Jie Li

Understanding the relationship between transient local structure and correlated charge transport is essential for designing low-temperature electrolytes. Here, a physically constrained quadruplet-conditioned Green–Kubo (GK) framework is developed to establish a quantitative connection between transient local topology and correlated charge transport in reciprocal KF–NaF–AlF3–Al2O3 melts. The framework conservatively decomposes GK cross-correlation terms into element-resolved apparent transport contributions and assigns them to chemically interpretable quadruplet local environments. Molecular dynamics simulations reproduce the experimental density, viscosity, and ionic conductivity with mean relative errors of 1.32%, 6.18%, and 4.19%, respectively. Structural analysis reveals that compositional variation reconstructs both the first Al coordination shell and the surrounding second-neighbor chemical environment through the redistribution of free fluoride, fluoroaluminate, and oxygen-containing local motifs. The Nernst–Einstein approximation systematically overestimates the GK conductivity by a factor of 1.34–1.73, highlighting the essential role of interelement cross-current correlations in collective charge transport. Element-resolved decomposition further shows that alkali cations dominate the positive apparent transport contributions, whereas Al exhibits a negative apparent contribution and O contributes negligibly to the net charge current. The quadruplet-conditioned analysis further reveals that composition-driven local topological reconstruction continuously redistributes GK cross-correlation terms among transient local environments, thereby governing correlated charge transport. The proposed framework quantitatively links composition, transient local topology, and GK correlated transport, providing a physically constrained interpretation of ionic conductivity and a general framework for analyzing correlated transport in compositionally complex molten electrolytes.

The side ledge is essential for maintaining thermal stability and protecting the sidewall lining in an aluminum reduction cell. Its shape and temperature distribution strongly influence cell operation and energy efficiency. However, conventional computational fluid dynamics (CFD) methods, while accurate, are computationally intensive and unsuitable for fast evaluation under changing operating conditions. To overcome this limitation, this study develops a CFD-driven machine learning surrogate model for rapid prediction of cross-sectional temperature fields and side ledge morphology in an aluminum reduction cell under magnetohydrodynamic (MHD) conditions. High-fidelity training data are first generated from MHD-CFD simulations. Key physical variables, including heat generation, effective thermal transport properties, and velocity components, are extracted from multiple cross-sections prior to side ledge formation to form the input dataset. Five machine learning methods—Decision Tree, Random Forest, XGBoost, K-Nearest Neighbors, and Support Vector Regression—are then developed to predict the resulting temperature field and side ledge profile after solidification. The performance of each model is systematically compared in terms of accuracy and applicability. Among the tested models, Random Forest demonstrates the best overall performance. Its predicted temperature fields closely match CFD results, with a maximum temperature deviation below 0.23 °C, while the average side ledge thickness error is only 0.0153 m. Moreover, the proposed surrogate model reduces computation time from approximately 168 h to 3 min compared with CFD simulations, while maintaining high predictive accuracy. Overall, the proposed method enables fast and accurate evaluation of thermal states, supports operational optimization, and provides a foundation for digital twin development of aluminum reduction cells.

Developing high-energy sodium-ion batteries (SIBs) with layered cathodes at elevating voltage is hindered by the trade-off between the oxidative resistance and the sluggish ion kinetics of viscous fluorinated electrolytes. Here, we introduce benzotrifluoride (BTF) as a non-coordinating diluent in a fluorinated carbonate electrolyte to regulate the solvation structure. Through steric and dipolar effects, BTF promotes the participation of fluorinated carbonates in the primary solvation sheath while retaining controlled anion involvement. This reconstructed solvation environment simultaneously accelerates bulk ion transport and facilitates the formation of a robust, fluorine-rich cathode electrolyte interphase (CEI), enabling oxidative resistance beyond 5 V and optimized ionic conductivity. When adapting this electrolyte, the NaNi1/3Fe1/3Mn1/3O2 (NFM) cathode delivers a discharge capacity of 147.6 mAh g−1 at 4.2 V with improved cycling stability compared to baseline fluorinated electrolytes. This work demonstrates the efficacy of aromatic diluent-mediated solvation engineering for SIBs.

The O3-type NaNi_1/3Fe_1/3Mn_1/3O₂ layered oxide cathode is appealing for building low-cost sodium-ion batteries (SIBs), but the insufficient specific capacity limits its practical application. Elevating the charging cutoff voltage to trigger the anionic redox reaction (ARR) effectively boosts capacity, yet balancing capacity and cycling stability remains challenging. Herein, we propose a Na–O–Mg/Ti electronic configuration modulation strategy to synergistically enhance capacity and cycling stability by activating reversible ARR. The tailored configuration weakens σ hybridization to activate more lattice oxygen for charge compensation, while enhancing π hybridization to regulate the oxygen oxidation depth and promote oxygen redox reversibility. The reversible anionic redox reaction drives electron transfer on oxygen, thus alleviating O–O repulsion during deep desodiation and fundamentally mitigating detrimental phase transition. Benefiting from the special electronic configuration, the modified material showcases a synergetic enhancement in both specific capacity and cycling stability, exhibiting great application potential.

To address the lack of voltage plateau, low plateau capacity, and poor cycling stability in pitch-derived carbon anodes, a hard carbon material was synthesized via CO₂-assisted etching combined with high-temperature carbonization of preoxidized pitch. Preoxidation introduces C-O/C═O groups into pitch, suppressing its pyrolysis melting and enabling uniform nanopore formation. Subsequent CO₂ etching at 800 °C selectively expands micropores while reducing oxygen content (from 14.94% to 8.05%), and final carbonization further converts open pores into closed pores. These integrated strategies endow the material with outstanding sodium storage performance, achieving an initial Coulombic efficiency of 90%, a reversible capacity of 347.6 mAh g^-1 (including a plateau capacity of 249.4 mAh g^-1), and 87.3% capacity retention after 200 cycles at 100 mA g^-1. The enhanced stability originates from the formation of a thin solid electrolyte interphase with organic-inorganic gradient structure and a triphasic mechanism involving adsorption (>0.10 V), intercalation (0.01-0.10 V), and pore filling (<0.01 V), highlighting the critical role of closed-pore engineering of pitch-derived hard carbon for high-performance sodium-ion batteries (SIBs).

Mn₂O₃ emerges as a viable anode catalytic layer candidate for nonferrous metal electrodeposition, yet its industrial adoption is hindered by acid-triggered structural collapse and Mn³⁺ overoxidation. Here, we demonstrate a heterointerfacial engineering strategy that integrates carbon scaffolding with Ce-doped Mn₂O₃ (C-Ce-Mn₂O₃), achieving high stability in concentrated sulfuric acid (160 g·L^-1) under aggressive polarization. The C-Ce-Mn₂O₃ anode sustained operation for 104.3 h at a current density of 1 A·cm^-2 before reaching the operational failure threshold, whereas pristine Mn₂O₃ failed within 53.0 h under identical conditions, demonstrating 100.7% longer operational durability, corresponding to the 1095-day theoretical lifetime 2.07-fold over pristine Mn₂O₃. Density functional theory reveals that the injection of electrons from the Ce 4f orbital into toward Mn(III) optimizes the spin-down electronic state of Mn 3d and serves as an electron-sacrificing buffer zone for Mn(III), avoiding the overoxidation of Mn(III). The test results of Proto-LXRD indicate that carbon fiber can effectively reduce the internal stress of Mn₂O₃, increase the coating strength, and suppress the cracking and shell formation of the catalytic layer during electrochemical corrosion.