Next Energy最新文献

The use of kesterite materials in photovoltaic solar cells holds great promise due to their abundance, non-toxic nature, cost-effectiveness, and excellent optoelectronic properties. However, the power conversion efficiency of kesterite solar cells remains considerably below the Shockley-Queisser limit efficiency. This underscores the need for continuous development of new cell designs to maximize kesterite's potential for solar energy conversion. In this study, we presented a novel design for a kesterite solar cell incorporating semi-ellipsoidal nanostructures into the active layer to overcome its limitations and achieve higher efficiencies. Comprehensive simulations were conducted to study the effect of these nanostructures on solar cell performance. An extensive parametric study was also performed to identify the design parameters for the best performance. The results revealed that the presence of nanostructures significantly enhances power conversion efficiency, reaching a remarkable 17.6%, overcoming many challenging obstacles facing kesterite solar cells and making them more competitive in the ever-expanding solar cell market.

As the demand for high-performance and long-lasting batteries continues to escalate, understanding the degradation mechanisms of Li-ion batteries (LIBs) has become a pressing concern. In this study, we employed the acoustic emission (AE) technique to detect and quantify the internal changes occurring within LIBs during the degradation processes. Our goal was to propose a comprehensive method to categorize the AE data and correlate them with different battery events, which has not yet been properly established in the state of the art. Two commercial pouch cells at different levels of degradation were monitored using the AE technique during their cycling, and the changes in their electrochemical and mechanical behavior were analyzed. A thorough investigation of the AE hits enabled us to identify 4 distinct AE types in terms of frequency, which could reflect multiple battery degradation events, including intercalation-induced stress, gas generation, and particle/electrode cracking. Our proposed approach was compared with the conventional methods presented in past studies, demonstrating its compatibility in explaining different battery phenomena and the coupled behavior of those phenomena. Overall, this work offers a new approach to in-operando AE analysis of LIBs, which helps further development of the AE technique as a real-time and nondestructive diagnostic tool for LIBs.

Supercapacitors have witnessed significant development in recent years due to their high power density, fast charging rate, and excellent cycle stability, which can be used in wearable devices, electric wheel loader, and other energy storage systems for needing high discharge rate. Designing a simple synthetic protocol to simultaneously produce electrode materials with high activity and stability is a significant challenge for high-performance supercapacitors. Herein, we developed an one-step in situ electrochemical oxidation method to develop MXene/TiO₂@Co₃O₄ nanosheets at room temperature and neutral solution from their corresponding MXene-Co-MOF. The dual role of in-situ electrochemical oxidation reaction was presented: (1) the electrochemical oxidation reaction facilitates the decomposition of Co₃(HHTP)₂ MOF to Co₃O₄ and the transformation of the part of MXene to TiO₂; (2) the electrochemical oxidation reaction enhances the Faradaic activity of electrode materials by forming more active sites on weak crystalline MXene/TiO₂@Co₃O₄. The electrochemically tuned MXene/TiO₂@Co₃O₄ nanosheets grown directly on the Ni foam electrodes exhibit high specific capacitance of up to 2403 F g⁻¹ at current density of 1 A g⁻¹. When assembled into an asymmetric supercapacitors (ASC) device, the MXene/TiO₂@Co₃O₄//AC device obtains a high energy density of 55.8 Wh kg⁻¹ at a power density of 799.7 W kg⁻¹ and appears 78.6% retention after 5000 cycles stability test. The improved activities are attributed to the introduction of oxygen vacancies, more active sites with poor-crystalline phase. This work provides a promising in situ electrochemistry strategy to develop electrode materials alternatives for supercapacitor applications.

