LiMn1.5Ni0.25Fe0.2M0.05O4 Nanoparticles as a Cathode Material for Rechargeable Li-Ion Batteries

2020 ◽  
Vol 835 ◽  
pp. 149-154
Author(s):  
Haitham A. Abdellatif ◽  
Mostafa M.M. Sanad ◽  
Elsayed M. Elnaggar ◽  
Mohamed M. Rashad ◽  
Gamal M. El-Kady
Keyword(s):  
Annealing Temperature ◽  
Sol Gel ◽  
Combustion Method ◽  
Xrd Analysis ◽  
Charge Transfer Resistance ◽  
Li Ion Batteries ◽  
Transfer Resistance ◽  
Auto Combustion ◽  
Li Ion ◽  
Kinetic Diffusion

New series of spinel LiNi0.25Fe0.2Mˊ0.05Mn1.5O4 (Mˊ = Cu, Mg or Zn) cathode materials have been purposefully tailored using sol-gel auto-combustion method at low annealing temperature ~ 700°C for 3 h. The XRD analysis showed that all substituted (LNFMO-Mˊ) samples are comported with the main structure of undoped (LNFMO) with crystalline disordered spinel Fd-3m structure. TEM images revealed the octahedron-shape like morphology for the particles and the LNFMO-Zn sample has the widest particle size distribution. EIS spectra evidenced that a typical one semicircle (LNFMO-Mg) was revealed for each cell, suggesting the absence of ionic conductivity contribution. The values of charge transfer resistance (Rct) were equal to 9.3, 6.7, 6.0 and 4.4 kΩ for LNFMO, LNFMO-Cu, LNFMO-Mg indicating that the Zn-doped sample has the fastest kinetic diffusion rate and lowest activation energy of conduction.

The oxygen vacancy in Li-ion battery cathode materials

2020 ◽  
Vol 5 (11) ◽  
pp. 1453-1466
Author(s):  
Zhen-Kun Tang ◽  
Yu-Feng Xue ◽  
Gilberto Teobaldi ◽  
Li-Min Liu
Keyword(s):  
Oxygen Vacancies ◽  
Charge Transfer Resistance ◽  
Material Structure ◽  
Rate Performance ◽  
Li Ion Batteries ◽  
Li Ion Battery ◽  
Ion Diffusion ◽  
Transfer Resistance ◽  
Accelerated Degradation ◽  
Li Ion

Oxygen vacancies can promote Li-ion diffusion, reduce the charge transfer resistance, and improve the capacity and rate performance of Li-ion batteries. However, oxygen vacancies can also lead to accelerated degradation of the cathode material structure, and lead to phase transition etc.

Structural, magnetic and high frequency (1–6 GHz) parameters of Sr-substituted BaFe2O4 monoferrites synthesized by sol–gel method

2019 ◽  
Vol 33 (19) ◽  
pp. 1950219 ◽  
Author(s):  
Mukhtar Ahmad ◽  
Jawaria Shaheen ◽  
Waseem Abbas Hashmi ◽  
Majid Niaz Akhtar ◽  
Muhammad Asif
Keyword(s):  
Single Phase ◽  
Sol Gel ◽  
Combustion Method ◽  
Xrd Analysis ◽  
Anisotropy Constant ◽  
Dielectric Parameters ◽  
Single Phase Sample ◽  
Heat Treated Sample ◽  
Auto Combustion ◽  
Phase Spinel

In this work, Sr-substituted samples of single-phase spinel monoferrites with chemical formula [Formula: see text] (x = 0.00, 0.33, 0.67, 1.00) were synthesized using sol–gel auto-combustion method. In order to confirm the single-phase formation of these samples, a sample (x = 0.00) was chosen for heat treatment at different temperatures (100, 300, 400, 600 and [Formula: see text]) for 4 h. The heat treated sample was then investigated by X-ray diffraction (XRD) analysis and results showed that a single-phase sample can be successfully synthesized at a temperature of [Formula: see text], which is much lower than that reported in earlier literature for synthesis of same structured samples. All the synthesized samples were then sintered at [Formula: see text] for 4 h to achieve better crystallinity. From XRD patterns, lattice parameters, cell volume and XRD density as a function of Sr-substitution were calculated. Scanning electron microscopy (SEM) results showed that the grain size increased as the temperature was increased. Fourier transform infrared spectroscopy (FTIR) results confirmed the single-phase spinel monoferrites at [Formula: see text]. From M–H loops (x = 0.0, 0.33, 0.67 and 1.00), different magnetic parameters such as saturation magnetization [Formula: see text], remanance [Formula: see text], coercivity [Formula: see text] and magnetic moment [Formula: see text] were calculated. Magnetocrystalline anisotropy constant and Y–K angles of Sr-doped Ba monoferrites were also calculated. In addition, the variation of different dielectric parameters (real permittivity, imaginary permittivity, real permeability, imaginary permeability, ac conductivity and loss tangent) as a function of frequency (1–6 GHz) has been discussed in this work. The results suggest that the synthesized materials have many advantages over previously reported single-phase spinel monoferrites.

