The fast-charging performance of hard carbon (HC) anodes with low sodiation plateau potentials critically depends on Na+ transport within the electrolyte and across the electrode-electrolyte interface. Anion-derived solid electrolyte interphases (SEIs) are known to reduce interfacial resistance and facilitate rapid ion transport. Introducing steric hindrance in solvents can weaken cation-solvent coordination and promote the formation of anion-derived SEIs. However, a universal strategy for comparing solvent steric effects remains elusive. Herein, Molar volume and Sterimol parameters are employed to qualitatively assess steric effects in alkyl mononitriles, a class of solvents capable of supporting high-ionic-conductivity electrolytes. Using this approach, trimethylacetonitrile (TMAN) is identified as a sterically hindered solvent with weak coordinating ability. TMAN-based electrolytes reduce Na+ desolvation energy and enhance anion participation in the primary solvation shell, yielding compact, low-impedance SEIs on HC anodes. Consequently, a simple electrolyte of 1 M sodium bis(fluorosulfonyl)imide in TMAN enables HC fast charging at 3C without sodium plating, while Ah-level HC||NaNi1/3Fe1/3Mn1/3O2 pouch cells retain 93.1% of their capacity after 3000 cycles at 1C, and 91.7% after 1300 cycles at 3C charging rate. This study established a generalizable solvent screening strategy, laying the foundation for the efficient development of electrolytes.

Abstract Solid-state sodium batteries are promising candidates for next-generation energy storage systems due to their safety, sustainability, and cost-effectiveness. In this study, a novel composite solid polymer electrolyte (SPE) composed of polyaniline (PANI), gelatin, and NaTFSI was synthesized using four different solvents (NMP, toluene, hexane, and THF) to investigate the solvent effect on electrochemical performance. Among them, the toluene-based electrolyte exhibited the highest ionic conductivity (4.64 × 10⁻⁴ S·cm⁻¹) and the lowest interfacial resistance (~260 Ω) at room temperature. The materials were characterized using FTIR, XRD, SEM, EDX, and TGA to analyze their structural, morphological, and thermal properties. Thermal analysis confirmed enhanced stability upon salt incorporation, while structural and morphological studies revealed improved polymer chain interaction and uniform ion dispersion. Moreover, the sodium symmetric cell (Na/SPE/Na) demonstrated stable cycling at 1 mA cm⁻² without dendrite formation, and the full Na–S cell exhibited high and stable specific capacities ranging from 591 to 778 mAh g⁻¹ over multiple cycles at 0.1 C. These findings highlight the critical role of solvent evaporation rate in tuning polymer morphology, crystallinity, and ionic transport, and demonstrate that the proposed PANI–gelatin–NaTFSI system provides a sustainable and cost-effective route for room-temperature solid polymer electrolytes in sodium-based energy storage application

Abstract Layered transition metal oxides (LTMOs, e.g., Na x Ni y Mn 1− y O 2 ) are critical cathode materials for sodium‐ion batteries (SIBs). However, they grapple with significant structural degradation during cycling, primarily caused by micro‐strain induced by TM heterogeneity during synthesis. Herein, we engineered a vortex microreactor to intensify fluid mixing during co‐precipitation processes, thereby achieving carbonate precursors with highly uniform elemental distribution. CFD simulations revealed fundamental microreactor hydrodynamics. Villermaux–Dushman experiments confirmed ≤0.62 ms molecular‐scale mixing, achieving near‐complete homogenization. The resulting precursors enabled exceptionally uniform TM distribution, yielding a P2‐type LTMO cathode with outstanding Ni/Mn homogeneity. Comparing with ball milling synthetics, this cathode exhibits superior rate capability, delivering an impressive 77.51 at 3000 mA g −1 while retaining 90% of the capacity measured at 150 mA g −1 . This work establishes micromixing engineering as a critical lever for inducing uniform TM distribution in LTMOs and provides a scalable platform for preparing SIBs cathode materials.