Climate change and global warming represent critical challenges for the 21st century, partly attributable to the combustion of fossil fuels. The adoption of alternative energy sources presents viable solutions to mitigate these challenges. Among the strategies to address climate change, lithium-ion batteries (LIBs) have emerged as increasingly important. However, the advancement of LIB technology is hindered by the phenomenon of thermal runaway (TR), which constitutes the primary failure mechanism of LIBs, potentially leading severe fires and explosions. This review provides a comprehensive understanding of the TR mechanisms in LIBs, which vary significantly depending on the battery’s materials. Extensive research has been conducted on the component materials of LIBs, the causes triggering TR, and the mechanisms underlying TR in laboratory settings. Yet, further research to fully understand and mitigate TR is necessary as it is a highly complex process that is readily influenced by both external conditions and internal reactions. For LIBs composed of different materials, the processes and mechanisms underlying TR exhibit significant variations. Therefore, this review emphasizes the need to study various battery cells to gain a comprehensive understanding of the TR mechanisms. The focus of this review lies in elucidating the diverse TR mechanisms, preventive methods, and highlighting recent key progresses in research aimed at improving the safety of LIBs. Finally, this review concludes with recommendations for future research and development on the safety of LIBs, emphasizing the need for a more coherent view of TR mechanisms and LIB safety.

Polyoxymethylene dimethyl ethers (DMM_x, CH₃O(CH₂O)_xCH₃, x = 1–8) are appealing oxygenated chemicals with potential applications mainly used as sustainable fuels and solvents. The growth of longer C-O chain for direct oxidation of dimethyl ether (DME) to DMM_x is especially important, but the construction of the acid sites with different strengths and matched redox sites faces great difficulties. Herein, the gradient acidity and enhanced oxidizability have been successfully created by regulating coordination structure of titanium sulfate (Ti(SO₄)_x). The formation of a higher proportion of weak-medium acid sites and appropriate redox sites over a Ti(SO₄)_x/activated carbon (AC) catalyst with nitrogen treatment significantly promotes the synthesis of larger molecules, with DMM_2–3 selectivity up to 42.2%. Combined with the characterizations, designed experiments and theoretical calculations, the configurations of Ti(SO₄)_x and their local chemical environment are revealed. The different distortions of Ti(SO₄)_x structure in nitrogen atmosphere result in the various coordination unsaturated Ti atoms located at the center of polyhedral, which is the main reason for the gradient acidity distribution and enhanced oxidative property.

The development of highly efficient lead-free solar cells is essential for sustainable energy production in the face of depleting fossil fuel resources and the negative effects of climate change. Perovskite solar cells (PSCs) containing lead pose considerable environmental and public health hazards, in addition to thermal stability and longevity challenges. Here, a novel lead-free solar cell design of the configuration, ITO/PC₆₁BM/CH₃NH₃SnI₃/PEDOT:PSS/Mo, is investigated for improved light harvesting capabilities, enhanced device performance, and better operational efficiency under various temperature conditions. The optimal thickness of the light-absorbing layer, CH₃NH₃SnI₃, was found to be 1000 nm for maximum quantum efficiency (QE). Further, the temperature tolerance of the solar cell was evaluated using Mott-Schottky (MS) capacitance analysis and showed that the model cell retains about 95% of its power at 400 K, demonstrating excellent thermal stability and robust performance. The solar cell also shows promising electrical output parameters, including a short-circuit current density (J_sc) of 34.84 mA/cm², open-circuit voltage (V_oc) of 1.5226 V, Fill factor (FF) of 71.04%, and an impressive power conversion efficiency (PCE) of 37.66% at 300 K. The effect of buffer layers such as CdS, ZnS, ZnSe, and V₂O₅ on the electrical outcomes of the model cell structure has been critically examined. Additionally, parasitic resistances and doping characteristics on the operational performance of the cell have been explored in detail. This work therefore, provides remarkable insights in the field of solar energy harvesting, offering potential sustainable energy generation solutions, supporting de-carbonization of the environment and climate change mitigation efforts towards an energy sustainable future.

