Recent Developments in Supercapacitor Electrodes: A Mini Review

The use of nonrenewable fossil fuels for energy has increased in recent decades, posing a serious threat to human life. As a result, it is critical to build environmentally friendly and low-cost reliable and renewable energy storage solutions. The supercapacitor is a future energy device because of its higher power density and outstanding cyclic stability with a quick charge and discharge process. Supercapacitors, on the other hand, have a lower energy density than regular batteries. It is well known that the electrochemical characteristic of supercapacitors is strongly dependent on electrode materials. The current review highlights advance in the TMOs for supercapacitor electrodes. In addition, the newly discovered hybrid/pseudo-supercapacitors have been discussed. Metal oxides that are employed as electrode materials are the focus of this study. The discovery of nanostructured electrode materials continues to be a major focus of supercapacitor research. To create high-performance electrode materials from a morphological standpoint, various efforts have been attempted. Lastly, we analyze the supercapacitor’s evolving trend and our perspective for the future generations of supercapacitors.

Modeling of Hierarchical Cathodes for Li-Air Batteries with Improved Discharge Capacity

The non-aqueous Li-air battery is considered to be a promising energy source for electric-vehicles owing to its ultrahigh theoretical power density. However, its commercialization is limited by the attained lower energy density value, which is mainly due to pore blockage and passivation which requires a more strategic design of the cathode. In this work, we have developed and validated a detailed one-dimensional continuum model of Li-Air battery that helps in examining the potential of hierarchical cathodes in guiding and enhancing the efficiency of ions transport and discharge product formation inside microstructures. The obtained results reveal the importance of reducing the tortuosity (shorten the path of oxygen transport) and increasing porosity at the airside of the hierarchical cathode, which improved discharge capacity at approximately 20.9 and 56%, respectively. The improved capacity is due to enhanced effective oxygen transport, impregnation of electrolyte, alignment of pores, and formation of permeable and low crystalline aggregates of Li2O2. Hence, strategies considering these insights can help in the design and fabrication of non-aqueous Li-air batteries with enhanced power density and capacity.

Recent Progress and Trends in the Development of Microbial Biofuels from Solid Waste—A Review

This review covers the recent progress in the design and application of microbial biofuels, assessing the advancement of genetic engineering undertakings and their marketability, and lignocellulosic biomass pretreatment issues. Municipal solid waste (MSW) is a promising sustainable biofuel feedstock due to its high content of lignocellulosic fiber. In this review, we compared the production of fatty alcohols, alkanes, and n-butanol from residual biogenic waste and the environmental/economic parameters to that of conventional biofuels. New synthetic biology tools can be used to engineer fermentation pathways within micro-organisms to produce long-chain alcohols, isoprenoids, long-chain fatty acids, and esters, along with alkanes, as substitutes to petroleum-derived fuels. Biotechnological advances have struggled to address problems with bioethanol, such as lower energy density compared to gasoline and high corrosive and hygroscopic qualities that restrict its application in present infrastructure. Biofuels derived from the organic fraction of municipal solid waste (OFMSW) may have less environmental impacts compared to traditional fuel production, with the added benefit of lower production costs. Unfortunately, current advanced biofuel production suffers low production rates, which hinders commercial scaling-up efforts. Microbial-produced biofuels can address low productivity while increasing the spectrum of produced bioenergy molecules.

Experimental Characterization of Phase Change Materials for Refrigeration Processes

Latent heat storage units for refrigeration processes are promising as alternatives to water/glycol-based storage due to their significantly higher energy densities, which would lead to more compact and potentially more cost-effective storages. In this study, important thermophysical properties of five phase change material (PCM) candidates are determined in the temperature range between −22 and −35 °C and their compatibility with relevant metals and polymers is investigated. The goal is to complement existing scattered information in literature and to apply a consistent testing methodology to all PCMs, to enable a more reliable comparison between them. More specifically, the enthalpy of fusion, melting point, density, compatibility with aluminum, copper, polyethylene (PE), polypropylene (PP), neoprene and butyl rubber, are experimentally determined for 1-heptanol, n-decane, propionic acid, NaCl/water mixtures, and Al(NO3)3/water mixtures. The results of the investigations reveal individual strengths and weaknesses of the five candidates. Further, 23.3 wt.% NaCl in water stands out for its very high volumetric energy density and n-decane follows with a lower energy density but better compatibility with surrounding materials and supercooling performance. The importance of using consistent methodologies to determine thermophysical properties when the goal is to compare PCM performance is highlighted.

