Operational Window Research Articles

Recent progress offlexible solid-state supercapacitors: electrodes, electrolytes and practical application.

Flexible solid-state supercapacitors (FSSCs) have garnered significant attention due to their advantages, including lightness, adaptability, enhanced safety, and extensive operational potential windows. These features make them highly suitable as energy storage devices for the next generation of portable and flexible electronics. The recent surge in the development and remarkable breakthroughs in novel wearable electronics have further propelled research into FSSCs. Nevertheless, several pressing issues need to be addressed in this field, including synthesizing flexible electrode materials with superior electrochemical energy storage capabilities, enhancing the physicochemical properties of solid gel polymer electrolytes, particularly in extreme environments, and ensuring effective contact between electrodes and gel electrolytes. This paper presents an overview of the latest advancements in FSSCs, focusing on electrode materials and electrolytes. Additionally, it delves into the current challenges and future prospects of FSSCs.

Numerical Investigation of CO and NO Production From Premixed Hydrogen/Methane Fuel Blends

Abstract There is significant interest in utilizing hydrogen as an energy carrier in a net-zero carbon energy economy. A variety of fundamental and practical issues associated with premixed hydrogen/methane combustion must be addressed, particularly flame flashback, combustion instabilities, and NOx emissions. Significantly less attention has been given to CO emissions from hydrogen blending. However, recent H2 blending engine tests have clearly noted major reductions in CO emissions, reductions which substantially exceed what would be expected based upon C atom mass balances in the fuel. Moreover, NOx, CO, and combustor operability always tradeoff with each other, and so, for example, these CO reductions can also enable operational or design modifications to reduce NOx emissions and/or wider operability windows. This paper addresses H2 blending effects on CO emissions, addressing both the direct influences on CO emissions, as well as how it influences NOx–CO tradeoffs. The paper presents computations that differentiate between the kinetic and equilibrium effects of H2 blending, as well as how H2 blending can lead to reductions in both NOx and CO by moving the Pareto front downward. Finally, this work suggests that H2 blending, in addition to its CO2 reductions, can also increase plant operational flexibility and so provide additional value propositions to an evolving electricity market.

Improving Bulk and Interfacial Lithium Transport in Garnet-Type Solid Electrolytes through Microstructure Optimization for High-Performance All-Solid-State Batteries.

Garnet-type Li6.4La3Zr1.4Ta0.6O7 (LLZTO) is regarded as a highly competitive next-generation solid-state electrolyte for all-solid-state lithium batteries owing to reliable safety, a wide electrochemical operation window of 0-6 V versus Li+/Li, and a superior stability against Li metal. Nevertheless, insufficient interface contacts caused by pores, along with Li dendrite growth at these voids and grain boundary regions, have hindered their commercial application. Herein, we suggest a method to produce high-quality LLZTO using LiAlO2 (LAO) as a chemical additive that leads to an improved microstructure with larger grain size (∼25 μm), a high relative density (∼96%), lower porosity (∼3.7%), and continuous secondary phases in grain boundary regions. This improved structure results in (i) improved Li-ion conductivity and enhanced interfacial resistance between Li metal and LLZTO by a denser structure with fewer pores and (ii) suppression of Li dendrite penetration in the electrolyte by secondary phases in grain boundary regions.

Identification of Deactivation Mechanisms by the Periodic Transient Kinetic Method

AbstractThe understanding of deactivation processes in heterogeneous catalysis is key for the development of new materials and exploration of new operation windows. In this contribution, the periodic transient kinetic method (PTK) is used to identify and separate catalyst deactivation processes for the first time. The PTK method is applied for a standard Ni/Al2O3 catalyst in CO and CO2 methanation for 24 h and compared to steady‐state experiments. For the example reactions, the study exhibits different deactivation behavior for CO and CO2 methanation. The results demonstrate that the PTK method delivers an insight into the deactivation process and furthermore gives evidence for the underlying mechanism.

