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P2-Na0.67Ni0.33Mn0.67O2 is a promising cathode for sodium-ion batteries in large-scale energy storage applications due to their advantages of low cost, high energy density, superior sodium ion conductivity, and good air stability, whereas their structural rearrangement at high voltage above 4.2 V and the appearance of Na+/vacancy ordering result in fast capacity decay and poor rate capability, which lead to unsatisfactory performance that fails to meet practical demands. In this paper, we propose a dual-ion doping strategy coupling both cations and anions. Thanks to their collaborative effect, the optimized cathode material P2-Na0.67Ni0.33Mn0.57Ti0.1O1.95F0.05 exhibits greatly improved stability in the voltage range of 2.3–4.3 V at a high rate. Specifically, it retains 79.59% of its initial capacity after 500 cycles at 5C, in contrast to 19.91% of the undoped material. Experimental and theoretical investigations on working mechanisms illustrate that Ti4+ and F− dual-ion doping effectively suppresses the P2–O2 phase transition and facilitates sodium ion diffusion kinetics. Moreover, a P2-Na0.67Ni0.33Mn0.57Ti0.1O1.95F0.05//hard carbon full cell delivers a high reversible capacity of 122 mA h g−1 with a high energy density of 365 W h kg−1 based on the mass of the cathode material. This study provides an efficient strategy to promote the application of layered oxide cathodes in practical sodium-ion batteries. [ABSTRACT FROM AUTHOR]

Sodium‐metal batteries (SMBs) are regarded as key for next‐generation energy storage due to their high theoretical energy and potential cost‐effectiveness. However, Na‐metal systems remain challenged by several factors, including uncontrollable metallic dendrite growth for liquid systems and unstable solid electrolyte interphase (SEI) with most organic electrolytes, which limit the feasibility of SMBs. Here, the authors detail the interrelated degradation mechanisms. Afterward, the recent advances in improving the electrochemical performance of SMBs are highlighted. The strategies can be subdivided into the following taxonomy: The utilization of three‐dimensional (3D) conductive skeletons; the introduction of protective layers; the development of compatible electrolyte systems; and the employment of alloy anodes. Designing deposition substrates for the "'hostless"' Na has a great effect on reducing the current density and buffering the plating‐stripping volume expansion. The artificial interface approach would introduce efficient mechanical modulus or film‐forming type barriers, which can inhibit detrimental parasitic reactions. Improved solvent‐electrolyte combinations and additives tailored for Na will promise to suppress Na dendrite growth by obtaining a more stable SEI. The formation of alloy phase with Na can tune the bulk properties of the metal per se. Finally, the research challenges and possible development directions of SMBs are also discussed. [ABSTRACT FROM AUTHOR]

Two severe dust storm (DS) events (15–17 March and 28–29 March) hit northern China in 2021 consecutively. The lower atmospheric vertical dynamic and thermal structures during the two cases were compared using the ground-based sensor data from the microwave radiometer and radar wind profiler, combined with the environmental and meteorological observations data in Jinan, China. It was found that both cases occurred under the background of cold vortexes over northeastern China. The dust was transported through the cold air on the northwest route. During the dust period, 2–3 km was the west or northwest airflow, and below 2 km was the northeast wind. The variation in the dynamic structure determined the duration of the DS. During the DS maintenance phase, the vertical wind shear (VWS) below 3 km measured approximately 10 m∙(s∙km)−1. The increased VWS during the dust intrusion period facilitated the transportation of dust. In contrast, the more significant VWS was not conducive to the maintenance of DS, and the shift to south wind control in the upper middle layer indicated the weakening of DS. In both cases, we observed a cliff-like decrease in relative humidity as a prominent indicator of dust outbreaks, occurring approximately 2–5 h beforehand. The diurnal difference between the vertical temperature and relative humidity during the dust maintenance period was found to be insignificant. [ABSTRACT FROM AUTHOR]

