Magnesium Doping Research Articles

Effect of the position of Mg replacing Ni on O3-NaNi1/3Fe1/3Mn1/3O2 on the structural stability of cathode materials

O3-NaNi1/3Fe1/3Mn1/3O2 (NaNFM) materials are susceptible to complex phase transitions during electrical cycling leading to poor structural, capacity retention and multiplicity properties. These drawbacks hinder the application of NaNFM in sodium-ion batteries. Here, Mg2+ with larger ionic radius was used to dope its transition metal layer Ni site. The effects of Mg2+ doped NaNFM crystal structure and transition metal valence states on its electrochemical properties were investigated by XRD, SEM, and XPS. The capacity retention of NaNMFM-0.02 (84.05 %) was higher than that of NaNFM (73 %) after 200 cycles of the material at 5C. In addition, NaNMFM-0.02 achieved a first discharge specific capacity of 146.5 mAh/g at high voltage. Based on structural and electrochemical analyses, this improvement is attributed to the fact that magnesium acts as a “pillar” to stabilize the crystal structure of NaNFM, while magnesium doping reduces the Jahn-Teller effect. As a result, the material has better electrochemical properties.

Photoluminescence and photocatalytic activity of sol gel synthesized Mg doped TiO2 nanoparticles

The influence of magnesium doping on the optical properties, structural characteristics, and photocatalytic performance of TiO2 nanoparticles was investigated. Pure and Mg-doped TiO2 nanoparticles with varying weight percentages of magnesium were synthesized via the sol–gel method, followed by calcination at 100 °C for 12 h and annealing at 400 °C for 2 h to promote crystallization. X-ray diffraction (XRD) analyses confirmed the formation of crystalline mixed phases of anatase and rutile TiO2 nanoparticles, exhibiting their crystalline nature upon synthesis. Scanning electron microscopy (SEM) images were employed to study the morphological features of the samples, while energy dispersive spectroscopy (EDS) provided insights into their elemental composition. Photoluminescence (PL) emission spectra revealed ultraviolet (UV) to visible region emission for both pure and doped TiO2 samples. The photocatalytic activity was evaluated by monitoring the degradation of methyl orange under natural sunlight irradiation, elucidating the impact of visible light exposure. Furthermore, investigations were conducted to assess the influence of catalyst loading, initial dye concentration, and pH of the dye solution on the methyl orange removal efficiency. The 3 wt% Mg doped TiO2 exhibited 95 % of decolorization of Methyl Orange. X-ray photoelectron spectroscopy measurements was performed to verify the elemental composition and chemical valence states of each element. The scavenger test in photodegradation mechanism revealed that the main reactive species was superoxide species. The electron species resonance (ESR) measurement demonstrate that the synthesized sample shows the low spin state of Mg2+ in TiO2. The correlation between Mg doping on photocatalytic activity and crystal structure were studied. Theoretical calculations were performed to gain insights into the potential mechanism underlying the tuning of luminescent and photocatalytic properties of Mg-doped TiO2 nanoparticles, enabling a comprehensive discussion.

First Principle Investigations of Structural, Electronic and Thermal Properties of Pristine, Metal and Non-Metal Doped Silicene for Thermoelectric Applications

Silicene, a two-dimensional hexagonal silicon layer, exhibits exceptional electronic and thermoelectric properties. However, its application in semiconductors is hindered by its zeroband gap, which could be overcome by modifying its electronic properties through doping. In this paper, Density Functional Theory (DFT) calculations were performed to investigate the band gap opening in silicene by studying the effect of magnesium and sulphur doping on its electronic, structural and thermal properties. Pristine silicene has a lattice constant of 3.86 Å and a zero-band gap. Upon doping with 12.5% S and Mg atoms, the lattice constant modifies to 3.45 Å and 3.93 Å, respectively, resulting in a direct band gap opening. For 25% Mg and S doping, the result shows that Mg and S effectively alter the band structure and the band gap of silicene monolayer at various configurations. The maximum band gap was 0.98 eV and 1.22 eV for Mg and S doping into the meta position to the reference point R, respectively. The power factor significantly increases with doping, reaching 1.20 x 1011 WK-2m-1 and 1.40 x 1011 WK- 2 m-1 for 12.5% Mg and S doping compared to 7.4 x 1010 WK-2m-1 for pristine silicene. This substantial enhancement indicates improved thermoelectric performance, making silicene a promising candidate for thermoelectric applications. Results demonstrate that tuning the band gap through doping can simultaneously enhance the power factor, highlighting the potential of Mg/S-doped silicene for efficient energy harvesting and conversion.