Medium and high temperature H2S removal via phosphazene polyoxometalate ionic liquids: Performance evaluation and mechanism exploration

The development of non-aqueous solvent desulfurizer is crucial to addressing the challenges associated with traditional liquid-phase wet desulfurization technologies. Based on this, we prepared a series of phosphazene polyoxometalate ionic liquids (PPILs) based of 1-butyl-3-methylimidazolium chloride using different kinds of phosphazenes (PNs) combined with polyoxometalate (POM), and used for hydrogen sulfide (H2S) dynamic absorption experiments. The effects of PN type and ratio, temperature and desulfurizer concentration on the desulfurization performance of different PPILs were explored. Among them, PPILs@IBuPN-9 as the optimal desulfurizer could keep almost 100 % desulfurization efficiency in the medium and high temperature range (100–200 °C). The results showed that the combination of PNs with POM significantly improved and widened the H2S removal performance and the operational temperature window of the desulfurizer. Besides, PPILs@IBuPN-9 required only air regeneration to maintain relatively stable cycle performance for at least four times and the sulfur capacity could be efficiently increased during multiple regenerations. It was found that the hydrogen bonding sites on IBuPN network formed significantly enhanced the H2S capture ability of PPILs and the sulfur capacity was substantially improved by S2− substitution of oxygen atoms in the POM according to the characterization results and density functional theory calculations. This study promotes the deep integration of polyoxometalate chemistry with ionic liquids in the field of gas purification and promotes the development of non-aqueous phase desulfurization process.

Cost-Effective Acetonitrile-Based Precursor Solution Mitigates Heterogeneous Nucleation for Efficient and Stable Perovskite Solar Cells.

Solution-processing is the primary method for fabricating high-efficiency perovskite solar cells (PSCs), where solvent choice critically influences film formation and quality. Although additives can optimize film formation dynamics by balancing nucleation and growth of perovskite, they can also induce heterogeneous nucleation due to competitive coordination and varying crystallization kinetics, leading to compositional heterogeneity and structural disorders. Herein, a perovskite precursor solution is developed using acetonitrile (ACN) as a weak coordination host solvent instead of the traditional N,N-dimethylformamide (DMF). The ACN-based perovskite precursor solution reduces heterogeneous nucleation typically caused by the competitive coordination effect of DMF, and cuts costs by half compared to DMF-based precursor solutions. This approach promotes a single crystallization pathway via a dimethyl sulfoxide-solvated intermediate phase to α-FAPbI3, which extends the anti-solvent operation window, and enhances the crystallinity of perovskite films, and reduces defect states. The power conversion efficiencies (PCE) of 23.62% and 20.13% is achieved for the PSC and minimodule, respectively. The PSC retains over 97% of its initial efficiency after 800h of continuous illumination under maximum power point tracking (MPPT). These findings provide valuable insights into solvent interactions in perovskite film formation and offer a cost-effective strategy for improving the device's performance and stability.

Grain Structure Engineering in Screen-Printed Silver Flake-Based Inks for High-Temperature Printed Electronics Applications.

We extensively studied serigraphic screen-printed commercial silver flake inks loaded with silicon inclusions in order to achieve pinning at the grain boundaries. Based on grain size measurements using electron backscattered diffraction (EBSD), commercial silver ink with silicon microparticle content of 5 wt.% shows significant grain growth retardation compared to pristine silver ink, which stabilizes electrical conductivity up to 700 °C via a Zener pinning mechanism. The modified silicon-loaded silver ink experiences a two-times increase in grain size when heated up to 700 °C, compared to a seven-times increase for pristine silver ink. In turn, this enables operation temperatures significantly higher than the conventional operational window of microparticle-based silver inks, which are usually limited to 400 °C. Using isothermal exposures of 10 min up to 4 h, this phenomenon is observed at temperatures ranging from 250 °C to 900 °C. The electrical conductivity stability, grain size evolution and oxide contents were studied up to 4 h. The activation energy of silver ink with silicon inclusions is 54% lower than for pristine silver ink due to the pining effect, which retards grain growth via the Zener mechanism. Most importantly, the electrical resistivity remains stable up to 700 °C, which is more than twice the operation limit for off-the-shelf screen-printable silver flake inks. Hence, we demonstrate that adding controlled amounts of silicon particles to silver inks for grain structure engineering can open new vistas of possibilities for screen-printed metallic inks.