Recycling cathode materials from spent lithium‐ion batteries (LIBs) is critical to a sustainable society as it will relief valuable but scarce recourse crises and reduce environment burdens simultaneously. Different from conventional hydrometallurgical and pyrometallurgical recycling methods, direct regeneration relies on non‐destructive cathode‐to‐cathode mode, and therefore, more time and energy‐saving along with an increased economic return and reduced CO2 footprint. This review retrospects the history of direct regeneration and discusses state‐of‐the‐art development. The reported methods, including high‐temperature solid‐state, hydrothermal/ionothermal, molten salt thermochemistry, and electrochemical method, are comparatively introduced, targeting at illustrating their underlying regeneration mechanism and applicability. Further, representative repairing and upcycling studies on wide‐applied cathodes, including LiCoO2 (LCO), ternary oxides, LiFePO4 (LFP), and LiMn2O4 (LMO), are presented, with an emphasis on milestone cases. Despite these achievements, there remain several critical issues that shall be addressed before the commercialization of the mentioned direct regeneration methods. [ABSTRACT FROM AUTHOR]

Sodium‐based layered oxide cathodes are competitive candidates for commercial sodium‐ion batteries owing to their high theoretical capacities, low costs, and simple synthesis. P3‐type layered oxides with large open channels enable fast Na+ transport and hence good rate performance. However, the lower crystal symmetry of P3‐type oxides and variation of Na+ contents in the Na layer during desodiation/sodiation lead to large electrostatic repulsion changes between TMO2 slabs (TM=Transition Metal), resulting in irreversible phase transitions, and fast performance degradation. Herein, a potential Na+ conductor Na2SeO4 is first found that it can be easily in situ grown on P3‐Na0.45Ni0.2Mn0.8O2 to form a novel heterostructure P3‐Na0.45Ni0.2Mn0.8O2/Na2SeO4. The synergy between P3‐Na0.45Ni0.2Mn0.8O2 and Na2SeO4 functions in promoting Na+ diffusion and suppressing P3‐O3 phase transitions upon deep sodiation, which results in recorded high‐rate capability (68.2% capacity retention with retained 83.9 mAh g−1 capacity at 6400 mA g−1) and superior cycling stability (capacity retention 75% after 1000 cycles) among all reported P3‐type cathodes. Thus, it is believed that this novel heterostructure design opens a new pathway to promote practical applications for layered oxide cathodes in sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

In the search of cathode materials for Na-ion batteries, iron-based compounds have attracted much attention due to the abundant resource, easy access, and environmental friendliness of iron. Herein, we report the synthesis, structure, and electrochemistry of a previously unknown compound in the Na–Fe–F system, formulated as Na2FeF4. It is prepared by an easy and mild hydrothermal reaction with oxalate as a Fe2+ protector. Based on the single crystal x-ray diffraction analysis, it crystallizes in space group Pmcb with a = 3.255 (3) Å, b = 5.591(7) Å, and c = 9.557(1) Å. The crystal structure features edge-sharing FeF6 octahedra to form [FeF4]∞ chains with Na+ ions located between chains. In electrochemical investigations, it is demonstrated that the material can deliver a reversible capacity of ∼90 mAh g−1 for 300 cycles in the window of 1.5–4.3 V with redox reactions at ∼3.0 V (vs Na+/Na). Such an activity originates from the Fe3+/Fe2+ redox couple, confirmed by x-ray absorption spectra and first-principles calculations. [ABSTRACT FROM AUTHOR]

Solid polymer electrolytes (SPEs) offer inherent advantages for battery applications, such as high safety and excellent processability, but their practical use is limited by challenges like low ionic conductivity, subpar mechanical properties, and instability of the electrode/electrolyte interface. Here, novel SPEs are developed by embedding 2D MXenes decorated at the surface with methoxypolyethylene glycol chains into poly(vinylidene fluoride)‐hexafluoropropylene matrices, enhanced with succinonitrile as a plasticizer. This innovative design improves the compatibility of the modified MXene in poly(vinylidene fluoride)‐hexafluoropropylene and, together with the synergistic effects of succinonitrile, promotes the dissociation of lithium salt. The SPE achieves ionic conductivity of 1.49 × 10−4 S cm−1 at 30 °C, and a Li‐ion transference number of 0.59. These results are supported by comprehensive experimental characterization, COMSOL simulations, and DFT calculations. This SPE enables stable and reversible Li plating/stripping for over 2100 h in Li/Li symmetric cells, while fabricated Li/LiFePO4 full cells deliver a notable capacity of 135.4 mAh g−1 with an average Coulombic efficiency of 98.9% after 100 cycles at 0.2 C. Furthermore, the Li/LiNi0.6Co0.2Mn0.2O2 full cells also demonstrate a capacity of 140.5 mAh g−1 after over 200 cycles at 0.5 C, showcasing an impressive capacity retention rate of 99.6%. [ABSTRACT FROM AUTHOR]