scholarly journals Modelling the Impedance Response of Graded LiFePO4 Cathodes for Li-Ion Batteries

2022 ◽  
Author(s):  
Ross Drummond ◽  
Chuan Cheng ◽  
Patrick Grant ◽  
Stephen Duncan
Keyword(s):  
Electrochemical Impedance ◽  
Current Collector ◽  
Charge Transfer Resistance ◽  
Type Model ◽  
Li Ion Batteries ◽  
Li Ion Battery ◽  
Transfer Resistance ◽  
Electrode Current ◽  
Degradation Rates ◽  
Li Ion

Abstract Graded electrodes for Li-ion batteries aim to exploit controlled variations in local electrode microstructure to improve overall battery performance, including reduced degradation rates and increased capacity at high discharge rates. However, the mechanisms by which grading might deliver performance benefit, and under what conditions, are not yet fully understood. A Li-ion battery electrochemical model (a modified Doyle-Fuller-Newman type model capable of generating impedance functions) is developed in which local microstructural changes are captured in order to understand why and when graded electrodes can offer performance benefits. Model predictions are evaluated against experimental electrochemical impedance data obtained from electrodes with micro-scale, controlled variations in microstructure. A region locally enriched with carbon at the electrode/current collector interface is shown to significantly reduce the overpotential distribution across the thickness of a LiFePO$_4$-based Li-ion battery cathode, resulting in a lower charge transfer resistance and impedance. The insights gained from the LiFePO$_4$-based electrodes are generalised to wider design principles for both uniform and graded Li-ion battery electrodes.

scholarly journals Magnetocrystalline and Surface Anisotropy in CoFe2O4 Nanoparticles

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1288 ◽  
Author(s):  
Alexander Omelyanchik ◽  
María Salvador ◽  
Franco D’Orazio ◽  
Valentina Mameli ◽  
Carla Cannas ◽  
...  
Keyword(s):  
Particle Size ◽  
Magnetic Anisotropy ◽  
Annealing Temperature ◽  
Ac Susceptibility ◽  
Sol Gel ◽  
Combustion Method ◽  
Anisotropy Constant ◽  
Silica Matrix ◽  
Thermal Treatments ◽  
Auto Combustion

The effect of the annealing temperature Tann on the magnetic properties of cobalt ferrite nanoparticles embedded in an amorphous silica matrix (CoFe2O4/SiO2), synthesized by a sol-gel auto-combustion method, was investigated by magnetization and AC susceptibility measurements. For samples with 15% w/w nanoparticle concentration, the particle size increases from ~2.5 to ~7 nm, increasing Tann from 700 to 900 °C. The effective magnetic anisotropy constant (Keff) increases with decreasing Tann, due to the increase in the surface contribution. For a 5% w/w sample annealed at 900 °C, Keff is much larger (1.7 × 106 J/m3) than that of the 15% w/w sample (7.5 × 105 J/m3) annealed at 700 °C and showing comparable particle size. This indicates that the effect of the annealing temperature on the anisotropy is not only the control of the particle size but also on the core structure (i.e., cation distribution between the two spinel sublattices and degree of spin canting), strongly affecting the magnetocrystalline anisotropy. The results provide evidence that the magnetic anisotropy comes from a complex balance between core and surface contributions that can be controlled by thermal treatments.

Effect of annealing temperature on structural and magnetic properties of strontium hexaferrite nanoparticles synthesized by sol–gel auto-combustion method

2015 ◽  
Vol 29 (27) ◽  
pp. 1550190 ◽  
Author(s):  
Ebrahim Roohani ◽  
Hadi Arabi ◽  
Reza Sarhaddi ◽  
Saeedeh Sudkhah ◽  
Ameneh Shabani
Keyword(s):  
Crystal Structure ◽  
Thermal Decomposition ◽  
Magnetic Properties ◽  
Thermogravimetric Analysis ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Combustion Method ◽  
Strontium Hexaferrite ◽  
Auto Combustion ◽  
Ft Ir

