Enhanced and stabilized charge transport boosting by Fe-doping effect of V2O5 nanorod for rechargeable Zn-ion battery

Recent advances in electrospinning nanofiber materials for aqueous zinc ion batteries

Aqueous zinc ion batteries (AZIBs) are regarded as one of the most promising large-scale energy storage systems because of their considerable energy density and intrinsic safety. Nonetheless, the severe dendrite growth of the Zn anode, the serious degradation of the cathode, and the boundedness of separators restrict the application of AZIBs. Fortunately, electrospinning nanofibers demonstrate huge potential and bright prospects in constructing AZIBs with excellent electrochemical performance due to their controllable nanostructure, high conductivity, and large specific surface area (SSA). In this review, we first briefly introduce the principles and processing of the electrospinning technique and the structure design of electrospun fibers in AZIBs. Then, we summarize the recent advances of electrospinning nanofibers in AZIBs, including the cathodes, anodes, and separators, highlighting the nanofibers' working mechanism and the correlations between electrode structure and performance. Finally, based on insightful understanding, the prospects of electrospun fibers for high-performance AZIBs are also presented.

Realising higher capacity and stability for disordered rocksalt oxyfluoride cathode materials for Li ion batteries

Disordered rocksalt (DRX) materials are an emerging class of cathode materials for Li ion batteries. Their advantages include better sustainability through wider choices of transition metal (TM) elements in the materials and higher theoretical capacities due to the redox reaction contributions from both the TM and O elements compared with state-of-the-art cathode materials. However, the realisable capacities of the DRX materials need to be improved as their charge transport kinetics and cycling stability are still poor. Here, Li1.2Mn0.4Ti0.4O2 (LMTO) and Li1.3Mn0.4Ti0.3O1.7F0.3 (LMTOF) are synthesised with abundant TMs of Mn and Ti only. Three approaches of partial substitution of O with F, reducing particle size and C coating on the particle surface are used simultaneously to improve realisable capacity, rate capability and stability. We rationalise that the improved electrochemical performance is due to the improved short and long range Li+ diffusion kinetics, electrical conductivity and reduced O loss. These strategies can also be applicable to a variety of DRX materials to improve performance.

Fe-doped V2O5layered nanowire cathode material with high lithium storage performance

As a lithium-ion battery cathode material with high theoretical capacity, the application of V₂O₅is limited by its unstable structure and low intrinsic conductivity. In this paper, we report a Fe doped V₂O₅nanowire with a layered structure of 200-300 nm diameter prepared by electrostatic spinning technique. The 3Fe-V₂O₅electrode exhibited a superb capacity of 436.9 mAh g^-1in the first cycle when tested in the voltage range of 2.0-4.0 V at current density of 100 mA g^-1, far exceeding its theoretical capacity (294 mAh g^-1), and the high capacity of 312 mAh g^-1was still maintained after 50 cycles. The superb performance is mainly attributed to its unique layered nanowire structure and the enhanced electrical conductivity as well as optimized structure brought by Fe-doping. This work made the homogeneous doping and nanosizing of the material easily achieved through electrostatic spinning technology, leading to an increase in the initial capacity of the V₂O₅cathode material and the cycling stability compared to the pure V₂O₅, which is an extremely meaningful exploration.

Two Birds with One Stone: Boosting Zinc-Ion Insertion/Extraction Kinetics and Suppressing Vanadium Dissolution of V2O5 via La3+ Incorporation Enable Advanced Zinc-Ion Batteries

Aqueous zinc-ion batteries (ZIBs) with cost-effective and safe features are highly competitive in grid energy storage applications, but plagued by the sluggish Zn²⁺ diffusion kinetics and poor cyclability of cathodes. Herein, a one-stone-two-birds strategy of La³⁺ incorporation (La-V₂O₅) is developed to motivate Zn²⁺ insertion/extraction kinetics and stabilize vanadium species for V₂O₅. Theoretical and experimental studies reveal the incorporated La³⁺ ions in V₂O₅ can not only serve as pillars to expand the interlayer distance (11.77 Å) and lower the Zn²⁺ migration energy barrier (0.82 eV) but also offer intermediated level and narrower band gap (0.54 eV), thus accelerating the electron/ion diffusion kinetics. Importantly, the steadily doped La³⁺ ions effectively stabilize the V-O bonds by shortening the bond length, thereby inhibiting vanadium species dissolution. Therefore, the resulting La-V₂O₅-ZIBs deliver an exceptional rate capacity of 405 mA h g^-1 (0.1 A g^-1), long-term stability with 93.8% retention after 5000 cycles (10 A g^-1), and extraordinary energy density of 289.3 W h kg^-1, outperforming various metal-ions-doped V₂O₅ cathodes. Moreover, the La-V₂O₅ pouch cell presents excellent electrochemical performance and impressive flexibility and integration ability. The strategies of incorporating rare-earth-metal ions provide guidance to other well-established aqueous ZIBs cathodes and other advanced electrochemical devices.