Thermal energy storage (TES) is a key enabler for the large-scale utilization of intermittent renewable energy sources like solar and wind power, and it also offers an efficient pathway for industrial electrification and decarbonization. However, the widespread adoption of TES is hindered by the high cost of conventional TES materials, such as alumina, magnesium oxide, and other ceramics. This study investigates the feasibility of converting coal gangue, an abundant industrial waste with considerable environmental impact, into a low-cost, mechanically stable, and thermally efficient material for medium-to high-temperature sensible heat storage applications. Three representative coal gangue samples from the Ordos region in Inner Mongolia, China, were calcined at temperatures ranging from 1000 to 1300 ℃ to optimize their phase compositions, mechanical strengths, and thermophysical properties. Among the samples, Sample A from Jungar exhibited the best overall performance, achieving a volumetric heat storage density of approximately 555 kWh m⁻³ at 1200 ℃, which is comparable to typical sensible heat storage materials, while maintaining good mechanical integrity and satisfactory cyclic stability. With near-zero raw-material cost, a simple single-step preparation process, and potential policy incentives for solid-waste utilization, the coal-gangue-based composites developed here offer clear economic and environmental advantages and introduce a promising, low-cost material system for sustainable TES applications at medium-to high-temperature levels.

Hydrogen generation during thermal runaway significantly elevates the risk of explosive combustion in lithium-ion batteries. Although hydrogen generated from binders constitutes a minor fraction, its absolute quantity remains substantial in large-scale stationary energy storage systems. Moreover, binder decomposition occurs during the later stages of thermal runaway with rapid reaction rates, further raising the danger level. Herein, graphite anode with polyacrylonitrile binder is in situ cyclized to eliminate the active hydrogen, while maintaining superior cohesiveness. On one hand, cyclized polyacrylonitrile with largely reduced hydrogen atoms can prevent binder-induced hydrogen generation and realize a reduction of hydrogen fraction by over 23%. As the three-dimensional cross-linking binders increase the thermal stability of anodes, the peak decomposition temperature of solid electrolyte interphase is increased from 150 to 200 ℃ to above 200 ℃, while the peak reaction temperature between lithiated graphite and the electrolyte is delayed by at least 15 ℃. On the other hand, the transformation from linear to cyclic molecular structures of cyclized polyacrylonitrile enables uniform and tight encapsulation of graphite and enhanced cohesiveness. Capacity retentions of 97% after 200 cycles in half cells and 72% after 800 cycles in full cells are achieved.

Hard-sphere/pseudo-particle modeling (HS-PPM) provides a parallel and more versatile implementation of molecular dynamics simulation based on hard-sphere model at large scales with remarkable performance. For more practical applications, however, more sophisticated and realistic boundary conditions have to be incorporated. In this work, the artifact of inlet-outlet coupling due to periodic boundary is basically eliminated by adding collisions at both ends and proportional-integral-differential (PID) control of density at the outlet based on implicit boundary conditions, maintaining reasonable flow field there for both high (up to 13.0) and low (down to 0.0) Mach numbers. Moreover, geometrically complex boundaries are approximated by a large number of polygonal (in particular, triangular) elements, instead of exact analytical descriptions, to balance the accuracy and efficiency. Given the challenges of nanoscale experimentation, the drag coefficients from simulation conducted at matching dimensionless numbers were compared with macroscopic results. With these improvements, the flow around a conical particle and the Inflatable Re-entry Vehicle Experiment (IRVE) was successfully simulated and demonstrated consistent to experiment and numerical results from direct simulation Monte Carlo (DSMC) towards the continuum flow limit (with the Knudsen number ranging from 0.1 to 1.7). Furthermore, the drag coefficient of nano-particles in fluid flow, which is challenging for experimental measurement, was obtained from simulation results, and the potential of HS-PPM in simulating particles and systems with complex structures is exemplified by the gas flow and diffusion in porous micro/nano-particles.