Synthesis of low-temperature NH3-SCR catalysts for MnOx with high SO2 resistance using redox-precipitation method with mixed manganese sources

It remains a big challenge to enhance the SO2 resistance of catalyst in low-temperature NH3-SCR reduction. In this work, a series of MnOx-a%Mn (a = 0, 1, 3, 5, 10) catalysts were prepared by introducing manganese acetylacetonate during the reaction between lactic acid and KMnO4, based on the molar ratio of manganese acetylacetonate to KMnO4. Notably, MnOx-5 %Mn exhibited more than 95 % NO conversion and 100 % N2 selectivity at 80–240 °C. Moreover, the catalyst demonstrated excellent sulfur resistance by sustaining over 90 % NO conversion at 140 °C at the presence of 100 ppm SO2 for more than 6 h. Furthermore, XPS characterization indicated that adding manganese acetylacetonate enhanced electron transfer efficiency and improved the reduction capacity of the catalyst due to the interconversion between Mn3+ and Mn4+, which improved electron transfer efficiency. The enhanced reduction capacity of the catalyst promoted the formation of oxygen vacancies and surface-adsorbed oxygen species (Oα), avoiding over-oxidation of NH3. The results elucidated that manganese acetylacetonate could optimize the overall performance by modulating the synergistic effect between the oxidizing ability and surface acidity of the catalyst. Therefore, the MnOx-5 %Mn catalyst possessed a broad operational temperature window (40–240 °C) and SO2 resistance in the NH3-SCR reaction, indicating its potential for practical application.

Designing Contact Independent High-Performance Low-Cost Flexible Electronics.

Organic semiconductors enable low-cost solution processing of optoelectronic devices on flexible substrates. Their use in contemporary applications, however, is sparse due to persistent challenges in achieving the requisite performance levels in a reliable and reproducible manner. A critical bottleneck is the inefficiency associated with charge injection. Here, large-scale simulations are employed to identify operational windows where key device parameters that are difficult to control experimentally, such as the contact resistance, become less consequential to overall device functionality. This design methodology overcomes injection barrier limitations in organic field-effect transistors (OFETs), leading to high charge carrier mobility and significantly expanding the range of suitable electrode materials. Leveraging this new understanding, all-organic, solution-deposited OFETs are successfully fabricated on flexible substrates. These devices incorporate printed contacts and showcase mobilities exceeding 5cm2Vs-1. These results provide a route for accessing the fundamental limits of material properties even in the absence of ideal contacts - a critical step in establishing reliable structure/property relationships and optimal material design paradigms. While reducing the injection barrier and contact resistance remains critical for achieving high OFET performance, this work demonstrates a path toward consistently achieving high charge carrier mobility through device geometry design, ultimately reducing processing complexity and cost.

Optimizing the grasping behavior of a soft robot's gripper

AbstractIn this study, smart composite materials based on 4D printing technology were used to determine the grasping ability of four‐claw gripper of soft robot. First, fused deposition modeling (FDM) is used to prepare polylactic acid (PLA) strips on the surface of a rectangular bamboo substrate to create a single‐claw gripper for a smart composite soft robot, while using stimulus (heat) to deform and recover its original shape. Here, the authors first evaluate the deformation and recovery angle of the single‐claw gripper of the smart composite soft robot, as well as various processing parameters such as heating temperature and time. This study then used FDM to print PLA ribbons on cross‐shaped bamboo sheets to design the four‐claw gripper of soft robot and its gripper technology was actuation type. Then, the four‐claw gripper of soft robot was used to grab the table tennis ball to test its grasping ability. Finally, four processing parameters (width of claw, pitch of PLA ribbon, heating temperature, and heating time) were applied to determine the grasping ability of the four‐claw gripper of soft robot. The optimal processing parameters for the grasping ability of the four‐claw gripper of soft robot were width of claw of 20.2 mm, pitch of PLA ribbon of 1 mm, heating temperature of 200°C, and the heating time of 15 s. The authors also applied the operation window of two processing parameters to discuss the success of the grasping ability of the four‐claw gripper of soft robot. The innovation of this study is the use of PLA/bamboo composite materials as the four‐claw gripper of soft robot and these materials are cheap, easy to obtain, and can be recycled naturally. This study uses a simple thermal stimulus to enable the four‐claw gripper of soft robot to easily grasp irregular objects.Highlights The innovative composite material of polylactic acid and bamboo fabricated by 3D printing. Width of claw and heating temperature are the key factors on grasping ability. Operating window of grasping ability appears on four‐claw gripper of soft robot.

