐metal layers is used to suppress the elongation of the Mn? O bond and to improve the electrochemical activity, leading to the highly reversible Na storage mechanism. A high discharge capacity of ≈220 mAh g^?1 (≈605 Wh kg^?1) is delivered at 0.05 C (13 mAg^?1) with a high reversible capacity of ≈140 mAh g^?1 at 3 C and excellent capacity retention of 80% over 200 cycles. This performance is associated with the reversible P′2–OP4 phase transition and small volume change upon charge and discharge (≈3%). The nature of the sodium storage mechanism in a full cell paired with a hard carbon anode reveals an unexpectedly high energy density of ≈542 Wh kg^?1 at 0.2 C and good capacity retention of ≈81% for 500 cycles at 1 C (260 mAg^?1).     

2D Metal Organic Framework Nanosheet: A Universal Platform Promoting Highly Efficient Visible‐Light‐Induced Hydrogen Production

2D metal organic frameworks (MOF) have received tremendous attention due to their organic–inorganic hybrid nature, large surface area, highly exposed active sites, and ultrathin thickness. However, the application of 2D MOF in light‐to‐hydrogen (H₂) conversion is rarely reported. Here, a novel 2D MOF [Ni(phen)(oba)]_n·0.5nH₂O (phen = 1,10‐phenanthroline, oba = 4,4′‐oxybis(benzoate)) is for the first time employed as a general, high‐performance, and earth‐abundant platform to support CdS or Zn_0.8Cd_0.2S for achieving tremendously improved visible‐light‐induced H₂‐production activity. Particularly, the CdS‐loaded 2D MOF exhibits an excellent H₂‐production activity of 45 201 µmol h^?1 g^?1, even exceeding that of Pt‐loaded CdS by 185%. Advanced characterizations, e.g., synchrotron‐based X‐ray absorption near edge structure, and theoretical calculations disclose that the interactive nature between 2D MOF and CdS, combined with the high surface area, abundant reactive centers, and favorable band structure of 2D MOFs, synergistically contribute to this distinguished photocatalytic performance. The work not only demonstrates that the earth‐abundant 2D MOF can serve as a versatile and effective platform supporting metal sulfides to boost their photocatalytic H₂‐production performance without noble‐metal co‐catalysts, but also paves avenues to the design and synthesis of 2D‐MOF‐based heterostructures for catalysis and electronics applications.     

A triazole‐based fluorescence probe for detecting Hg2+ ions and its biological application

A new compound, ethyl 5‐phenyl‐2‐(p‐tolyl)‐2H‐1,2,3‐triazole‐4‐carboxylate was successfully introduced and synthesized as a novel rhodamine B derivative named REPPC, and characterized by ¹H nuclear magnetic resonance (NMR), ¹³C NMR, and high resolution mass spectrometry (HRMS). It showed an obvious fluorescence and UV–visible light absorption enhancement towards Hg²⁺ ion without interference from common metal ions in N,N‐dimethylformamide–H₂O (pH 7.4). The spirolactam ring moiety of rhodamine in REPPC was converted to the open‐ring form generating a 1:1 complex with the intervention of a mercury ion, verified by electrospray ionization‐mass spectroscopy testing and density functional theory calculation. REPPC was used to visualize the level of mercury ions in living HeLa cells with encouraging results.     

3D‐Branched ZnO/CdS Nanowire Arrays for Solar Water Splitting and the Service Safety Research

Modulation of broadband light trapping through assembly of 3D structures and modification with narrow band‐gap semiconductors provide an effective way to improve the photoelectrochemical (PEC) performance. Here, 3D‐branched ZnO nanowire arrays (NWAs) modified with cadmium sulfide (CdS) nanoparticles are designed and synthesized via solution chemical routes. The 3D‐branched ZnO NWA–CdS nanoparticle photoanodes show an excellent PEC performance in UV and visible region and the maximum photo‐to‐hydrogen conversion efficiency reaches to 3.1%. The high performance of 3D‐branched ZnO NWA–CdS composites is mainly attributed to the excellent carrier collection capability and high light‐trapping ability of 3D‐branched ZnO NWAs as well as the excellent photocatalytic activity of CdS nanoparticles in the visible region. In addition, the photocorrosion mechanism of 3D‐branched ZnO NWA–CdS photoanodes is systematically investigated, and a protective TiO₂ layer is deposited onto the photoanodes to elevate the PEC stability. The results benefit a deeper understanding of the role of 3D‐branched structures decorated with narrow band‐gap semiconductors in solar water splitting.     

