Search Results (931)

The development of highly efficient, stable, and cost-effective non-precious metal electrocatalysts to replace conventional platinum-based materials holds profound significance for accelerating the commercialization of advanced energy conversion devices, such as zinc–air batteries (ZABs). Herein, we propose a facile and highly efficient strategy to prepare a defect-rich, highly active nitrogen-doped porous carbon-based electrocatalyst (denoted U-Fe-N-C, urea-assisted iron–nitrogen–carbon material), via high-temperature co-pyrolysis of heme with urea. Our results demonstrate that urea not only serves as an excellent nitrogen source during pyrolysis, introducing abundant topological defects and heteroatom doping sites, but also induces the carbon substrate to form a hierarchical sponge-like porous structure with a high specific surface area. This unique microenvironment effectively prevents the agglomeration of iron species at high temperatures, achieving enhanced dispersion of iron species stabilized within the nitrogen-rich carbon matrix. Electrochemical evaluations reveal that under the optimal synthesis conditions (a precursor mass ratio of 1:3, calcination at 900 °C), U-Fe-N-C exhibits excellent oxygen reduction reaction (ORR) catalytic performance, delivering a half-wave potential of 0.731 V vs. RHE, and shows long-term operational durability that significantly surpasses that of commercial Pt/C. Furthermore, liquid rechargeable zinc–air batteries assembled with U-Fe-N-C as the air cathode deliver remarkable cycling stability, operating for up to 270 h of charge–discharge cycling without noticeable performance degradation. This study not only provides useful insights into the mechanisms of pore formation and assistance but also offers a practical perspective for the rational design and scalable synthesis of high-performance metal–nitrogen–carbon (M-N-C) electrocatalysts. Full article

This study presents the development and field testing of a Pressurized Driving-Down Air Multilevel Sampler (PDA-MLS), an integrated groundwater sampling device designed for depth-discrete sampling in boreholes affected by floating non-aqueous phase liquids (NAPLs). Conventional sampling methods—such as low-flow pumps, bailers, and packer-isolated systems—often fail under these conditions due to limited accessibility, cross-contamination, or disturbance of the water column. The proposed system addresses these limitations through a controlled pressurized-gas actuation mechanism that transfers groundwater from multiple PTFE-membrane chambers installed at discrete depths. This configuration enables low-disturbance sampling below floating contaminant layers. The use of chemically inert materials (stainless steel and PTFE) minimizes sampling artifacts and ensures compatibility with volatile organic compound (VOC) analyses. A simplified hydraulic conceptual framework describing inflow, outflow, and pressure-driven displacement was developed to support purge-duration estimation and operational parameter definition. The device was tested in a 90 m deep fractured limestone aquifer contaminated by tetrachloroethylene (PCE), where floating hydrocarbons limited the applicability of conventional sampling techniques. Field testing showed stable discharge conditions (~145–160 mL/min), repeatable sampling cycles, and successful collection of depth-discrete groundwater samples under the investigated site conditions. No evidence of sampler-related hydrocarbon entrainment was observed in the collected samples within the analytical detection limits of the adopted laboratory methods. To the authors’ knowledge, the PDA-MLS represents one of the few groundwater sampling systems specifically designed to combine low-disturbance multilevel sampling with operation in wells affected by floating NAPL. These features make it a promising tool for environmental monitoring, high-resolution characterization of fractured aquifers, and long-term assessment of contaminated sites. Full article

Liquid electrolytes in conventional lithium-ion batteries pose safety risks associated with flammability, leakage, and explosion, whereas solid polymer electrolytes are generally limited by insufficient ionic conductivity at ambient temperature, restricting the development of high-energy lithium batteries. To address these issues, flexible poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based gel polymer electrolyte membranes (GPEs) were prepared via a slit-coating process combined with UV curing. NASICON-type lithium aluminum titanium phosphate (Li_1.3Al_0.3Ti_1.7P₃O₁₂, LATP) and garnet-type tantalum-doped lithium lanthanum zirconate (Li_6.4La₃Zr_1.4Ta_0.6O₁₂, LLZTO) were introduced as inorganic ceramic fillers to improve the ion-transport and interfacial properties of the GPE. Among the investigated samples, the PVDF-HFP-based GPE containing 10 wt% LLZTO exhibited the best overall performance, with an ionic conductivity of 3.40 × 10⁻⁴ S·cm⁻¹ at ambient temperature and a Li⁺ transference number of 0.77. Cyclic voltammetry results showed that the LLZTO-modified electrolyte membrane exhibited sharper and more symmetric redox peaks, higher peak current response, and better curve overlap during repeated cycles, indicating improved electrochemical reversibility and interfacial stability. In addition, LLZTO incorporation enhanced the mechanical strength, broadened the electrochemical stability window, and improved the flame-retardant behavior of the membrane. The LiFePO₄/GPE/Li cell assembled with the optimized membrane delivered an initial discharge capacity of 160 mAh·g⁻¹ at 0.1 C and maintained 80 mAh·g⁻¹ at 1 C, demonstrating good rate capability. Moreover, a capacity retention of 96% was maintained after 100 cycles at 0.1 C, confirming excellent cycling stability. Therefore, this work provides an effective strategy for the structural optimization and scalable preparation of high-performance gel polymer electrolyte membranes for lithium battery applications. Full article

