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Proton exchange membranes (PEMs) with superior characteristics are needed to advance fuel cell technology. Nafion, the most used PEM in direct methanol fuel cells (DMFCs), has excellent proton conductivity but suffers from high methanol permeability and long-term performance degradation. Thus, this study aimed to create a healable PEM with improved durability and methanol barrier properties by combining sulfonated poly(ether ether ketone) (SPEEK) and poly-vinyl alcohol (PVA). The effect of changing the N,N-dimethylacetamide (DMAc) solvent concentration during membrane casting was investigated. Lower DMAc concentrations improved water absorption and, thus, membrane proton conductivity, but methanol permeability increased correspondingly. For the best trade-off between these two characteristics, the blend membrane with a 10 wt% DMAc solvent (SP10) exhibited the highest selectivity. SP10 also showed a remarkable self-healing capacity by regaining 88% of its pre-damage methanol-blocking efficiency. The ability to self-heal decreased with the increasing solvent concentration because of the increased crosslinking density and structure compactness, which reduced chain mobility. Optimizing the solvent concentration during membrane preparation is therefore an important factor in improving membrane performance in DMFCs. With its exceptional methanol barrier and self-healing characteristics, the pioneering SPEEK/PVA blend membrane may contribute to efficient and durable fuel cell systems. [ABSTRACT FROM AUTHOR]

Self‐healing proton‐exchange membranes (PEMs) made of poly(vinyl alcohol) (PVA) and Nafion were synthesized using the freeze‐thaw method. Since PVA is more selective towards water than methanol, the blend membrane successfully reduced methanol permeability and improved selectivity compared to the recast Nafion membrane. The addition of PVA also helped the membrane self‐heal by promoting the formation of hydrogen bonds. In contrast to the pristine Nafion, which exhibited even more severe methanol crossover after being damaged than before, the Nafion‐PVA membrane underwent a self‐healing process and regained much of its methanol barrier function. These advantageous characteristics of the Nafion‐PVA membrane suggest its potential use in direct methanol fuel cells (DMFCs). [ABSTRACT FROM AUTHOR]

Getting the direct methanol fuel cell (DMFC) closer to mass production requires the creation of a high-performance and long-lasting proton exchange membrane (PEM). In this study, self-healable PEMs, Nafion-poly(vinyl alcohol)/phosphotungstic acid (N-PVA/HPW), were prepared through a simple freezing–thawing method. HPW acted as proton conductors, while PVA with reversible hydrogen bonds contributed to the self-repair ability of the membrane. The proton conductivity of the N-PVA/HPW membranes was found to be comparable to that of the pristine Nafion membrane owing to the additional proton-conducting sites and improved water retention provided by the HPW. Along with this, the packed structure of the mixed-matrix membranes led to a lower methanol permeability in all the N-PVA/HPW membranes compared to recast Nafion. As a result, N-PVA/HPW20 membrane with acceptable proton conductivity (0.062 S cm−1) and reduced methanol permeability (2.75 × 10−6 cm2 s−1) achieved the highest selectivity, where selectivity is a well-known indicator of a membrane's suitability for use in DMFC. The N-PVA/HPW20 membrane successfully recorded a peak power density of 2.7 mW cm−2, which is 10.7% higher than the value of recast Nafion. Another highlight of these mixed-matrix membranes is their ability to recover up to 93% of their initial methanol barrier properties after being damaged. This fascinating self-healing property of the membrane is believed to have the potential to extend the service life of DMFC. [ABSTRACT FROM AUTHOR]

Nafion based proton exchange membrane (PEM) has long been used as conventional PEM in direct methanol fuel cell (DMFC) industry. However, the high cost of Nafion membrane and other drawbacks like high methanol crossover hinder the advancement of this industry. This study aims to develop a low cost membrane using sulfonated poly ether ether ketone (SPEEK) polymer. Silica and silicotungstic acid (SiWA) were incorporated into the membrane matrix using solution casting method. The optimum loading of the additives was tuned and it is discovered that the SPEEK membrane containing 10 wt% of silica and 5 wt% of SiWA has the best performance due to its high proton conductivity and moderately low methanol permeability. The performance of the membrane can further be enhanced by adding (3-aminopropyl)triethoxysilane (APTES) and carbonyldiimidazole (CDI) as coupling agents. Inclusion of APTES and CDI in SPEEK could not only improve the compatibility between organic SPEEK and inorganic additives, but also improve the homogeneity and dispersity of the additives. As a result, the resultant membrane with a better dimensional stability achieves high selectivity (10.60 × 104 S.s/cm3) up to 6.5 times more than pristine SPEEK membrane and 1.3 times higher than the commercial Nafion 117 membrane. • SPEEK/SiO 2 -SiWA was produced with APTES as coupling agent and CDI as promoter. • SPEEK1-AC achieved selectivity of 6.5 times higher than pristine SPEEK. • Silica-supported SiWA increased the proton conductivity of SPEEK membrane. • Improvement in homogeneity between organic SPEEK and inorganic additives. [ABSTRACT FROM AUTHOR]