Sodium-ion batteries face some critical anode-level barriers: sluggish Na+ transport, conversion-induced instability, and poor temperature adaptability. Here, we develop a vacancy-based synergy in Co9S8@ZnS/C synthesized by metal-organic framework-templated sulfidation. The Co-Zn-S system provides sodiophilic vacancies that lower Na+ diffusion barriers and further strengthen the interfacial field. This self-reinforcing synergy is validated through in situ X-ray diffraction and in situ Raman spectroscopy, demonstrating reversible conversion/alloying and interfacial reconstruction. The Co9S8@ZnS/C anode delivers exceptional performance, including a high capacity of 458.7 mAh g-1 after 400 cycles at 1.0 A g-1 and a remarkable ultralong stability of 249.1 mAh g-1 after 4000 cycles at 15.0 A g-1, with robust operation from -10 to 50 °C. Full cells paired with Na3V2(PO4)3 demonstrate excellent stability, validating their practical viability. This work establishes a generalizable vacancy-abundant design principle that deterministically links defect thermodynamics and electrostatics to long-term Na storage across diverse operating conditions.

Sodium-ion batteries (SIBs) are attracting attention as cost-effective alternatives to lithium-ion batteries (LIBs) for large-scale energy storage. Among SIB cathodes, P2-Na0.67Ni0.33Mn0.67O2 delivers high capacity and rate capability but suffers from rapid capacity fading under high-voltage charging due to a detrimental P2-O2 phase transition and interfacial side reactions. Here, we demonstrate a dual-modification strategy combining Cu2+ doping and MgO surface coating to address these challenges. The dual-modified cathode (Na0.67Ni0.28Cu0.05Mn0.67O2@MgO) delivers markedly improved performance: a high-capacity retention of 90.88% after 200 cycles at 1 C and significantly enhanced rate capability (95.23 mAh g-1 at 10 C). Ex situ XRD analyses reveal that the P2-O2 phase transition is effectively suppressed, leading to minimal structural change during cycling. DFT calculations reveal that the Cu-MgO dual modification synergistically enhances the electronic conductivity of the electrode and suppresses transition-metal layer gliding. The results indicate that Cu2+ doping enhances structural stability by regulating Na+/vacancy ordering and suppressing the high-voltage phase transition, whereas the MgO coating alleviates electrolyte-induced surface degradation and enhances Na+ diffusion kinetics. This work offers a valuable reference for designing high-performance cathode materials in sodium-ion battery systems.

Electrolyte design plays an important role in the development of lithium-ion batteries and sodium-ion batteries. Battery electrolytes feature a large design space composed of different solvents, additives, and salts, which is difficult to explore experimentally. High-fidelity molecular simulation can accurately predict the bulk properties of electrolytes by employing accurate potential energy surfaces, thus guiding the molecule and formula engineering. At present, the overly simplified classic force fields rely heavily on experimental data for fine-tuning, thus its predictive power on microscopic level is under question. In contrast, the newly emerged machine learning interatomic potential (MLIP) can accurately reproduce the ab initio data, demonstrating excellent fitting ability. However, it is still haunted by problems such as low transferability, insufficient stability in the prediction of bulk properties, and poor training cost scaling. Therefore, it cannot yet be used as a robust and universal tool for the exploration of electrolyte design space. In this work, we introduce a highly scalable and fully bottom-up force field construction strategy called PhyNEO-Electrolyte. It adopts a hybrid physics-driven and data-driven method that relies only on monomer and dimer EDA (energy decomposition analysis) data. With a careful separation of long/short-range and nonbonding/bonding interactions, we rigorously restore the long-range asymptotic behavior, which is critical in the description of electrolyte systems. Through this approach, we significantly improve the data efficiency of MLIP training, allowing us to achieve much larger chemical space coverage using much less data while retaining reliable quantitative prediction power in bulk phase calculations. PhyNEO-Electrolyte thus serves as an important tool for future electrolyte optimization.