Atomic Fe‐Doped MOF‐Derived Carbon Polyhedrons with High Active‐Center Density and Ultra‐High Performance toward PEM Fuel Cells

A metalorganic gaseous doping approach for constructing nitrogen‐doped carbon polyhedron catalysts embedded with single Fe atoms is reported. The resulting catalysts are characterized using scanning transmission electron microscopy, X‐ray photoelectron spectroscopy, and X‐ray absorption spectroscopy; for the optimal sample, calculated densities of Fe–N_x sites and active N sites reach 1.75812 × 10¹³ and 1.93693 × 10¹⁴ sites cm^‐2, respectively. Its oxygen reduction reaction half‐wave potential (0.864 V) is 50 mV higher than that of 20 wt% Pt/C catalyst in an alkaline medium and comparable to the latter (0.78 V vs 0.84 V) in an acidic medium, along with outstanding durability. More importantly, when used as a hydrogen–oxygen polymer electrolyte membrane fuel cell (PEMFC) cathode catalyst with a catalyst loading as low as 1 mg cm^‐2 (compared with a conventional loading of 4 mg cm^‐2), it exhibits a current density of 1100 mA cm^‐2 at 0.6 V and 637 mA cm^‐2 at 0.7 V, with a power density of 775 mW cm^‐2, or 0.775 kW g^–1 of catalyst. In a hydrogen–air PEMFC, current density reaches 650 mA cm^‐2 at 0.6 V and 350 mA cm^‐2 at 0.7 V, and the maximum power density is 463 mW cm^‐2, which makes it a promising candidate for cathode catalyst toward high‐performance PEMFCs.     

Transient formation of the oxo–iron(IV) porphyrin radical cation during the reaction of iron(III) tetrakis‐5,10,15,20‐(N‐methyl‐4‐pyridyl)porphyrin with hydrogen peroxide in aqueous solution

The reaction of iron(III) tetrakis‐5,10,15,20‐(N‐methyl‐4‐pyridyl)porphyrin (Fe(III)TMPyP) with hydrogen peroxide (H₂O₂) and the catalytic activity of the reaction intermediates on the luminescent peroxidation of luminol in aqueous solution were studied by using a double‐mixing stopped‐flow system. The observed luminescence intensities showed biphasic decay depending on the conditions. The initial flashlight decayed within <1 s followed by a sustained emission for more than 30 s. Computer deconvolution of the time‐resolved absorption spectra under the same conditions revealed that the initial flashlight appeared during the formation of the oxo–iron(IV) porphyrin, TMPyPFe(IV) = O, which is responsible for the sustained emission. The absorption spectra 0.0–0.5 s did not reproduce well by a simple combination of the two spectra of Fe(III)TMPyP and TMPyPFe(IV) = O, indicating that transient species was formed at the initial stage. Addition of uric acid (UA) caused a significant delay in the initiation of the luminol emission as well as in the formation of the TMPyPFe(IV) = O. Both of them were completely diminished in the presence of UA equimolar with H₂O₂, while mannitol had no effect at all. The delay of the light emission as well as the appearance of TMPyPFe(IV) = O was directly proportional to the [UA]₀ but other kinetic profiles were not changed significantly. Based on these observations and the kinetic analysis, we confirmed the involvement of the oxo–iron(IV) porphyrin radical cation, (TMPyP)^·+Fe(IV) = O, as an obligatory intermediate in the rate‐determining step of the overall reaction, Fe(III)TMPyP + H₂O₂ → TMPyPFe(IV) = O, with a rate constant of k = 4.3 × 10⁴/mol/L/s. The rate constants for the reaction between the (TMPyP)^·+Fe(IV) = O and luminol, and between the TMPyPFe(IV) = O and luminol were estimated to be 3.6 × 10⁶/mol/L/s and 1.31 × 10⁴/mol/L/s, respectively. Copyright © 2003 John Wiley & Sons, Ltd.     

