Li-cycling properties of nano-crystalline (Ni1 − x Zn x )Fe2O4 (0 ≤ x ≤ 1)

Multifunctional NiFe2O4 nanoparticles for sodium-ion batteries, sensing, and photocatalysis

NiFe2O4 NPs synthesized by co-precipitation method exhibited excellent electrochemical properties towards sodium ion batteries and oxidation of uric acid. NiFe2O4 NPs also exhibited good catalytic activity for simultaneous degradation of multiple dyes.

A new spinel high-entropy oxide (Mg0.2Ti0.2Zn0.2Cu0.2Fe0.2)3O4 with fast reaction kinetics and excellent stability as an anode material for lithium ion batteries

It is well known that transition metal oxides (TMOs) have attracted extensive attention as promising anodes for next-generation lithium ion batteries (LIBs) owing to their low cost and high theoretical capacities. However, the huge volume changes upon lithiation/delithiation cycling gradually cause drastic particle pulverization in the electrodes, thus leading to fast capacity fading and limiting their practical applications. High-entropy oxides with enhanced electronic conductivity and multiple electrochemically active elements display stepwise lithium storage behaviors, thus efficiently alleviating the volume change induced electrode pulverization problem. Herein, we report the synthesis of a new kind of spinel (Mg_0.2Ti_0.2Zn_0.2Cu_0.2Fe_0.2)₃O₄ material via a facile one-step solid state reaction method and subsequent high-energy ball-milling. When used as anodes for LIBs, the submicrometer-sized (Mg_0.2Ti_0.2Zn_0.2Cu_0.2Fe_0.2)₃O₄ particles exhibit superior lithium storage properties, delivering a large reversible capacity of 504 mA h g⁻¹ at a current density of 100 mA g⁻¹ after 300 cycles, and notably an exceptional rate capacity of 272 mA h g⁻¹ at 2000 mA g⁻¹. Our work highlights that rational design of high-entropy oxides with different electrochemically active elements and novel structures might be a useful strategy for exploring high-performance LIB anode materials in next-generation energy storage devices.

Here we present novel (Mg_0.2Ti_0.2Zn_0.2Cu_0.2Fe_0.2)₃O₄ materials prepared via one-step solid state reaction method and subsequently high-energy ball-milling. When used as anodes for LIBs, it exhibits superior lithium storage properties.

Unveiling the Reaction Mechanism during Li Uptake and Release of Nanosized "NiFeMnO4": Operando X-ray Absorption, X-ray Diffraction, and Pair Distribution Function Investigations

Here, we report that the trimetallic nanosized oxide NiFeMnO₄ consists of a mixture of NiO and a strained cubic spinel phase, which is clearly demonstrated by analysis of the pair distribution function (PDF) and synchrotron X-ray data. Such a finding can easily be overlooked by using only inhouse X-ray powder diffraction, leading to inaccurate assumption of the stoichiometry and oxidation states. Such advanced characterization is essential because a homogeneous distribution of the elements is observed in energy-dispersive X-ray spectroscopy maps, giving no hints for a phase separation. Cycling of the sample against Li delivers a high reversible capacity of ≈840 mAh/g in the 50th cycle. Operando X-ray absorption spectroscopy (XAS) experiments indicate that ≈0.8 Li/fu is consumed without detectable changes of the electronic structure. Increasing amounts of Li, Mn³⁺, and Fe³⁺ are simultaneously reduced. The disappearance of the pre-edge features in X-ray absorption near-edge spectroscopy indicates movement of these cations from tetrahedral sites to octahedral sites. PDF analysis of the pattern after an uptake of 2 Li/fu evidences that the principal structure can be sufficiently well modeled assuming coexisting NiO, a mixed monoxide, and a small amount of residual spinel phase. Thus, the majority of cations is located on octahedral sites. Furthermore, an improvement of the PDF model is achieved taking into account small amounts of LiOH. The ⁷Li MAS NMR spectrum of this sample clearly shows the signal of Li in a diamagnetic environment, excluding Li-O-TM bonds. A further increase of the Li content leads to a successive conversion of the cations to nanosized metal particles embedded in a LiOH/Li₂O matrix. Ex situ XAS results indicate that Fe can be reversibly reoxidized to Fe³⁺ during charge whereas Mn does not reach the oxidation state observed in the pristine material. After excessive cycling, reoxidation of metallic Ni is suppressed and contributes to a capacity loss compared with the early discharge/charge cycles.

Mechanochemically induced transformation of CoO(OH) into Co3O4 nanoparticles and their highly reversible Li storage characteristics

A simple synthetic method for the mechanochemically induced transformation of cobalt oxyhydroxides (CoO(OH)) into cobalt oxide (Co₃O₄) nanoparticles is developed and applied to Li-ion batteries.

