Ultra-High-Performance Concrete (UHPC) demonstrates substantial potential in civil engineering applications owing to its superior mechanical characteristics and enhanced durability. The material's exceptional workability and structural adaptability make it particularly effective for thin-layer strengthening of aging concrete structures. Pumping technology has become prevalent in construction operations due to operational efficiency and site adaptability. Existing investigations have documented performance variations in conventional concrete materials under diverse pumping conditions. These studies indicate material-specific response patterns, with post-pumping mechanical properties exhibiting notable disparities across concrete categories. However, the mechanical behavior evolution of UHPC under pumping conditions remains insufficiently explored, particularly given its distinct material composition compared to conventional concrete. This study conducts a controlled experimental investigation to evaluate the mechanical performance variation of UHPC subjected to three transport-casting conditions: non-transported baseline, screw pump transportation, and piston pump transportation. Through systematic comparison of pre- and post-pumping mechanical parameters, the research aims to clarify the pumping-induced performance modifications in UHPC.

With transport methods (direct casting without transport, screw pump transport, piston pump transport), casting directions (random casting, parallel casting, perpendicular casting; Here parallel casting denotes casting along the long axis of prismatic specimens, while perpendicular casting denotes casting perpendicular to this axis), and steel fiber volume fractions (0%, 1%, 2%) as test parameters, 11 specimen groups were fabricated. Each group comprised 4 prismatic specimens for flexural strength testing and 4 cubic specimens (cut from the prisms) for cubic compressive strength testing. During flexural testing, electrical resistance strain gauges with a 20 mm gauge length were bonded to the tensile face of specimens to quantify longitudinal strain development within the pure bending zone prior to crack initiation. High-precision displacement transducers were vertically aligned at mid-span to quantify flexural deflection, complemented by dual auxiliary sensors longitudinally mounted on opposing sides of the specimen's tensile surface to monitor elongation within the pure bending zone. Following mechanical testing, prismatic specimens were longitudinally divided into four sections. Each exposed surface was digitally imaged using high-resolution photographic equipment. Subsequent computational analysis quantified the angular deviation between steel fiber orientations and corresponding cross-sectional normals through dedicated image processing algorithms.

Screw pump transport casting significantly influenced fiber orientation in specimens. Compared with directly cast specimens, at a 1% fiber content, the fiber orientation angle of screw-pumped parallel-cast specimens decreased by 9.8° across the full section, with the orientation coefficient increasing from 0.454 to 0.607; at 2% fiber content, the orientation angle decreased by 10.6°, and the coefficient increased from 0.461 to 0.637. Which indicates that screw pump transport with parallel casting significantly enhances fiber orientation in the mixture, with similar orientation effects across different fiber contents. Piston pump transport had no significant impact on fiber orientation. Compared to direct casting, at 1% fiber content, the piston-pumped parallel and perpendicular casting methods reduced fiber orientation angles by 1.9° and 0.2°, respectively, and increased the orientation coefficients by 5.7% and 0.4%, indicating no obvious fiber orientation occurred during piston pump transport. A significant wall effect was observed in fiber distribution across specimen sections: fiber orientation coefficients at the edges were higher than those in the middle for all specimens, with notable differences across casting methods. The difference in orientation coefficients between edge and middle sections reached 30%-35% for directly cast specimens; this was reduced to 5%-10% for screw-pumped parallel-cast specimens but expanded to 35%-45% for perpendicular-cast specimens; piston-pumped specimens exhibited edge-middle differences of 15%-20%. Compression tests showed that UHPC compressive strength decreased by 2.6%-8% after transport, though the reduction was not significantly affected by pumping method, casting direction, or fiber content—primarily attributed to disturbance of the UHPC pore structure during pumping. Flexural tests revealed that at 1% and 2% steel fiber contents, screw pump transport with parallel casting increased flexural strength by 19.9% and 32.1%, respectively, compared to non-pumped direct casting. Flexural strength of piston-pumped specimens remained similar to direct casting, with differences within 6%.

Based on the test results, the recommended values for the steel fiber orientation coefficient in UHPC under different transport and casting methods are as follows: 0.5 for UHPC with direct casting or piston pump transport-casting, 0.62 for UHPC with screw pump parallel casting, and 0.38 for UHPC with screw pump perpendicular casting. When screw pumps are employed, material placement direction should align with the structure's principal stress direction. No directional constraints are required for piston pump applications. The flexural strength of UHPC under different transport methods and casting directions was predicted using the proposed fiber orientation coefficients, and the predicted results closedly matched the experimental measurements.

Calcium sulfate hemihydrate is widely used in the construction and industrial fields, and its application effect largely depends on its dispersibility. Early studies mostly used anionic polymer dispersants to improve its performance. Later, with the application of polycarboxylate superplasticizers (PCE) in the cement and concrete fields, the exploration of its application in half-water gypsum began. Research shows that the charge characteristics and side chain structure of PCE have a significant impact on its adsorption behavior and dispersibility. Introducing functional groups using strong complexation ability of Ca²⁺ can improve its dispersibility. However, the mechanism of the influence of PCE molecules' adsorption behavior and dispersibility in calcium sulfate hemihydrate paste with high SO₄^2- concentration and weak acidity is still unclear. Therefore, three types of PCE containing carboxyl groups, sulfonic acid groups and phosphate ester groups were synthesized. Through various means, the dispersibility and interface interaction mechanism of these PCE in the calcium sulfate hemihydrate system were systematically studied, providing a theoretical basis for the development of high-performance PCE molecules.