FTIR and dielectric relaxation analysis for PVC-Pb3O4 polymer nanocomposites

This work studies the FTIR as well as dielectric characteristics of the PVC-Pb3O4 nanocomposite films. FTIR analysis shows the small shift in 650, 845 and 1732 cm− 1 band positions as a confirmation of interaction between Pb3O4 nanoparticles with PVC polymer matrix. The real permittivity (ε1) decreases with increasing frequency for all samples with the appearance of a relaxation peak at high temperatures. The dielectric loss data (ε2) of the PVC-Pb3O4 nanocomposite revealed a shift of the dielectric absorption peak towards high frequency with increasing the temperature. The activation energy values for both α and β relaxations almost decreased with increasing the Pb3O4 concentration. The energy density of samples containing Pb3O4 has a lower energy density than the pure PVC polymer film. The exponent s often increased with increasing the temperature, and this behavior is consistent with overlapping large-polaron tunneling model. The DC activation energy decreased when the percentage of Pb3O4 increased to 3.0 wt% and then increased at 4.0 wt%. Additionally, a convergence between these values and the activation energies of α and β relaxations observed, which is indicates that the same type of charge carriers participate in the processes.

Transient Structural Analysis of a Skid Mounted on a Hydrogen Tube Trailer under Shock and Vibration Induced by Road Irregularities

Due to environmental pollution and depletion of fossil fuels, hydrogen is becoming an increasingly practical, clean and environmentally friendly option for transportation and energy storage among all green alternative energy sources introduced. Hydrogen storage and delivery is expensive because of the lower energy density per unit volume as compared with conventional fossil fuels. Hence, hydrogen is usually stored in a gaseous state and delivered via tube trailers or pipelines. In this study, a transient structural analysis of a skid structure mounted on a hydrogen tube trailer was performed under shock load induced by road irregularities. The dynamics of the driving trailer according to the unevenness of the road surface were obtained through multibody dynamic simulations considering the full car model equipped with 64 hydrogen tubes. The transient structural analysis of the tube skid was performed by considering the resulting acceleration values as constraints. Through the sequential simulations, we evaluated the structural safety of the designed tube skid mounted on a trailer during hydrogen transport.

Biomass-Derived Carbonaceous Materials to Achieve High-Energy-Density Supercapacitors

Biomass-derived carbonaceous materials are considered as one of the most perspective electrodes for symmetric supercapacitors working with alkaline-basic electrolytes. However, they still exhibit lower energy density. Herein, we demonstrate the capacitance performance of the commercial carbon product (YP-50F, “Kuraray Europe” GmbH), obtained from coconuts, in symmetric supercapacitors by using lithium and sodium organic electrolytes. It is found that YP-50F delivers higher energy density when lithium electrolyte containing LiBF4 salt is employed. The sodium electrolyte with NaPF6 salt is less aggressive toward YP-50F than that of LiPF6 salt, as a result of which a good capacitance performance is observed in the sodium electrolyte. The contributions of surface functional groups of YP-50F, as well as its compatibility with non-aqueous lithium and sodium electrolyte, are discussed on the basis of post-mortem scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) data analyses. The obtained correlations could be of significance in order to design sustainable supercapacitors with high energy density.

Effects of Labelling and Increasing the Proportion of Lower-Energy Density Products on Online Food Shopping: A Randomised Control Trial in High- and Low-Socioeconomic Position Participants

Reducing the energy density (ED) of product selections made during online supermarket food shopping has potential to decrease energy intake. Yet it is unclear which types of intervention are likely to be most effective and equitable. We recruited 899 UK adults of lower and higher socioeconomic position (SEP) who completed a shopping task in an online experimental supermarket. Participants were randomised in a 2 × 2 between-subjects design to test the effects of two interventions on the ED of shopping basket selections: labelling lower-ED products as healthier choices and increasing the relative availability of lower-ED products within a range (referred to as proportion). Labelling of lower-ED products resulted in a small but significant decrease (−4.2 kcal/100 g, 95% CIs −7.8 to −0.6) in the ED of the shopping basket. Increasing the proportion of lower-ED products significantly decreased the ED of the shopping basket (−17 kcal/100 g, 95% CIs −21 to −14). There was no evidence that the effect of either intervention was moderated by SEP. Thus, both types of intervention decreased the ED of foods selected in an online experimental supermarket. There was no evidence that the effectiveness of either intervention differed in people of lower vs. higher SEP.

Optimization and performance assessment of Solar Towers

The present paper investigates possible strategies to improve the competitiveness of Solar Towers, considered the best option over CSP technologies. Nevertheless, many aspects still penalize the tower systems, mainly the higher installation costs and the lower energy density. The optimal design of the heliostat layout and the selection of the optimal tower height are fundamental to improve the performance of CRS. A new model for optimizing and simulating solar tower plants, based on an in-house Matlab® code, has been developed and validated. A technical and an economic optimization procedure allows to select the plant configuration with the maximum efficiency or the minimum LCOE, respectively. The case study is focused on a solar field of 6000 heliostats, corresponding to a nominal power of 100 MWe. The tower height shows a strong influence on the heliostat layout and solar field performance; however, the annual energy yield shows a nearly asymptotic behavior when the tower height is increased. An economic optimization leads to a less dense layout to limit the tower impact on the cost; a penalty in efficiency of around 6% can reduce the LCOE of more than 5%. The minimization of land utilization, saving 24% of the occupied area, has a penalization of about 8% in terms of LCOE.