Abstract Fuel cells and solar energy are promising candidates for electricity generation. It is forecast that fuel cells and solar power systems will play an important role in reducing the greenhouse gas footprint and replacing fossil fuels. Therefore, the limitations of fuel cells and solar power systems, such as low efficiency, high cost, and low reliability, must be addressed appropriately to enable their full potentials. Metal foam is a new class of material that has gained immense attention due to its excellent properties suitable for a wide range of applications. Its unique characteristics distinguish it from typical solid metals. The properties of metal foam can be modified during the fabrication stage by manipulating its physical structure. The goal of this paper is to review the application of metal foam in fuel cells and solar power systems. Besides, the performance of metal foam in fuel cells and solar systems is also discussed. Metal foam has been applied to the electrodes, gas diffusion layer and flow field of fuel cells to enhance performance, especially in regard to current density and flow distribution. Furthermore, metal foam is a heat exchanger for the solar energy harvesting system to improve its efficiency. Superior performances in experimental testing allows the possibility of commercialization of metal foam products in the renewable energy field. Highlights • This article reviews the past research on metal foam in fuel cell and solar power systems. • Metal foam applications on bipolar plates, electrodes and the gas diffusion layer in a fuel cell. • Metal foam as a thermal management system in solar power systems. • Barriers and future perspectives of metal foam applications in fuel cells and solar power systems. [ABSTRACT FROM AUTHOR]

Thermal management system is crucial for a Lithium-ion battery pack as cycle life, driving range of electric vehicle, usable capacity and safety are heavily dependent on the operating temperature. Optimum operating temperature of Lithium-ion battery pack is about 25–40 °C. Power availability of the battery pack may differ according to the operating temperature. Although air cooling is the simplest and cheapest cooling solution, the cooling capacity is still limited by the low specific heat capacity. This will cause large variation of temperature of cells across the battery pack. In this study, mist cooling is proposed for battery pack thermal management system. Experiments and numerical simulations are conducted to investigate the thermal performance of conventional dry air cooling and mist cooling. Simulation results are then validated with the experimental data. The simulation results show that mist cooling can offer lower and more uniform temperature distribution compared to dry air cooling. Mist cooling with mass flow rate of 5 gs −1 and 3% mist loading fraction is sufficient to ensure the surface temperature of the battery module maintained to below 40 °C. Therefore, mist cooling is a potential solution for the thermal management system of Lithium-ion battery pack. [ABSTRACT FROM AUTHOR]

• Performance of aluminium-air battery is investigated. • Polypropylene pad helps to reduce the corrosion on aluminium anode. • Dual electrolyte system performed better than single electrolyte system. • Reducing corrosion helps to improve the performance of the aluminium-air battery. • EIS and Tafel analysis are used to evaluate the corrosion behaviour. Battery energy storage systems are widely used in modern electronic devices and electric vehicles. Metal-air batteries are among the electrochemical energy storage systems that provide high energy density and eco-friendly solutions. Aluminium-air batteries hold a significant advantage with their high theoretical specific energy and have the potential to replace lithium-ion batteries in the future. In this study, the electrical performance and corrosion inhibition characteristics of a polypropylene-based single and dual electrolyte system for aluminium-air batteries were investigated experimentally. The study revealed that a polypropylene separator can reduce the corrosion of the aqueous aluminium-air battery system by up to 40 %, improving the anodic utilization efficiency to 93 %. Electrochemical impedance spectroscopy analysis was used to characterize the single and dual electrolyte aluminium-air battery and propose equivalent circuit models. Compared to 1 M KOH electrolyte in a single electrolyte system, the solution resistance of a dual electrolyte aluminium-air battery was reduced by about 40 % using a combination of 1 M of KOH electrolyte and 1 M of H 2 SO 4. This reduction is attributed to the enhancement of the oxygen reduction reaction at the air cathode. A high KOH electrolyte concentration will increase the corrosion of the aluminium anode but can improve the battery's voltage. At 3 M KOH electrolyte, the plateau voltage is recorded at about 0.6 V while the discharge time reached 44 min when using aluminium alloy 6061 as the anode. The battery model developed in this work provides a fundamental basis for predicting the performance of aluminium-air battery packs. [ABSTRACT FROM AUTHOR]