To address heat accumulation, localized hot spots, and non-uniform temperature distribution in large-capacity lithium iron phosphate energy storage battery modules under high ambient temperature and high-rate charge/discharge conditions, this study proposes a fin-enhanced phase change material (PCM)-air hybrid thermal management structure for a 100 Ah prismatic lithium iron phosphate battery and a 2P18S energy storage battery module. First, the battery thermal model is validated using single-cell experimental data reported in the literature. Subsequently, a three-dimensional transient fluid–solid coupled heat transfer model is established by considering transient battery heat generation, PCM solid–liquid phase change, air-side flow and heat transfer, and temperature-dependent thermophysical properties. User-defined functions are employed to implement the transient heat source and temperature-dependent material properties. Under identical boundary conditions, the thermal management performances of three configurations, namely Fin-Air, PCM-Air, and Fin-PCM-Air, are compared. The effects of ambient temperature (20 °C, 25 °C, and 30 °C) and inlet air velocity (1 m/s, 2 m/s, and 3 m/s) on the maximum module temperature, temperature uniformity, PCM liquid fraction evolution, and flow field distribution are quantitatively analyzed. The results show that, compared with the Fin–Air system without PCM and the PCM-Air system without fins, the Fin-PCM-Air configuration reduces the maximum module temperature by 1.57% and 0.25%, respectively, at an ambient temperature of 30 °C and an inlet air velocity of 3 m/s. After four charge–discharge cycles, the peak maximum temperature of the module is approximately 38.56 °C, and the peak maximum temperature difference remains below 3.6 K, indicating good temperature uniformity and latent heat buffering capability. In addition, the air velocity trade-off analysis indicates that increasing the inlet air velocity can improve cooling performance but also increases the air-channel pressure drop and fan power consumption. Therefore, the Fin-PCM-Air structure is more suitable for high-thermal-load conditions, and its practical application should comprehensively consider cooling benefits, additional mass, manufacturing cost, and long-term reliability. This study provides a reference for the design and engineering application of hybrid thermal management structures for large-capacity energy storage battery modules. Full article

This study proposes a multi-objective optimization strategy for the structural design of liquid-cooled channels in battery systems, aiming to identify liquid-cooled plate design schemes with better cooling performance and acceptable flow resistance. Optimal Latin hypercube sampling (OLHS) was combined with computational fluid dynamics (CFD) simulations to construct a CFD-generated dataset that includes the maximum temperature and system pressure drop. Then, modeFRONTIER was employed to integrate surrogate-model training, rapid prediction, and non-dominated sorting genetic algorithm II (NSGA-II) optimization, thereby obtaining the Pareto optimal set. The technique for order preference by similarity to ideal solution (TOPSIS) decision method was further introduced to determine the final optimal design. Results indicate that the optimized liquid-cooling system exhibits outstanding comprehensive performance in terms of balancing heat dissipation and flow resistance at a 5 C discharge rate. Remarkably, sensitivity analysis shows that inlet velocity is the dominant factor affecting the maximum battery temperature, with a correlation coefficient of −0.789. The maximum temperature of the battery module is effectively limited to 30.07 °C, while the flow pressure drop is only 799.58 Pa, achieving an excellent balance between heat dissipation efficiency and energy consumption. Full article