Effect of magnesium doping on the structure, optical properties and photocatalytic efficiency of ZnO nanostructures deposited by atmospheric pressure MOCVD

ZnO nanostructures doped by magnesium impurity were grown on Si substrates by atmospheric pressure MOCVD deposition using Zn and Mg acetylacetonates as initial precursors. XRD patterns confirm the successful incorporation of Mg ions into ZnO lattice. Room-temperature photoluminescence spectra of Mg-doped ZnO nanostructures demonstrate near-band edge emission and visible deep-level emission with ratios 2.9, 1.3 and 0.3 correspondingly for 1, 2.4 and 5.7 at. % of Mg in ZnO nanostructures. Raman measurements showed decreasing in intensity for ZnO modes with increasing Mg content. The best photodegradation rate constant was observed for ZnO NS with 2.4 at. % of Mg.

Synergistic effect of samarium and PVP doped MgO nanostructures for RhB degradation and inhibition of DNA gyrase with molecular docking studies

Various concentrations (2 and 4 wt%) of Samarium (Sm3+) with a fixed amount (3 wt%) of polyvinylpyrrolidone (PVP) doped magnesium oxide (MgO) nanostructures (NSs) were synthesized via facile co-precipitation route. Trivalent dopant (Sm3+) and PVP narrowed the effective band gap of MgO and, controlled the recombination dynamics of the electron-hole pair and stabilized the nanostructures. This innovative treatment aimed to harness the potential ability of MgO to target bacterial cells and eliminate notorious dyes from wastewater. Advanced analytical (EDS and elemental mapping), crystallographic (XRD, SAED, FESEM, TEM and HR-TEM), and optical (UV–Vis and Raman) techniques were operated to probe their exclusive properties. The Sm/PVP-doped MgO displayed a pronounced catalytic activity against RhB dye in an acidic medium (96.42 %). Moreover, antibacterial activity was investigated using an agar well diffusion approach. At a high dosage, the % efficacy of pure and doped nanostructures against MDR S. aureus was 55.05, 65.64, 30.06 and 46.01, respectively. In silico docking investigation indicated that Sm/PVP-doped MgO NSs could inhibit DNA gyrase enzyme in S. aureus.

Enhancement of antimicrobial properties and cytocompatibility through silver and magnesium doping strategies on copper oxide nanocomposites

In the present study, silver (Ag), magnesium (Mg), and the various molar ratios of Ag:Mg-doped copper oxide nanocomposites (CuO NCs) were synthesized by the co-precipitation method. The CuO NC samples calcined at 500 °C were further analyzed for their morphological, structural, functional, and optical properties. Adding single and dual doping increased the pristine CuO band gap from 1.28 to 1.50 eV. The Ag and Mg metal peaks were revealed in the Fourier transform infrared (FTIR) analysis, while an elevated Mg band was observed in all Mg-doped samples in the Raman results. All CuO NCs showed a monoclinic crystalline structure, flake, and rod-like morphologies. Microbes of Bacillus subtilis, Shigella dysenteriae, and Candida albicans were tested against different concentrations of CuO NCs. Better results for all tested microbes were observed with the 2 mg concentration. The high cytotoxicity effect was observed in the pristine and Cu:Ag (94:6) sample, and other CuO NCs, which demonstrated over 80 % viability in RAW 246.7 cells at a concentration of 0.5 µg/ml. Remarkably, over 94 % cell viability at 0.5 µg/ml was achieved with the Cu:Ag:Mg (94:3:3) NCs ratio, owing to the synergistic effect of the ion-releasing ability of Cu2+, Ag2+, and Mg2+ ions. It possesses a distinctive high aspect ratio shape, is ion-releasing, and has excellent cytocompatibility. The suitability of the Cu:Ag:Mg (94:3:3) NCs ratio for addressing microbial challenges in healthcare is suggested by their distinct characteristics, indicating the promising potential for future biomedical applications.