Using MAA, SMAS and HEMAP as the main chains, PCEs containing carboxylic acid groups (PCE-C), sulfonic acid groups (PCE-S) and phosphate groups (PCE-P) were synthesized. The synthesized water reducers were subjected to tests such as PCE molecular structure characterization, gypsum paste test, hardened gypsum performance test, simulated gypsum pore solution test, quantum chemical calculation and molecular dynamics simulation.

Through comprehensive analysis of ¹H NMR spectrum and FTIR spectrum, it can be known that carboxylic acid groups, sulfonic acid groups and phosphate groups were successfully introduced into the three PCEs respectively. GPC showed that the conversion rate of the monomers was above 90%. The performance test of gypsum paste showed that the three water-reducing agents all had dispersing effects on gypsum, among which the dispersing effect and retention effect of PCE-S were the best. After introducing Na₂SO₄ (SS), the influence on the other two water-reducing agents was significant, while PCE-S still showed good fluidity. The water-reducing agents prolonged the setting time of gypsum, while the introduction of SS reduced the setting time of gypsum to a certain extent. PCE-S exhibited better crystal growth regulation ability and had a relatively small impact on the strength of the gypsum hardened paste. The introduction of SS led to a slight decrease in the absolute values of the zeta potential of PCE-S and PCE-P, indicating high adsorption stability in the presence of sodium sulfate. In the adsorption capacity test, PCE-S showed a higher saturated adsorption capacity, and it was least disturbed by SS. The introduction of SS significantly increased the particle size of PCE and broadened the particle size distribution, weakening the electrostatic stability between molecules. The pH titration test showed that PCE-S and PCE-P had higher charge density in the gypsum system. The static charge density distribution of gypsum crystal surfaces showed that the sulfonic acid groups induced obvious electron cloud rearrangement and structural reconstruction on the gypsum surface, and through the "cooperative adsorption effect" induced by surface reconstruction, its macroscopic adsorption capacity and dispersion effect could be significantly enhanced.

The type of PCEs adsorption groups significantly affects its dispersion performance in the calcium sulfate hemihydrate system. PCE-S shows the best improvement in fluidity and resistance to sulfate interference, followed by PCE-P and PCE-C, with the poorest performance. The degree of ionization and apparent charge density of PCE in the calcium sulfate hemihydrate environment play an important regulatory role. PCE-S and PCE-P almost completely ionize at the experimental pH, for both having a higher apparent charge density and enhancing electrostatic adsorption with Ca²⁺ and the degree of molecular unfolding, thereby improving its dispersion stability. The sulfonic acid groups achieve enhanced "cooperative adsorption effect" by inducing significant electronic rearrangement and crystal plane reconstruction on the (001) surface of calcium sulfate hemihydrate, thereby improving its performance in macroscopic adsorption capacity and dispersion properties. Additionally, PCE-S possesses a higher affinity for Ca²⁺, evidenced its stronger complexation capacity and superior competitive adsorption against SO₄^2-. Its increased steric hindrance and high surface coverage further lead to enhanced dispersion efficiency.

Shanxi Province, as one of the regions with the largest accumulation of coal gangue in China, faces an urgent demand for efficient resource utilisation of bulk solid waste to promote regional sustainable development. The rapidly developing 3D printing construction technology, with its precise control over material distribution and the advantage of forming complex components without molds, provides an innovative path for the large-scale consumption of solid waste. Existing research focuses on the application of coal gangue as fine aggregate substitute in printing mortar, while studies regarding its utilisation as coarse aggregate in 3D printed concrete remain unreported. It is vital to reveal the micro/mesoscale mechanisms governing the printability and fracture mechanics behaviour of such concrete material, in order to develop low-carbon coal gangue-based concrete materials and advance their engineering applications. This study innovatively uses coal gangue as a coarse aggregate and combines it with 3D printing technology to produce a novel 3D printed coal gangue concrete (3DP-CC), offering a data foundation and experimental reference for the resourceful and intelligent application of coal gangue.

In the experiment, 3DP-CC specimens were prepared with coal gangue contents of 0%, 10%, 20%, and 40% by mass. Firstly, the printing properties were evaluated, including flowability, buildability, extrudability, and printable time. Flowability was measured using a concrete slump cone in accordance with the JG/T 248 standard. Buildability was assessed through cylindrical slump and layer stacking tests. Extrudability was determined by evaluating the continuity and uniformity of the extruded filaments, with measurements of their width and thickness. Printable time was recorded as the duration over which the mixture could be extruded smoothly and consistently. Secondly, the internal microstructures of the 3DP-CC were examined using high-resolution X-ray CT scanning technology, allowing for the analysis of pore and aggregate characteristics. Finally, uniaxial compression and three-point bending tests were performed to determine the compressive and flexural strengths. The anisotropy index λ was introduced to quantify the directional variation in mechanical strength, followed by an analysis of the underlying mechanisms by which printing direction and coal gangue content influence mechanical properties. Failure modes were examined to highlight the critical roles of weak interlayer and interstrip interfaces, thereby providing further insight into the microscopic mechanisms governing the mechanical anisotropy of 3DP-CC.