Various hydraulic automatic gates play an important role in water resources regulation. This study proposes a novel suspended hydraulic automatic control gate for tidal marine energy generation with adaptive one-sided flow-through characteristics. To evaluate its hydraulic performance and regulation mechanism, model experiments were conducted in a laboratory flume under different upstream and downstream water levels and discharge conditions. Gate opening states, hydraulic parameters, and flow field structures were obtained, while computational fluid dynamics simulations were used to reproduce and analyze the experimental flow field. The results show that the gate opening angle and water level jointly control the discharge capacity, and significant differences exist in the flow structure and discharge behavior between free and submerged outflow conditions. The numerical model further reveals vortex structures, velocity stratification, and gas–liquid two-phase distributions near the gate. Variations in gate structural parameters, discharge, and downstream water level significantly affect moment equilibrium, flow regime, and discharge capacity. The proposed discharge formula effectively predicts variations in gate flow and force characteristics under different hydraulic conditions, showing good applicability and engineering value. The suspended hydraulic automatic control gate has a simple structure, strong adaptability, and promising potential for tidal water regulation and engineering applications. Full article

Effective thermal management is crucial for the performance, thermal safety, and lifespan of lithium-ion batteries in electric vehicles (EVs). Thermal management strategies are essential for preventing overheating, thermal imbalance, and the associated risk of thermal runaway. Nanofluids are emerging and attracting considerable attention as potential coolants for high-power energy storage and electronics systems. This review updates and summarizes the most recent advances in nanofluid-based cooling strategies for battery thermal management systems (BTMSs) over the past five years, emphasizing their implications for battery thermal safety. Three main nanofluid-based cooling strategies have been evaluated in depth, including nanofluid-based indirect liquid cooling, nanoparticle-enhanced PCM cooling, and nanofluid-based heat pipe cooling. Various nanofluid formulations, including mono, hybrid, and ternary nanofluids, have been considered and evaluated for their heat dissipation under high charge/discharge and abuse-relevant conditions. Thermal and hydraulic performance characteristics, including maximum temperature, maximum temperature difference, and pressure drop, have been comprehensively evaluated for different nanofluid-based cooling strategies. The findings demonstrated that nanofluids significantly improved heat transfer rates and enhanced temperature control efficiency. In particular, hybrid and ternary nanofluids exhibit superior thermal performance and effectively suppress the escalation of safety-critical temperatures. Beyond summarizing cooling performance, this review further discusses the role of nanofluid-based cooling strategies as functional thermal-control layers within intelligent BTMS architectures. Particular attention is given to their compatibility with sensing networks, BMS-/VCU-level supervisory control, predictive thermal models, actuator responsiveness, fault-warning algorithms, and long-term reliability under realistic driving and fast charging conditions. Therefore, this review provides architecture-oriented insights for developing safe, energy-efficient, and control-ready BTMSs for next-generation high-power and connected EVs. Full article

Transformer oil is a critical insulating medium in high-voltage equipment, and its discharge characteristics under high electric fields significantly limit overall performance. Current negative streamer classification methods rely primarily on propagation velocity, failing to effectively explain the underlying transition rules and mechanisms. To address this, we developed an impulse discharge experimental platform featuring a shadowgraph optical diagnostic system. By analyzing the morphological evolution, current pulses, and light emission signals of negative streamers across various voltage levels and liquid pressures, this study elucidates their transition mechanisms and mode classifications. The results demonstrate that negative streamer discharge initiates in a primary subsonic mode with a thin-rod channel. It then evolves into either a heavily branched, thick-channeled secondary mode (bush-like) or a faster, less-branched tertiary mode. Under sufficiently high overvoltage, it transitions to a supersonic quaternary mode with filamentary channels. Notably, negative streamer development exhibits distinct gaseous characteristics, and the channel deformation process aligns with the Rayleigh theory of bubble dynamics in liquids. Finally, appropriately increasing liquid pressure compresses the streamer channel, facilitating the transition from the secondary to the tertiary mode. Full article

A reduced-order framework was developed to describe the outlet initial conditions of a pressure-swirl nozzle under reduced-gravity conditions and to clarify how gravity modifies the nozzle-exit state relative to the corresponding 1 g baseline. Under normal gravity, the baseline outlet state was established through CFD-informed identification of the discharge coefficient and initial spray cone angle, from which the outlet axial and tangential velocity components were reconstructed. Gravity-induced deviations were then introduced through compact correction relationships for the outlet descriptors and liquid-film geometry. The outlet parameters were evaluated over pressure drops of 0.1–0.5 MPa and gravity levels from 1 g to 10⁻⁵ g. The results indicate that operating pressure mainly determines the baseline outlet state, whereas reduced gravity acts primarily as a correction to that baseline. Under forward-gravity injection, decreasing gravity reduces the axial and tangential velocity components, discharge coefficient, and initial spray cone angle, while increasing the outlet liquid-film thickness. A CFD-based comparison at 0.3 MPa indicates that the framework captures the first-order trends of normalized outlet velocity components and liquid-film thickness within the investigated conditions. Independent experimental validation is not included in this study and remains necessary for future quantitative assessment. Full article