Improving high-voltage cycling and stabilizing the electrode-electrolyte interface of nickel-rich layered cathodes by magnesium doping

Next-generation lithium-ion batteries will rely on nickel-rich layered oxides as cathode materials, but these materials are associated with structural and voltage losses. Magnesium (Mg) doping helps improve the performance of the nickel-rich layered cathode material. The Mg-modified LiNi0·90Mn0·05Co0·05O2 (NMC-90) has been successfully synthesized through a co-precipitation technique followed by calcination at 850 °C. Modified NMC-90 exhibits better-organized layers and improved interfacial properties than pristine ones based on structural, chemical, and morphological studies. In a voltage range of 2.8–4.5 V, Mg (0.01 mol%)-doped NMC-90 (NMC-M1) composite cathode shows an excellent discharge capacity of 211.11 mAh/g, whereas pristine NMC-90 (NMC-M0) attains only 210.59 mAh/g at 0.1C with an initial coulombic efficiency of 89.5 % for NMC-M1 and 87.5 % for NMC-M0 cathode. The NMC-M1 cathode demonstrated an impressive enhancement in cyclability after 60 cycles compared to the NMC-M0 at 1C rate, in which the NMC-M1 cathode attains a high capacity retention of 80 % while the NMC-M0 cathode shows only 37 %. This study illustrates the importance of studying the effects of elemental doping on cell performance. It will drive the future development of cathode materials with high Ni and low Co content.

Impacts of ultraviolet absorption by zinc oxide nanoparticle modifiers on asphalt aging

Ultraviolet absorption ability of modifiers is essential to protect asphalt from ageing. However, the detailed correlation between them remains unclear. In this study, zinc oxide nanoparticles were used as modifiers, and their ultraviolet absorption ability was manipulated by magnesium and aluminum doping. The influence of ultraviolet absorption ability of the nanoparticles on asphalt ultraviolet ageing was investigated experimentally, and their correlation was revealed in detail by curve fitting. The results show that aluminum doping enhances the ultraviolet absorption ability of nanoparticles, leading to superior anti-aging performance in aluminum-doped zinc oxide modified asphalt compared to pure zinc oxide. Conversely, magnesium doping shows a contrary modification. Evaluating the ultraviolet absorption ability of nanoparticle modifiers by bandgap and absorption intensity, we found that softening point increments, viscosity ageing index, and sulfoxide index exhibit a decreasing trend mainly in the bandgap range of 3.269 to 3.334 eV, whereas carbonyl index shows a decreasing trend mainly in the lower bandgap range of 3.183 to 3.269 eV. This phenomenon is primarily due to the different reactivity of carbon and sulfur with oxygen in asphalt. Curve fitting analysis revealed an exponential correlation between the ageing index of asphalt and the ultraviolet absorption ability of nanoparticles. To achieve superior anti-ultraviolet ageing performance, the nanoparticles should possess an absorption intensity above 0.961 a.u. and a bandgap below 3.299 eV. Moreover, stronger ultraviolet absorption ability of nanoparticles is needed to prevent the formation of carbonyl compounds. The underlying correlation established in the present work has significant implications for selecting suitable modifiers to prevent ultraviolet ageing of asphalt.