The test results indicate that both the compressive and flexural strengths of 3DP-CC exhibit a trend of first increasing and then decreasing with rising coal gangue content, accompanied by notable mechanical anisotropy. At coal gangue contents of 10% and 20%, strength improved significantly while anisotropy was reduced. In contrast, a content of 40% led to a decrease in strength and an increase in anisotropy. These findings suggest that an appropriate amount of coal gangue coarse aggregate can provide skeletal support, thereby enhancing the mechanical performance of concrete and mitigating anisotropic effects. However, when the coal gangue content is too high, the low strength and high brittleness of the gangue itself, combined with an increase in medium and large pores, result in diminished overall strength and greater anisotropy.

Coal gangue content also has a pronounced effect on the pore structure of 3DP-CC, with total porosity initially decreasing and then increasing as the gangue content rises. At coal gangue contents of 10% and 20%, the total porosity of the specimens is 1.8% and 2.1%, respectively—both lower than the 3.9% observed in the control 3DPM. However, the total porosity increases to 3.4% in the 3DP-CC-40 specimens. From a microstructural perspective, the morphology of coal gangue aggregates plays a significant role in this change. The aggregates exhibit rough surfaces and angular shapes, which lead to loose packing and reduced efficiency in filling medium and large pores. Consequently, the number of pores with equivalent diameters greater than 1 mm increases in 3DP-CC-40 specimens. Furthermore, the water absorption capacity of coal gangue affects the internal pore structure of the concrete. As the aggregates absorb water, the moisture content in the surrounding matrix decreases, resulting in increased matrix porosity.

In terms of failure modes, the compressive behaviour of 3DP-CC is strongly influenced by the loading direction. When loading is applied on the x-face, the failure pattern on the y-side face shows cracks initiating at both edges, propagating inward, and then extending vertically downward. These cracks often penetrate the interlayer interfaces, leading to a relatively brittle failure mode. In contrast, loading on the y-face or z-face produces a distinctive "π"-shaped crack pattern on the x-face, accompanied by spalling damage on both sides, indicating that the weak interlayer and interstrip interfaces play a critical role in crack development. The failure mode under three-point bending is also dependent on the loading direction. When the x-face serves as the loading surface, all specimens—regardless of coal gangue content—exhibit through-thickness, straight cracks and undergo brittle fracture into two parts. When the y-face is loaded, through-thickness cracks are absent in specimens with 0% coal gangue but present in those with higher contents. For loading on the z-face, only specimens with 40% coal gangue exhibit through-thickness cracks, while others show no visible cracking on the loading surface. These observations suggest that specimens loaded on the x-face exhibit greater brittleness, with cracks more readily propagating along interstrip interfaces.

The coal gangue content significantly influences the performance of 3D printed concrete (3DP-CC). Optimal mechanical properties—both compressive and flexural strength—are achieved at a coal gangue content of 10~20%, attributed to the skeletal support provided by the gangue particles and the associated reduction in porosity. However, at a content of 40%, both strengths significantly decrease due to the inherent weakness and brittleness of coal gangue, its tendency to induce cracking, and the increase in macroporosity. The pore structure exhibits a non-linear response to coal gangue content: total porosity decreases when the content is below 20%, but rises sharply at 40% as a result of insufficient fine aggregate filling, leading to the formation of numerous large pores. 3D printing introduces directional porosity, with the upper layers exhibiting slightly higher porosity. In addition, pronounced mechanical anisotropy is observed, as quantified by the anisotropy index. Increasing the coal gangue content tends to reduce the anisotropy of compressive strength. In contrast, the anisotropy of flexural strength exhibits a non-monotonic trend: it initially decreases and then increases, reaching a maximum at 40% gangue content. Failure is predominantly governed by weak interlayer and interstrip interfaces, along which cracks consistently propagate under both compressive and flexural loading. Coal gangue aggregates influence crack trajectories—cracks either bypass or penetrate the aggregates depending on local strength fluctuations. These findings offer valuable insights for the design of sustainable 3D printed concrete, emphasizing the importance of optimizing coal gangue content and microstructures to balance strength, anisotropy, and resource utilisation.

With the continuous development of infrastructure in China, the demand for concrete has increased significantly. As a critical raw material in concrete production, sand has also seen a sustained rise in consumption. It is estimated that global annual sand usage ranges between 40 and 50 billion tons. Due to the non-renewable and non-recyclable nature of river sand, its excessive extraction has led to the rapid depletion of existing reserves. To enhance resource efficiency, the construction industry has gradually implemented a variety of mitigation strategies, such as incorporating recycled coarse aggregates into concrete and employing manufactured sand as a substitute for river sand. The use of manufactured sand not only alleviates the environmental degradation caused by overexploitation of river sand but also offers a practical solution to the growing scarcity of this natural resource. Manufactured sand is produced by mechanically crushing and screening rock particles. Compared with river sand, it is characterized by a rougher surface texture and a higher content of stone powder, which can significantly influence the long-term mechanical performance of concrete. Creep, defined as the time-dependent deformation of concrete under sustained loading, plays a crucial role in determining the structural stability and durability. However, existing creep models for concrete have proven inadequate in accurately predicting the creep behavior of manufactured sand concrete. In recent years, machine learning techniques have been increasingly applied to the prediction of creep behavior in recycled aggregate concrete, ultra-high-performance concrete, and concrete incorporating mineral admixtures, demonstrating excellent fitting accuracy and generalization capabilities. Compared with traditional predictive models, machine learning approaches are better suited to handling complex issues such as multi-factor coupling and nonlinear relationships. However, their limitations are also notable: these models often function as "black boxes," lacking physical interpretability, and are highly dependent on the quality and quantity of input data, making it difficult to uncover the underlying physical mechanisms of creep. To address these challenges, some researchers have introduced explainable algorithms to improve model transparency and robustness Simultaneously, other studies have explored explicit modeling techniques to directly generate predictive formulas. Nonetheless, the resulting expressions are often overly complex and lengthy, limiting their applicability in practical engineering scenarios.

