Spinel Structure Research Articles

Correlation Between Li-Fe Anti-Site and Memory Effect of LiFePO4 in Li-Ion Batteries.

In Li-ion batteries, the origin of memory effect in Al-doped Li4Ti5O12 has been revealed as the reversible Al-ion switching between 8a and 16c sites in the spinel structure, but it is still not clear about that for olivine LiFePO4, which is one of the most important cathode materials. In this work, a series of Na-doped and Ti-doped LiFePO4 are prepared in a high-temperature solid-state method, electrochemically investigated in Li-ion batteries and characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Magic-Angle-Spinning Nuclear Magnetic Resonance (MAS NMR). Compared with non-doped LiFePO4, the Ti doping can simultaneously suppress the memory effect and the Li-Fe anti-site, while they are simultaneously enhanced by the Na doping. Meanwhile, the Ti doping improves the electrochemical performance of LiFePO4, opposite to the Na doping. Accordingly, a schematic diagram of phase transition is proposed to interpret the memory effect of LiFePO4, in which the memory effect is attributed to the defect of Li-Fe anti-site.

Radiation-Induced Synthesis and Superparamagnetic Properties of Ferrite Fe3O4 Nanoparticles.

Ultra-small magnetic Fe3O4 nanoparticles are successfully synthesized in basic solutions by using the radiolytic method of the partial reduction in FeIII in the presence of poly-acrylate (PA), or by using the coprecipitation method of FeIII and FeII salts in the presence of PA. The optical, structural, and magnetic properties of the nanoparticles were examined using UV-Vis absorption spectroscopy, high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and SQUID magnetization measurements. The HRTEM and XRD analysis confirmed the formation of ultra-small magnetite nanoparticles in a spinel structure, with a smaller size for radiation-induced particles coated by PA (5.2 nm) than for coprecipitated PA-coated nanoparticles (11 nm). From magnetization measurements, it is shown that the nanoparticles are superparamagnetic at room temperature. The magnetization saturation value Ms = 50.1 A m2 kg-1 of radiation-induced nanoparticles at 60 kGy is higher than Ms = 18.2 A m2 kg-1 for coprecipitated nanoparticles. Both values are compared with nanoparticles coated with other stabilizers in the literature.

Crystal Facet Control of Nickel–Cobalt Sulfide Nanostructure and Study of Supercapacitor Performance

Supercapacitors require excellent cycling stability and rate capability for electrodes. The NiCo2S4 spinel structure has caught much attention for its high conductivity and high theoretical specific capacity. However, due to the lack of active sites, it has been restricted in supercapacitors. In this research, the NiCo2S4 nano-material with needle, sheet and porous network morphologies were prepared by the addition of different kinds of surfactants via a simple hydrothermal method. At 1[Formula: see text]mA/cm2, capacitance of these NiCo2S4 nanomaterials is measured as 2.09[Formula: see text]F/cm2, 3.22[Formula: see text]F/cm2, and 4.42[Formula: see text]F/cm2, respectively. It was found that the exposure ratio of (111) and (220) crystal facets also has an effect on electrochemical performance, and NiCo2S4 with I[Formula: see text]/I[Formula: see text] of 3:1 showed better performance. Furthermore, NiCo2S4-PN//AC asymmetrical supercapacitor was assembled with NiCo2S4-PN serving as positive electrode and activated carbon (AC) as negative electrode. At a power density of 7.284[Formula: see text]mW/cm2, energy density achieved was 0.625[Formula: see text]mWh/cm2. Additionally, capacitance retention rate remained at 79.6% of initial capacitance after 1500 cycles. These outcomes are of great significance for developing more efficient, stable and reliable transition metal sulfide-based supercapacitors.

Formation of a Porous Crystalline Mg1‒ x Al2O y Overlayer on Metal Catalysts via Controlled Solid-State Reactions for High-temperature Stable Catalysis.