Physico‐Chemical and Antimicrobial Features of Magnesium Doped Hydroxyapatite Nanoparticles in Polymer Matrix

AbstractMagnesium doped hydroxyapatite nanoparticles in dextran matrix (7MgHApDx) with average size diameter of 18.2 ± 0.5 nm are synthesized by co‐precipitation. The surface morphology and shape of 7MgHApDx particles are established by scanning electron microscopy (SEM). The stability that is evaluated by ultrasound measurements and zeta potential reveals a good stability. More than that, the functional groups present in the studied samples are identified by Fourier transform infrared spectroscopy studies. The antimicrobial properties of 7MgHApDx suspensions are determined against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, and Candida albicans ATCC 10231 microbial strains.

Aloe vera-assisted biogenic synthesis of tunable magnesium oxide nanoparticles for enhanced photocatalytic and antibacterial applications

In this study, magnesium oxide (MgO) nanoparticles (NPs) tuned via doping with transition metal ions, Co2+/Cu2+/Zn2+ have been synthesized biologically using Aloe vera leaf extract as an encapsulating agent. These pure and doped MgO NPs have been characterized by using various physico-chemical characterization techniques. X-ray diffraction (XRD) analysis confirms the formation of face-centered cubic structures of pure and doped MgO NPs with their average crystallite sizes ranging from 8.11-17.83 nm. X-ray photoelectron spectroscopic (XPS) analysis confirmed the presence of doped element in their +2 oxidation state. UV-Visible spectral analysis revealed a significant reduction in band gap energies in nano-dimensions which further gets modified upon doping (1.76 − 4.9 eV). Our findings also demonstrated the engagement of phytochemicals as capping agents in Fourier transform infrared (FTIR) examination. Scanning electron microscopic (SEM) and Transmission electron microscopic (TEM) analysis provided insights into the morphologies and particle sizes. Elemental analysis by Energy dispersive X-ray (EDX) confirms the presence of Co, Cu, and Zn elements in doped MgO NPs. The photocatalytic degradation of dyes has confirmed that Co and Cu doping substantially enhance the photocatalytic activity compared to both undoped and Zn-doped MgO NPs. Furthermore, these nanoparticles demonstrate superior efficiency in degrading the cationic dye Malachite green (MG) compared to the anionic dye Methyl orange (MO). Regarding their antibacterial properties, only Cu doping induces a notable antibacterial effect in MgO NPs, particularly against gram-positive bacteria. Additionally, these nanoparticles exhibit substantial antioxidant activities. These tailored MgO nanoparticles exhibit potential for applications in wastewater treatment.

Controlling lithium cobalt oxide phase transition using molten fluoride salt for improved lithium-ion batteries

LiCoO2 is a historic lithium-ion battery cathode that continues to be used today because of its high energy density. However, the practical capacity of LiCoO2 is limited owing to the harmful phase transition at high voltages, which prevents the realization of its theoretical capacity. Here, we treat LiCoO2 particles with a molten salt of MgF2–LiF as a reaction accelerator to facilitate the diffusion and doping of magnesium into bulk LiCoO2 and to form a stable coating layer on the particle surface. Ex situ X-ray diffraction analysis confirms the inhibition of the harmful phase transition and the emergence of a different phase as the modified LiCoO2 was charged up to 4.7 V. The modified LiCoO2 shows high electrochemical performance during high-voltage operation. This technology provides a guideline for the suppressing fundamental degradation associated with phase transition and achieving ultra-high energy density LiCoO2 cathodes.

