Research

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9 pages, 1669 KiB

Open AccessArticle

Thermal Balance of a Water Thermal Accumulator Based on Phase Change Materials

by Grigorii S. Bocharov, Alexey V. Dedov, Alexander V. Eletskii, Artem O. Vagin, Alexander V. Zacharenkov and Michail A. Zverev

J. Compos. Sci. 2023, 7(9), 399; https://doi.org/10.3390/jcs7090399 - 20 Sep 2023

Viewed by 897

Abstract

The arrangement of a water thermal accumulator (WTA) containing phase change materials (PCM) is presented and analyzed. The hot or cool water is used as a working body. The accumulator contains two concentric cylindrical tubes. The inner tube is used for hot or [...] Read more.

The arrangement of a water thermal accumulator (WTA) containing phase change materials (PCM) is presented and analyzed. The hot or cool water is used as a working body. The accumulator contains two concentric cylindrical tubes. The inner tube is used for hot or cool water flowing, while the volume between the inner and outer tubes is filled with PCM. The thermal energy in the accumulator is stored as a result of flowing the hot water through the inner tube due to the phase transition in PCM. This accumulated energy can be extracted from PCM as a result of flowing the cool water through the inner tube. For the enhancement of the thermal conduction coefficient, the PCM is doped with the nanocarbon particles having a thermal conductivity coefficient exceeding that of PCM by 4–5 orders of magnitude. The thermal balance of the accumulator is calculated on the basis of the solution of the time-dependent heat conduction equation by taking into account the heat absorbed and released as a result of the phase transition as well as the convection thermal exchange in the melted PCM. The calculation results determine the interconnection between the thermal conductivity of PCM and the characteristic time of thermal exchange between PCM and the working body. The calculations indicate that the characteristic thermal exchange time decreases as the thermal conduction coefficient enhances, so that the dependence becomes close to saturation at the thermal conductivity coefficient of about 5 W/m K. Such a coefficient can be reached by doping the paraffin-based PCM with a reduced graphene oxide at a content of about 2% (weight). Full article

(This article belongs to the Special Issue Composites for Energy Storage Applications, Volume II)

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11 pages, 1810 KiB

Open AccessCommunication

Photocatalytic Biohydrogen Production Using ZnO from Aqueous Glycerol Solution with Aid of Simultaneous Cu Deposition

by Mahmudul Hassan Suhag, Ikki Tateishi, Mai Furukawa, Hideyuki Katsumata, Aklima Khatun and Satoshi Kaneco

J. Compos. Sci. 2023, 7(9), 361; https://doi.org/10.3390/jcs7090361 - 29 Aug 2023

Viewed by 1485

Abstract

Biodiesel has gained a great deal of attention as a new sustainable energy alternative to petroleum-based fuels. The subsequent increased biodiesel production requires new utilization of glycerol, which is a byproduct of biodiesel synthesis. Photocatalytic biohydrogen generation using ZnO with the aid of [...] Read more.

Biodiesel has gained a great deal of attention as a new sustainable energy alternative to petroleum-based fuels. The subsequent increased biodiesel production requires new utilization of glycerol, which is a byproduct of biodiesel synthesis. Photocatalytic biohydrogen generation using ZnO with the aid of simultaneous deposition of copper from an aqueous biomass-derivative glycerol solution was investigated. The effects of the concentration of glycerol solution, Cu ion concentration, and reaction temperature on biohydrogen generation were investigated. The photocatalytic biohydrogen production rate increased as the concentration of aqueous glycerol solution increased, and the observed data could be fitted to the Langmuire–Hinshelwood kinetic models. The photocatalytic H₂ production efficiency with ZnO could be significantly improved by simultaneous Cu deposition. The photocatalytic biohydrogen production rate was dependent on temperature, and increased as the temperature increased. Under the optimal conditions, the photocatalytic H₂ production rate was 72 µmol h⁻¹ g⁻¹ from the aqueous biomass-derivative glycerol solution. Possible mechanisms for the oxidation of glycerol solution and photocatalytic hydrogen generation were proposed. Full article

(This article belongs to the Special Issue Composites for Energy Storage Applications, Volume II)

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18 pages, 5656 KiB

Open AccessArticle

Research on Improving Energy Storage Density and Efficiency of Dielectric Ceramic Ferroelectric Materials Based on BaTiO₃ Doping with Multiple Elements

by Jiaxuan Sun and Yuanzhe Li

J. Compos. Sci. 2023, 7(6), 233; https://doi.org/10.3390/jcs7060233 - 05 Jun 2023

Cited by 6 | Viewed by 1431

Abstract

In order to promote the research of green energy in the situation of increasingly serious environmental pollution, dielectric ceramic energy storage materials, which have the advantages of an extremely fast charge and discharge cycle, high durability, and have a broad use in new [...] Read more.

