Silicon-based Composites Research Articles

The performance of CO2 reduction by dielectric barrier discharge plasma coupled Cu-Ni binary silicon-based composites

As a major greenhouse gas, the rational conversion and utilization of CO2 can help reduce carbon emissions and mitigate the greenhouse effect. In this study, mesoporous SiO2 as a carrier, with CuO and NiO employed to construct a binary metal composite silica-based catalyst, coupled with dielectric barrier discharge (DBD) plasma, for the conversion of CO2. Physicochemical analysis confirmed the successful introduction of CuO into the mesoporous SiO2. NiO and CuO bimetals were dispersed on SiO2 surfaces with large specific surface areas, ensuring an optimal distribution of metal oxide. Gas chromatography was utilized to investigate the performance of DBD-coupled x%CuO-3 %NiO/Si for CO2 conversion. The results indicated that the CuO-NiO binary composite silica catalysts significantly improved CO2 conversion, CO yield, and energy efficiency compared to the monometallic 3 %NiO/Si materials. Further microstructural analysis of the 9 %CuO-3 %NiO/Si catalyst revealed near-elliptic particles with dimensions of 200 by 500 nm and a large number of irregular fine particles attached to the surface. When the CuO loading reached an optimal level and the input power was set at 30 W, the energy efficiency of the 9 %CuO-3 %NiO/Si catalyst increased by 119.6 %. The CuO-NiO binary composite Si-based catalyst developed in this study boasts simple operation and environmental friendliness, making it highly significant for CO2 treatment.

Covalently Linking Reduced Graphene Oxide Facilitated Electrodeposition of MoS2 on Silicon Pyramidal Photocathode To Enhance Hydrogen Evolution.

In recent years, increasing attention has been paid to photoelectrochemical (PEC) hydrogen production owing to the utilization of sustainable solar energy and its promising performance. Silicon-based composites are generally considered ideal materials for PEC hydrogen production. However, slow reaction kinetics and poor stability are still key factors hindering the development of silicon-based photoelectrocatalysts. Herein, we present an n+-p Si pyramidal photocathode assembly method to load reduced graphene oxide (rGO) onto the surface of the n+-p Si pyramid by covalently linking (Si/rGO). rGO is utilized as a conductive layer to reduce the interfacial charge-transfer resistance. Then, MoS2 can be successfully electrodeposited on the surface of Si/rGO to form the Si/rGO/MoS2 composite, which possesses excellent PEC hydrogen evolution performance with a high and stable photocurrent of -41.6 mA cm-2 and a hydrogen evolution rate of about 18.1 μmol min-1 cm-2 under 0 V (vs RHE). The covalently linking rGO layer effectively enhances the transfer of photogenerated carriers between the Si substrate and MoS2. MoS2 provides abundant hydrogen evolution active sites, which accelerate the surface reaction kinetics, as well as a protective layer for the Si pyramidal array structure. This work provides a low-cost, convenient, and efficient way of preparing silicon-based photocathodes.

Thin-Film SiOx Coated Carbon Nanofibers As Stable Anodes for Lithium-Ion Batteries

With the increase in the capacity of cathode materials in lithium-ion batteries(LIBs), the demand for novel anode materials with high theoretical energy density is following. Up to now, many candidates have been reported; silicon-based composites are considered a prospective alternative due to their abundant reserves and high energy density. However, The primary disadvantage of Si, electrochemical irreversibility during the charge/discharge process, hinder widespread use.In this study, we adapted SiOx-coated carbon nanofibers (SiOx-CNFs) composite to the binder-free anode current collector for lithium-ion batteries. The composite has a structure where a thin amorphous SiOx (thickness ~100nm) is coated on the CNFs surface and is successfully synthesized by electrospinning and sputtering. This structure, surface SiOx-coated porous CNF, breaks through the significant drawback of Si-based composites, pulverization of Si element during the charge/discharge cycle. In addition to this, due to the structure of porous CNF, we achieved the curtail of electrode weight.Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) analyses are carried out to confirm the morphology and crystallinity. Furthermore, with cyclic voltammetry analysis, fast reaction kinetics and excellent electrochemical reversibility are verified. The cycle test is also conducted to prove excellent capacity and cyclic stability.