Insights into the preparation and photoluminescence properties of MgTi2O5: Eu3+ red phosphor with high color purity for w-LED applications

As one of the critical components for achieving high-quality white light emitting diodes (w-LEDs) are efficient phosphors, a series of intense red emitting Eu3+doped magnesium dititanate (Mg(1-x)Ti2O5: xEu3+; x = 0, 0.005, 0.008, 0.01, 0.02 and 0.03 mol) phosphors were prepared via solid-state reaction method. The X-ray diffraction (XRD) patterns confirmed the phase purity and orthorhombic structure of the prepared phosphors. The Ti-O functional groups were detected from the Fourier transform infrared (FTIR) spectra and Field emission scanning electron microscopy (FESEM) images revealed agglomerated spherical-like shaped phosphor particles. Under 465 nm excitation, intense red emission corresponding to 5D0→7FJ (J = 0, 1, 2, 3, and 4) transitions of Eu3+ ions were recorded in the photoluminescence (PL) spectra with an intense peak at 615 nm. The optimum concentration of Eu3+ ions was determined to be 1 mol% and the concentration quenching mechanism was due to the interaction between adjacent Eu3+ ions. The lifetime values of the samples were in the millisecond range and the internal quantum efficiency was determined to be 31.65 %. The Commission Internationale de l'Eclairage (CIE) coordinates of the optimum sample Mg0.99Ti2O5:0.01Eu3+ are (0.6421, 0.3575), lies in the red region with 99.9 % color purity and have warm correlated color temperature (CCT) values. Therefore obtained results suggest that the prepared Mg(1-x)Ti2O5:xEu3+phosphors can be used as an efficient red phosphor for w-LED applications.

Evaluation of Antimicrobial and Antifungal Effects of Ag and Mg Dual-Doped Zinc Oxide Nanoparticles against Staphylococcus Epidermidis, Pseudomonas Aeruginosa, and Candida Albicans

Background: Microbial infectious diseases are one of the serious health problems that have attracted the attention of the public as a threat to human health all over the world. Zinc oxide nanoparticles due to their various properties such as antibacterial, antifungal, and anticancer are of great interest. Methods: The antimicrobial activity of synthesized un-doped and silver and magnesium-doped zinc oxide nanoparticles with Salvadora persica extract against different strains of Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans was investigated through two methods of broth diffusion and the minimum microbial inhibitory concentration (MIC). Results: According to results, MIC of un-doped and silver and magnesium-doped zinc oxide nanoparticles showed 160, 80, 40, and 40 µg/mL on Staphylococcus epidermidis, and 80, 40, 40, and 40 µg/mL on Staphylococcus aureus. These values on Pseudomonas aeruginosa were obtained ˃5120, 640, 320, and 320 µg/mL. Conclusion: The results of the broth dilution method on Staphylococcus epidermidis and Staphylococcus aureus showed the presence of silver has a very good inhibition effect on these bacteria. In Pseudomonas aeruginosa and Candida albicans fungus, it has been observed that by increasing the amount of silver and magnesium doping, the inhibitory rate of nanoparticles on Gram-negative bacteria and fungi has increased.

Electrochemical performance of La0.8A0.2TiO3-δ (A = Li, Mg) based perovskites for solid oxide fuel cell electrode

ABSTRACT For potential use as an electrode in SOFCs, the effects of lithium and magnesium doping for phase development and conductivity of LaTiO3 have been investigated. Using a 1000°C sintering temperature, dense ceramics are created via the traditional solid oxide reaction method. Phase study shows the presence of perovskite phase with monoclinic crystal assembly. Structural characteristics of doped and undoped perovskites were calculated using the VESTA tool. Through the computed XRD spectral analysis, unit cell dimensions are established. To quantify sub-atomic characteristics and examine lattice components, CrystalMaker software also calculates electron density and lattice range. CrystalMaker program is useful for simulating porosity distributions and analysing impure inclusions in crystallisation.The electrical conductivity of the perovskites was analysed using impedance spectrometry and Li-doped structures display a significant increase in conductivity in the phase borderline of disordered perovskite.