A Facile Synthesis of ZnCo2O4 Nanocluster Particles and the Performance as Anode Materials for Lithium Ion Batteries

ABSTRACT

ZnCo₂O₄ nanocluster particles (NCPs) were prepared through a designed hydrothermal method, with the assistance of a surfactant, sodium dodecyl benzene sulfonate. The crystalline structure and surface morphology of ZnCo₂O₄ were investigated by XRD, XPS, SEM, TEM, and BET analyses. The results of SEM and TEM suggest a clear nanocluster particle structure of cubic ZnCo₂O₄ (~100 nm in diameter), which consists of aggregated primary nanoparticles (~10 nm in diameter), is achieved. The electrochemical behavior of synthesized ZnCo₂O₄ NCPs was investigated by galvanostatic discharge/charge measurements and cyclic voltammetry. The ZnCo₂O₄ NCPs exhibit a high reversible capacity of 700 mAh g^-1 over 100 cycles under a current density of 100 mA g^-1 with an excellent coulombic efficiency of 98.9% and a considerable cycling stability. This work demonstrates a facile technique designed to synthesize ZnCo₂O₄ NCPs which show great potential as anode materials for lithium ion batteries.

Facile Synthesis of Nix Zn1-x Fe2 O4 (x=0, 0.25, 0.5, 0.75, 1) as Anode Materials for Lithium Storage

Ni_x Zn_1-x Fe₂ O₄ (x=0, 0.25, 0.5, 0.75, 1) compounds were prepared by a hydrothermal method and subsequent heat treatment. The physical characteristics of the samples were investigated by field-emission SEM, XRD, X-ray photoelectron spectroscopy, and TEM. The electrochemical properties of Ni_x Zn_1-x Fe₂ O₄ (x=0, 0.25, 0.5, 0.75, 1) as anode materials were tested for lithium-ion batteries. The lithium-storage properties of the electrodes were assessed by cyclic voltammetry and galvanostatic cycling. Among the five samples, Ni_0.25 Zn_0.75 Fe₂ O₄ shows good electrochemical performance with a discharge capacity of 1488 mAh g^-1 in the initial cycle and 856 mAh g^-1 after 100 cycles.

Ultrafast pyro-synthesis of NiFe2O4 nanoparticles within a full carbon network as a high-rate and cycle-stable anode material for lithium ion batteries

NiFe₂O₄ nanoparticles fully anchored within a carbon network were prepared via a facile pyro-synthesis method without using any conventional carbon sources.

Facile synthesis of ZnFe2O4 with inflorescence spicate architecture as anode materials for lithium-ion batteries with outstanding performance

Inflorescence spicate ZnFe₂O₄ with outstanding electrochemical performance has been synthesized using a simple method based on precipitation.

Lithium storage properties of pristine and (Mg, Cu) codoped ZnFe2O4 nanoparticles

ZnFe2O4 and MgxCu0.2Zn0.82-xFe1.98O4 (where x = 0.20, 0.25, 0.30, 0.35, and 0.40) nanoparticles were synthesized by sol-gel assisted combustion method. X-ray diffraction (XRD), FTIR spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) surface area studies were used to characterize the synthesized compounds. ZnFe2O4 and the doped compounds crystallize in Fd3m space group. The lattice parameter of ZnFe2O4 is calculated to be a = 8.448(3) Å, while the doped compounds show a slight decrease in the lattice parameter with an increase in the Mg content. The particle size of all the compositions are in the range of ∼50-80 nm, and the surface area of the compounds are in the range of 11-12 m(2) g(-1). Cyclic voltammetry (CV), galvanostatic cycling, and electrochemical impedance spectroscopy (EIS) studies were used to investigate the electrochemical properties of the different compositions. The as-synthesized samples at 600 °C show large-capacity fading, while the samples reheated at 800 °C show better cycling stability. ZnFe2O4 exhibits a high reversible capacity of 575 mAh g(-1) after 60 cycles at a current density of 100 mA g(-1). Mg0.2Cu0.2Zn0.62Fe1.98O4 shows a similar capacity of 576 mAh g(-1) after 60 cycles with better capacity retention.