A Strategy for Synthesis of Carbon Nitride Induced Chemically Doped 2D MXene for High‐Performance Supercapacitor Electrodes

A step‐by‐step strategy is reported for improving capacitance of supercapacitor electrodes by synthesizing nitrogen‐doped 2D Ti₂CT_x induced by polymeric carbon nitride (p‐C₃N₄), which simultaneously acts as a nitrogen source and intercalant. The NH₂CN (cyanamide) can form p‐C₃N₄ on the surface of Ti₂CT_x nanosheets by a condensation reaction at 500–700 °C. The p‐C₃N₄ and Ti₂CT_x complexes are then heat‐treated to obtain nitrogen‐doped Ti₂CT_x nanosheets. The triazine‐based p‐C₃N₄ decomposes above 700 °C; thus, the nitrogen species can be surely doped into the internal carbon layer and/or defect site of Ti₂CT_x nanosheets at 900 °C. The extended interlayer distance and c‐lattice parameters (c‐LPs of 28.66 Å) of Ti₂CT_x prove that the p‐C₃N₄ grown between layers delaminate the nanosheets of Ti₂CT_x during the doping process. Moreover, 15.48% nitrogen doping in Ti₂CT_x improves the electrochemical performance and energy storage ability. Due to the synergetic effect of delaminated structures and heteroatom compositions, N‐doped Ti₂CT_x shows excellent characteristics as an electrochemical capacitor electrode, such as perfectly rectangular cyclic voltammetry results (CVs, R² = 0.9999), high capacitance (327 F g^?1 at 1 A g^?1, increased by ≈140% over pristine‐Ti₂CT_x), and stable long cyclic performance (96.2% capacitance retention after 5000 cycles) at high current density (5 A g^?1).     

Lithium Fluoride Based Electron Contacts for High Efficiency n‐Type Crystalline Silicon Solar Cells

Low‐resistance contact to lightly doped n‐type crystalline silicon (c‐Si) has long been recognized as technologically challenging due to the pervasive Fermi‐level pinning effect. This has hindered the development of certain devices such as n‐type c‐Si solar cells made with partial rear contacts (PRC) directly to the lowly doped c‐Si wafer. Here, a simple and robust process is demonstrated for achieving mΩ cm² scale contact resistivities on lightly doped n‐type c‐Si via a lithium fluoride/aluminum contact. The realization of this low‐resistance contact enables the fabrication of a first‐of‐its‐kind high‐efficiency n‐type PRC solar cell. The electron contact of this cell is made to less than 1% of the rear surface area, reducing the impact of contact recombination and optical losses, permitting a power conversion efficiency of greater than 20% in the initial proof‐of‐concept stage. The implementation of the LiF_x/Al contact mitigates the need for the costly high‐temperature phosphorus diffusion, typically implemented in such a cell design to nullify the issue of Fermi level pinning at the electron contact. The timing of this demonstration is significant, given the ongoing transition from p‐type to n‐type c‐Si solar cell architectures, together with the increased adoption of advanced PRC device structures within the c‐Si photovoltaic industry.     

Active‐Site Imprinting: Preparation of Fe–N–C Catalysts from Zinc Ion–Templated Ionothermal Nitrogen‐Doped Carbons

Atomically dispersed Fe–N–C catalysts are considered the most promising precious‐metal‐free alternative to state‐of‐the‐art Pt‐based oxygen reduction electrocatalysts for proton‐exchange membrane fuel cells. The exceptional progress in the field of research in the last ≈30 years is currently limited by the moderate active site density that can be obtained. Behind this stands the dilemma of metastability of the desired FeN₄ sites at the high temperatures that are believed to be a requirement for their formation. It is herein shown that Zn²⁺ ions can be utilized in the novel concept of active‐site imprinting based on a pyrolytic template ion reaction throughout the formation of nitrogen‐doped carbons. As obtained atomically dispersed Zn–N–Cs comprising ZnN₄ sites as well as metal‐free N₄ sites can be utilized for the coordination of Fe²⁺ and Fe³⁺ ions to form atomically dispersed Fe–N–C with Fe loadings as high as 3.12 wt%. The Fe–N–Cs are active electocatalysts for the oxygen reduction reaction in acidic media with an onset potential of E₀ = 0.85 V versus RHE in 0.1 m HClO₄. Identical location atomic resolution transmission electron microscopy imaging, as well as in situ electrochemical flow cell coupled to inductively coupled plasma mass spectrometry measurements, is employed to directly prove the concept of the active‐site imprinting approach.     

