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Na3V2(PO4)3 (NVP) is regarded as one of the most promising cathode materials for sodium-ion batteries (SIBs). However, it suffers from a dense bulk structure and low intrinsic electronic conductivity, which lead to limited electrochemical performances. Herein, we propose a surfactant-assisted molding strategy to regulate the pore-forming process in NVP/C composite cathode materials. More precisely, the forming process of the pores in NVP could be easily controlled by utilizing the huge difference in critical micelle concentration of a surfactant (cetyltrimethylammonium bromide, CTAB) in water and ethanol. By reasonably modulating the ratio of water and ethanol in the solution, the as-synthesized NVP/C sample exhibited a three-dimensional interconnected structure with hierarchical micro/meso/macro-pores. Benefiting from these hierarchical porous structures in NVP/C, the structural stability, contact surface with the electrolyte, and electronic/ionic conductivity were improved simultaneously; whereby the optimized porous NVP/C sample exhibited an excellent high-rate performance (61.3 mA h g−1 at 10 C) and superior cycling stability (90.2% capacity retention after 500 cycles at 10 C). [ABSTRACT FROM AUTHOR]

The corrosion of zinc anode significantly undermines the stability of aqueous zinc-based energy storage devices (ZnESDs), potentially leading to cell failure even explosions. In this study, we mixed a high concentration electrolyte (21 m LiTFSI) with a conventional 2 m Zn(OTF) 2 electrolyte to highly reduce the activity of solvent water, which can greatly suppress the corrosion of zinc anode at room temperature and high temperatures. We systematically studied the phenomenon of ZnWiS inhibiting zinc anode corrosion at different temperatures and investigated its principle through experiments and theoretical calculations. As a result, the Zn||Zn symmetric cells demonstrated remarkable stability, sustaining over 3642 h at room temperature and over 112 h at 80 °C. Moreover, the as assembled aqueous zinc ion hybrid supercapacitors (ZHSC) also exhibited excellent cycling stability for over 5220 h at room temperature and over 165 h at 80 °C. In contrast, ZHSC assembled with 2 m Zn(OTF) 2 can only cycle 80 h at room temperature, and 9 h at 80 °C. These findings confirm that reducing water activity in the electrolyte effectively contributes to achieving highly stable aqueous ZnESDs, and the universality of this strategy offering promise for its application in various aqueous metal ion energy storage devices. [Display omitted] • Reducing water activity could tremendously inhibit the zinc anodes corrosion. • The assembled ZHSCs can cycle for over seven months at room temperature. • The assembled ZHSCs can cycle for 165 h at 80 °C. [ABSTRACT FROM AUTHOR]

The operation of electrochemical energy storage (EES) devices at low temperatures as normal as at room temperature is of great significance for their low‐temperature environment application. However, such operation is plagued by the sluggish ions transport kinetics, which leads to the severe capacity decay or even failure of devices at low‐temperature conditions. In this review, the difficulties of ions transport in electrolyte, electrolyte/electrode interface, and electrode material at low temperatures are discussed in depth, and the reported strategies to solve the corresponding problems are surveyed subsequently. Finally, the views on how to build high‐performance low‐temperature‐available EES devices as well as their development directions are put forward. [ABSTRACT FROM AUTHOR]

As a promising anode material in supercapacitors, vanadium nitride has been widely concerned due to its ultra‐high theoretical specific capacitance. However, its routine test capacitance value is still far from the theoretical value and its energy storage mechanism is controversial. In order to solve these two key problems, here we prepare interplanar spacing expanded vanadium nitride materials with different impurity atoms intercalation from two anionic precursors of vanadium‐based metal organic frameworks with different functional groups. The obtained vanadium nitride reaches a higher specific capacitance; and further, through ex situ X‐Ray diffraction and in situ Raman, the charge storage of vanadium nitride is contributed by two processes: the first benefit is from the K+ de/intercalation in the interplanar spacing, and the other one is derived from the redox reaction with OH− by adsorption on surface. Furthermore, both of the first principle calculation and extended experiments support this idea. We believe that such detailed research on the energy storage mechanism can provide a clear idea for the application of metal nitrides in supercapacitors and other energy storage devices. [ABSTRACT FROM AUTHOR]

The adsorption of metal ions and the further utilization of adsorbent materials help solve serious environmental pollution; therefore, transforming them into supercapacitor electrode materials could be a promising possibility. Here, we used pectin as a heavy metal ion adsorbent to prepare a series of vanadium-containing precursors, and different vanadium nitride and carbon composites were prepared via annealing with varied water contents in the precursors. By studying these composites, we found that the addition of water can effectively improve the final oxygen content of the product chemical oxygen, thereby improving the wettability or hydrophilicity of the composite material. Furthermore, hydrophilicity or wettability improves some electrochemical characteristics, particularly the voltage drop. Electrodes with a high voltage drop have poor hydrophilicity, and hence a systematic study from phenomena to mechanisms associated with voltage drop is conducted in detail. [ABSTRACT FROM AUTHOR]