Advanced TiO2/Al2O3 Bilayer ALD Coatings for Improved Lithium-Rich Layered Oxide Electrodes.

Surface modification is a highly effective strategy for addressing issues in lithium-rich layered oxide (LLO) cathodes, including phase transformation, particle cracking, oxygen gas release, and transition-metal ion dissolution. Existing single-/double-layer coating strategies face drawbacks such as poor component contact and complexity. Herein, we present the results of a low-temperature atomic layer deposition (ALD) process for creating a TiO2/Al2O3 bilayer on composite cathodes made of AS200 (Li1.08Ni0.34Co0.08Mn0.5O2). Electrochemical analysis demonstrates that TiO2/Al2O3-coated LLO electrodes exhibit improved discharge capacities and enhanced capacity retention compared with uncoated samples. The TAA-5/AS200 bilayer-coated electrode, in particular, demonstrates exceptional capacity retention (∼90.4%) and a specific discharge capacity of 146 mAh g-1 after 100 cycles at 1C within the voltage range of 2.2 to 4.6 V. The coated electrodes also show reduced voltage decay, lower surface film resistance, and improved interfacial charge transfer resistances, contributing to enhanced stability. The ALD-deposited TiO2/Al2O3 bilayer coatings exhibit promising potential for advancing the electrochemical performance of lithium-rich layered oxide cathodes in lithium-ion batteries.

The Influence of Annealing and Film Thickness on the Specific Properties of Co40Fe40Y20 Films.

Cobalt Iron Yttrium (CoFeY) magnetic film was made using the sputtering technique in order to investigate the connection between the thickness and annealing procedures. The sample was amorphous as a result of an insufficient thermal driving force according to X-ray diffraction (XRD) examination. The maximum low-frequency alternate-current magnetic susceptibility (χac) values were raised in correlation with the increased thickness and annealing temperatures because the thickness effect and Y addition improved the spin exchange coupling. The best value for a 50 nm film at annealing 300 °C for χac was 0.20. Because electron carriers are less constrained in their conduction at thick film thickness and higher annealing temperatures, the electric resistivity and sheet resistance are lower. At a thickness of 40 nm, the film's maximum surface energy during annealing at 300 °C was 28.7 mJ/mm2. This study demonstrated the passage of photon signals through the film due to the thickness effect, which reduced transmittance. The best condition was found to be 50 nm with annealing at 300 °C in this investigation due to high χac, strong adhesion, and low resistivity, which can be used in magnetic fields.

Effect of Annealing and Thickness of Co40Fe40Yb20 Thin Films on Various Physical Properties on a Glass Substrate.

The aim of this work is to investigate the effect of annealing and thickness on various physical properties in Co40Fe40Yb20 thin films. X-ray diffraction (XRD) was used to determine the amorphous structure of Co40Fe40Yb20 films. The maximum surface energy of 40 nm thin films at 300 °C is 34.54 mJ/mm2. The transmittance and resistivity decreased significantly as annealing temperatures and thickness increased. At all conditions, the 10 nm film had the highest hardness. The average hardness decreased as thickness increased, as predicted by the Hall-Petch effect. The highest low-frequency alternative-current magnetic susceptibility (χac) value was discovered when the film was annealed at 200 °C with 50 nm, and the optimal resonance frequency (ƒres) was in the low frequency range, indicating that the film has good applicability in the low frequency range. At annealed 200 °C and 50 nm, the maximum saturation magnetization (Ms) was discovered. Thermal disturbance caused the Ms to decrease when the temperature was raised to 300 °C. The optimum process conditions determined in this study are 200 °C and 50 nm, with the highest Ms, χac, strong adhesion, and low resistivity, which are suitable for magnetic applications, based on magnetic properties and surface energy.

The Influence of Oxidation on the Magnetic, Electrical, and Mechanical Properties of Co40Fe40Yb20 Films.