In order to promote the research of green energy in the situation of increasingly serious environmental pollution, dielectric ceramic energy storage materials, which have the advantages of an extremely fast charge and discharge cycle, high durability, and have a broad use in new energy vehicles and pulse power, are being studied. However, the energy storage density of ordinary dielectric ceramic ferroelectric materials is low, so, in this paper, we have divided eight components based on BaTiO₃ (BT). Through the traditional solid phase sintering method, AB positions were replaced with various elements of different proportions to improve their energy storage density and the energy storage efficiency of BT-based ferroelectric materials. In this paper, we studied the results of XRD, Raman, ferroelectric, dielectric, and impedance tests of doped samples, and the best components were determined. The (1−x)BT−xBi(

{M g}_{1 / 3} {Z n}_{1 / 3} {T a}_{1 / 6} {N b}_{1 / 6}

)O₃ series of ceramics are made by the incorporation of five elements, Bi³⁺, Mg²⁺, Zn²⁺, Ta⁵⁺, and Nb⁵⁺. With the rising electric hysteresis loop of the doping amount x thin, the saturation polarization strength and residual polarization strength decrease, and the energy storage density rises first and then decreases. The dielectric characteristic after x = 0.08 showed a flat dielectric peak, indicating that the ferroelectric relaxation had been formed. The energy storage density and efficiency of the best component x = 0.12 reached 1.75 J/cm³ and 75%, respectively, and the Curie temperature was about −20 °C, so it has the potential to be used at room temperature. Full article

(This article belongs to the Special Issue Composites for Energy Storage Applications, Volume II)

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15 pages, 4160 KiB

Open AccessArticle

Simple Mixed-Acid-Treated Carbon Fiber Electrodes with Oxygen-Containing Functional Groups for Flexible Supercapacitors

by Yongbo Wang, Hui Li, Bowen Cui, Xiaodan Xu and Yanxiang Wang

J. Compos. Sci. 2023, 7(6), 231; https://doi.org/10.3390/jcs7060231 - 05 Jun 2023

Cited by 3 | Viewed by 1249

Abstract

Flexible supercapacitors are demanded for energy storage of wearable electronics. In this paper, a simple strategy for preparing flexible carbon fibers (CFs) with good energy storage capacity using a mixed acid treatment process is reported. When the volume ratio of concentrated sulfuric acid [...] Read more.

Flexible supercapacitors are demanded for energy storage of wearable electronics. In this paper, a simple strategy for preparing flexible carbon fibers (CFs) with good energy storage capacity using a mixed acid treatment process is reported. When the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1, the carbon fiber electrodes have the best electrochemical performance with a high capacitance of 27.83 F g⁻¹ at 15 mA g⁻¹ and extremely high capacitance retention of 79.9% after 500 cycles at 100 mA g⁻¹. Furthermore, their energy density can reach 3.86 Wh kg⁻¹ with a power density of 7.5 W kg⁻¹. Such an excellent electrochemical performance of carbon fiber electrodes is attributed to their surface rich oxygen-containing functional groups, rough surface, and a certain number of graphene quantum dots (GQDs). Importantly, the all-solid-state flexible supercapacitor performs excellent bending stability performance with a capacitance retention of almost 100% after 500 times of bending at 180°, showing good prospects and applications in the field of flexible energy storage devices. Full article

(This article belongs to the Special Issue Composites for Energy Storage Applications, Volume II)

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12 pages, 3214 KiB

Open AccessArticle

Porous NiMoO₄-NrGO as a Battery-Like Electrode Material for Aqueous Hybrid Supercapacitors

by Shahrzad Arshadi-Rastabi, Rasoul Sarraf-Mamoory, Ghadir Razaz, Nicklas Blomquist, Jonas Örtegren and Håkan Olin

J. Compos. Sci. 2023, 7(6), 217; https://doi.org/10.3390/jcs7060217 - 26 May 2023

Cited by 1 | Viewed by 1056

Abstract

Recently, much research has investigated nanocomposites and their properties for the development of energy storage systems. Supercapacitor performance is usually enhanced by the use of porous electrode structures, which produce a larger surface area for reaction. In this work, a biocompatible polymer of [...] Read more.