To tackle these challenges, a novel modeling framework that integrates both implicit and explicit techniques is proposed. First, a dataset of manufactured sand concrete creep was constructed. Advanced implicit machine learning models, including the Feature Token Transformer, Physics-Informed Neural Networks (PINNs), TabNet, and XGBoost, were employed to predict the creep behavior of manufactured sand concrete. Feature importance analysis was subsequently conducted based on model outputs to identify the most influential variables. Next, AutoFeat was used to automatically generate and select polynomial features from the identified key variables, thereby constructing a high-order explicit model capable of achieving accurate creep prediction. Furthermore, neural symbolic regression (NSR) was introduced to automatically discover nonlinear relationships among variables through symbolic function composition, yielding concise, physically meaningful analytical expressions.

Existing concrete creep prediction models, when applied to manufactured sand concrete, exhibit substantial errors due to their inability to effectively capture the material-specific characteristics and time-dependent behavior. This highlights an urgent need for the development of more targeted and robust predictive models.

The constructed implicit machine learning models—TabNet, FT-Transformer, PINNs, and XGBoost—demonstrated excellent predictive performance. These models effectively capture the complex and nonlinear relationships between the creep behavior of manufactured sand concrete and various influencing factors.

Explicit prediction models for concrete creep compliance were developed based on two approaches: AutoFeat and Neural Symbolic Regression (NSR). Both methods successfully generated functional expressions that map input parameters to the target output, thereby enhancing model interpretability. The AutoFeat-based model combined SHAP-based feature importance analysis with Pearson correlation analysis during feature selection, ultimately yielding an interpretable model primarily composed of first-order linear terms, complemented by selected second- and third-order interaction terms. In contrast, the NSR method exhibited a superior capacity for capturing nonlinear dependencies. It automatically identified key variables and constructed complex mathematical formulations characterized by nested structures and nonlinear operator combinations, providing deeper insight into the underlying mechanisms governing creep development.

Under comparable levels of predictive accuracy, both AutoFeat and Neural Symbolic Regression are capable of generating explicit expressions with clear mathematical structures, significantly enhancing model interpretability. Despite differences in feature selection strategies and model architectures between implicit and explicit modeling approaches, both demonstrate strong fitting performance with respect to real-world data, thereby validating the feasibility of modeling concrete creep through multiple methodological pathways. The integrated application of both approaches facilitates an optimized balance between predictive accuracy and interpretability.

Rechargeable lithium-ion batteries (LIBs) are critical energy storage devices widely used in smartphones, electric vehicles, and hybrid vehicles due to their high efficiency and versatility. Spinel LiMn₂O₄ stands out as a promising cathode material owing to its eco-friendliness, safety, and cost-effectiveness. However, its practical application is limited by rapid capacity fading during cycling, especially under high current densities or elevated temperatures (55 ℃), caused by Jahn-Teller (J-T) distortion, Mn³⁺ dissolution, and oxygen defects. To address these issues, doping LiMn₂O₄ with elements like Al³⁺, B³⁺, Ni²⁺, or Mg²⁺ is a common strategy to stabilize Mn's average oxidation state (+3.5) and suppress J-T distortion. Concurrently, crystal facet engineering optimizes performance: truncated octahedral particles with dominant (111) facets (low surface energy, dense Mn packing) minimize Mn dissolution, while (100)/(110) facets enhance Li⁺ mobility for improved rate capability. Combining doping and facet control has emerged as a key research focus. For instance, B-doped LiMn_1.96B_0.06O₄ exhibited 110.3 mA·h·g^-1 at 5.0 C with 51.8% capacity retention after 2000 cycles, outperforming undoped LiMn₂O₄. Ni—B co-doping further refined morphology and boosted retention to 70.6%. Similarly, Mg—Al co-doped LiMg_0.03Al_0.10Mn_1.87O₄ retained 76.2% capacity after 1000 cycles at 10.0 C, while Zn—Al doping achieved 70%-75% retention over 2000 cycles. These studies highlight how doping regulates crystal growth, favoring truncated octahedral morphologies with balanced stability and kinetics. Building on this, our work synthesizes LiB_0.08Al_yMn_1.92-yO₄ (y=0.01, 0.02, 0.04, 0.06, 0.08) via solid-state combustion to study Al doping's impact. Results reveal that Al content modulates facet growth: low doping levels yield two-facet (111/100) truncated octahedrons, while higher doping introduces (110) facets, ultimately leading to quasi-spherical particles. This controlled facet producing strategy is designed to optimize structural stability and electrochemical performance for advanced LIBs.