Natural gas hydrates represents a huge source of energy. At the same time substantial leakages of natural gas from hydrates contributes significantly to climate changes. One of the most important reasons for these natural gas fluxes is leakage of seawater in to the hydrates from seafloor, through fracture systems. Hydrate dissociates if surrounding seawater is less than hydrate stability limit. Another interesting aspect of natural gas hydrates is the potential for safe CO₂ storage. These different aspects of hydrates in natural sediments put demands on thermodynamic models. In addition to accurate description of pressure temperature hydrate stability there also a need to describe hydrate dissociation in concentration gradients towards surrounding water or surrounding gas as two examples. In this work we present new experimental data and an extensive thermodynamic model for hydrate. In contrast to conventional thermodynamic models for hydrate the model is consistent since all thermodynamic properties are derived from the Gibbs free energy. In this work we examine mixtures of CH₄, C₂H₆, N₂, CO₂ from the China Sea and some synthetic mixtures, using this model. Maximum CO₂ content in these mixtures are 60 mol% and the rest is dominated by CH₄. Agreement between experimental data and model calculations are generally good and average deviations are below 5.5% for all the systems and conditions examined. Another aspect of the model is the ability for incorporation of effects of mineral surfaces. Specifically it is illustrated that adsorption of water on rust dominates liquid water drop out from gas as compared to water dew-point. Production of natural gas with such high CO₂ content requires a strategy for CO₂ separation and storage. It is proposed that the CH₄ is separated from the C₂H₆, CO₂ and N₂ and cracked to H₂ and CO₂ using steam. Thermodynamic analysis indicates a significant potential for safe CO₂ storage in natural gas hydrate and H₂ as the only export product.

The generation of plastic waste and waste cooking oil is a serious environmental concern because of worldwide waste disposal issues. At the same time, increasing demand and contemporary geopolitics make fossil fuels a significant worldwide problem. As a result, there has been an increase in demand for alternate fuel for CI engines. To overcome these twin problems can be addressed by converting waste into liquid fuels. This research explores an intriguing area by mixing waste cooking oil biodiesel and waste plastic oil to create a mixture that remarkably seems like the physico-chemical properties of diesel fuel in a society that is looking for sustainable alternatives. So, in this investigation, a ternary fuel blend of Petro-diesel, waste cooking oil biodiesel (WCOB), and waste plastic oil (WPO) was used in the diesel engine. To enhance the properties of fuel, combustion, emission, and performance parameters of diesel engines, a ternary blend of B20P20D60 was employed in the CI engine as an alternative fuel. In the ternary fuel blends, WCOB, WPO, and diesel content were 20%, 20%, and 60%, respectively. The results were compared with conventional diesel fuel, showing that the ternary fuel blend B20P20D60 has an improved brake thermal efficiency of up to 1.71% at 80% loading and reduced emissions (HC, CO, NO_x) compared to conventional diesel. Because of this, the ternary blends have significant potential for use in diesel engines.

Current work focuses on the development of flexible membranes of cellulose acetate containing lead dioxide for supercapacitor applications. The functionality of cellulose acetate and lead dioxide are analyzed by Fourier transform infrared spectroscopy. The degree of crystallinity is studied using X-ray Diffraction. The degree of hydrophilicity is discussed by water contact angle measurements. A Universal Testing Machine is used to examine the mechanical properties. The electrochemical performances are illustrated using Cyclic voltammetry, Electrochemical impedance Spectroscopy and Galvanostatic charge-discharge techniques. The highest recorded specific capacitance is 148 F g⁻¹ at a current density of 40 mA g⁻¹ for a membrane of 1 wt% lead dioxide in cellulose acetate. Capacitance retention of 89% after 5000 cycles is attained. The power density of 56 W kg⁻¹ and energy density of 10 Wh kg⁻¹ is achieved. The cellulose acetate doped with lead dioxide membranes can provide a better electrode material matrix for flexible energy storage.

Layer spacing of vanadium oxide can be effectively expanded by metal ion, however, its conductivity and electrochemical kinetics still require improvement. This work expands the layer spacing using manganese ion and help to improve conductivity and electrochemical kinetics by graphene. The results demonstrate that the layer spacing can be adjusted from 12.1 Å for pristine vanadium oxide (VOH) to 13.6 Å for manganese vanadium oxide (MnVO). Due to graphene introduction, it decreases to 11.6 Å for manganese vanadium oxide/graphene composite (MnVO-0.05–8/GN-15). Notably, the optimized composite delivers higher specific capacity of 507.5 mAh g⁻¹ for MnVO-0.05–8/GN-15 than that of MnVO (410.4 mAh g⁻¹) and VOH (370.1 mAh g⁻¹) at current density of 0.5 A g⁻¹. Furthermore, the MnVO-0.05–8/GN-15 exhibits fast Zn²⁺ ion diffusion ability, achieving high energy density of 403.51 Wh kg⁻¹ and retaining an excellent cycle stability of 85.7% after 2000 cycles at a current density of 3 A g⁻¹.