Advanced Energy Conversion Materials

Chemical Synthesis of Gadolinium Oxide Mediated Electrodes for Supercapacitor Application: Effect of Contact Angle

Dilip. K. Sahoo, Vaibhav. D. Patake — Tue, 25 Jun 2024 00:00:00 +0800

Thin films of gadolinium oxide and gadolinium oxide-based electrodes were deposited on a stainless steel substrate employing the successive ionic layer adsorption and reaction (SILAR) method. The X-ray diffraction (XRD) study showed the formation of amorphous material on a substrate and the composition of the material was confirmed by the energy dispersive study (EDS). The water contact angle measurement showed the super-hydrophobic surface of the deposited material. The morphology showed gadolinium oxide resembled finger chip-type morphology while fungus-like and crocodile-back-like morphologies were observed for gadolinium oxide-copper oxide and gadolinium oxide-activated carbon (AC) composite correspondingly. The cyclic voltammetric measurement for supercapacitor application was carried out in a 0.2 M non-aqueous KCl electrolyte. It designated that the gadolinium oxide electrode with 94.22° contact angle had 106.25 F·g^-1 specific capacitance. The super capacitance of electrodes was found to be depending on the contact angle concerning composition and morphology. The gadolinium oxide-copper oxide having 156.70° water contact angle possessed a specific capacitance of 52.66 F·g^-1 while the gadolinium oxide-AC composite electrode carried 76.20 F·g^-1 specific capacitance for 157.49° contact angle.

Heat Transfer Optimization of Series-Wound Space Radiators

XueTao Cheng — Fri, 24 May 2024 00:00:00 +0800

In spacecraft, the analysis and optimization of space radiators are very important for improving the performance of thermal control system. In this paper, a physical and mathematical model for heat transfer optimization of series-wound space radiators is set up. With the model, a system with five space radiators is optimized to obtain the optimal distributions of total thermal conductance that lead to the maximum heat transfer rate for fixed inlet temperature of the fluid and the minimum inlet temperature of the fluid for fixed heat transfer rate, respectively. The influences of the operation parameters on the optimization results are discussed. When the inlet temperature or the heat transfer rate is fixed, it is shown that the value of total thermal conductance has little effect on the optimal distribution. When the total thermal conductance is fixed, the results show that neither the inlet temperature of the fluid nor the heat transfer rate is an important factor that affects the optimization results. Furthermore, the applicability of the entropy generation minimization and the entransy theory to the analysis of the system is also discussed. Both the theoretical analysis and the numerical results show that the entransy theory is always applicable to the optimization problems, while the entropy generation minimization is not.

Performance Optimisation of Proton Exchange Membrane Fuel Cell by Modifying Anode Flow Field Design

Tue, 25 Jun 2024 00:00:00 +0800

The study addresses the problem of optimizing the performance of proton exchange membrane (PEM) fuel cells, which are crucial for clean and efficient energy production. Traditional internal combustion (I.C.) engines are less efficient, with efficiencies below 35%, and contribute significantly to pollution. In contrast, PEM fuel cells have the potential for higher efficiencies and cleaner operation. This research is important as it seeks to enhance the efficiency of PEM fuel cells, thereby promoting sustainable energy solutions. The methods used in this study involved designing a 12 W capacity PEM fuel cell with both conventional and modified anode flow field designs. Performance optimization was carried out by comparing these designs under various operational conditions, measuring overall voltage efficiencies. The important results showed that the modified anode flow field design achieved an overall voltage efficiency of 45.52%, compared to 42.43% for the conventional design. This improvement of 7.2% in efficiency is significant and highlights the benefits of optimizing the anode flow field in PEM fuel cells. From these results, it can be concluded that modifying the anode flow field can lead to substantial improvements in fuel cell performance. The novelty of this work lies in its detailed experimental comparison and quantitative evidence of the enhanced performance of the modified anode flow field design, advancing previous efforts in the literature by providing clear and significant efficiency gains. This study goes beyond prior research by demonstrating a practical approach to increasing the efficiency of PEM fuel cells, which is essential for their broader application in clean energy technologies.

Enhanced Dielectric Response in PVDF-HFP-GO-Ta₂O₅ Nanocom- posites: Synthesis and Characterization

Thu, 23 May 2024 00:00:00 +0800

A solution-casting approach was employed to synthesize polymer composites by incorporating tantalum pentoxide (Ta₂O₅) and graphene oxide (GO) into a PVDF-HFP (polyvinylidene fluoride-co-hexafluoropropylene) matrix. We conducted a thorough examination of the structure, morphology, and dielectric characteristics of these composites using X-ray diffraction, scanning electron microscopy, and impedance analysis. The current research showed that the composites reinforced with Ta₂O₅ in the GO-PVDF-HFP material had a consistent and noticeable look inside the PVDF-HFP matrix, suggesting effective integration. Furthermore, the relationship between the dielectric and electrical characteristics of the PVDF-HFP-GO-Ta₂O₅ composites at different weight percentages of Ta₂O₅ and frequencies has been investigated. This study revealed that the PVDF-HFP-GO-Ta₂O₅ composite films exhibited a high dielectric constant of 85, with negligible dielectric loss (< 1.5) and excellent AC conductivity (1 × 10^-3) at 102 Hz. This suggests their potential appropriateness for energy storage applications. It may offer a simple and direct way to process PVDF-HFP-GO-Ta₂O₅ nanocomposite films that have superior dielectric properties. This might enable them to be highly promising candidates for a wide range of energy storage applications.

Insight on Electronic and Thermal Behaviors of Conductive MXene- Ti₃C₂T_x-Based Polymeric Hybrid Material and Their Capacitive Energy Storage Applications: A Review

Fri, 24 May 2024 00:00:00 +0800

The increasing research focus on two-dimensional carbides known as MXenes has garnered significant attention due to their effective capacitive properties, leading to their application in energy storage devices. Recently, the emerging technique of incorporating MXene into polymer matrices to form hybrid nanoclusters has significantlycontributed to modern nanoarchitectonics. However, there is no available review that elaborately discusses the thermal and electrical behaviors of these hybrid nanoclusters. This paper provides detailed insights into the thermal and electrical properties of conductive MXene-Ti₃C₂T_x-based polymeric hybrid nanoclusters. Further elucidation is given to their applications in energy storage devices, with a special interest in MXene-polypyrrole, MXene-polyaniline, and MXene-poly (3, 4 ethylenedioxythiopene) polystyrene sulfonate nanoclusters. Additionally, to address the challenges associated with electron transport within the atoms of the nanoclusters, we concluded by offering suggestions on a potential approach to alleviate these challenges and enhance their electrical performance for future applications.