Catalyst deactivation by sintering and coking is a long-standing issue in metal-catalyzed harsh high-temperature hydrocarbon reactions. Ultrathin oxide coatings of metal nanocatalysts have recently appeared attractive to address this issue, while the porosity of the overlayer is difficult to control to preserve the accessibility of embedded metal nanoparticles, thus often leading to a large decrease in activity. Here, we report that a nanometer-thick alumina coating of MgAl2O4-supported metal catalysts followed by high-temperature reduction can transform a nonporous amorphous alumina overlayer into a porous Mg1‒xAl2Oy crystalline spinel structure with a pore size of 2‒3 nm and weakened acidity. The high porosity stems from the restrained Mg migration from the MgAl2O4 support to the alumina overlayer through solid-state reactions at high temperatures. The resulting Ni/MgAl2O4 and Pt/MgAl2O4 catalysts with a porous crystalline Mg1‒xAl2Oy overlayer achieved remarkably high stability while preserving much higher activity than the corresponding alumina-coated Ni and Pt catalysts on MgO and Al2O3 supports in the reactions of dry reforming of methane and propane dehydrogenation, respectively.

Formation of a Porous Crystalline Mg1‐xAl2Oy Overlayer on Metal Catalysts via Controlled Solid‐State Reactions for High‐temperature Stable Catalysis

AbstractCatalyst deactivation by sintering and coking is a long‐standing issue in metal‐catalyzed harsh high‐temperature hydrocarbon reactions. Ultrathin oxide coatings of metal nanocatalysts have recently appeared attractive to address this issue, while the porosity of the overlayer is difficult to control to preserve the accessibility of embedded metal nanoparticles, thus often leading to a large decrease in activity. Here, we report that a nanometer‐thick alumina coating of MgAl2O4‐supported metal catalysts followed by high‐temperature reduction can transform a nonporous amorphous alumina overlayer into a porous Mg1‐xAl2Oy crystalline spinel structure with a pore size of 2–3 nm and weakened acidity. The high porosity stems from the restrained Mg migration from the MgAl2O4 support to the alumina overlayer through solid‐state reactions at high temperatures. The resulting Ni/MgAl2O4 and Pt/MgAl2O4 catalysts with a porous crystalline Mg1‐xAl2Oy overlayer achieved remarkably high stability while preserving much higher activity than the corresponding alumina‐coated Ni and Pt catalysts on MgO and Al2O3 supports in the reactions of dry reforming of methane and propane dehydrogenation, respectively.

Facile synthesis of porous ZnCo2O4 micro–flower decorated with SWCNTs toward superior lithium storage performance

Binary metal oxides ZnM2O4 (A = Co, Fe, Mn) with spinel structures have been widely studied for their high theoretical specific capacity, relatively low cost, controllable morphology and synergistic effect between metal oxides with different charging and discharging mechanisms. However, the electrochemical properties are seriously affected by the huge volume change during cycles and poor electronic conductivity. In this work, porous ZnCo2O4 micro–flowers self–assembled from nano–sheets are successfully prepared by a simple solvothermal method followed by a heat treatment process without the aid of any soft/hard templates, and the resulting ZnCo2O4 active material is further decorated with SWCNTs. The phase composition, morphology characteristic, specific surface area, pore size distribution, elemental valence state and other information of the as–prepared samples are analyzed by relevant techniques such as XRD, FTIR, FESEM, (HR)TEM, TGA, Raman, N2 adsorption/desorption measurement and XPS. As anode materials in Li–ion batteries, the ZnCo2O4/SWCNTs product exhibits high charge/discharge specific capacity, excellent cycling stability and remarkable rate capability. Excellent electrochemical performance benefits from the special micro–/nano–structure characteristics of the as–synthesized ZnCo2O4/SWCNTs electrode material and good dynamic characteristics during cycling.

Exploring nanovoids in spinel ceramics using positron–positronium trapping model

The investigation focused on nanovoids (free-volume defects) in spinel MgAl2O4 ceramics, synthesized at various temperatures, both before and after saturation (water-immersion), utilizing the positron annihilation spectroscopy method. The findings were analyzed within the framework of a multi-channel model. It was demonstrated that this model integrates channels capturing positrons by volumetric defects and the decay of ortho-positronium atoms. Within this refined approach, the first component reflects the microstructural characteristics of the spinel structure, the second component corresponds to volumetric defects near grain boundaries, while the third pertains to the “pick-off” process of ortho-positronium annihilation within water-filled nanopores of the ceramics.