In this paper, strontium hexaferrite nanoparticles were synthesized by the sol–gel auto-combustion method. Effect of annealing temperature on crystal structure, morphology and magnetic properties of nanoparticles was investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). Also, the thermal decomposition of as-synthesized powdered samples has been studied by thermogravimetric analysis (TGA). The XRD patterns confirmed the formation of single phase M-type hexagonal crystal structure for powders annealed above 950[Formula: see text]C, whereas the presence of hematite ([Formula: see text]-Fe2O3) as secondary phase was also observed for sample annealed at 900[Formula: see text]C. Furthermore, the crystallinity along with the crystallite size were augmented with annealing temperature. Comparison of the FT-IR spectra of the samples before and after annealing treatment showed the existence of metal–oxygen stretching modes after annealing. The thermogravimetric analysis confirmed the thermal decomposition of as-burnt powders happened in three-stage degradation process. The TEM images showed the nanoparticles like hexagonal-shaped platelets as the size of nanoparticles increases by increasing the annealing temperature. With increasing annealing temperature, the magnetic saturation and the coercivity were increased to the maximum value of 74.26 emu/g and 5.67 kOe for sample annealed at 1000[Formula: see text]C and then decreased.

Effect of annealing temperature on dielectric properties of iron oxide prepared by sol–gel auto combustion method

2021 ◽  
Vol 577 (1) ◽  
pp. 38-51
Author(s):  
Sk Yasnur ◽  
Prasenjit Maji ◽  
Apurba Ray ◽  
Himadri Mullick ◽  
Sachindranath Das
Keyword(s):  
Iron Oxide ◽  
Dielectric Properties ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Combustion Method ◽  
Auto Combustion

scholarly journals Ti3Si0.75Al0.25C2 Nanosheets as Promising Anode Material for Li-Ion Batteries

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3449
Author(s):  
Jianguang Xu ◽  
Qiang Wang ◽  
Boman Li ◽  
Wei Yao ◽  
Meng He
Keyword(s):  
Anode Materials ◽  
High Capacity ◽  
Lithium Ion ◽  
Charge Transfer Resistance ◽  
Rate Performance ◽  
Li Ion Batteries ◽  
Transfer Resistance ◽  
Li Ion ◽  
Enhanced Electrochemical Performance ◽  
Small Charge

Herein we report that novel two-dimensional (2D) Ti3Si0.75Al0.25C2 (TSAC) nanosheets, obtained by sonically exfoliating their bulk counterpart in alcohol, performs promising electrochemical activities in a reversible lithiation and delithiation procedure. The as-exfoliated 2D TSAC nanosheets show significantly enhanced lithium-ion uptake capability in comparison with their bulk counterpart, with a high capacity of ≈350 mAh g−1 at 200 mA g−1, high cycling stability and excellent rate performance (150 mAh g−1 after 200 cycles at 8000 mA g−1). The enhanced electrochemical performance of TSAC nanosheets is mainly a result of their fast Li-ion transport, large surface area and small charge transfer resistance. The discovery in this work highlights the uniqueness of a family of 2D layered MAX materials, such as Ti3GeC2, Ti3SnC2 and Ti2SC, which will likely be the promising choices as anode materials for lithium-ion batteries (LIBs).

Preparation and electrical properties of gadolinium-doped strontium tungstate electrolyte for SOFC

2020 ◽  
Vol 13 (03) ◽  
pp. 2050010
Author(s):  
Jihai Cheng ◽  
Ming Wang
Keyword(s):  
Electrical Properties ◽  
Electrochemical Impedance ◽  
Sol Gel ◽  
Combustion Method ◽  
Xrd Analysis ◽  
Doping Amount ◽  
Sintered Ceramic ◽  
Auto Combustion ◽  
Electrical Conductivities ◽  
Text Content

Gadolinium-doped strontium tungstate (Sr[Formula: see text]GdxWO[Formula: see text]) powders were synthesized by the sol–gel auto-combustion method, and their electrical properties were investigated. The phase formation of Sr[Formula: see text]GdxWO[Formula: see text] powders was studied by the X-ray diffraction (XRD) analysis. The characterization of microstructure was carried out on the sintered ceramic discs. Electrochemical impedance spectroscopy (EIS) was used to estimate the electrical properties. The results displayed that these crystalline powders were scheelite-type tetragonal structures and demonstrated higher sinterability. The Sr[Formula: see text]GdxWO[Formula: see text] electrolyte ceramics with a relative density over 95% of the theoretical density were obtained after the sintering process. The electrical conductivities of Sr[Formula: see text]GdxWO[Formula: see text] increased significantly with increasing of doped-Gd[Formula: see text] content and reached [Formula: see text] S[Formula: see text]cm[Formula: see text] at 800∘C, when the doping amount was [Formula: see text]. At last, this study demonstrated that Sr[Formula: see text]GdxWO[Formula: see text] is an effective strategy to optimize middle or low-temperature SOFC.

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