Nanomechanical characterization of nanostructured Lu2SiO5 environmental barrier coatings by nano-indentation

Nanostructured rare-earth silicates are widely considered as environmental barrier coatings for the new generation of silicon-based composites. In current work, the nanostructured Lu2SiO5 coatings were deposited successfully using nanostructured Lu2SiO5 feedstocks by atmospheric plasma spraying (APS). Moreover, the nanomechanical properties of Lu2SiO5 coatings were characterized systematically by nano-indentation. Results indicate that the grain growth of Lu2SiO5 coatings is not obvious compared to Lu2SiO5 feedstocks. The nanostructured Lu2SiO5 coatings exhibit bi-modal nanomechanical properties. The elastic modulus and nanohardness of Lu2SiO5 coatings are 148.84 ± 28.00 GPa and 8.51 ± 4.12 GPa, respectively. In addition, the elastic work and plastic work of Lu2SiO5 coatings are 10.387 ± 1.283 nJ and 18.437 ± 6.823 nJ, respectively. The proportion of consumption of energy of Lu2SiO5 coatings is 0.636 ± 0.099 during indentation, which means that nanostructured Lu2SiO5 coatings process an excellent wear resistance.

Analysis of research progress in improving the performance of silicon-based anode materials for lithium-ion batteries: a combination of nanostructured silicon and silicon-based composites

With the development and wide-use of lithium-ion batteries, silicon, due to its high theoretical specific capacity and superior fast charging performance, is being studied intensively and extensively as a new generation of anode materials for the batteries. However, challenges of large volume expansion and poor electrical conductivity has limited the performance and commercial applications of silicon-based anode materials, which is led by pulverization of silicon particles, low initial coulombic efficiency, and unstable solid-electrolyte interphase films. To solve the issues, five main strategies have been proposed correspondingly: nanostructured silicon, silicon-based composites, new binders, new electrolyte additives, and pre-lithiation. Among them, the approaches of nanostructured silicon (0D, 1D, 2D) and silicon-based composites (silicon/carbon, silicon/metal, silicon/transition metal oxide) are practical and effective, thus being explored in depth as the focus of many researches, respectively. After summarizing and analyzing the research progress in enhancing the performance of silicon-based anode materials, it is inferred that the advantages of nanostructured silicon are complementary with those of silicon-based composite materials. Silicon-based nanocomposite materials, as the combination of nanostructured silicon and silicon-based composites, are comparatively more significant and useful than either of those. Therefore, the trend of combining the two strategies to achieve a better improvement is unstoppable.

Freestanding carbon fiber-confined yolk-shelled silicon-based anode for promoted lithium storage applications

A flexible carbon fiber-confined yolk-shelled silicon-based composite is reported as an anode material for lithium storage applications. Silicon nanoparticles (Si NPs) are confined by the N-doped hollow carbon cages (Si-NHC) and these uniform dispersed yolk-shell-structured Si-NHC units were encapsulated by the carbon fibers within an interconnected three-dimensional (3D) framework (Si-NHC@CNFs). For the encapsulated yolk-shelled Si-NHC, the void space between the inner Si NPs and outer NHC can accommodate the structural changes of Si NPs during charging/discharging processes, leading to effectively improved structural stability and cycling life. More importantly, all the Si-NHC units were bridged together through a conductive CNFs “highway” to enhance the overall conductivity and tap density further. As observed, Si-NHC@CNFs exhibited an initial discharge capacity of 1364.1 mAh·g−1 at 1000 mA·g−1 and 678.9 mAh·g−1 at 2000 mA·g−1. Furthermore, the reversible capacity was well maintained at 752.2 mAh·g−1 at 500 mA·g−1 after 6000 ultra-long cycles.Graphical abstract

Modelling and analysis of the volume change behaviors of Li-ion batteries with silicon-graphene composite electrodes