Effect of polypyrrole-derived N-doped carbon coating on the sodium storage properties of NiCo2S4 synthesized by recycling discarded mobile phone batteries

NiCo2S4 with a spherical spinel structure was innovatively synthesized from discarded mobile phone batteries using a simple hydrothermal method, and the surface was coated with N-doped carbon to form NiCo2S4@NC. The products were used as anode materials of sodium-ion batteries to study the effect of the N-doped carbon layer on the electrochemical properties, structure and morphology. The results of XRD, FESEM and TEM revealed that the N-doped carbon layer derived by carbonizing polypyrrole had a minimal effect on the structure and morphology of NiCo2S4, but was coated on the surface of NiCo2S4 with different thicknesses to adjust the electrochemical performance. The presence of N-doped carbon in NiCo2S4@NC was confirmed by Raman spectroscopy. The mesoporous structure of NiCo2S4 and NiCo2S4@NC was corroborated by N2 adsorption-desorption isotherm analysis, and the optimal specific surface area and pore size were 23.14 cm2/g and 18.0 nm, respectively. X-ray photoelectron spectroscopy indicated that Co2+/Co3+ and Ni2+/Ni3+ coexist in the spinel NiCo2S4@NC50 synthesized upon adding 50 μL of pyrrole monomer. NiCo2S4@NC50 outperformed other products in terms of its electrochemical properties, where its initial discharge specific capacity under the current density of 0.1 A g−1 was 1099.6 mA h g−1 and the specific capacity following 100 cycles reached 327.5 mA h g−1. NiCo2S4@NC50 exhibited an optimal electrochemical performance and demonstrated a competent approach toward recycling discarded mobile phone batteries and building electrodes with high performance for use in energy equipment.

Enhancing redox stability through metal substitution in nickel ferrite for chemical looping hydrogen production via water splitting

NiFe2O4 oxygen carrier has tremendous potential for application in chemical looping hydrogen production via water splitting. However, it exhibits poor high-temperature cycling stability. The current study investigates the impact of substituting other elements (Cu, Ce, La or K) for Fe in NiFe2O4 on the hydrogen production performance during the chemical looping water splitting process. No crystalline phase of oxides for Fe, La or Ni has been detected in the XRD patterns, indicating that substituting element has been successfully doped into the spinel structure of NiFe2O4. After the substitution with the other elements such as K, La, and Ce, the hydrogen yield of the oxygen carrier has been improved, with the highest hydrogen yield observed for the NiLa0.02Fe1.98O4 oxygen carrier. Through optimized experiments, the optimum substitution amount of La is 10%, resulting in the formation of NiLa0.2Fe1.8O4. With the substitution of 10% Fe by La, the hydrogen production performance of the fresh oxygen carrier is increased from 170 mL/kg to 297 mL/kg, which can be explained by various characterization results. Lattice distortion and an obvious increase in oxygen vacancy content are observed in NiLa0.2Fe1.8O4, with the reduction peak shifting to the low-temperature region. In addition, compared to NiFe2O4, NiLa0.2Fe1.8O4 exhibits better cycling stability in 30 cycles. Finally, the changes of structure and morphology for NiFe2O4, NiLa0.2Fe1.8O4 before and after 30 cycles have been comparatively analyzed using XRD, XPS, SEM, BET, and H2-TPR.

Thickness-dependent morphological, structural, and optical properties of cobalt ferrite films

ABSTRACT A facile and prudent approach has been developed to deposit cobalt ferrite (CoFe2O4) films on the surface of the precursor solution by purging ammonia vapors over it. The vigorous technique to control the thickness of the film attributes spectacular characteristics to this approach. The study of CoFe2O4 films has been carried out by using FE-SEM, AFM, XRD, and UV-Visible spectroscopy. FE-SEM micrographs confirm the formation of the thin films composed of nanoparticles. The AFM micrographs indicate an increase in the root mean square roughness value with purged NH3 concentration due to the aggregation of nanoparticles. The observed XRD spectra show a cubic spinel structure of CoFe2O4 films with an increase in crystallite size in the range of 20–45 nm on increasing the NH3 concentration. UV – Visible spectroscopic investigations show a decrease in the band gap energy from 2.84 to 2.37 eV on account of the increased concentration of NH3 vapors.

The study of structural, frequency and temperature dependence of electrical and dielectric properties of CuO-substituted Ni-Zn nanocrystalline ferrites for MLCI applications

ABSTRACT The Cu2+ ion-substituted Ni-Zn ferrites were synthesised by the citrate gel auto-combustion method. The structural and micro-structural analyses of all samples were done using XRD and SEM, respectively. XRD studies confirmed that all samples belong to a cubic spinel structure. The cation distributions of all samples were estimated using relative X-ray intensity calculations. Room temperature, temperature variation, electrical resistivity, initial permeability and dielectric properties were carried out by an impedance analyser. The dielectric and permeability values decreased with increasing frequency. The addition of Cu2+ ions in the present system modifies the cation distribution which results in a gradual decrease of magnetisation values. The temperature dependence of initial permeability showed a sharp decrease with increasing temperature. This indicates the formation of a single phase of materials. The maximum permeability value obtained at x = 0.10 is directly related to the grain size. These temperature variation studies indicate that all these materials are well-suitable for MLCI applications.