A typical body-centered cubic (BCC) CoFe(110) peak was discovered at approximately 2θ = 44.7°. At 2θ = 46°, 46.3°, 47.7°, 55.4°, 54.6°, and 56.4°, the Yb2O3 and Co2O3 oxide peaks were visible in all samples. However, with a heat treatment temperature of 300 °C, there was no typical peak of CoFe(110). Electrical characteristics demonstrated that resistivity and sheet resistance reduced dramatically as film thickness and annealing temperatures increased. At various heat treatments, the maximum hardness was 10 nm. The average hardness decreased as the thickness increased, and the hardness trend decreased slightly as the annealing temperature was higher. The highest low-frequency alternative-current magnetic susceptibility (χac) value was discovered after being annealed at 200 °C with 50 nm, and the optimal resonance frequency (fres) was discovered to be within the low-frequency range, indicating that the Co40Fe40Yb20 film can be used in low-frequency applications. The maximum saturation magnetization (Ms) was annealed at 200 °C for 50 nm. Thermal disturbance caused the Ms to decrease as the temperature reached to 300 °C. The results show that when the oxidation influence of as-deposited and thinner films is stronger than annealing treatments and thicker thickness, the magnetic and electrical properties can be enhanced by the weakening peak of the oxide, which can also reduce interference.

Effects of Annealing and Thickness of Co60Fe20Yb20 Nanofilms on Their Structure, Magnetic Properties, Electrical Efficiency, and Nanomechanical Characteristics.

X-ray diffraction (XRD) analysis showed that metal oxide peaks appear at 2θ = 47.7°, 54.5°, and 56.3°, corresponding to Yb2O3 (440), Co2O3 (422), and Co2O3 (511). It was found that oxide formation plays an important role in magnetic, electrical, and surface energy. For magnetic and electrical measurements, the highest alternating current magnetic susceptibility (χac) and the lowest resistivity (×10-2 Ω·cm) were 0.213 and 0.42, respectively, and at 50 nm, it annealed at 300 °C due to weak oxide formation. For mechanical measurement, the highest value of hardness was 15.93 GPa at 200 °C in a 50 nm thick film. When the thickness increased from 10 to 50 nm, the hardness and Young's modulus of the Co60Fe20Yb20 film also showed a saturation trend. After annealing at 300 °C, Co60Fe20Yb20 films of 40 nm thickness showed the highest surface energy. Higher surface energy indicated stronger adhesion, allowing for the formation of multilayer thin films. The optimal condition was found to be 50 nm with annealing at 300 °C due to high χac, strong adhesion, high nano-mechanical properties, and low resistivity.

A study on Ti-doped Fe3O4 anode for Li ion battery using machine learning, electrochemical and distribution function of relaxation times (DFRTs) analyses.

Among many transition-metal oxides, Fe3O4 anode based lithium ion batteries (LIBs) have been well-investigated because of their high energy and high capacity. Iron is known for elemental abundance and is relatively environmentally friendly as well contains with low toxicity. However, LIBs based on Fe3O4 suffer from particle aggregation during charge-discharge processes that affects the cycling performance. This study conjectures that iron agglomeration and material performance could be affected by dopant choice, and improvements are sought with Fe3O4 nanoparticles doped with 0.2% Ti. The electrochemical measurements show a stable specific capacity of 450 mAh g-1 at 0.1 C rate for at least 100 cycles in Ti doped Fe3O4. The stability in discharge capacity for Ti doped Fe3O4 is achieved, arising from good electronic conductivity and stability in microstructure and crystal structure, which has been further confirmed by density functional theory (DFT) calculation. Detailed distribution function of relaxation times (DFRTs) analyses based on the impedance spectra reveal two different types of Li ion transport phenomena, which are closely related with the electron density difference near the two Fe-sites. Detailed analyses on EIS measurements using DFRTs for Ti doped Fe3O4 indicate that improvement in interfacial charge transfer processes between electrode and Li metal along with an intermediate lithiated phase helps to enhance the electrochemical performance.

Vibrational and electrochemical studies of pectin-a candidate towards environmental friendly lithium-ion battery development.