LiB_0.08Mn_1.92O₄ and LiB_0.08Al_yMn_1.92-yO₄ (y=0.01, 0.02, 0.04, 0.06, 0.08) were synthesized by stoichiometric mixing of Li₂CO₃, H₃BO₃, MnCO₃, and Al(OH)(CH₃COO)₂ (total 30 g) with 1.5 g citric acid as a combustion agent. The mixture was ball-milled in ethanol for 10 h, dried, and calcined at 500 ℃ for 1 h. After grinding, it was sintered at 650 ℃ for 6 h. Products were labeled as B_0.08 and B_0.08Al_y. Cathode slurry was prepared by blending active material, carbon black, and PVDF (8∶1∶1) with NMP solvent, followed by 30 min ball milling. The slurry was coated onto Al foil, dried at 80 ℃ for 4 h, and cut into 14 mm discs (active material loading: about 1.0 mg/cm²). CR2032 coin cells were assembled in an Ar-filled glovebox using Li metal anode, LiPF₆ electrolyte (1.0 M in EC/DMC/EMC), and Celgard 2320 separator. Material phases were analyzed via XRD (Cu K_α, 10°-80°). Morphology and microstructure were examined by FE-SEM and TEM. Surface composition and valence states were determined via XPS. Electrochemical tests (Land CT2001A) included cycling (25/55 ℃, 3.0-4.5 V) and rate performance. CV and EIS were conducted using a CHI604D workstation.

XRD analysis confirmed that B_0.08 and B—Al co-doped samples crystallized in the spinel LiMn₂O₄ structure (). B—Al co-doping enhanced crystallinity, with diffraction peaks intensifying until y(Al)≥0.06, beyond which crystallinity declined. A lattice contraction was observed via (400) peak shifts, attributed to smaller B³⁺/Al³⁺(0.0400/0.0535 nm) replacing Mn³⁺(0.0645 nm) and shorter B/Al—O bonds, suppressing J-T distortion. SEM revealed that B—Al co-doping refined particle uniformity and morphology: B_0.08Al_0.02 exhibited truncated octahedral single-crystals with high (111) and minor (100)/(110) facets, while higher Al content (y≥0.04) led to spherical polyhedrons due to reduced facet growth rates. TEM/SAED confirmed improved crystallinity for B_0.08Al_0.02, with distinct lattice fringes (0.476 nm for (111)) and ordered diffraction patterns. XPS verified B³⁺/Al³⁺ incorporation and a higher Mn⁴⁺ ratio (B_0.08Al_0.02∶ Mn³⁺/Mn⁴⁺=47.29%/52.71%), stabilizing the Mn—O framework. Electrochemical tests demonstrated superior performance for B_0.08Al_0.02∶ At 5.0 C, it retained 83.9% capacity after 500 cycles (vs. 71.3% for B_0.08) due to suppressed Mn dissolution and enhanced Li⁺ transport from truncated octahedral morphology. High-rate testing (15.0 C, 20.0 C) showed B_0.08Al_0.02 retained 77.2% capacity after 500 cycles, outperforming B_0.08 (58.2%). Elevated-temperature (55 ℃) cycling revealed B_0.08Al_0.02 maintained 70% capacity retention (200 cycles), attributed to reduced side reactions and structural stability. CV and EIS confirmed faster Li⁺ diffusion (D_Li⁺: 3.14×10^-11 cm²·s^-1) and lower charge-transfer resistance for B_0.08Al_0.02. Kinetic analysis showed a lower activation energy (24.76 kJ/mol vs. 28.53 kJ/mol for B_0.08), indicating an enhanced reaction kinetics.

B—Al co-doped LiB_0.08Al_yMn_1.92-yO₄ (y=0.01, 0.02, 0.04, 0.06, 0.08) cathode materials were synthesized via solid-phase combustion. B—Al co-doping enhanced crystal growth and facet evolution: particles transitioned from truncated octahedrons with two facets (111, 100) to those incorporating (111), (100), and (110) facets as Al content increased. At y(Al)≥0.04, spherical-like polyhedrons dominated. The optimized LiB_0.08Al_0.02Mn_1.90O₄ (B_0.08Al_0.02) exhibited superior crystallinity and well-defined truncated octahedral single-crystals. B_0.08Al_0.02 demonstrated exceptional rate capability and cycling stability. At 1.0 C, 5.0 C, 10.0 C, 15.0 C, 20.0 C, and 55 ℃/5.0 C, initial discharge capacities reached 114.7, 102.8, 86.3, 82.6, 75.3, and 107.4 mA·h·g^-1, respectively. After 500 cycles, capacity retention rates were 83.9% (5.0 C), 81.9% (10 C), 90.3% (15.0 C), 77.2% (20.0 C), and 62.0% (55 ℃/5.0 C), outperforming other samples. CV and EIS analyses demonstrated superior electrochemical properties for the B_0.08Al_0.02, including a higher Li⁺ diffusion coefficient (3.14×10^-11 cm²·s^-1), a lower apparent activation energy (24.76 kJ/mol), and a reduced charge-transfer resistance (114.2 Ω). These results indicate enhanced Li⁺ transport kinetics and improved structural stability.