Fabrication of nickel aluminate based electrochemical sensor for dopamine detection

Nickel aluminate nanoparticles (NiAl2O4 NPs) spinel structure is synthesized via a simple solution combustion method using aqueous nickel nitrate, aluminum nitrate and citric acid. The crystal structure and microstructure of the prepared NiAl2O4 NPs are confirmed by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectrum, scanning and transmission electron microscopy (SEM/TEM). The characterized NiAl2O4 NPs are applied on a glassy carbon electrode (GCE) to design electrochemical sensor for the detection of dopamine (DA) using cyclic voltammograms (CV) and differential pulse anodic stripping voltammograms. The proposed electrochemical sensor exhibits excellent sensing activity with a low detection limit of 1.78 μM and applicable for a wide linear concentration range of 10 μM–140 μM. Further, the proposed electrode exhibits well resolved differential pulse voltammogram for the dopamine in presence of interfering uric acid and ascorbic acid.

A remarkable permeability enhancement of Ni1−xZnxFe2O4 (x = 0.65 and 0.70), using a multi-compound calcined additive

In this study, entanglement of composition, additive and/or sintering conditions and their effects on magnetic properties of soft ferrites, nickel zinc spinel ferrites (Ni1−xZnxFe2O4, x = 0.65 and 0.70) which were prepared via conventional solid-state reaction method investigated. Also an equiponderant calcined mixture of Bi2O3, CaO, CeO2, SiO2, Al2O3, Y2O3 and nanotitania was mixed thoroughly and used as a multi-compound calcined additive (MCCA). Calcined ferrite powders were crushed, dry and wet milled, dried, mixed with different amounts of MCCA (0.0, 0.5, 1.0, 1.5 and 2.0 wt%), formed in toroidal shapes and finally sintered at different temperatures, from 1150 up to 1360 °C for 3 h. X-ray diffraction assessment confirmed formation of the single phase cubic spinel structures. Initial permeability and Q-factor spectra of the toroids were obtained from 0.1 to 1000 kHz, using an LCR meter. The results show that initial permeability of each sample has a maximum and addition of MCCA to the ferrites leads to a marvelous increase in permeabilities. Additionally, MCCA decreases the optimum sintering temperature too. The optimum amounts of additive were 1.0 and 0.5 wt% for the x = 0.65 (μ′ = 492, Ts = 1280 °C) and x = 0.70 (μ′ = 478, Ts = 1320 °C), respectively. Permeability spectra illustrate that utility zone of the Ni0.35Zn0.65Fe2O4 and Ni0.3Zn0.7Fe2O4 are both less than 100 and 10 kHz, respectively. The results represent that there is a strong entanglement between composition, additive and/or sintering conditions. It can be concluded the MCCA added Ni0.35Zn0.65Fe2O4, is suitable for application in the switching power supplies.

Catalytic Dehydrogenation on Ultradisperse Sn-Promoted Ir Catalysts Supported on MgAl2O4 Prepared by Different Techniques

Ir and IrSn catalysts with different Sn contents (0.5, 0.7 and 0.9 wt%) were prepared using MgAl2O4 supports synthesized using two different techniques (the citrate–nitrate combustion and coprecipitation methods). Both supports, with a spinel structure, presented low acidity and good textural properties. However, the support prepared by coprecipitation had higher specific surface area and pore volume than the one prepared by combustion, which would favor the dispersion of the metals to be deposited. Likewise, during the preparation of the catalytic materials, a very good interaction was achieved between the metals and both supports, which was confirmed by the presence of sub-nanometer atomic clusters in the mono- and bimetallic catalysts. Regarding the catalytic properties, while the monometallic Ir/MgAl2O4 samples lead to a very low conversion of n-butane and a selectivity towards hydrogenolysis products, the addition of Sn to Ir increases the conversion, decreases hydrogenolysis and therefore sharply increases the selectivity towards the different butenes. Catalysts with higher Sn loadings present better catalytic behavior. One of the roles of the Sn promoter would be to geometrically modify the Ir clusters, drastically decreasing the hydrogenolytic activity. This effect, added to the strong electronic modification of the Ir sites by the action of Sn, with probable Ir-Sn alloy formation, is responsible for the high catalytic performance of these bimetallic catalysts.

