The magnetic-control-electric and corresponding dielectric behavior of the ZnO/NiFe/ZnO multilayer films have been demonstrated by applying an ultrathin bimetallic NiFe inserting layer into ZnO ...films, and fabricated by radio-frequency magnetron sputtering at room temperature without introducing any oxygen gas during deposition process. At first, a high quality crystalline ZnO(002) textured film was deposited and exhibited a dielectric constant value of around 10 confirmed at room temperature with the Agilent 42941B probe and 4294A impedance meters ranged from 40 Hz to 20 MHz. Once ZnO inserted with a 5 nm-thick NiFe inserting layer, the value of dielectric constant was dramatically increased from 10 to 12.5. This phenomenon can be attributed to redistribute the strongly interface charges between ZnO and NiFe layers and accompany with the relaxation of internal stress of ZnO. On the other hand, the external magnetic field induced dielectric variation can also be clearly observed, and the ZnO film with NiFe inserting layer demonstrates a 0.05%-0.10% dielectric tunability. The magnetic-control-electric and corresponding dielectric behavior of ZnO/NiFe/ZnO multilayers with a single inserting NiFe layer compared with that of pure ZnO film also conclude the magnetoelectric effect in present multilayered structures. Moreover, the grain size of the ZnO films was gradually increased from 32.5 nm to 40.5 nm while inserting with an ultrathin NiFe bimetallic layer. This grain structure transition can be attributed to the lattice misfit between ZnO and NiFe. This research work demonstrates that a single NiFe insering layer can effectively control the dielectric and magnetic characters in the ZnO/NiFe/ZnO multilayered structures and provide valuable multifunctional behaviors for potential novel applications design such as ferroic sensor.
The advancement of lithium-ion battery technology relies on the development of materials that not only improve performance but also align with environmental sustainability. This work presents a novel ...water-based pectin-PEG binder for LiFePO4 cathodes that combines eco-friendliness with electrochemical innovation. The binder material is made by mixing pectin, a flexible natural substance, with polyethylene glycol through a radical copolymerization process. This combination gives the binder both flexibility and a boost in electrical performance. Our experimental results demonstrate that LFP cathodes with this binder have an intriguing self-healing ability in comparison with the conventional PVDF binder, enhanced charge-discharge capacities, improved cycling stability, and higher ionic conductivity. Specifically, electrodes utilizing the pectin-PEG binder exhibit an impressive retention of discharge capacity. They maintain roughly 150 mAh g−1 after 500 cycles at 1C with 99% retention, and about 141 mAh g−1 with 97% retention at 3C. Cyclic voltammetry (CV) confirms that the PP binder maintains its ionic diffusion properties at high sweep rates, whereas galvanostatic intermittent titration technique reveals a much higher lithium ion diffusion coefficient (DLi+) within the operational voltage range of the LFP-PP250 electrodes. These findings establish an attractive direction for the development of electrodes for high-energy density, sustainable lithium-ion batteries.
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•The pectin-PEG binders offer eco-friendliness and innovation for LiFePO4 cathodes.•The pectin-PEG binder exhibits self-healing properties, enhancing battery life.•CV and GITT analyses show enhanced lithium ion diffusivity.•The pectin-PEG binder improves the battery performance of the LFP cathodes.•Electrodes maintain ∼150mAh g−1 after 500 cycles at 1C and ∼141mAh g−1 at 3C.
The intrinsic zinc oxide (ZnO) thin films with controllable crystallographic orientation have been synthesized on Si(100) substrates using plasma-enhanced chemical vapor deposition (PECVD) system ...without any buffer layer. Based on X-ray diffraction (XRD) results, the evolution of crystallographic orientation of ZnO thin films from polar c-plane (0002), polar c-plane and nonpolar m-plane (101̅0) coexist to nonpolar m-plane and a-plane (112̅0) coexist was achieved by a simple factor of controlling synthesized temperature. The plane-view morphological images exhibited that the surface texture and grain shape of ZnO thin films could have evolved from hexagonal to stripelike grains when the ZnO crystallographic orientation changed from perpendicular to parallel to the substrate. The characterization analysis indicated that the zinc precursor diethylzinc (DEZn), Zn(C2H5)2 played a key role on the crystallographic orientation evolution of ZnO thin films during the early stage of the growth process because DEZn not only can serve as Zn precursor but also can be employed as passivating agent to influence the crystal growth under different synthesized temperatures. Room-temperature Hall effect measurement showed that intrinsic ZnO thin film with stripelike grains possessed the lowest value of resistivity ∼7.11 × 102 Ω cm, which had an estimated carrier concentration and mobility of about 5.73 × 1014 cm–3 and 15.34 cm2/V s, respectively. The water contact angle (CA) measurement was also provided to determine the surface wettability and surface free energy of ZnO thin films, indicating that CA could be adjusted via different crystallographic orientation of ZnO thin film.