A water-based synthesis and electrode fabrication protocol for sodium-rich Prussian blue (Na–PB) cathodes designed for sustainable aqueous sodium-ion batteries was adopted. Using a citric-acid-assisted co-precipitation method followed by aqueous Na⁺ ion exchange, the process consistently yielded 3.113 g of high-quality Na–PB per 400 mL batch under mild conditions (<80 °C). Electrodes were fabricated via doctor-blade coating onto aluminium foil using a biodegradable carboxymethyl cellulose (CMC) binder and conductive additive, completely eliminating toxic organic solvents. X-ray diffraction confirmed a highly crystalline cubic (slightly rhombohedral-distorted) phase with low [Fe(CN)₆] vacancy content (<10%), while scanning electron microscopy revealed uniform cubic particles ranging from 200 to 800 nm. Brunauer–Emmett–Teller analysis indicated moderate specific surface areas (12–18 m² g⁻¹) with mesoporous characteristics. The results demonstrate that structurally optimized Na–PB cathodes can be produced through an environmentally benign and scalable approach, and future work should incorporate electrochemical performance evaluation and long-term cycling studies to support practical battery applications.

Mn-based layered oxide cathodes are pivotal for advancing sodium-ion batteries, yet their practical deployment is hindered by structural instability and complex phase transformations during cycling. This review provides a systematic overview of recent strategies aimed at rational design and performance enhancement of these materials. It begins with fundamental thermodynamic principles governing phase formation, particularly P2/O3 structural dichotomy, and highlights the critical roles of sodium content, transition metal chemistry, and ionic potential in determining crystal stability. The emergence of high-entropy engineering is examined as a powerful approach to suppress detrimental phase transitions through configurational entropy stabilization, lattice distortion, and synergistic multi-element interactions. Furthermore, the integration of machine learning with multidimensional descriptors including electronegativity-weighted entropy and cationic potential enables more accurate predictions of phase behavior in complex compositional spaces. The review also highlights the decisive influence of synthesis protocols, where precise control over calcination conditions, atmosphere, and local elemental distribution enables the formation of targeted phase architectures, such as P2/O3 intergrowth, which exhibit superior electrochemical robustness. Collectively, these advances illustrate a shift from empirical trial and error toward a theory-guided, data-informed framework for designing high-performance layered oxide cathodes.

Lanthanide doping induced electrochemical enhancement of layered δ-MnO2 nanoflowers cathode for sodium-ion batteries.

Solution-processed poly(vinylidene difluoride)-cellulose acetate/Na1+xAlxTi2-x(PO4)3 composite quasi-solid electrolyte for safe and high-performance quasi-solid-state sodium-ion batteries

Synergistic Bulk/Interface Engineering Enables High- Voltage Cycling of O3-type Layered Oxides Cathode Material in Sodium-Ion Batteries

ABSTRACT In the context of carbon neutrality, collaborative “power generation‐energy storage” system is an inevitable requirement for promoting the green transformation of energy structure. However, the design of related key materials still faces severe challenges. Here, a strategy for the combined use of energy materials is proposed, in which carbon materials derived from discarded bamboo are simultaneously applied to direct carbon solid oxide fuel cell (DC‐SOFC) and sodium‐ion battery (SIB), forming a resource complementary energy loop. By comparing rapid Joule heating with traditional tube furnace heating processes, the system elucidates the regulating mechanisms of the carbon material microstructure and their strengthening effect on the electrochemical performance. When the optimized carbon material is used as DC‐SOFC fuel, a maximum power density of 515.3 mW cm −2 and 1570 mAh of electricity can be achieved; As an SIB anode, it exhibits a reversible capacity of 327.6 mAh g −1 with an initial Coulombic efficiency of 90.4%. This work not only realizes the high‐value utilization of waste biomass, but also provides feasible material basis and technical ideas for building future integrated and clean energy systems.

Exploring YB monolayer as a potential anode material for Li and Na-ion batteries

Bonding layer reinforcing the interface of binder-free Sb-based electrode for improved cycling stability of sodium ion batteries

Functionalized carbon materials for high-energy sodium-ion batteries: Progress, mechanisms, and perspectives

A facile synthetic strategy to MnS/NC submicrospheres for high-performance sodium-ion battery anodes

Rational design and prospective application of low-cost sodium iron sulfate cathodes for energy-storage sodium-ion battery

Emerging anode materials for low-temperature sodium-ion batteries: Challenges, recent advances, and perspectives

Alkali-tailored walnut shell hard carbon anodes with synergistic pore-kinetics optimization for sodium-ion batteries

Artificial neural networks for sodium-ion batteries: A molecular descriptor approach to performance prediction