Three-stage ocean wave elements extraction using deep learning based on in-situ monocular videos from offshore infrastructure

Ocean wave elements refer to statistical descriptions of waves in ocean engineering, serving to evaluate the fatigue and damage of offshore infrastructures and expand the operational time window for offshore construction activities. In-situ measurement of waves is an effective approach to acquire wave elements. However, traditional non-contact equipment is costly and unsuitable for continuous wave elements acquisition near offshore structures. Therefore, this study utilizes monocular vision to extract marine information, focusing on the accurate recognition of significant wave height and peak frequency near infrastructures. A three-stage wave elements extraction method is proposed: preprocessing with infrared enhancement and highlight removal, Convolutional Neural Network (CNN) feature extraction phase, and convolutional Long Short-Term Memory (convLSTM) regression network based on a self-attention memory mechanism. This approach accurately regresses significant wave heights and peak frequencies from in-situ monocular videos of the ocean, achieving mean absolute percentage errors (MAPE) of 3.01% for significant wave height and 4.07% for peak frequency. Additionally, ablation experiments are conducted at each stage to validate the effectiveness of the method.

Stability Analysis of Surface Wellhead Retention in Offshore Exploration Wells

Abstract When offshore exploration wells are carried out, a narrow operating window and prolonged construction period may be encountered, which may lead to the evacuation of the drilling platform. The conductor will be left freestanding in the sea water, posing a great risk to wellhead stability. In this paper, based on finite element simulation of offshore exploratory well freestanding conductors, the stability analysis method is built and evaluation of a well is carried out. It is concluded that in 1 year return period and sea conditions by hanging load return period of 10 years of sea condition, the stability all meet the conditions, but there in 10 years return period of sea state by hanging load and 50 years return period of sea condition did not meet the requirements of stability. In cases where stability requirements are not met, alternative means of retaining the wellhead are recommended. This study has certain guiding significance for the safe and efficient operation of offshore exploration wells.

Comprehensive characterization of the irradiation effects of glassy carbon

Carbon materials have become increasingly diverse, finding applications in high-temperature and high-radiation environments. Glassy carbon, an allotrope known for its exceptional chemical inertness and desirable mechanical properties. However, understanding neutron irradiation effects in glassy carbon has proven challenging, primarily because of its unique nanopore structure. This study presents a highly detailed microstructural characterization investigation of neutron-induced changes in glassy carbon, revealing how changes in nanopore structure and crystallinity impact the irradiation-induced shrinkage. Aberration-corrected scanning transmission electron microscopy (STEM) reveals pore closure that leads to material densification in the irradiated samples. Dimensional analysis combined with comparison to historical data suggest significant length shrinkage to occur. Neutron and in situ electron irradiation experiments suggest that glassy carbon transforms into so-called carbon onions, supporting the concept of shrinkage saturation. Investigating irradiation temperature effects using STEM, electron energy loss spectroscopy, x-ray diffraction, and Raman spectroscopy revealed partial amorphization at 210 °C–230 °C and preserved order in glassy carbon at 860 °C, coinciding with pore closure. Thermal property measurements were also conducted to assess the effects of densification and other changes in the atomic structure of glassy carbon. The results of this study have broad implications in the deployment of glassy carbon to nuclear environments, based around the observed changes in the thermal properties, and demonstrates the operational window for the onset of densification.

Low-Temperature and High-Rate Rechargeable Aluminum Batteries Enabled by Ternary Eutectic Electrolytes.