Pectin polymers are considered for lithium-ion battery electrodes. To understand the performance of pectin as an applied buffer layer, the electrical, magnetic, and optical properties of pectin films are investigated. This work describes a methodology for creating pectin films, including both pristine pectin and Fe-doped pectin, which are optically translucent, and explores their potential for lithium-ion battery application. The transmission response is found extended in optimally Fe-doped pectin, and prominent modes for cation bonding are identified. Fe doping enhances the conductivity observed in electrochemical impedance spectroscopy, and from the magnetic response of pectin evidence for Fe3+ is identified. The Li-ion half-cell prepared with pectin as binder for anode materials such as graphite shows stable charge capacity over long cycle life, and with slightly higher specific capacity compare with the cell prepared using polyvinylidene fluoride (PVDF) as binder. A novel enhanced charging specific capacity at a high C-rate is observed in cells with pectin binder, suggesting that within a certain rate (∼5 C), pectin has higher capacity at faster charge rates. The pectin system is found as a viable base material for organic-inorganic synthesis studies.

Electrochemical Performance of Orthorhombic CsPbI3 Perovskite in Li-Ion Batteries.

A facile solution process was employed to prepare CsPbI3 as an anode material for Li-ion batteries. Rietveld refinement of the X-ray data confirms the orthorhombic phase of CsPbI3 at room temperature. As obtained from bond valence calculations, strained bonds between Pb and I are identified within PbI6 octahedral units. Morphological study shows that the as-prepared δ-CsPbI3 forms a nanorod-like structure. The XPS analysis confirm the presence of Cs (3d, 4d), Pb (4d, 4f, 5d) and I (3p, 3d, 4d). The lithiation process involves both intercalation and conversion reactions, as confirmed by cyclic voltammetry (CV) and first-principles calculations. Impedance spectroscopy coupled with the distribution function of relaxation times identifies charge transfer processes due to Li metal foil and anode/electrolyte interfaces. An initial discharge capacity of 151 mAhg-1 is found to continuously increase to reach a maximum of ~275 mAhg-1 at 65 cycles, while it drops to ~240 mAhg-1 at 75 cycles and then slowly decreases to 235 mAhg-1 at 100 cycles. Considering the performance and structural integrity during electrochemical performance, δ-CsPbI3 is a promising material for future Li-ion battery (LIB) application.

Effect of Yttrium Addition on Structure and Magnetic Properties of Co60Fe20Y20 Thin Films.

In this paper, a Co60Fe20Y20 film was sputtered onto Si (100) substrates with thicknesses ranging from 10 to 50 nm under four conditions to investigate the structure, magnetic properties, and surface energy. Under four conditions, the crystal structure of the CoFeY films was found to be amorphous by an X-ray diffraction analyzer (XRD), suggesting that yttrium (Y) added into CoFe films and can be refined in grain size and insufficient annealing temperatures do not induce enough thermal driving force to support grain growth. The saturation magnetization (MS) and low-frequency alternate-current magnetic susceptibility (χac) increased with the increase of the thicknesses and annealing temperatures, indicating the thickness effect and Y can be refined grain size and improved ferromagnetic spin exchange coupling. The highest Ms and χac values of the Co60Fe20Y20 films were 883 emu/cm3 and 0.26 when the annealed temperature was 300 °C and the thickness was 50 nm. The optimal resonance frequency (fres) was 50 Hz with the maximum χac value, indicating it could be used at a low frequency range. Moreover, the surface energy increased with the increase of the thickness and annealing temperature. The maximum surface energy of the annealed 300 °C film was 30.02 mJ/mm2 at 50 nm. Based on the magnetic and surface energy results, the optimal thickness was 50 nm annealed at 300 °C, which has the highest Ms, χac, and a strong adhesion, which can be as a free or pinned layer that could be combined with the magnetic tunneling layer and applied in magnetic fields.

Annealing Effect on the Characteristics of Co40Fe40W10B10 Thin Films on Si(100) Substrate.