Summary: Concentrated photovoltaic cell (CPV) is a solar energy harvesting device that converts solar energy into electrical energy. However, the performance and efficiency of the CPV are heavily dependent on the temperature. Besides, nonuniformity of temperature distribution on the CPV will lead to thermal aging and affects the cycle life. Hence, an effective cooling system is required to remove excess heat generated to ensure that the CPV operates at optimum operating temperature with minimum variation of temperature. Metal foam is a new class of material that possesses huge potential for thermal management. In this study, a functionally graded metal foam is proposed for the CPV thermal management system. Computational thermal fluid dynamic analysis is conducted to investigate the effect of porosity and pore density on the flow field and thermal performance of the aluminum foam heat sink. The investigation results revealed that 10 PPI functionally graded aluminum foam heat sink with two stages of porosity gradient 0.794 and 0.682 produced the lowest pressure drop and highest thermal performance. Temperature difference of 3.9°C was achieved for a solar cell with total heat generation of 900 W under water mass flow rate of 20 gs−1. [ABSTRACT FROM AUTHOR]

The scale-down trend increases the chips’ density and the high power handling capability generates unnecessary heat which can disrupt the reliability of the electronic devices. Therefore, various types of cooling solution have been proposed to enhance heat dissipation from the electronic devices. One of the solution is using inexpensive straight-channel heat sink. However, the presence of large temperature gradient between the upstream and downstream in the straight-channel can shorten the life span of the device and subsequently reduce the reliability. In this study, a novel segmented micro-channel is introduced to improve the thermal performance of the straight-channel heat sink. Computational fluid dynamic analysis are performed to investigate the performance of the micro-channel heat sink. The bottom of the heat sink is subjected to a constant heat flux condition and water is used as a coolant. Following that, Taguchi-grey method is applied to optimize the design of the segmented micro-channel. The effect of fin width, fin length, fin transverse distance, number of segments, channel width and mass flow rate on the specific performance, variation of temperature and pressure drop are investigated. The results indicate that a three segments of segmented micro-channel, fin width-1 mm, fin length-2 mm, fin transverse distance-5 mm and channel width-1 mm have successfully enhance the heat transfer performance with minimum pressure drop. It is also found that the optimized micro-channel heat sink is able to cool the chip with heat flux of 800 W to 56.6 °C and pumping power of 0.13 W using 15 gs −1 of water. [ABSTRACT FROM AUTHOR]

Abstract: For the first time, thin‐film nanocomposite (TFN) nanofiltration membranes incorporated with graphene oxide (GO) were synthesized and used to separate phosphorus from water sources of varying properties. Prior to phosphorus removal tests, two different TFN membranes and one control thin‐film composite (TFC) membrane were subject to standard characterization in order to determine pure water flux, salt rejection, surface hydrophilicity, pore size, and porosity. By incorporation of GO, the water flux of composite membranes could be significantly improved with minimum decrease in salt rejection, mainly due to improved surface hydrophilicity coupled with enlarged pore size and overall structural porosity. Especially the TFN‐1 membrane was found to perform better owing to its good combination of water flux and solute rejection, higher water flux, and comparable phosphorus rejection in comparison to the TFC membrane. [ABSTRACT FROM AUTHOR]

Air pollution is a widely discussed topic amongst the academic and industrial spheres as it can bring adverse effects to human health and economic loss. As humans spend most of their time at the office and at home, good indoor air quality with enriched oxygen concentration is particularly important. In this study, polysulfone (PSF) hollow fiber membranes fabricated by dry-jet wet phase inversion method were coated by a layer of polydimethylsiloxane (PDMS) or poly(ether block amide) (PEBAX) at different concentrations and used to evaluate their performance in gas separation for oxygen enrichment. The surface-coated membranes were characterized using SEM and EDX to determine the coating layer thickness and surface chemical properties, respectively. Results from the gas permeation study revealed that the PSF membrane coated with PDMS offered higher permeance and selectivity compared to the membrane coated with PEBAX. The best performing PDMS-coated membrane demonstrated oxygen and nitrogen gas permeance of 18.31 and 4.01 GPU, respectively with oxygen/nitrogen selectivity of 4.56. Meanwhile, the PEBAX-coated membrane only showed 12.23 and 3.11 GPU for oxygen and nitrogen gas, respectively with a selectivity of 3.94. It can be concluded the PDMS coating is more promising for PSF hollow fiber membrane compared to the PEBAX coating for the oxygen enrichment process. [ABSTRACT FROM AUTHOR]