Sol–Gel Synthesis and Characterizations of Spinel Nickel Chromite (NiCr2O4) Nanoparticles to Study their Photocatalytic, Antibacterial and Anticancer Activities

A facile and cost-effective sol–gel technique has been used to synthesize nickel chromite (NiCr2O4) nanoparticles (NCNPs) at 700°C to investigate their photocatalytic together with antibacterial and anticancer activities. The synthesized nanopowder was characterized by Thermogravimetric thermal analysis (TG-DTA), X-ray Diffraction Spectroscopy (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), High-Resolution Transmission Electron Microscopy (HR-TEM), Fourier Transform-Infrared Spectroscopy (FT-IR), X-ray Photon Electroscopy (XPS) and UV–Visible Diffuse Reflectance Spectroscopy (UV-DRS) and Photoluminescence (PL). Beyond 700°C, the thermal durability of NCNPs was confirmed by TG-DTA analysis. The synthesized NPs were cubic structured corresponding to their spinel structure, a crystallite size of 38[Formula: see text]nm and an optical bandgap of 2.7[Formula: see text]eV. The PL spectra revealed emission bands in the visible and UV regions. The surface-phase-pure elemental and electronic arrangement of the NCNPs were verified by X-ray photon spectroscopy. Photocatalytic activity of NCNPs against Methylene Blue dye revealed 89% degradation in 1[Formula: see text]h. The in vitro antibacterial and anticancer activities of NCNPs were also examined. Among the tested microbes, Staphylococcus aureus exhibited the highest level of sensitivity (9[Formula: see text]mm), while Escherichia coli had the lowest (5[Formula: see text]mm) against NCNPs. The MTT test revealed the significant cytotoxicity of NCNPs against carcinogenic HeLa and MCF-7 cells. Thus, the synthesized NCNPs could be rated as potential photocatalytic, bactericidal and anticarcinogenic agents.

Role of the Microstructure in the Li-Storage Performance of Spinel-Structured High-Entropy (Mn,Fe,Co,Ni,Zn) Oxide Nanofibers

High-entropy oxides with spinel structure (SHEOs) are promising anode materials for next-generation lithium-ion batteries (LIBs). In this work, electrospun (Mn,Fe,Co,Ni,Zn) SHEO nanofibers produced under different conditions are evaluated as anode materials in LIBs and thoroughly characterised by a combination of analytical techniques. The variation of metal load (19.23 or 38.46 wt% relative to the polymer) in the precursor solution and of calcination conditions (700 °C/0.5 h, or 700 °C/2 h followed by 900 °C/2 h) affects the morphology, microstructure, crystalline phase, and surface composition of the pristine SHEO nanofibers and the resulting electrochemical performance, whereas mechanism of Li+ storage does not substantially change. Causes of long-term (≥650 cycles) capacity fading are elucidated via ex situ synchrotron X-ray absorption spectroscopy. The results evidence that the larger amounts of Fe, Co, and Ni cations irreversibly reduced to the metallic form during cycling are responsible for faster capacity fading in nanofibers calcined under milder conditions. The microstructure of the active material plays a key role. Nanofibers composed by larger and better-crystallized grains, where a stable solid/electrolyte interphase forms, exhibit superior long-term stability (453 mAh g−1 after 550 cycles at 0.5 A g−1) and rate-capability (210 mAh g−1 at 2 A g−1).

Healing the structural defects of spinel MnFe2O4 to enhance the electrocatalytic activity for oxygen reduction reaction