This research explores the behavior of Co40Fe40W10B10 when it is sputtered onto Si(100) substrates with a thickness (tf) ranging from 10 nm to 100 nm, and then altered by an annealing process at temperatures of 200 °C, 250 °C, 300 °C, and 350 °C, respectively. The crystal structure and grain size of Co40Fe40W10B10 films with different thicknesses and annealing temperatures are observed and estimated by an X-ray diffractometer pattern (XRD) and full-width at half maximum (FWHM). The XRD of annealing Co40Fe40W10B10 films at 200 °C exhibited an amorphous status due to insufficient heating drive force. Moreover, the thicknesses and annealing temperatures of body-centered cubic (BCC) CoFe (110) peaks were detected when annealing at 250 °C with thicknesses ranging from 80 nm to 100 nm, annealing at 300 °C with thicknesses ranging from 50 nm to 100 nm, and annealing at 350 °C with thicknesses ranging from 10 nm to 100 nm. The FWHM of CoFe (110) decreased and the grain size increased when the thickness and annealing temperature increased. The CoFe (110) peak revealed magnetocrystalline anisotropy, which was related to strong low-frequency alternative-current magnetic susceptibility (χac) and induced an increasing trend in saturation magnetization (Ms) as the thickness and annealing temperature increased. The contact angles of all Co40Fe40W10B10 films were less than 90°, indicating the hydrophilic nature of Co40Fe40W10B10 films. Furthermore, the surface energy of Co40Fe40W10B10 presented an increased trend as the thickness and annealing temperature increased. According to the results, the optimal conditions are a thickness of 100 nm and an annealing temperature of 350 °C, owing to high χac, large Ms, and strong adhesion; this indicates that annealing Co40Fe40W10B10 at 350 °C and with a thickness of 100 nm exhibits good thermal stability and can become a free or pinned layer in a magnetic tunneling junction (MTJ) application.

Impact of Annealing on Magnetic Properties and Structure of Co40Fe40W20 Thin Films on Si(100) Substrate.

Co40Fe40W20 monolayers of different thicknesses were deposited on Si(100) substrates by DC magnetron sputtering, with Co40Fe40W20 thicknesses from 10 to 50 nm. Co40Fe40W20 thin films were annealed at three conditions (as-deposited, 250 °C, and 350 °C) for 1 h. The structural and magnetic properties were then examined by X-ray diffraction (XRD), low-frequency alternative-current magnetic susceptibility (χac), and an alternating-gradient magnetometer (AGM). The XRD results showed that the CoFe (110) peak was located at 2θ = 44.6°, but the metal oxide peaks appeared at 2θ = 38.3, 47.6, 54.5, and 56.3°, corresponding to Fe2O3 (320), WO3 (002), Co2O3 (422), and Co2O3 (511), respectively. The saturation magnetization (Ms) was calculated from the slope of the magnetization (M) versus the CoFeW thickness. The Ms values calculated in this manner were 648, 876, 874, and 801 emu/cm3 at the as-deposited condition and post-annealing conditions at 250, 350, and 400 °C, respectively. The maximum MS was about 874 emu/cm3 at a thickness of 50 nm following annealing at 350 °C. It indicated that the MS and the χac values rose as the CoFeW thin films' thickness increased. Owing to the thermal disturbance, the MS and χac values of CoFeW thin films after annealing at 350 °C were comparatively higher than at other annealing temperatures. More importantly, the Co40Fe40W20 films exhibited a good thermal stability. Therefore, replacing the magnetic layer with a CoFeW film improves thermal stability and is beneficial for electrode and strain gauge applications.

Effect of Annealing on the Structural, Magnetic and Surface Energy of CoFeBY Films on Si (100) Substrate.

The structure, magnetic properties, optical properties and adhesion efficiency of CoFeBY films were studied. Co40Fe40B10Y10 alloy was sputtered onto Si (100) with a thickness of 10-50 nm, and then annealed at room temperature, 100 °C, 200 °C and 300 °C for 1 h. X-ray diffraction (XRD) showed that the CoFeBY films deposited at room temperature are amorphous. Annealing at 100 °C gave the films enough thermal energy to change the structure from amorphous to crystalline. After annealing, the CoFeBY thin film showed a body-centered cubic (BCC) CoFeB (110) characteristic peak at 44°. However, the low-frequency alternative-current magnetic susceptibility (χac) and saturation magnetization (MS) increased with the increase of thickness. CoFeBY thin films had the highest χac and MS after annealing at 300 °C compared to that at other temperatures. After annealing at 300 °C, the surface energy of CoFeBY film is the maximum at 50 nm. Higher surface energy indicated stronger adhesion.