Silicon-based composites are recognized as one of the most promising negative electrode materials owing to their high theoretical capacity. However, during (dis)charging, the silicon particles undergo significant volume changes, resulting in electrode thickness variation over the cycle. This maps to the cell scale as a change in cell thickness, which translates into outward pressure. To demonstrate the impact of swelling on the cell thickness variation, a model is developed using the moving boundary approach. The ratios of the composites are classified in detail to accurately analyse the contribution of two materials to the capacity. The impacts of the electrode design, such as the thickness of the active layer and the porosity of the negative electrode, as well as the operating conditions on the electrochemical performance and thickness variation of the cell are also investigated. The capacity contribution increases from 85% to 92% when the silicon content increases, and then changing the electrode structure. When the porosity raises from 40% to 60% and the thickness of the negative active layer increases from 55 μm to 85 μm, the capacity utilization varies from 58% to 79% and from 68% to 59%, respectively. In the rate test, the cell thickness variation reduces from 2.49 μm to 1.56 μm when the rate changes from 0.5 C to 2 C. The expansion/contraction behaviour of the active particles during the lithiation/delithiation process is utilized to investigate the variation of cell thickness under different conditions. The optimized simulation is applied to establish the stress variation model to provide insight into the stress evolution during cycling, which can be employed to more accurately assess the performance and potential risk.

ZIF-67-derived porous nitrogen-doped carbon shell encapsulates photovoltaic silicon cutting waste as anode in high-performance lithium-ion batteries

The rapid development of the photovoltaic industry generates nearly 35 wt% micron-scale silicon powder waste in the form of a paste. This study reports the in-situ synthesis of ZIF-67 on the surface of low-cost silicon cutting waste. Submicron-scale porous cage-like silicon-based composites were obtained by carbonization. This hollow framework structure facilitated the large volume expansion/contraction of Si during charging/discharging. The porous nitrogen-doped carbon layer not only yielded rapid transport channels for Li+ and electrons but also improved the electrical conductivity of the material. In addition, the excellent pseudocapacitive performance of the Si@NC-ZIF composite also enhanced lithium storage. The composite exhibited excellent capacity retention of 1623.05 mAh/g after 100 cycles at 200 mA g−1, with the retention rate reaching 86.29 %. When the current was switched from 2000 to 100 mA g−1, the discharge capacity recovered to 1453.35 mAh/g, showing excellent rate performance. This study provides a new approach for the recycling and value-added utilization of photovoltaic silicon cutting waste in lithium-ion battery anodes.

Effects of transition metals for silicon-based lithium-ion battery anodes: A comparative study in electrochemical applications

The strength, conductivity, elasticity, inactivity against lithium, and tunability properties of transition metals (TMs) are the major reasons these metals are used to synthesize silicon-based lithium-ion battery (LIBs) composite anodes. This is because TMs significantly influence and improve the overall electrochemical performance of LIB electrodes by mitigating the undesired expansion of silicon. The effects of different elemental transition metals copper (Cu), titanium (Ti), nickel (Ni), and iron (Fe) on the electrochemical performance of silicon-based composites were compared, and the phases formed during milling were correlated to the behavior of the composites in which they are present. The excellent performance of these electrodes was attributed to the reaction mechanism of transition metals after the first conversion reaction during lithiation and remained inactive during the ensuing cycles. It was found that the strength and ductile nature of nickel accounts for relieving mechanical stress induced on Silicon during the insertion and extraction of lithium ions. All copper-containing composites showed high stability in cycling but low capacity, which is attributed to the high amounts of copper, contained in these composites and the reaction of copper with silicon during milling. The presence of titanium improved the electrical conductivity and mechanical strength of the electrodes. Iron-containing composites were observed to highly withstand deformation due to the strength of the matrix. Moreover, the addition of 10 wt. percentage carbon improved the cycle performance and rate capability of Cu-Fe-Si-C, Cu-Ni-Si-C, Ni-Fe-Si-C, and Ni-Ti-Si-C. These composites showed stable cycling performance of 654.42 mAh g–1, 686.16 mAh g–1, 657.56 mAh g–1, and 643.29 mAh g–1 respectively after 100 cycles capacity at 1 C.