Polypropylene (PP) separators are widely used in lithium-ion battery (LIBs) separators due to their excellent mechanical properties, high resistance of electrolyte corrosion, superior ionic permeability, easy processability, and low cost. However, PP separators have poor affinity with electrolytes and lack the function of inhibiting lithium dendrite growth, which limits the performance of LIBs. In this paper, polypropylene/polydopamine (PP-PDA_x) composite separator was rapidly prepared by solution polymerization under the catalytic action of sodium periodate (SP), and its properties were systematically studied. The results show that when the modification time is 4 h and the deposition amount of PDA nanoparticles is 0.075 mg·cm^-2, that is, the PP-PDA₄ separator has the maximum electrolyte absorption rate of 324%, the contact angle drops to 9°, and it also exhibits the best electrochemical performance with an ionic conductivity of 0.51 mS·cm^-1. When a LiFePO₄/PP-PDA₄ separator/Li coin-type battery is assembled, the discharge capacity can still remain at 113.9 mAh·g^-1 after 100 cycles at 1C. In addition, the PP-PDA₄ separator shows a remarkable ability to inhibit lithium dendrite growth.

1.2 g of Tris was dissolved in deionized water, and adding hydrochloric acid solution to adjust pH to 8.5 dissolved a certain amount of dopamine hydrochloride in the prepared Tris buffer solution. The polypropylene separator was rolled into a column and immersed in the solution for 5 min to make the surface of the polypropylene septum was evenly wetted on separator. Added Sodium periodate to the solution and fully steep for 2, 4 h, and 6 h. After that, PP-PDA_x separators were be obtained after drying.

In this paper, the optimal sample is PP-PDA₄ that the polydopamine deposition is 0.075 mg·cm^-2, PP separator as a control group. PP-PDA₄ electrolyte contact angle decreased 82% to 9°, the tensile strength increased from 101 MPa to 110 MPa. And tested the separators electrochemical performance, the ionic conductivity increased from 0.26 mS·cm^-1 to 0.51 mS·cm^-1. Introduced positive and negative electrode materials to assemble the full cell, and the discharge specific capacity of PP-PDA₄ was the highest, which was up to 128.2 mAh·g^-1, and tested the rate performance of the full cell in the range of voltage from 2.5 V to 4.2 V, and the current density from 0.2 C to 2C. the discharge capacity of PP-PDA₄ is increased by 9%, 17%, 30%, and 9% compared with PP at 0.5, 1, 2 C, and 0.2 C. Finally, assembled Li/separator/Li batteries to evaluated the ability of PP-PDA₄ to inhibit lithium dendrites, and PP-PDA₄ could work stably for 400 h and maintain at a lower voltage polarization. Meanwhile, the SEM photographs of the lithium film after cycling showed that the lithium deposition was more uniform.

In summary, PP-PDA_x separator were synthesized rapidly via solution polymerization catalyzed by SP. This strategy exploits the intrinsic properties of PDA to enhance the affinity between the separator and the electrolyte, thereby markedly improving electrochemical performance and concurrently inhibiting lithium dendrite formation. Under the catalytic effect of SP, the optimum modification time is only 4 h. This treatment not only improves wettability but also significantly boosts electrochemical performance, without compromising the separator's integrity.

As the depth of resource exploitation in our country increases, power shock disasters occur frequently in underground engineering, which will severely restrict the rapid development of the economy. In the process of strengthening the foundation with fly ash concrete, the strengthened body not only bears static loads but also dynamic loads, forming initial defects such as joints and cracks inside. The development, extension, and penetration of cracks under dynamic loads will further reduce the stability of the strengthened structure. Therefore, it is urgent to deeply study the mechanical properties of fly ash concrete with cracks under dynamic loads.

Dynamic impact tests were carried out with the split Hopkinson pressure bar (SHPB) test system on the samples with different fracture angles. Digital image correlation system (DIC) was used to monitor the deformation of surface strain. Characteristics of the samples with different fracture angles after dynamic impact were compared and analyzed including the dynamic strength, energy dissipation and fractal fracture.

The results show that with the increase of the crack angle, the peak stress-strain presents a typical V-shaped pattern, reaching the minimum value at 30°. With the increase of fracture angle, the initial damage zone also moved from the fracture tip to the middle of the fracture, and then the damage range gradually expanded until the formation of macro failure. The failure modes are tensile failure (0°), shear failure (30°), tension-shear mixed failure (45° and 60°) and collapse failure (90°), respectively. The dissipated energy of the sample firstly increase and then decrease with the increase of the fracture angle, reaching the maximum value at 30°. The process of energy accumulation and transformation in fractured rock mass is characterized by the strain energy density. With the increase of the crack angle of the sample, the fractal value of the sample first increases and then decreases, and reaches a maximum value at 30°, indicating that a higher degree of sample breakage associated with dissipates relatively large energy. Based on fracture mechanics, the analytical solution of stress around the crack is given, and the variation of crack initiation angle, stress distribution and energy dissipation under different crack angles is theoretically explained, which is in good agreement with the experimental measurements.

This paper uses the SHPB and DIC systems to conduct dynamic impact tests on specimens with cracks at different angles, and compares and analyzes the dynamic strength, energy dissipation, and fracture fractal characteristics of specimens with different crack angles after dynamic impact, and gives the theoretical results of the stress around the crack. To provide some theoretical support for the deformation control of cracked concrete mixed with fly ash under dynamic action.