Soft Template‐Controlled Growth of High‐Quality CsPbI3 Films for Efficient and Stable Solar Cells

The unfavorable morphology and inefficient utilization of phase transition reversibility have limited the high‐temperature‐processed inorganic perovskite films in both efficiency and stability. Here, a simple soft template‐controlled growth (STCG) method is reported by introducing (adamantan‐1‐yl)methanammonium to control the nucleation and growth rate of CsPbI₃ crystals, which gives rise to pinhole‐free CsPbI₃ film with a grain size on a micrometer scale. The STCG‐based CsPbI₃ perovskite solar cell exhibits a power conversion efficiency of 16.04% with significantly reduced defect densities and charge recombination. More importantly, an all‐inorganic solar cell with the architecture fluorine‐doped tin oxide (FTO)/NiO_x/STCG‐CsPbI₃/ZnO/indium‐doped tin oxide (ITO) is successfully fabricated to demonstrate its real advantage in thermal stability. By suppressing the inductive effect of defects during the phase transition and utilizing the unique reversibility of the phase transition for the high‐temperature‐processed CsPbI₃ film, the all‐inorganic solar cell retains 90% of its initial efficiency after 3000 h of continuous light soaking and heating.     

Na‐Mn‐O Nanocrystals as a High Capacity and Long Life Anode Material for Li‐Ion Batteries

Searching for a new material to build the next‐generation rechargeable lithium‐ion batteries (LIBs) with high electrochemical performance is urgently required. Owing to the low‐cost, non‐toxicity, and high‐safety, the family of manganese oxide including the Na‐Mn‐O system is regarded as one of the most promising electrode materials for LIBs. Herein, a new strategy is carried out to prepare a highly porous and electrochemically active Na_0.55Mn₂O₄·1.5H₂O (SMOH) compound. As an anode material, the Na‐Mn‐O nanocrystal material dispersed within a carbon matrix manifests a high reversible capacity of 1015.5 mA h g^?1 at a current density of 0.1 A g^?1. Remarkably, a considerable capability of 546.8 mA h g^?1 remains even after 2000 discharge/charge cycles at the higher current density of 4 A g^?1, indicating a splendid cyclability. The exceptional electrochemical properties allow SMOH to be a promising anode material toward LIBs.     

Uniform Pomegranate‐Like Nanoclusters Organized by Ultrafine Transition Metal Oxide@Nitrogen‐Doped Carbon Subunits with Enhanced Lithium Storage Properties

Uniform pomegranate‐like nanoclusters (NCs) organized by ultrafine transition metal oxide@nitrogen‐doped carbon (TMO@N–C) subunits (diameter ≈ 4 nm) are prepared on a large scale for the first time through a facile, novel, and one‐pot approach. Taking pomegranate‐like Fe₃O₄@N–C NCs as an example, this unique structure provides short Li⁺/electron diffusion pathways for electrochemical reactions, structural stability during cycling, and high electrical conductivity, leading to superior electrochemical performance. The resulting pomegranate‐like Fe₃O₄@N–C NCs possess a high specific capacity (1204.3 mA h g^?1 at 0.5 A g^?1 over 100 cycles), a stable cycle life (1063.0 mA h g^?1 at 1 A g^?1, 98.4% retention after 1000 cycles), and excellent rate capacities (606.0 mA h g^?1 at 10 A g^?1, 92.0% retention; 417.1 mA h g^?1 at 20 A g^?1, 91.7% retention after 1000 cycles).