When B and V are added to CoFe material, the mechanical strength and spin tunneling polarization of a CoFe alloy can be improved and enhanced by the high tunneling magnetoresistance (TMR) ratio. ...Based on these reasons, it is worthwhile investigating Co40Fe40V10B10 films. In this work, X-ray diffraction (XRD) showed that Co40Fe40V10B10 thin films have some distinct phases including CoFe (110), CoFe (200), FeB (130), and V (110) diffracted peaks with the strongest diffracted peak for 30 nm. The lowest low-frequency alternate-current magnetic susceptibility (χac) was detected at 30 nm because the large grain distribution inducing that high coercivity (Hc) enhances the spin coupling strength and low χac. The external field (Hext) had difficulty rotating in the spin state, hence, the spin sensitivity was reduced and the χac value decreased due to increased surface roughness. The 20 mm thickness had the highest χac 1.96 × 10−2 value at 50 Hz of an optimal resonance frequency (fres). The surface energy increased from 34.2 mJ/mm2 to 51.5 mJ/mm2 for Co40Fe40V10B10 films. High surface energy had corresponding strong adhesive performance. According to the magnetic and surface energy results, the optimal thickness is 20 nm due as it had the highest χac and strong adhesion.
Abstract
In the archetypal lithium-rich cathode compound Li
1.2
Ni
0.13
Co
0.13
Mn
0.54
O
2
, a major part of the capacity is contributed from the anionic (O
2−/−
) reversible redox couple and is ...accompanied by the transition metal ions migration with a detrimental voltage fade. A better understanding of these mutual interactions demands for a new model that helps to unfold the occurrences of voltage fade in lithium-rich system. Here we present an alternative approach, a cationic reaction dominated lithium-rich material Li
1.083
Ni
0.333
Co
0.083
Mn
0.5
O
2
, with reduced lithium content to modify the initial band structure, hence ~80% and ~20% of capacity are contributed by cationic and anionic redox couples, individually. A 400 cycle test with 85% capacity retention depicts the capacity loss mainly arises from the metal ions dissolution. The voltage fade usually from Mn
4+
/Mn
3+
and/or O
n−
/O
2−
reduction at around 2.5/3.0 V seen in the typical lithium-rich materials is completely eliminated in the cationic dominated cathode material.
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.
X-ray diffraction indicated an amorphous state of all annealed films, indicating that boron in CoFeW films could refine grain size and low annealing temperatures did not induce sufficient thermal ...driving force to support grain growth. The saturation magnetization (Ms) and low-frequency alternate-current magnetic susceptibility (χac) increased with the increase in the thicknesses and annealing temperatures, indicating the thickness effect and magneto-nanocrystalline anisotropy. The highest Ms and χac values of Co40Fe40W10B10 films were estimated to be 1233 emu/cm3 and 2.8, at an annealing temperature of 350 °C and thickness of 100 nm. Surface energy increased with the increase in thickness and annealing temperature. The highest surface energy of 100 nm thick Co40Fe40W10B10 film was 38.52 mJ/mm2 at 350 °C. The Co40Fe40W10B10 film had the highest transmittance when annealing temperature was 200 °C and 10 nm, and its transmittance rate was 32.7%. The transmittance decreased with the increase in thickness and annealing temperatures, while a higher thickness may inhibit the transfer of photon signals through the film, causing a low transmittance. In this study, the optimal condition of magnetic and adhesive properties of Co40Fe40W10B10 film was found to be 100 nm with annealing at 350 °C due to high Ms, large χac, and strong adhesion.