Rechargeable aluminum batteries (RABs) have garnered extensive scientific attention as a promising alternative chemistry due to the inherent advantages associated with aluminum (Al) metal anodes, including their high theoretical capacities, cost-effectiveness, environmental friendliness, and inherent non-flammable properties. Nonetheless, the practical energy density of RABs is constrained by the electrolytes that support lower operational voltage windows. Herein, we report a ternary eutectic electrolyte composed of 1-ethyl-3-methylimidazolium chloride ([C2C1im]Cl):1-butyl-3-methylimidazolium chloride ([C4C1im]Cl):aluminum chloride (AlCl3) for the application of RABs. The electrolyte exhibits a high operational potential window (~3V vs. Al/Al3+ on SS 316) and high ionic conductivity (~8.3 mS.cm-1) while exhibiting only a low temperature glass transition at -65 oC suitable for all-climate conditions. Al||graphene nanoplatelets cell delivers a high capacity of ~117 mAh/g, and ~43 mAh/g at a very high current densities of 1A/g and 5A/g, respectively. The cells render a reversible capacity of 20 mAh/g at -20 oC and 17 mAh/g at -40 oC, indicating their suitability for operation under extreme environmental conditions. We comprehensively evaluated the design and optimization of carbon paper-based battery systems. The ternary eutectic electrolyte demonstrates exceptional electrochemical performance, thus signifying its substantial potential for utilization in high-performance energy storage systems in all climates.

Investigating screw-agitator speed ratio impact on feeding performance in pharmaceutical manufacturing using discrete element method

In continuous powder handling processes, precise and consistent feeding is crucial for ensuring the quality of the final product. The intermixing effect caused by agitators, which alters the powder’s bulk density, flow rate, and flow patterns, plays a significant role in this process, yet it is often overlooked. This study combines discrete element method (DEM) modeling and experiments using a commercial-scale feeder to propose a Digital Twin (DT) framework. The DEM model accurately captures key flow features, such as bypass trajectories, stagnant zones, and preferential flow patterns, while providing quantitative predictions for the feed factor and zones prone to material accumulation. Scenario analysis is performed to identify the most favorable operating ranges of the screw-agitator ratio and screw speed, considering the cohesive properties of the powder. The study demonstrates that powders with poor flow characteristics require tighter operational constraints, as the screw-agitator ratio is susceptible to variations in mass feed rate. This contribution highlights the importance of selecting an appropriate screw-agitator ratio instead of maintaining a fixed value. Properly choosing this ratio helps determine an optimal operation window, which aims to achieve a minimum agitation level needed to induce unhindered flow and reduce variability in the mass flow rate.

γ‐Valerolactone Enabling Spontaneously Inhibited Iodide Oxidation for High‐Quality Perovskite Single Crystal Fabrication

AbstractThe iodide precursor oxidation has persistently plagued solution grown iodine‐based perovskite single crystals (IPSCs) that inevitably introduce undesirable triiodide ion (I3−) defects and severely hindering crystal quality, despite IPSCs having garnered remarkable progress in multifarious photoelectronic applications. In this work, the spontaneously inhibited iodide oxidation is discovered in an eco‐friendly solvent, γ‐Valerolactone (GVL), and demonstrates a universal solution approach for fabricating high‐quality IPSCs. Compared to the routine γ‐Butyrolactone (GBL) system, GVL provides a lowered growth temperature and a significantly broadened inverse temperature operation window, thereby improving the theoretical utilization rate of perovskite precursors up to 88.6%. More importantly, due to its higher open‐ring hydrolysis energy, GVL can spontaneously inhibit the iodide precursors oxidation without any additional reductant and therefore effectively prevent the forming I3− defects. Typically, the as‐fabricated MAPbI3 single crystal possesses an extremely low trap density of 3.57 × 108 cm−3 and a high carrier mobility‐lifetime (µτ) product of 2.74 × 10−3 cm2 V−1, which enables its photodetection capabilities to be on a par with the state‐of‐art MAPbI3 single crystal photodetectors. This work paves an efficacious and green pathway for high‐quality IPSC fabrication toward advanced optoelectronic utilizations.