Sulfureted polyacrylonitrile derived carbon encapsulated silicon as high-performance anode material for lithium-ion batteries

Silicon-based materials are the most promising anode materials for the next generation of lithium-ion batteries. However, the low conductivity, large volume effect, and continuous formation of solid-electrolyte-interface (SEI) film; resulted in low rate-capability, severe electrode pulverization, and aerogenesis, which hinders their practical application. To enhance the electrochemical performance of silicon-based materials, in this work, sulfur-doped carbon derived from sulfurized polyacrylonitrile is used as a carbon matrix for confining and encapsulating nano silicon particles. It is found that sulfur doping can effectively enhance the cycle stability of the silicon-based composite. The as-prepared silicon/sulfur-doped carbon composite with a moderate silicon content (∼16.7 wt%) exhibits an initial discharge capacity of 1735 mAh g−1 and is maintained at 699 mAh g−1 after 200 cycles. Even at the current density of 1 A g−1, the 0.5gSi@SPANdC composite also exhibits good cycle stability and a relatively high reversible capacity of 546.1mAh g−1 after 400 cycles.

Exploring the practical applications of silicon anodes: a review of silicon-based composites for lithium-ion batteries

Exploring the practical applications of silicon anodes: a review of silicon-based composites for lithium-ion batteries

Preparation and evaluation of gamma shielding properties of silicon-based composites doped with WO3 micro- and nanoparticles

This study aims to investigate the shielding properties of silicon-based WO3 composites against gamma radiation. The filler particles in micro and nano-size were prepared with a wet chemical synthesis method. Consequently, different weight percentages of micro and nano WO3 composites (5, 10, 15, 20, 30, 50, and 70 wt%) were produced. Structural and morphological characterizations of the composites were investigated using SEM and EDS analyses. Moreover, for the thermal characterization of the nanocomposites and to prove the thermal stability, TGA analysis was carried out. The results indicated that adding WO3 nanoparticles to the silicon matrix decreases the glass transition temperature of the composites. Additionally, shielding properties of the nano and micro composites were investigated using a NaI(Tl) scintillator detector at different photon energies and experimental results verified by MCNP Monte Carlo code and XCOM program. It was illustrated that, especially at lower energies, in both micro-and nanocomposites samples, by increasing the weight percentages of the filler particles, shielding abilities of the composites enhance appreciably.

A Review on Si-Based Ceramic Matrix Composites and their Infiltration Based Techniques

This review paper aims to look at silicon-based ceramic matrix composites and infiltration-based approaches for them. There are many different types of infiltration-based manufacturing processes, each with its own set of features. The best technique is chosen depending on the needs and desired attributes. With these considerations in mind, any type of infiltration might be selected to meet the requirements. Silicon-based ceramics has been highly used in the fields of aerospace, medical, automobile, electronics, and other various industries so it is important to study about their applications as well. This review outlines the evolution of composites from early 7000 BCE to composites today and discussed about various infiltration techniques for manufacturing silicon based ceramic matrix composites. This article also gives the comprehensive review of general characteristics and mechanical properties of silicon-based composites used in a variety of engineering sectors. The application section entails the wide range of engineering fields with consideration of infiltration techniques, which would be helpful for researchers to study and correlate the different infiltration techniques for end applications.

Preparation and Evaluation of Gamma Shielding Properties of Silicon-Based Composites Doped with Wo3 Micro-And Nanoparticles

Preparation and Evaluation of Gamma Shielding Properties of Silicon-Based Composites Doped with Wo3 Micro-And Nanoparticles

A comprehensive Monte Carlo study to design a novel multi-nanoparticle loaded nanocomposites for augmentation of attenuation coefficient in the energy range of diagnostic X-rays