Solid-state batteries (SSBs) are emerging as a transformative alternative to conventional lithium-ion batteries (LIBs) for next-generation electric vehicles (EVs) by replacing flammable liquid electrolytes with solid-state materials. Compared with current LIB systems delivering approximately 160–300 Wh/kg at the pack level, SSBs are projected to achieve 400–800 Wh/kg, enabling improvements in driving range of nearly 50–100% while simultaneously reducing battery pack mass by 10–30%. These improvements directly enhance vehicle-level energy efficiency by lowering energy consumption from typical values of 150–180 Wh/km in present EVs to projected levels of 110–140 Wh/km in optimized SSB-based architectures. Furthermore, reduced internal resistance and improved electrochemical stability can increase round-trip efficiency from approximately 85–95% in conventional LIBs to values approaching 95–98% under optimized solid-state configurations. The enhanced thermal stability of solid electrolytes significantly reduces the need for active cooling systems, decreasing parasitic thermal-management energy consumption from 10–30% of total vehicle energy demand to below 5–15% in advanced SSB systems. Fast-charging capability is also substantially improved, with projected charging times decreasing from 20–40 min to approximately 10–15 min for 10–80% state-of-charge operation, while maintaining improved safety and reduced risk of thermal runaway. In addition, SSBs demonstrate projected cycle lifetimes exceeding 3000–5000 cycles, compared with 1000–2000 cycles for conventional LIBs, thereby lowering battery replacement frequency and lifecycle energy losses. This paper examines the electrochemical fundamentals, thermal behavior, charging/discharging efficiency, and vehicle-level implications of SSB technology for EV applications. Comparative analyses demonstrate that replacing LIBs with SSBs can increase EV driving range from approximately 400 km to 700–800+ km under equivalent battery mass conditions, while also improving coulombic efficiency beyond 99.5% and reducing self-discharge rates to below 1–2% per month. Current industrial case studies from Toyota, Factorial Energy, Mercedes-Benz, CATL, BYD, QuantumScape, and Samsung SDI further confirm accelerating commercialization pathways toward 2027–2030. Overall, the study demonstrates that SSBs are not merely incremental battery improvements but represent a system-level efficiency technology capable of simultaneously enhancing energy density, reducing thermal and electrical losses, extending vehicle range, accelerating charging, and improving long-term sustainability. Despite persistent challenges related to manufacturing scalability, interfacial resistance, and cost, SSBs are positioned to become a critical enabler of highly efficient, long-range, and safer electric mobility systems beyond 2030. Full article

Liquid-cooled battery thermal management systems are essential for maintaining thermal safety, temperature uniformity, and hydraulic efficiency in electric vehicle battery modules. However, improving heat dissipation often increases pressure drop and pumping demand, making the thermal–hydraulic trade-off a key challenge in cooling plate design. This study develops a CFD–GPR–NSGA-II-based multi-objective optimization framework for a mini-channel liquid cooling plate applied to a cylindrical 18650 lithium-ion battery module under a 4C discharge condition. The mini-channel thickness, wall thickness, and coolant inlet velocity are selected as design variables, while the maximum battery temperature, temperature difference, and pressure drop are used as objective functions. Sixty design samples are generated using Latin hypercube sampling and evaluated through CFD simulations. Gaussian process regression models are then constructed to approximate the nonlinear relationships between the design variables and the thermal–hydraulic responses, and the trained surrogate models are coupled with NSGA-II to identify Pareto-optimal solutions. The selected compromise design is finally verified using a full CFD simulation. Compared with the initial configuration, the CFD-verified optimized design reduces the maximum temperature, temperature difference, and pressure drop by 0.569 K, 0.557 K, and 338.612 Pa, respectively. Although the reduction in peak temperature is moderate, the optimized design improves temperature uniformity by 10.06% and reduces pressure drop by 43.25%, demonstrating a balanced improvement in thermal and hydraulic performance. A heat-load robustness check further confirms that the optimized design maintains a predictable thermal response under different heat generation levels. These results indicate that the proposed CFD–GPR–NSGA-II framework provides an effective and computationally efficient approach for designing mini-channel liquid cooling plates for electric vehicle battery thermal management. Full article