Crystallization control is crucial during glass production. In glass crystallization theory, it has been hypothesized that there is a direct relationship between glass-crystal interfacial energy and nucleation rate. Since it is difficult to measure interfacial energy directly, classical nucleation theory is used to obtain it. However, the estimation process is complex; various measurement data such as the nucleation rate, viscosity, and Gibbs free energy barriers between the glass and crystal are required. Overall, estimating the glass-crystal interfacial energy is time-consuming. In this regard, the interfacial energy can be directly obtained using molecular dynamics (MD) simulations. In this study, we implemented an interface model to estimate the glass-crystal interfacial energy based on the theory of Tielemann et al., which was recently introduced to generate crystal orientation planes using minimum-energy cuts. To the best of our knowledge, this is the first work in which the crystal orientation plane determined based on a minimum-energy cutting process has been used to build a glass-crystal interface in a more realistic environment (i.e., hypothesizes that a minimum-energy structure may occur during crystal nucleation) and calculate the interfacial energy. To achieve this, we considered stoichiometric alkali (Li, Na, and K) disilicate (2SiO₂) glasses and crystals, as some early-stage experimental data have been reported, which are highly beneficial for validating the MD results. The effects of different potential models were also investigated and found that they had a significant impact on the reproduction of the experimental trend.

Simulations were performed using the LAMMPS package. The temperature and pressure were controlled with the Nose-Hoover thermostat and barostat, respectively. After setting up the glass-crystal interface using NPT, we ran MD simulations with NVT for another 200 ps to calculate the interfacial energy. The MD simulations were performed with a time step of 1 fs. Periodic boundary conditions were applied in all directions. Cutoff distances were applied according to references. We used three interatomic potential (SHIK, Du, and Pedone) models to estimate the interfacial energies of Li₂O-2SiO₂ glass-Li₂O-2SiO₂ (001), Na₂O-2SiO₂ glass-Na₂O-2SiO₂ (010), and K₂O-2SiO₂ glass-K₂O-2SiO₂ (001). All three of these potential functions are widely used. The glass structure was fabricated from the crystal structures by simulating a melt-quenching process. First, the Li₂O-2SiO₂ (001), Na₂O-2SiO₂ (010), and K₂O-2SiO₂ (001) crystal structures were prepared. Half the crystal was kept fixed, while the other half was melted at 3500 K with a canonical ensemble (NVT) for 300 ps and then quenched to 300 K at a cooling rate of 5 K/ps. After the melt-quenching process, the crystal part was unfixed and relaxed for 200 ps with a glassy structure using an isobaric-isothermal ensemble (NPT) at a temperature of 300 K. An interfacial model was developed by the theory of Tielemann et al, where the crystal plane was determined through the minimum energy cut in the crystal structure.

We first evaluated the glass density by calculating the local density profile along the z-direction of Li₂O-2SiO₂ glass-Li₂O-2SiO₂ (001), Na₂O-2SiO₂ glass-Na₂O-2SiO₂ (010), and K₂O-2SiO₂ glass-K₂O-2SiO₂ (001). The glass structures show density results comparable to the experimental data.

The calculated interfacial energy values using the SHIK potential show a similar experimental trend, while the Du and Pedone potentials are unable to reproduce the experimental trend. However, the potentials of Du and Pedone show better values of interfacial energy for the glass-crystal interface of Li₂O-2SiO₂ than the SHIK. Our MD results demonstrate that among the potential models, SHIK is a good candidate for calculating interfacial energy in terms of experimental reproduction.

We analyzed the interfacial coordination number (i.e., cation-anion) in the contact area between the glass and crystal surfaces. These coordination numbers are difficult to estimate experimentally. Typically, the coordination number is determined in the bulk region of a glass or crystal structure. We found that the interfacial coordination number varies significantly at the glass-crystal interface of Li₂O-2SiO₂, Na₂O-2SiO₂, and K₂O-2SiO₂. Among the interfacial systems, coordination number values of two, three, four, and five were observed, the most frequently observed value was one. The values were significantly lower at four and five for K₂O-2SiO₂ and Na₂O-2SiO₂, respectively. Our MD results demonstrated that the cation (Li, Na, and K)-anion environments were not the same in the interfacial domain. For further evaluation, we calculated the bond strength-coordination number.

The bond strength-coordination number has been reported for chalcogenide glasses. In the present work, the bond strength-coordination number is introduced for glass-crystal interface systems. The calculated results of bond strength-coordination number show a decreasing trend in the order Li > Na > K, which is similar to interfacial energy. Overall, analysis revealed that the alkali (Li, Na, and K)—O bond plays a crucial role in the interfacial strength.

We developed an interface model using molecular dynamics simulations based on the minimum energy cut of crystals with glassy structures. The minimum energy cut of the crystal was determined by applying Tielemann theory. The modeled interfaces were between glass and crystals in stoichiometric alkali (Li, Na, and K) disilicates. The interface model reproduced the experimental interfacial energy trend of Li > Na > K; the interatomic potential model was found to have a significant effect on reproduction. The MD results indicate that the SHIK-based MD model could reproduce the experimental results better than the other potential models. In addition, the interfacial coordination number was also calculated, which varies depending on the alkalinity of Li, Na, and K. Using the interfacial coordination number, the bond strength-coordination number was estimated, and found that the interfacial energy trend Li > Na > K is related to the bond strength-coordination number.