Recently, much research has investigated nanocomposites and their properties for the development of energy storage systems. Supercapacitor performance is usually enhanced by the use of porous electrode structures, which produce a larger surface area for reaction. In this work, a biocompatible polymer of starch medium was used to create the porous nanostructure. Two powders, i.e., Nickel molybdate/reduced graphene oxide (NiMoO₄-rGO) and Nickel molybdate/nitrogen-doped reduced graphene oxide (NiMoO₄-NrGO), were synthesized using the deposition method in a medium containing starch, nickel nitrate salts, sodium molybdate, and graphene oxide powder. In terms of electrochemical performance, the NiMoO₄-NrGO electrode displayed a higher specific capacitance, i.e., 932 Fg⁻¹ (466 Cg⁻¹), than the NiMoO₄-rGO electrode, i.e., 884 Fg⁻¹ (442 Cg⁻¹), at a current density of 1 Ag⁻¹. In fact, graphene oxide sheets could lose more oxygen groups in the presence of ammonia, resulting in increased electrical conductivity. For the asymmetric supercapacitor of NiMoO₄-NrGO//AC, the specific capacitance at 1 Ag⁻¹, energy density, and power density were 101.2 Fg⁻¹ (111.32 Cg⁻¹), 17 Wh kg⁻¹, and 174.4 kW kg⁻¹, respectively. In addition, this supercapacitor material displayed a good cycling stability of over 82%. Full article

(This article belongs to the Special Issue Composites for Energy Storage Applications, Volume II)

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11 pages, 2517 KiB

Open AccessArticle

Fast Charging of a Thermal Accumulator Based on Paraffin with the Addition of 0.3 wt. % rGO

by Sergey A. Baskakov, Yulia V. Baskakova, Eugene N. Kabachkov, Elizaveta V. Dvoretskaya, Victor N. Vasilets, Zhi Li and Yury M. Shulga

J. Compos. Sci. 2023, 7(5), 193; https://doi.org/10.3390/jcs7050193 - 08 May 2023

Viewed by 1334

Abstract

The composite of paraffin with reduced graphene oxide (paraffin/rGO) was obtained at 70 °C by the mechanical mixing of the components followed by ultrasonic dispersion. The introduction of only 0.3 wt.% rGO stained the paraffin black. It has been shown that thermal batteries [...] Read more.

The composite of paraffin with reduced graphene oxide (paraffin/rGO) was obtained at 70 °C by the mechanical mixing of the components followed by ultrasonic dispersion. The introduction of only 0.3 wt.% rGO stained the paraffin black. It has been shown that thermal batteries made from 160 grams of pure paraffin and 160 grams of the composite are equally slow at charging when placed in boiling water. However, two minutes of microwave heating increases the temperature of the pure paraffin battery to only 32 °C, while the temperature of the paraffin/rGO composite battery rises to 74 °C, which is above the paraffin solid–liquid phase transition temperature. Full article

(This article belongs to the Special Issue Composites for Energy Storage Applications, Volume II)

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11 pages, 3366 KiB

Open AccessCommunication

Application of Rh/TiO₂ Nanotube Array in Photocatalytic Hydrogen Production from Formic Acid Solution

by Mahmudul Hassan Suhag, Ikki Tateishi, Mai Furukawa, Hideyuki Katsumata, Aklima Khatun and Satoshi Kaneco

J. Compos. Sci. 2022, 6(11), 327; https://doi.org/10.3390/jcs6110327 - 02 Nov 2022

Cited by 6 | Viewed by 1575

Abstract

Titanium dioxide nanotubes (TNTs) were fabricated via electrochemical anodization process. Photocatalytic hydrogen generation from formic acid solution was investigated using TNTs with simultaneous Rh deposition. The effects of calcination temperature and time for TNTs on hydrogen generation were studied. The maximum hydrogen generation [...] Read more.

Titanium dioxide nanotubes (TNTs) were fabricated via electrochemical anodization process. Photocatalytic hydrogen generation from formic acid solution was investigated using TNTs with simultaneous Rh deposition. The effects of calcination temperature and time for TNTs on hydrogen generation were studied. The maximum hydrogen generation (54 µmol) was observed when using TNTs with a 500 °C calcination temperature and 10 h calcination time under 5 h of black light (352 nm) irradiation. The reusability tests indicated that the TNTs with photodeposited Rh metal (Rh/TNT) had excellent stability up to the fifth cycle for hydrogen generation from formic acid solution. The TNTs were characterized before and after photodeposition of Rh metal via X-ray powder diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL), and diffuse reflectance spectroscopy (DRS). XRD revealed the presence of optimal anatase–rutile phase ratios in TNTs at 500 °C and 300 °C calcination temperatures. XRD and SEM revealed the deposition of Rh metal on the TNT surface at 300 °C and 500 °C calcination temperatures. It was observed that the light absorption ability of TNTs calcined at 500 °C was greater than that of TNTs calcined at 300 °C. The reaction mechanisms for the formation of TNTs and photocatalytic hydrogen production from formic acid solutions by TNTs with simultaneous Rh deposition were also proposed. Full article