Generation of Self-Assembled 3D Network in TPU by Insertion of Al2O3/h-BN Hybrid for Thermal Conductivity Enhancement.

Thermal management has become one of the crucial factors in designing electronic equipment and therefore creating composites with high thermal conductivity is necessary. In this work, a new insight on hybrid filler strategy is proposed to enhance the thermal conductivity in Thermoplastic polyurethanes (TPU). Firstly, spherical aluminium oxide/hexagonal boron nitride (ABN) functional hybrid fillers are synthesized by the spray drying process. Then, ABN/TPU thermally conductive composite material is produced by melt mixing and hot pressing. Then, ABN/TPU thermally conductive composite material is produced by melt mixing and hot pressing. Our results demonstrate that the incorporation of spherical hybrid ABN filler assists in the formation of a three-dimensional continuous heat conduction structure that enhances the thermal conductivity of the neat thermoplastic TPU matrix. Hence, we present a valuable method for preparing the thermal interface materials (TIMs) with high thermal conductivity, and this method can also be applied to large-scale manufacturing.

Electrochemistry and Rapid Electrochromism Control of MoO3/V2O5 Hybrid Nanobilayers.

MoO3/V2O5 hybrid nanobilayers are successfully prepared by the sol-gel method with a spin- coating technique followed by heat -treatment at 350 °C in order to achieve a good crystallinity. The composition, morphology, and microstructure of the nanobilayers are characterized by a scanning electron microscope (SEM) and X-ray diffractometer (XRD) that revealed the a grain size of around 20-30 nm, and belonging to the monoclinic phase. The samples show good reversibility in the cyclic voltammetry studies and exhibit an excellent response to the visible transmittance. The electrochromic (EC) window displayed an optical transmittance changes (ΔT) of 22.65% and 31.4% at 550 and 700 nm, respectively, with the rapid response time of about 8.2 s for coloration and 6.3 s for bleaching. The advantages, such as large optical transmittance changes, rapid electrochromism control speed, and excellent cycle durability, demonstrated in the electrochromic cell proves the potential application of MoO3/V2O5 hybrid nanobilayers in electrochromic devices.

Structure and Magnetic Properties of Co40Fe40V20 Thin Films.

This study investigated the structure and magnetic properties of Co40Fe40V20 thin films with a thicknesses (tf) of 10 nm to 100 nm on a glass substrate. The X-ray diffraction (XRD) patterns of the CoFeV films demonstrated a significant crystalline body-centered cubic (BCC) CoFe (110) structure when the thickness was between 60 and 100 nm, and an amorphous status were shown when the thickness was from 10 to 50 nm. The strongest crystalline XRD peak was at 60 nm because it had a continuous mode of film growth and induced a large grain distribution. The low-frequency alternating current magnetic susceptibility (Ï°ac) property decreased when the frequency increased. The lowest Ï°ac value was detected at 60 nm owing to the large grain distribution inducing high coercivity (Hc) and then enhancing the spin coupling strength. The external field (Hext) was difficult to rotate spin state, then deduces the spin sensitivity and Ï°ac value is decreased. The highest Ï°ac meant the spin sensitivity was maximized at the optimal resonance frequency. The 50-mm thickness had the highest Ï°ac 0.045 value at an fres of 100 Hz. The fres value was less than 1000 Hz at all CoFeV thicknesses, suggesting that CoFeV films would be suitable for low-frequency magnetic component applications. Moreover, the saturation magnetization (Ms) revealed a thickness effect when the thicknesses had a larger Ms. The Hc values were between 3 Oe and 10 Oe at all CoFeV films, except for 60 nm. The Hc of the 60 nm film was about 80 Oe due to the larger grain distribution, and it induced strong remanent magnetization (Mr) and a larger squareness ratio (Mr/Ms) of 92%. The results of the magnetic measurement showed that the 60 nm Co40Fe40V20 film had greater Hc and a good squareness ratio.