Ocimum sanctum-mediated co/cu/zn-doped magnesium oxide nanoparticles: Photocatalytic, antibacterial, and antioxidant properties for environmental remediation

This research intends to formulate Ocimum sanctum mediated pure and transition metal (Co2+/Cu2+/Zn2+) doped magnesium oxide nanoparticles (MgO NPs). The cubic structure of so synthesized MgO NPs was confirmed by XRD analysis. As per UV–visible spectral analysis, band gap (Eg) is tuned upon doping; doping with Co, Cu and Zn, their respective Eg are 1.65 eV, 1.96 eV and 3.66 eV in relation to MgO, Eg = 3.50 eV. The average particle size decreased from 17 nm for MgO NPs to 8–13 nm for doped MgO NPs, based on TEM analysis. EDX and XPS analysis verified the presence of Mg, O and dopants, Co, Cu and Zn in synthesized NPs. SEM investigations showed that NPs are agglomerated and spherical. Zn–MgO NPs outperform Co/Cu doped MgO NPs in their photocatalytic efficacy and comparative degradation of methyl orange (MO) and malachite green (MG) dyes confirmed that they are more efficient in degrading MG. Antibacterial investigation revealed that Cu and Zn doped MgO NPs are efficient antibacterial agents against B. subtilis and E. coli than MgO NPs. In this study, Co–MgO NPs were ineffective as antibacterial agents. S. aureus was found resistant to all NPs. Using the DPPH radical scavenging technique, these biosynthesized nanoparticles displayed 62–69 % antioxidant activity.

Synthesis and Characterization of (Ni,Co)xMn0.25-xMg0.75Fe2O4 Nanoparticles

Ni-Co-Mn-Mg ferrite nanoparticles with the formula (Ni,Co)xMn0.25-xMg0.75Fe2O4 were synthesized in this work by employing the sol-gel auto-combustion process, with nitrates used as the cations source and citric acid (C6H8O7) as the combustion agent. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), and a vibrating sample magnetometer (VSM) were used to characterize the structural, morphological, and magnetic properties of ferrite powders. The XRD measurements showed crystallite sizes ranging between 24 - 28 nm. The FE-SEM images show the presence of agglomeration as well as a non-homogeneous distribution of the samples. On the other hand, the stoichiometry of the reactant solutions that were used is in close agreement with the elemental analysis that was obtained from EDX showing that the composition was as expected. Manganese ferrite showed a decrease in magnetic parameters on magnesium doping, which was further enhanced in (Ni,Co)xMn0.25-xMg0.75Fe2O4 nanoparticles upon replacement of nonmagnetic manganese ions for nickel and cobalt ions. Results indicated that Ni-Co-Mn-Mg ferrite nanoparticles’ crystal morphology, structural, and magnetic properties were significantly influenced by the amounts of nickel and cobalt content.

Wide band gap tuning of Mg doped ZnO thin films for optoelectronic applications.

Zinc oxide (ZnO) thin films with magnesium (Mg) doping have demonstrated significant potential due to their wide band gap, which enables efficient absorption of ultraviolet (UV) radiation while maintaining transparency to visible light. Sol-gel spin coating methods were used to deposit Mg-doped ZnO thin films. The solution was made with methanol as the solvent, and the starting materials were magnesium acetate tetrahydrate and zinc acetate dihydrate. The integration of Mg content in deposited ZnO films was investigated for structural, morphological, and optical properties using an X-ray diffractometer (XRD), scanning electron microscope (SEM), energy dispersive X-ray analysis (EDAX), and UV-VIS spectrophotometer. Mg-doped ZnO films were produced on quartz substrates and post-annealed at 400°C. According to absorption coefficient calculations, the optical band gap of Mg-doped ZnO films is in the range of 5.4 eV which is ideal for a variety of applications in the field of optoelectronic devices.