Spinel metal oxides containing Mn, Co, or Fe (AB2O4, A/B = Mn/Fe/Co) are one of the most promising non-Pt electrocatalysts for oxygen reduction reaction (ORR) in alkaline conditions. However, the low conductivity of metal oxides and the poor intrinsic activities of transition metal sites lead to unsatisfactory ORR performance. In this study, eutectic molten salt (EMS) treatment is employed to reconstruct the atomic arrangement of MnFe2O4 electrocatalyst as a prototype for enhancing ORR performance. Comprehensive analyses by using XAFS, soft XAS, XPS, and electrochemical methods reveal that the EMS treatment reduces the oxygen vacancies and spinel inverse in MnFe2O4 effectively, which improves the electric conductivity and increases the population of more catalytically active Mn2+ sites with tetrahedral coordination. Moreover, the enhanced Mn-O interaction after EMS treatment is conducive to the adsorption and activation of O2, which promotes the first electron transfer step (generally considered as the rate-determining step) of the ORR process. As a result, the EMS treated MnFe2O4 catalyst delivers a positive shift of 40 mV in the ORR half-wave potential and a two-fold enhanced mass/specific activity. This work provides a convenient approach to manipulate the atomic architecture and local electronic structure of spinel oxides as ORR electrocatalysts and a comprehensive understanding of the structure-performance relationship from the molecular/atomic scale.

Structural, Optical, and Morphological Study of Manganese Substituted Cobalt Ferrite and Its Effect on the Magnetic and Dielectric Properties of PVA Composites

Nanopowders of Mn-substituted CoFe2O4 were prepared in different proportions using the sol-gel auto-combustion method and were structurally and morphologically studied. In another step, composites based on polyvinyl alcohol (PVA) with Mn-substituted CoFe2O4 fillers were prepared, and the effect of the Mn-substituted CoFe2O4 on the optical, magnetic, and dielectric properties was studied. X-ray analysis revealed the formation of polycrystalline Mn-substituted CoFe2O4. The results showed a decrease in the lattice constant with Mn2+ substituted and incorporated into the crystal structure of CoFe2O4. The Fourier confirmed the spinel structure of the Mn-substituted CoFe2O4 transform infrared spectrum where absorption bands appeared at 569–561 and 446–407 cm-1, which are attributed to tetrahedral and octahedral groups. The magnetic properties were affected when Mn ions were substituted with CoFe2O4, as shown by the results of VSM. It was observed that the saturation magnetization, remnant magnetization, and coercivity decreased with increasing Mn content. The dielectric constant and loss tangent of PVA/MnxCo1−xFe2O4 were also studied. The difference in the diameters of the substituted and host ions causes the dielectric constant to increase following the substitution of Mn ions.

Effect of morphological and particle size, structure on the physical properties of Sr doped cobalt chromite for catalysis application

The structural, optical, morphological, and catalytic behavior of the spinel cobalt chromite nanoparticles (NPs), which were successfully synthesised using a simple co-precipitation method, are investigated in this work. First, the catalytic performance test was used to determine the ideal doping Sr and doping amounts. The as-prepared sample's face-centered cubic spinel structure is confirmed by the powder X-ray diffraction pattern, and the average crystallite size is determined to be 22–15 ​nm. The prepared material had a structure resembling nanoparticles, and the SEM analysis showed that the size attained was approximately 28–16 ​nm. TEM analysis revealed that the prepared material and sizes had a hexagonal-like structure. DRS and PL spectra were used to determine the optical absorption and photoluminescence emissions, respectively. Decolorization of 4-Nitrophenol's yellow color is another area of interest in the catalytic characteristics of CoCr2O4 crystals doped with Sr. The catalysts employed were discovered to be readily recyclable and effective catalysts for the oxidation of styrene, with benzaldehyde as the end product.

Tunable microware dielectric properties of high-entropy (Mg1/2Zn1/2)0.4+xLi0.4(Co1/2Ni1/2)0.4-xAl2O4 ceramics with low loss

In present study, high-entropy (Mg1/2Zn1/2)0.4+xLi0.4(Co1/2Ni1/2)0.4–xAl2O4 (x = 0.00–0.40) ceramics were fabricated via the solid-state reaction approach. The high-entropy ceramics exhibited a spinel structure with short-range local disorder and long-range structural order. The reduction of Co2+ and Ni2+ content suppress the damping behavior of atomic vibrations, promoting the structural ordering and contributing to higher quality factor (Q×f). The x = 0.35 sample with sintering at 1550 °C exhibited great microwave dielectric properties: a low dielectric constant (εr) of 7.92, a high-quality factor of 135,525 GHz, and a temperature coefficient of resonance frequency (τf) of −49 × 10−6 °C−1. The εr value was jointly dominated by both polarizability and relative density. The Q×f value was primarily connected to relative density, atomic vibrations, and the degree of covalency. The τf value was highly associated with the bond strength. These findings demonstrate the effectiveness of adopting high-entropy composition design for significantly improving microwave dielectric properties.