•XRD patterns show amorphous structure.•MS and χac increased as the increase of thicknesses and annealing temperatures.•The highest Ms and χac values were estimated to be 1233 emu/cm3 and 2.8.•The transmittance of annealed 200°C film was 32.7 %, at a thickness of 10 nm.•The optimal condition was found to be 100 nm with annealing at 350°C.
Co60Fe20Y20 film was sputtered on glass substrate with a 10 nm to 50 nm under four annealed conditions and the structure, magnetic properties, surface energy, and optical property were examined. An ...amorphous structure of CoFeY films was revealed by an X-ray diffraction analyzer, suggesting that the addition of yttrium (Y) refined the grain size and the annealing temperatures were insufficient to support grain growth. The saturation magnetization (Ms) and low-frequency alternate-current magnetic susceptibility (χac) increased with the increase in the thicknesses and annealing temperatures, suggesting that the thickness effect and Y can refine grain size and induce ferromagnetic spin exchange coupling. The highest Ms and χac of Co60Fe20Y20 film were 735 emu/cm3 and 0.23 at an annealing temperature of 300 °C and 50 nm. The χac value of CoFeY film decreased significantly with the increase in measured frequency, while the maximum χac value increased significantly after heat treatment. The optimal resonance frequency (fres) corresponding to the maximum χac was 50 Hz, indicating the applicability of the film in a low-frequency range. The highest surface energy of the 50 nm was 31.84 mJ/mm2 at 300 °C, while the highest transmittance 58% was observed in as-deposited 10 nm film. The transmittance decreased with the increase in annealing temperatures and thickness. A higher thickness may inhibit photon signal transfer through the film, causing a low transmittance. Moreover, the specific properties of Co60Fe20Y20 films are compared with Co40Fe40B10Y10 films, which indicate that Co60Fe20Y20 films have high maximum χac, surface energy, and transmittance than Co40Fe40B10Y10 films.
•XRD patterns show amorphous structure.•Y can refine grain size and induce ferromagnetic spin exchange coupling.•The highest Ms and χac values were estimated to be 735 emu/cm3 and 0.23•The highest surface energy of 50 nm thick was 31.84 mJ/mm2.•The transmittance is 58 % at as-deposited 10 nm.
Silicon-based anode materials are gaining popularity in lithium-ion battery research due to their high theoretical specific capacity compared to the conventional graphite anode. However, the ...commercialization of silicon-based anode materials has been hampered by their limited electronic conductivity and significant volume expansion. To address these challenges, our strategy was conducted to prepare porous silicon@carbon (p-Si@C) nanocomposites as an anode material using a simple aqueous solution method. In this work, nitrogen-containing p-phenylenediamine was chosen as the carbon source for synthesizing the nanostructured p-Si@C composites. The excellent electrochemical performance can be achieved, with over 100 cycles, a specific capacity of 624 mAh g–1, and a high Coulombic efficiency of 97.2%. These promising results were attributed to efficient Li-ion transport and low volume expansion, which are confirmed by the distribution function of relaxation time plots coupled with impedance spectroscopy technique, followed by the calculation of the expansion rate obtained from the SEM cross-sectional image. Hence, our work not only clearly provides a simple yet valuable method for the preparation of nanostructured silicon-based anode material with good electrochemical performance but also demonstrates its potential for industrial battery-grade development.
The low-frequency alternating current magnetic susceptibility (χ
ac
) property decreased when the frequency increased. The highest χ
ac
meant the spin sensitivity was maximized at an f
res
. Of all ...CoFeVB thicknesses, the 20-mm thickness had the highest χ
ac
value (9.85 × 10
−3
) at an f
res
of 1000 Hz. The transmittance percentage decreased from 43% to 10% as the thicknesses changed from 10 to 40 nm. The absorbance of the CoFeVB films decreased. Finally, the surface energy revealed the lowest value at 20 nm. A high surface energy indicates high adhesive characteristics. The maximal surface energy of the 40-nm thickness was 38 mJ mm
−2
, indicating excellent adhesion. The optimal magnetic performance of 20-nm film, because it exhibits the highest χ
ac
value.
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