Abstract Introduction: The present study aimed to investigate the radiation protection properties of silicon-based composites doped with nano-sized Bi2O3, PbO, Sm2O3, Gd2O3, WO3, and IrO2 particles. Radiation shielding properties of Sm2O3 and IrO2 nanoparticles were investigated for the first time in the current study. Material and methods: The MCNPX (2.7.0) Monte Carlo code was utilized to calculate the linear attenuation coefficients of single and multi-nano structured composites over the X-ray energy range of 10–140 keV. Homogenous distribution of spherical nanoparticles with a diameter of 100 nm in a silicon rubber matrix was simulated. The narrow beam geometry was used to calculate the photon flux after attenuation by designed nanocomposites. Results: Based on results obtained for single nanoparticle composites, three combinations of different nano-sized fillers Sm2O3+WO3+Bi2O3, Gd2O3+WO3+Bi2O3, and Sm2O3+WO3+PbO were selected, and their shielding properties were estimated. In the energy range of 20-60 keV Sm2O3 and Gd2O3 nanoparticles, in 70-100 keV energy range WO3 and for photons energy higher than 90 keV, PbO and Bi2O3 nanoparticles showed higher attenuation. Despite its higher density, IrO2 had lower attenuation compared to other nanocomposites. The results showed that the nanocomposite containing Sm2O3, WO3, and Bi2O3 nanoparticles provided better shielding among the studied samples. Conclusions: All studied multi-nanoparticle nanocomposites provided optimum shielding properties and almost 8% higher attenuation relative to single nano-based composites over a wide range of photon energy used in diagnostic radiology. Application of these new composites is recommended in radiation protection. Further experimental studies are suggested to validate our findings.

Investigation of the Thermal Conductivity of Silicon-Base Composites: The Effect of Filler Materials and Characteristic on Thermo-Mechanical Response of Silicon Composite

Thermal conductivity is a key property in many applications from electronic to informatics. The interaction of fillers with Sylgard 184 was studied; this study explores new composites and the influence of metal particles (copper and nickel), carbon-based materials (carbon nanotubes and carbon black), and ceramic nanoparticles (boron nitride) as fillers to enhance thermal properties of silicon-based composites. The effect of the fillers on the final performances of the composite materials was evaluated. The influence of filler volume, dimension, morphology, and chemical nature is studied. Specifically, FT-IR analysis was used to evaluate curing of the polymer matrix. DSC was used to confirm the data and to further characterize the composites. Thermo-mechanical properties were studied by DMTA. The filler morphology was analyzed by SEM. Finally, thermal conductivity was studied and compared, enlightening the correlation with the features of the fillers. The results demonstrate a remarkable dependence among the type, size, and shape of the filler, and thermal properties of the composite materials. Underlining a that the volume filler influenced the thermal conductivity obtaining the best results with the highest added volume filler and higher positive impact on the k of the composites is reached with large particles and with irregular shapes. In contrast, the increase of filler amount affects the rigidity of the silicon-matrix, increasing the rigidity of the silicon-based composites.

Synthesis and characterization of nitrogen-doped carbon nanotubes

In this work, nitrogen-doped carbon nanotubes (N-CNTs) were prepared by a facile chemical vapor deposition method using Fe/SBA-15 molecular sieve as the catalyst and different organic amines as carbon source and nitrogen source. The morphology, structure and composition of the obtained samples were characterized by a series of analytical techniques. The results revealed that the as-obtained N-CNTs are hollow bamboo-like nanofibers with a diameter of 30–50 nm and have a smooth surface. The effects of different organic amines on the yield, composition, morphology and properties of the N-CNTs were investigated. The N-CNTs prepared from diethylamine (DEA) have the highest yield (2.2 g (g cat)−1). The water absorption of the as-synthesized N-CNTs samples increases with the increase in the molar ratio of N/C. The N-CNTs prepared from ethylenediamine (EDA) have the highest N/C molar ratio (0.35) and the highest water absorption (224.4 mg g−1). The thermal conductivity (TC) of the silicon-based composites increases with the increase of N-CNTs. However, the N/C molar ratio of N-CNTs has a negative effect on the TC of silicon-based composites.