The energy demand, depletion of fossil fuels, generation of plastic waste, and final disposal of waste cooking oil (WCO) have become major concerns due to industrialization and population growth, creating significant environmental challenges. These challenges have encouraged the development of sustainable alternatives for the valorization of residual feedstocks. On the one hand, global energy consumption continues to increase, promoting the search for alternative fuel sources; on the other hand, the improper disposal of plastic waste has motivated the development of recycling technologies for plastic residues that are difficult to recycle through conventional routes. Moreover, WCO is commonly discharged into drainage systems, contributing to water contamination. Therefore, this study evaluates the alkaline-assisted co-processing of waste cooking oil with crude and distilled expanded polystyrene (EPS) pyrolysis fractions to obtain liquid products with potential application as fuel blendstock components. Specifically, the work explores the co-valorization of WCO with two aromatic hydrocarbon fractions derived from EPS pyrolysis: crude EPS pyrolysis oil and its distillate fraction. These EPS-derived streams are evaluated as residual hydrocarbon co-feeds for the alkaline-assisted processing of WCO into liquid fuel-like products. The influence of the catalyst loading, WCO-to-EPS-derived fraction mass ratio, and EPS-derived fraction type was analyzed based on the liquid product yield. Furthermore, first-generation vegetable oils were tested under selected conditions to compare their behavior with WCO and assess the applicability of the process to different lipid feedstocks. Finally, the fuel-related properties of the obtained liquid products were evaluated through the density, kinematic viscosity, and heating value, and compared with commercial fuel specifications. The results showed liquid product yields up to 92%, kinematic viscosity values within the range of international fuel specifications under selected conditions, and heating values above 40 MJ/kg. However, the density values indicated limitations for direct use as standalone fuels; therefore, the obtained products should be considered as potential fuel blendstock components requiring further blending and chemical characterization studies. Full article

Plasma polymerization offers a solvent-free route to functional polymer materials, but the structural integrity and accessibility of functional groups in plasma-derived networks remain insufficiently validated. Herein, N-vinylimidazole (NVI) was polymerized using atmospheric-pressure dielectric barrier discharge (DBD) plasma in a liquid-film configuration to generate a chemically heterogeneous poly(N-vinylimidazole)-like material that could be recovered and evaluated in aqueous solution. ATR–FTIR and ¹H NMR spectroscopy indicate substantial vinyl-group consumption with retention of imidazole functionality. Functional behavior was probed using chromium(III) (Cr³⁺) as a model metal ion. UV–Vis spectroscopy revealed systematic changes in the Cr³⁺ d–d transition region (~580–600 nm) with increasing polymer concentration, consistent with ligand-field perturbation arising from interactions with imidazole donor sites. A monotonic increase in absorbance with an increasing ligand-to-metal ratio was observed, followed by plateau behavior at higher ratios, indicating saturation of accessible coordination environments. These results demonstrate that plasma-polymerized material retains chemically accessible imidazole functionalities capable of coordinating transition-metal ions in solution, establishing atmospheric-pressure plasma polymerization as a viable route to functional imidazole-containing materials. Full article

This study presents a comprehensive exergy-based thermodynamic analysis of a standalone liquid air energy storage (LAES) system integrated with internal thermal storage and an Organic Rankine Cycle (ORC) for sustainable large-scale energy storage applications. Unlike conventional studies, this work focuses on providing a scalable design framework by quantifying storage fluid requirements on a per-unit-mass-flow and per-MWh-capacity basis, enabling the results to be generalized for various power outputs and storage capacities. The proposed system configurations with two- and three-stage compression were compared in terms of liquid yield, round-trip efficiency (RTE), exergy efficiency, and storage fluid requirements. Results indicate that the optimal operating pressures are 190 bar for charging and 130 bar for discharging. At 200 bar charging pressure, the liquid yield increases from 0.51 (at 60 bar) to 0.86, while the maximum RTE reaches 62% in the base case and 68% with ORC integration. Incorporating ORC enhances the RTE by approximately 6–7% compared with conventional configurations through improved low-grade waste heat recovery and energy utilization. The two-stage compression configuration with ORC demonstrates the best thermodynamic performance, providing higher exergy efficiency, greater net power output, and lower thermal storage requirements. Furthermore, the reduction in thermal storage fluid demand contributes to improved resource utilization and lower infrastructure requirements for large-scale deployment. Additional sensitivity analyses indicate that thermal losses significantly reduce system performance, whereas ambient temperature fluctuations within ±15 K have only a minor influence on round-trip efficiency and liquid yield due to compensating effects between charging and discharging processes. The findings of this study provide scalable design insights for LAES systems and demonstrate the potential of ORC-assisted LAES technology to support renewable energy integration, sustainable grid flexibility, and low-carbon energy infrastructure development. Full article