Rambutan-like FeCO3 hollow microspheres: facile preparation and superior lithium storage performances

Rambutan-like FeCO3 hollow microspheres were prepared via a facile and economic one-step hydrothermal method. The structure and morphology evolution mechanism was disclosed through time-dependent experiments. After undergoing the symmetric inside-out Ostwald ripening, the resultants formed microporous/nanoporous constructions composed of numerous one-dimensional (1D) nanofiber building blocks. Tested as anode materials of Li-ion batteries, FeCO3 hollow microspheres presented attractive electrochemical performances. The capacities were over 1000 mAh g(-1) for initial charge, ~880 mAh g(-1) after 100 cycles at 50 mA g(-1), and ~710 mAh g(-1) after 200 cycles at 200 mA g(-1). The 1D nanofiber assembly and hollow interior endow this material efficient contact with electrolyte, short Li(+) diffusion paths, and sufficient void spaces to accommodate large volume variation. The cost-efficient FeCO3 with rationally designed nanostructures is a promising anode candidate for Li-ion batteries.

Morphologically robust NiFe2O4 nanofibers as high capacity Li-ion battery anode material

In this work, the electrochemical performance of NiFe2O4 nanofibers synthesized by an electrospinning approach have been discussed in detail. Lithium storage properties of nanofibers are evaluated and compared with NiFe2O4 nanoparticles by galvanostatic cycling and cyclic voltammetry studies, both in half-cell configurations. Nanofibers exhibit a higher charge-storage capacity of 1000 mAh g(-1) even after 100 cycles with high Coulmbic efficiency of 100% between 10 and 100 cycles. Ex situ microscopy studies confirmed that cycled nanofiber electrodes maintained the morphology and remained intact even after 100 charge-discharge cycles. The NiFe2O4 nanofiber electrode does not experience any structural stress and eventual pulverisation during lithium cycling and hence provides an efficient electron conducting pathway. The excellent electrochemical performance of NiFe2O4 nanofibers is due to the unique porous morphology of continuous nanofibers.

One-Pot Synthesis of Carbon-Coated ZnFe2O4 with Excellent Electrochemical Performance as an Anode in Lithium Ion Battery

Carbon-coated ZnFe2O4lithium anode with nanosize has been successfully synthesized by a one-pot green-chemical hydrothermal reaction with glucose as carbon source. An analysis of electrochemical performance showed that the prepared carbon-coated ZnFe2O4anode exhibited high capacity retention. The initial charge-discharge specific capacity was approximately 1388 mAhg-1and 1008 mAhg-1, respectively. And a reversible specific capacity could be maintained about 700 mAhg-1after 100 cycles at a constant current density of 100 mAg-1, indicating good cycle ability compared with majority reported literatures. The excellent electrochemical performance was related to the carbon coating and nanoparticles, with which the electric conductivity of the material increased and the volume expansion and pulverization of the particles became increasingly reduced.

Zn2SnO4 nanowires versus nanoplates: electrochemical performance and morphological evolution during Li-cycling

Zn2SnO4 nanowires have been synthesized directly on stainless steel substrate without any buffer layers by the vapor transport method. The structural and morphological properties are investigated by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrochemical performance of Zn2SnO4 nanowires is examined by galvanostatic cycling and cyclic voltammetry (CV) measurements in two different voltage windows, 0.005-3 and 0.005-1.5 V vs Li and compared to that of Zn2SnO4 nanoplates prepared by hydrothermal method. Galvanostatic cycling studies of Zn2SnO4 nanowires in the voltage range 0.005-3 V, at a current of 120 mA g(-1), show a reversible capacity of 1000 (±5) mAh g(-1) with almost stable capacity for first 10 cycles, which thereafter fades to 695 mAh g(-1) by 60 cycles. Upon cycling in the voltage range 0.005-1.5 V vs Li, a stable, reversible capacity of 680 (±5) mAh g(-1) is observed for first 10 cycles with a capacity retention of 58% between 10-50 cycles. On the other hand, Zn2SnO4 nanoplates show drastic capacity fading up to 10 cycles and then showed a capacity retention of 80% and 70% between 10 and 50 cycles when cycled in the voltage range 0.005-1.5 and 0.005-3 V, respectively. The structural and morphological evolutions during cycling and their implications on the Li-cycling behavior of Zn2SnO4 nanowires are examined. The effect of the choice of voltage range and initial morphology of the active material on the Li-cycleabilty is also elucidated.

Interconnected network of CoMoO₄ submicrometer particles as high capacity anode material for lithium ion batteries

Interconnected networks of CoMoO(4) submicrometer particles are prepared by thermolysis of polymer matrix based metal precursor solution. The material exhibited a high reversible capacity of 990 (±10) mAh g(-1) at a current density of 100 mA g(-1), with 100% capacity retention between 5 and 50 cycles. The improved electrochemical performance of CoMoO(4) submicrometer particles with interconnected network like morphology makes it promising as a high-capacity anode material for rechargeable lithium ion batteries.