(This article belongs to the Special Issue Composites for Energy Storage Applications, Volume II)

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14 pages, 5212 KiB

Open AccessArticle

Dielectric Properties and Energy Storage of Hybrid/Boron Nitride/Titanium Carbide/Epoxy Nanocomposites

by Chryssanthi Blatsi, Anastasios C. Patsidis and Georgios C. Psarras

J. Compos. Sci. 2022, 6(9), 259; https://doi.org/10.3390/jcs6090259 - 07 Sep 2022

Cited by 3 | Viewed by 1468

Abstract

In this study, hybrid boron nitride (BN)/titanium carbide (TiC)/epoxy resin composite nanodielectrics were manufactured and characterized. Their morphological and structural characterization was conducted via scanning electron microscopy (SEM) images and X-ray diffraction (XRD) patterns, whereas the dielectric behavior was studied by means of [...] Read more.

In this study, hybrid boron nitride (BN)/titanium carbide (TiC)/epoxy resin composite nanodielectrics were manufactured and characterized. Their morphological and structural characterization was conducted via scanning electron microscopy (SEM) images and X-ray diffraction (XRD) patterns, whereas the dielectric behavior was studied by means of broadband dielectric spectroscopy (BDS). Dielectric measurements were carried out from 30 to 160 °C and from 10⁻¹ to 10⁶ Hz, respectively. The dielectric results revealed the existence of three relaxation mechanisms, which from high to low frequencies, at constant temperature, refer to re-arrangement of polar-side groups (β-relaxation) of the macromolecular chains, transition from glassy to rubbery state of the amorphous polymer matrix (α-relaxation) and interfacial polarization (IP) between the polymer matrix and the nanofillers. It was found that, in general, nanodielectrics exhibited enhanced dielectric properties mainly due to the high dielectric permittivity of TiC and the fine dispersion of the fillers, confirmed also by the SEM images. Dynamic analysis conducted for the α-relaxation showed a Vogel–Fulcher–Tammann dependence on temperature. The ability of energy storing of the nanocomposites was examined via their energy density. Optimum performance is exhibited by the 5 phr TiC/1 phr BN/epoxy nanocomposite, reaching an energy storing ability nine times greater than the unfilled matrix. Full article

(This article belongs to the Special Issue Composites for Energy Storage Applications, Volume II)

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Review

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17 pages, 7237 KiB

Open AccessReview

Treatment of Biowaste for Electrodes in Energy Storage Applications: A Brief Review

by Samuel Ebenezer Kayode and Francisco J. González

J. Compos. Sci. 2023, 7(3), 127; https://doi.org/10.3390/jcs7030127 - 20 Mar 2023

Cited by 1 | Viewed by 2020

Abstract

Proper and innovative waste management methods still pose a major concern in our present world. Continuous accumulation of biowaste from bio-processing industries, household, organic residues and so on makes the environment polluted and endangers the health of man and other animals. The common [...] Read more.

Proper and innovative waste management methods still pose a major concern in our present world. Continuous accumulation of biowaste from bio-processing industries, household, organic residues and so on makes the environment polluted and endangers the health of man and other animals. The common waste management methods which include direct dumping into water bodies, open-air combustion, and as land fillers are obsolete and are the major causes of environmental pollution. Conversion of biowastes into valuable materials aids proper waste management, and helps to attain a cleaner environment, in addition to the fact that wastes are turned into wealth. Biowastes are rich in carbon and can serve as excellent precursors for the synthesis of important carbon materials such as activated carbon, graphene, carbon nanotubes etc. Three important methods of converting biowastes into carbon materials are discussed in this review. The electrochemical, adsorption, and electrocatalytic properties of the materials and the applications in electrochemical energy storage devices are also discussed in brief. This review focuses on the synthesis of carbon materials from biowaste residues and their use in developing electrode materials for batteries and supercapacitors. Future perspectives on the need to exploit greener technology for the conversion of biowastes into important carbon materials should be considered. Full article

(This article belongs to the Special Issue Composites for Energy Storage Applications, Volume II)

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