Electrochemical analysis on SnSeO3/ZnSeO3 nanocomposite

Nanocomposite SnSeO3/ZnSeO3 has been synthesized by hydrothermal method. X-ray powder diffraction confirms formation of SnSeO3/ZnSeO3 nanocomposite. It exhibits an interesting morphology of needle like nanorod structure. Thermal analysis reveals the thermal stability, decomposition behavior and critical temperatures where significant weight loss occurs. X-ray photoemission explains the role of the chemical state Sn, Zn, Se and O in SnSeO3/ZnSeO3. Electrochemical study has been made in both three electrode and two electrode system. In three electrode system, cyclic voltammetry exhibits a bell-shaped curve and the operational potential window is 0.8 V. The specific capacitance is 78.65 F/g for 5 mV scan rate. Chronopotentiometry shows quasi-triangular curves demonstrating the behavior of pseudo capacitors. Specific capacitances of 72.02 F/g was delivered at 1 A/g current density in 3M electrolyte of KOH. The plot of Nyquist for SnSeO3//ZnSeO3 confirms pseudo capacitor behavior. The series resistance Rs is low that is 0.78 Ω and charge transfer resistance is 0.42 Ω. Symmetric SnSeO3/ZnSeO3 supercapacitor device that is, two electrode system, is fabricated using 3M KOH electrolyte. Operational potential window is 1.5V. Cyclic voltammetry curves of the device show excellent capacitive behavior. The symmetric device produced specific capacitances of 39.37F/g, energy density 6.15 Wh kg-1 and power density 374.99 kW kg-1 at 1Ag-1 current density. The cell displayed 73.18% capacity retention, indicating excellent electrode stability for approximately 5000 cycles at a current density of 1 Ag-1 . Nyquist plot suggests that the system is stable and exhibits capacitive behavior.

Tailoring the proceeding of the NH3-SCO and NH3-SCR reactions over FeOx catalysts by modifying with NbOx

This study presents the synthesis of a series of FeOx-NbOx mixed oxide catalysts for the selective catalytic reduction (SCR) of NO by NH3. By meticulously controlling the Fe/Nb molar ratio, we have rationally tailored the proceeding of the main reaction of NO reduction and the side reaction of NH3 oxidation to NOx. The incorporation of NbOx introduced a significant number of acid sites, which enhanced the adsorption of NH3 on the catalyst surface, particularly at elevated temperatures. Additionally, the oxidative capacity of the catalyst was moderated by the addition of NbOx, hindering the over-oxidation of NH3 to NO or NO2, thus preserving more NH3 to act as a reductant for NO reduction. Consequently, the NbOx-enriched samples exhibited improved deNOx performance. However, an excessive amount of NbOx led to a notably weakened oxidative ability, which negatively impacted the activation of reactants and resulted in decreased NO conversion at lower temperatures. The optimized catalyst presented >80% NO conversion and >95% N2 selectivity within a temperature range of 250-400 °C. These findings offer valuable insights for the development of new catalysts with an extended operational temperature window.

Synthesis of desulfurization solvent networks based on process characteristics: New insights of desulfurization units and a novel synthesis method

Synthesis of desulfurization solvent network (DSN) can reduce the solvent circulation and the energy consumption for solvent regeneration. Based on the desulfurization process characteristics, this work proposes a novel graphic to explore the operating limitations of a desulfurization unit. A feasible operating window of the desulfurization unit is presented with three boundary lines to constrain the solvent reuse. Different cases for the solvent reuse between units are analyzed in details, and two rules for rich solvent reuse are proposed and proven. A novel hierarchical method is developed for the DSN synthesis. A refinery case is investigated using the proposed method. Four DSN designs are obtained, and the fresh solvent consumption can be reduced by 13.7 %. The accuracy of the four designs is verified by rigorous simulation, showing a maximum relative error of 1.22 %. The proposed method can show clear insights in DSN synthesis and give reliable and concise designs.

Development of a procedure for defining the operation window of annular centrifugal contactors

AbstractAlthough annular centrifugal contactors (ACCs) have been widely applied, their complex operation and its dependence on operational variables are still not fully quantified. That hinders their acceptance and precludes revealing their potential. Intuitive techniques to informedly operate ACCs while maximizing their gain are thus demanded. This work introduces a procedure to define the operation window of an extraction task on ACCs, using CINC V 02 variant, that demonstrates the feasible ranges of the operational variables and the maximum possible throughput. The overlapping impacts of the variables are also visualized, thus understood and, to enhance practicality, the procedure is converted into user‐interface software. The concept is intended to adapt to any task on ACCs and it is based on merging a hydraulic part focusing on the rotor and a statistical one modeling the annulus mass transfer. Additional insights on ACC's hydraulics and mass transfer dynamics are presented, including the time needed to establish the steady state.