Solid oxide fuel cells (SOFCs) are considered as a leading candidate for clean energy conversion due to their high efficiency and flexibility. Yttria-stabilized zirconia (YSZ) serves as an electrolyte material in SOFCs due to its high ionic conductivity and mechanical stability at a high operating temperature. However, the long-term stability of YSZ can be impaired via the cubic-tetragonal (c-t) phase transformation. This transformation leads to a decrease in ionic conductivity and mechanical integrity, which contributes to an overall degradation of SOFC performance. Despite its importance, most of the previous investigations primarily focused on electrochemical degradation mechanisms, while less attention was paid to the material stability of YSZ, especially at the Ni-YSZ interface. For instance, the atomic diffusion of Ni into YSZ during sintering can accelerate the phase transformation, leading to a significant decrease in ionic conductivity within 100 hours. Despite these findings, there is a lack of comprehensive quantitative analysis on the kinetics and morphological impacts of the c-t phase transformation at the Ni-YSZ interface. Moreover, the existing models often oversimplify an interplay between phase transformation and mechanical stress, restricting their ability to predict a long-term degradation behavior accurately. In this work, the phase field method was applied to simulate the c-t phase transformation in YSZ at the Ni-YSZ interface for elucidating its effect on the interface morphology and gaining insights into the SOFC degradation mechanisms.

A 3D microelastic phase field model was proposed to investigate the c-t phase transformation in YSZ. The evolution of both conserved and nonconserved order parameters were governed by the Allen-Cahn and Cahn-Hilliard equations, respectively. The total free energy was constructed under multiphysics coupling. The elastic constants for cubic YSZ and tetragonal YSZ were defined based on their respective crystal structures, with the values assigned to reflect their distinct mechanical properties. The misfit strain was determined using the lattice parameters for the cubic and tetragonal phases. The simulations were performed on a 64×64×64 voxel grid representing a single-crystal YSZ. The governing equations could be solved by the Fourier spectral method and a semi-implicit time-stepping scheme. The shape of the nucleus distribution was restricted to the YSZ surface to ensure a realism under SOFC operating conditions.

In this work, a dense YSZ disk with a diameter of 24 mm and a thickness of 0.5 mm was served as a substrate. After mechanical polishing and ultrasonic cleaning in acetone and ethanol, a stainless-steel shadow mask was employed to perform two perpendicular magnetron-sputtering depositions, producing a continuous Ni patterned film anode with a thickness of approximately 1 μm. For the cathode, a Pt paste was screen-printed onto the opposite side of the YSZ substrate. The discharge tests of the SOFC were carried out in a custom-designed alumina reaction chamber. Humidified 97% H₂ was supplied to the anode and pure O₂ to the cathode, both at a fixed flow rate of 50 mL_·min^-1. The cell was polarized at 0.7 V for 100 h. After testing, the Ni film was mechanically peeled off, regions where Ni detached were selected and the underlying YSZ surface morphology was examined by scanning electron microscopy (SEM).

The phase field simulations reveal that tetragonal variants preferentially nucleate at near the Ni-YSZ interface. High stresses appear at around the Ni-YSZ interfaces with the development of the t-variants. At certain iterations, high local stresses of exceeding 2 GPa can occur, leading to a radial growth of the variants into the bulk. A significant morphological evolution occurs, forming ridge structures along the YSZ surface and submicron pores in the interior at near the Ni-YSZ interface. The agreement between simulation data and experimental results confirms that the c-t phase transformation causes these morphological evolutions. The formation of pores is particularly detrimental as it disrupts the ion conduction pathways and weakens mechanical stability of YSZ, which can be correlated to the degradation of the SOFC performance.

In this work, a phase field modeling was used to simulate the c-t phase transformation in YSZ at the Ni-YSZ interface in SOFC anodes. The simulations accurately reproduced the morphological evolutions during long-term operation of SOFC, i.e., the formation of surface ridges and internal submicron pores, providing important insights into the SOFC degradation mechanisms. The preferential nucleation of tetragonal variants at the surface and stress-driven void formation could highlight some key factors affecting interface stability. Although the simulations were conducted based on a single crystal, this work could lay a foundation for future research on polycrystalline and porous YSZ substrates. This work could indicate strategies for improving SOFC durability, such as optimizing material compositions or designing stress-relieving structures via identifying stress generation as a primary driver of degradation. The findings of this work could contribute to advancing SOFC technology towards sustainable and efficient energy solutions.

Although artificial intelligence has a great potential in the field of flat glass, there are still some technical challenges and application bottlenecks, such as data quality, process complexity, dependence on professional knowledge, and talent shortage. In the future, it is necessary for the enhanced practicality and reliability of artificial intelligence technology in the complete production chain of flat glass to further strengthen the application research of artificial intelligence technology in practical scenarios such as formula adjustment, performance prediction, production process control, defect detection, logistics and warehousing of flat glass, solve the problems encountered in the process of technology implementation, and improve the connectivity of data and adjustment solutions between various production links. Meanwhile, it is important for the increasing application of artificial intelligence in the field of flat glass to establish unified industry standards and specifications. In the future, artificial intelligence will develop in the field of flat glass towards technological breakthroughs and innovation, as well as the expansion and deepening of application scenarios, thus promoting the integration of technological innovation and industrial transformation in the flat glass industry.