Ta and Ru Seed Layers Effect on the Crystallinity and Wettability of Co60Fe20V20 Films.

The following structures are deposited under the conditions (a) glass/Ru(X nm)/Co60Fe20V20(5 nm) and (b) glass/Ta(Y nm)/Co60Fe20V20(5 nm) at room temperature (RT), where X and Y is from 5 nm to 10 nm. X-ray diffraction (XRD) patterns of glass/Ru(X nm)/Co60Fe20V20(5 nm) and glass/Ta(Y nm)/Co60Fe20V20(5 nm) reveal a weak crystallization at peak ß-(200) as the thicknesses of Ta increase from 8 nm to 10 nm, and the patterns indicate an amorphous state as the thicknesses of all Ru films and Ta thicknesses increase from 5 nm to 7 nm. The average contact angles of glass/Ru(X nm)/Co60Fe20V20(5 nm) and glass/Ta(Y nm)/Co60Fe20V20(5 nm) are less than 90° with testing liquids deionized (DI) water and glycerol. The average contact angle of water on the surface is nearly 90 degrees, indicating it is hydrophobic. Moreover, the maximum surface energy of glass/Ru(9 nm)/Co60Fe20V20(5 nm) and glass/Ta(10 nm)/Co60Fe20V20(5 nm) are 44.5 mJ/m2 and 37.4 mJ/m2, demonstrating that the high surface energy corresponds to a strong adhesion, which can be combined with a magnetic tunneling layer of MgO or AlOx and is compatible with other semiconductor processes in magnetic recording media and photoelectric applications.

Tuning bandgap and surface wettability of NiFe2O4 driven by phase transition.

Stress variation induced bandgap tuning and surface wettability switching of spinel nickel ferrite (NiFe2O4, NFO) films were demonstrated and directly driven by phase transition via a post-annealing process. Firstly, the as-deposited NFO films showed hydrophilic surface with water contact angle (CA) value of 80 ± 1°. After post-annealing with designed temperatures ranged from 400 to 700 °C in air ambience for 1 hour, we observed that the crystal structure was clearly improved from amorphous-like/ nanocrystalline to polycrystalline with increasing post-annealing temperature and this phenomenon is attributed to the improved crystallinity combined with relaxation of internal stress. Moreover, super-hydrophilic surface (CA = 14 ± 1°) was occurred due to the remarkable grain structure transition. The surface wettability could be adjusted from hydrophilicity to super-hydrophilicity by controlling grain morphology of NFO films. Simultaneously, the saturation magnetization (Ms) values of NFO films at room temperature increased up to 273 emu/cm3 accompanied with transitions of the phase and grain structure. We also observed an exceptionally tunable bandgap of NFO in the range between 1.78 and 2.72 eV under phase transition driving. Meanwhile, our work demonstrates that direct grain morphology combined with the stress tuning can strongly modulate the optical, surface and magnetic characteristics in multifunctional NFO films.

Internal stress induced natural self-chemisorption of ZnO nanostructured films.

The energetic particles bombardment can produce large internal stress in the zinc oxide (ZnO) thin film, and it can be used to intentionally modify the surface characteristics of ZnO films. In this article, we observed that the internal stress increased from -1.62 GPa to -0.33 GPa, and the naturally wettability of the textured ZnO nanostructured films changed from hydrophobicity to hydrophilicity. According to analysis of surface chemical states, the naturally controllable wetting behavior can be attributed to hydrocarbon adsorbates on the nanostructured film surface, which is caused by tunable internal stress. On the other hand, the interfacial water molecules near the surface of ZnO nanostructured films have been identified as hydrophobic hydrogen structure by Fourier transform infrared/attenuated total reflection. Moreover, a remarkable near-band-edge emission peak shifting also can be observed in PL spectra due to the transition of internal stress state. Furthermore, our present ZnO nanostructured films also exhibited excellent transparency over 80% with a wise surface wetting switched from hydrophobic to hydrophilic states after exposing in ultraviolet (UV) surroundings. Our work demonstrated that the internal stress of the thin film not only induced natural wettability transition of ZnO nanostructured films, but also in turn affected the surface properties such as surface chemisorption.