Evolution of microstructure and thermal conductivity of multifunctional environmental barrier coating systems

Environmental barrier coating (EBC) systems are applied to the surface of silicon-based composites exposed to high temperature combustion gas flow paths in gas turbine engines. They reduce the rate of composite oxidation, its volatilization by reactions with water vapor, and the temperature of the composite as their thermal conductivity decreases. Current EBC systems consist of a silicon bond coat covered by an ytterbium disilicate (Yb2O3⋅2SiO2: YbDS) permeation resistant and low silica activity barrier. When applied by atmospheric-plasma spray deposition, this outer layer contains 10–15% of a secondary ytterbium monosilicate (Yb2O3⋅3SiO2: YbMS) phase. YbDS has a coefficient of thermal expansion (CTE) of 4–5×10−6 °C−1, similar to those of the silicon and the silicon-based composite, but a relatively high thermal conductivity of 5–7 W m−1 K−1. YbMS has a higher steam volatility resistance than YbDS, and it has a much lower thermal conductivity (∼2–2.5 W m−1 K−1) at ambient temperature compared to YbDS, but its higher, highly anisotropic CTE (3–11×10−6 °C−1) results in channel cracking which reduces environmental protection. Here, we use a combination of scanning electron beam and laser-based thermoreflectance methods to spatially map the distribution of the silicate phases and thermal conductivity at ambient temperature in a Si-ytterbium disilicate EBC system exposed to thermal cycling in water vapor. We show that during thermal cycling, diffusion of silica from the thermally grown oxide on the Si bond coat surface to nearby YbMS regions transforms this phase to YbDS, thereby reducing the risk of thermomechanical coating failure but decreasing its effective thermal resistance. We also show that as silica is volatilized at the water vapor–ytterbium silicate interface, YbDS is transformed to YbMS, restoring some of the thermal protection of the coating system lost by its reduction in thickness and the YbMS to YbDS transformation near the bond coat.

Long-Term Stable Hollowed Silicon for Li-Ion Batteries Based on an Improved Low-Temperature Molten Salt Strategy.

Nanostructured hollow silicon has attracted tremendous attention as high-performance anode materials in Li-ion battery applications. However, the large-scale production of pure hollowed silicon with long cycling stability is still a great challenge. Here, we report an improved low-temperature molten salt strategy to synthesize nanosized hollowed silicon with a stable structure on a large scale. As an anode material for rechargeable lithium-ion batteries, it exhibits a high capacity, excellent long cycling, and steady rate performance at different current densities. Especially, a high reversible capacity of 2028.6 mA h g–1 at 0.5 A g–1 after 150 cycles, 994.3 mA h g–1 at 3 A g–1 after 500 cycles, and 538.8 mAh g–1 at 5 A g–1 after 1200 cycles could be obtained. This kind of nanosized hollowed silicon can be applied as a basic anode material in silicon-based composites for long-term stable Li-ion battery applications.

The preparation and characterization of silicon-based composites doped with BaSO4, WO3, and PbO nanoparticles for shielding applications in PET and nuclear medicine facilities

Objective(s): The present study aimed to design new nanoparticle-based shielding materials for photons used in single-photon emission computed tomography and positron emission tomography facilities. Materials and Methods: Initially, the mass attenuation coefficients and half value layer (HVL) of the composites were comprehensively investigated based on a silicon rubber containing various ratios of micro- and nano-barium sulfate (BaSO4), lead oxide (PbO), and tungsten oxide (WO3) particles at 60, 80, 100, 150, 200, 300, 400, 500, and 600 keV photon energies using the MCNP-X6 Monte Carlo (MC) code and WinXCOM software. In the second stage, the composites composed of 10 wt% and 20 wt% WO3 and PbO particles were constructed in a liquid silicone rubber-based matrix. The mass attenuation coefficients and HVL of the designed shields were experimentally assessed using Cs-137 and Am-241 radioactive sources.Results: The particles sizes of PbO and WO3 were within the range of 50-200 nanometers. The MC and measurement results indicated that the linear attenuation coefficients of the composites were augmented with the addition of all the studied nano- and micro-particles. However, the PbO composites had more significant shielding properties compared to the BaSO4 and WO3 composites. Conclusion: According to the results, the nanocomposites had better ability to shield γ-rays at both energies compared to the micro-composites.