This study employs a benchmarked Discrete Element Method model to investigate the influence of particle shape on the compressibility behavior of granular assemblies within a controlled comparative framework. Twenty idealized particle geometries with different shape characteristics were analyzed under constrained compression at vertical stress levels ranging from 0.1 to 3.2 MPa. Macro- and micro-scale responses were evaluated using constrained modulus and average coordination number, together with additional contact-scale analyses to improve the interpretation of particle-scale behavior. The results indicate that both macro- and micro-scale responses remain strongly stress-dependent, suggesting that conventional indicators alone cannot fully isolate particle-shape effects. A stress-normalized scaling approach was therefore applied to reduce the dominant influence of stress and clarify geometry-related trends. The analyses demonstrate that increasing particle irregularity promotes denser contact networks, redistributes contact forces across more contacts, and alters local deformation mechanisms. The findings provide a comparative DEM-based assessment of shape-dependent compressibility and contact-scale force-deformation behavior in idealized granular assemblies.

Inertial migration of a neutrally buoyant rigid sphere in circular Poiseuille flow is strongly affected by particle rotation, yet its role remains poorly understood. This study employs three-dimensional fully-resolved CFD-DEM simulations to investigate inertial migration with and without particle rotation. The model is validated against experimental equilibrium radial positions. Simulation results reveal that suppressing rotation consistently shifts the equilibrium radial position toward the pipe centerline, but rotation's effect on the migration dynamics depends on the sphere's initial radial position. When rotation is suppressed, radial migration accelerates for the sphere released near the pipe wall, whereas radial migration slows for the sphere released closer to the centerline. While the freely rotating spheres experience a transition between different migration regimes as the sphere-to-pipe diameter ratio or the fluid Reynolds number increases, non-rotating spheres remain in the monotonic regime since they stabilize closer to the pipe centerline where both shear-gradient and wall-induced lift forces vanish. Moreover, suppressing rotation increases the entry length required for the sphere to achieve full migration. This study elucidates how particle rotation affects inertial migration and offers new insights into rotation-modulated lateral migration in microfluidics.

Developing sustainable dielectric ceramics with high energy storage performance under a moderate electric field is still a great challenge for the next generation pulse power capacitors. Herein, recycled photovoltaic waste glass (PVWG) was added into Bi₀.₅Na₀.₅TiO₃ (BNT)-based lead-free ceramics via a conventional solid-state route and sintered at 1120 ℃ for 2 h. The PVWG additive facilitated liquid-phase sintering, reduced porosity, promoted grain-boundary homogeneity and improved the dielectric breakdown strength. Therefore, the optimized BNT-08 ceramic exhibits a high relative density of 97.04 ± 0.15 %, a reduced remanent polarization (P_r) of 9.4 ± 0.3 μC cm⁻², an increased breakdown strength (E_b ~220 ± 5 kV cm⁻¹) and a significantly slimmer P-E hysteresis loop. Hence, a recoverable energy density (W_rec) of 1.76 ± 0.07 J cm⁻³ and an energy storage efficiency of 78 ± 2 % were obtained under a moderate electric field at 220 kV cm⁻¹. The enhanced energy storage performance was ascribed to the synergistic effects of structural stabilization, defect-regulated charge transport, and PVWG-induced microstructural refinement. This simple, low cost and environmentally friendly method demonstrates PVWG as a promising multifunctional additive for electroceramic applications in line with the circular strategy.

Although negative pressure crystallization of ammonium sulfate can mitigate low yield and long processing time in atmospheric pressure crystallization, it still faces challenges in enhancing crystallization efficiency and achieving a uniform crystal size distribution. To address these issues, this study proposed an ultrasound-assisted negative pressure crystallization technique. Under optimized conditions (pH = 7, 300 rpm, 80 ℃, 45 min, 180 W, 0.03 MPa), the yield increased by 27.64 g and the direct yield improved by 36.80% compared with negative pressure crystallization. XRD and FTIR confirmed that this process maintained the crystal structure of ammonium sulfate while enhancing crystallinity. Mechanistic studies revealed that, compared with negative pressure crystallization, the synergistic effect of ultrasound narrowed the metastable zone width (MSZW) by approximately 33%, lowering the nucleation energy barrier. Ultrasound cavitation generated numerous bubbles, providing heterogeneous nucleation sites and localized supersaturation driving forces, which jointly accelerated nucleation and reduced the solid-liquid transition time by 35.7%. Furthermore, compared with the negative pressure crystallization system, the ultrasonic negative pressure crystallization reduced the solution viscosity by 5.7%, enhancing mass transfer and crystal growth. Ultimately, ultrasound-assisted negative pressure crystallization produced crystals with more uniform size and more regular morphology, offering important theoretical insights for improving ammonium sulfate crystallization processes.