Influence of Magnesium Doping Concentrations and annealing on the Transmittance and Energy Band-gap of Sb2S3 Thin Films Deposited via Chemical Bath Deposition Technique

The incorporation of thin film materials into a wide range of technological applications has attracted considerable interest owing to their distinct properties and versatile functionalities. In this study, Magnesium alloyed and Antimony sulphide (Sb2S3) thin films were successfully deposited on glass substrates by chemical bath deposition technique. The films were grown at room temperature of constant pH. The concentrations of magnesium varied between 0.1M and 0.3M. The films were annealed at annealing temperature between 100˚C and 300˚C at a fixed annealing time of 1 hour. The films were characterized using UV-spectrophotometer to investigate the variation of optical and solid state properties with wavelength in the UV-VIS-NIR region. The result showed that the presence of the alloying agent and annealing treatments modified the optical and solid state properties of the films significantly. The transmittance of the films was high. Annealing led to reduced transmittance due to increased crystallite size, notably in films doped with 0.1M Mg2+ ions and annealed at 200˚C, suggesting enhanced photon absorption. The energy band gaps were found to be direct and in the range of 1.25 eV to 1.72 eV for the as grown films and 1.15eV to 1.3eV for the films annealed at annealing temperatures 300˚C. The study identifies a direct correlation between magnesium doping concentration, annealing conditions, and shifts in the energy band-gap of the films. The values of the energy band gaps are all within the range suitable for use of the layers as absorbers in hetero-junction solar cell devices for sustainable energy applications.

Enhanced power factor and figure of merit through magnesium doping in Sb2Si2Te6

We report here a high thermoelectric performance in magnesium (Mg) doped Sb2Si2Te6. The substitution of Mg2+ for Sb3+ in Sb2Si2Te6 induces a synergetic effect on electrical transport performance, exciting multi-band carrier transport behavior, enhancing carrier concentration, and increasing the density of states effective mass. Such effects lead to the highest power factor of 10.95 μW cm−1 K−2 at 824 K for the Sb1.99Mg0.01Si2Te6, representing a ∼22 % increase compared to pristine Sb2Si2Te6. In addition, Mg doping induces MgSb− point defects phonon scattering, resulting in a low thermal conductivity of ∼0.52 W m−1 K−1 at 824 K. The simultaneous optimization of the power factor and thermal conductivity in Sb1.99Mg0.01Si2Te6 leads to a peak ZT of ∼1.15 at 824 K and an average ZT of ∼0.68 (400−824 K), showing its potential for power generator at medium temperature.

Enhanced ionic conductivity and excellent lithium stability of garnet-type Li6.55Ga0.15La3Zr2O12 solid-state electrolytes by magnesium doping

Li7La3Zr2O12 (LLZO) garnet solid electrolyte has garnered significant attention as a highly promising material owing to its exceptional electrochemical properties. Nevertheless, it encounters challenges such as low ionic conductivity and inadequate interfacial properties compared to liquid electrolytes. In this study, we employed simultaneous doping of Mg2+ and Ga3+ to obtain a dense LLZO material with enhanced Li+ conductivity. By utilizing the conventional solid-state reaction method, garnet-structured oxides with a chemical composition of Li6.55+2xGa0.15La3Zr2-xMgxO12 (x = 0, 0.05, 0.1, 0.15) were synthesized. The phase composition, morphology, and lithium-ion conductivity were characterized to investigate the synergistic effects of two dopants on solid electrolytes. The density of Ga and Mg co-doped garnet pellets reached as high as 96 % - 97 %, and the peak lithium-ion conductivity of Li6.65Ga0.15La3Zr1.95Mg0.05O12 electrolyte at room temperature was obtained to be 1.13 mS cm−1. Additionally, when employed in a symmetrical Li/LLZO/Li cell, this Ga and Mg co-doped garnet electrolyte exhibited excellent electrochemical stability to lithium metal and demonstrated good performance for more than 200 h in the lithium plating/stripping cycle at a current density of 0.1 mA cm−2. The LiFePO4/Ga0.15Mg0.05/Au/Li cell delivers an initial discharge capacity of 153 mAh g−1 and retains a good capacity of 143.8 mAh g−1 after 30 charge-discharge cycles.