Sinkholes, a common geotechnical failure, have been reported more frequently in recent years due to complex climate change and urbanisation. This study investigates mechanisms of sinkhole development, considering the influence of triggering depth and compaction degree through experiments integrated with Particle Image Velocimetry (PIV) technique and Discrete Element Method (DEM). Laboratory tests simulating the formation of sinkhole in subgrade soil are carried out under varying triggering depths and void ratios, where the soil displacement is recorded over time. DEM simulations are performed and validated against the experimental results analysed by PIV technique. The results show good agreement between DEM and experimental investigations, especially in capturing time-dependent stages and displacement fields of sinkhole development. Furthermore, the numerical investigation indicates that increasing the triggering depth results in later development of sinkhole with greater vertical displacement around the triggering point to promote its propagation towards the ground surface. Interestingly, dense soil exhibits highly localised mobilisation confined within well-defined displacement boundaries, whereas loose soil displays a wider displacement zone characterised by a funnel-shaped pattern. The interparticle contact behaviour further releases the insightful mechanism of sinkhole progression, giving considerable value to our understanding and prediction of this catastrophic failure.

This paper develops a computational framework coupling a moisture-induced cohesive force model with the Coarse-Grained Discrete Element Method (CG-DEM) to efficiently and accurately simulate the mixed discharge process of wet coal in a laboratory-scale three-dimensional silo. The moisture-induced cohesive force model quantifies the effect of moisture on coal flowability by correlating moisture content with macroscopic mechanical parameters of the particles (cohesion, internal friction angle). Simulation results indicate that particle flow exhibits a significant central-channeling "funnel flow" characteristic, and the flow structure is dominated by the flowability of the lower coal layer. The moisture-induced cohesive force is a key factor controlling particle motion. The study further reveals the decisive influence of stacking sequence on the evolution of outlet coal quality: when the lower layer consists of high-moisture, poor-flowability Indonesian coal, the outlet calorific value shows a slow rising trend; conversely, when the lower layer consists of good-flowability Longwanggou coal, the outlet calorific value decreases rapidly. This research provides a reliable, low-cost numerical tool for understanding and predicting the discharge and mixing behavior of wet coal in industrial silos, offering guidance for optimizing coal blending and stabilizing the quality of feed coal.

The road performance of recycled asphalt pavement (RAP) is crucial for low-carbon road construction. However, existing studies lack refined simulation of the mesostructure involving RAP, new aggregates, aged asphalt, and new asphalt, leaving the effects of different RAP contents on stress distribution and damage mechanisms unclear. This study develops discrete element models to analyze the influence of RAP content on mesoscopic stress evolution, crack propagation, and aggregate breakage. The results show that when RAP content exceeds 45%, aged asphalt and RAP exhibit notably non-uniform distributions. The maximum normal stress occurs at the loading center, while the maximum shear stress is located at the bottom sides of the loading center. As RAP content rises from 15 % to 60 %, the number of effective microcracks increases by 2.04 times. The length and area of slip-bands grows rapidly, and the crack damage index D follows an exponential upward trend. Considering rutting resistance, crack resistance, and resource utilization efficiency comprehensively, the recommended suitable RAP content range is 30 % - 45 %, with the following threshold values: number of slip-bands≤8, average length of slip-bands≤48 mm, and D ≤ 7.5 %. The findings provide a theoretical basis for understanding the meso-mechanical behavior of recycled asphalt mixtures.