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Two-dimensional/three-dimensional hierarchical self-supporting potassium ammonium vanadate@MXene hybrid films exhibit excellent electrochemical performance. [Display omitted] Currently, aqueous zinc ion batteries (AZIBs) have grown to be a good choice for large-scale energy storage systems due to their high theoretical specific capacity, low redox potential, low cost, and non-toxicity of the aqueous electrolyte. However, it is still challenging to obtain high specific capacity and stability suitable cathodes. Herein, hierarchical self-supporting potassium ammonium vanadate@MXene (KNVO@MXene) hybrid films were prepared by vacuum filtration method. Due to the three-dimensional nanoflower structure of KNVO with dual ions intercalation, high conductivity of two-dimensional Ti 3 C 2 T x MXene, and the hierarchical self-supporting structure, the AZIB based on the KNVO@MXene hybrid film cathode possessed superior specific capacity (481 mAh/g at 0.3 A/g) and cycling stability (retaining 125 mAh/g after 1000 cycles at a high current density of 10 A/g). In addition, the storage mechanism was revealed by various ex-situ characterizations. Hence, a new viewpoint for the preparation of AZIB self-supporting cathode materials is presented. [ABSTRACT FROM AUTHOR]

• The few-layered MoS 2 nanosheets with different phase contents were prepared by an efficient controllable phase engineering. • The optimized material shows outstanding specific capacity and excellent long cycling performances. • The mechanisms involved were elucidated by systematical characterizations. • The DFT simulations reveal that the 1T phase MoS 2 has much lower Zn diffusion energy barriers. Recently, aqueous rechargeable Zn-ion batteries have attracted extensive attention, owing to their low-cost, high operational safety and environmental friendliness. However, the aqueous zinc-ion battery is still in a very infant stage, and the main challenge is to develop the ideal cathode due to the sluggish kinetics and low reversibility of divalent zinc ions. Herein, for the first time, we report controllable phase engineered few-layered MoS 2 nanosheet as cathode materials for rechargeable aqueous Zn-ion batteries and systematically study their performance. We found that the obtained MoS 2 with different phase contents showed distinct performance in the rechargeable aqueous zinc-ion battery. In particular, the MoS 2 nanosheets with ~70% 1T phase content displays excellent specific capacity and shows outstanding long-term cyclic stability. The mechanisms involved were clarified by not only comprehensive characterizations, but also the density functional theory (DFT) simulations that reveal the 1T phase MoS 2 has much lower Zn diffusion energy barriers. This study provides new insight into the effect of different phases on the performance of MoS 2 -based electrodes and will improve our understanding of developing better cathodes for the aqueous rechargeable Zn-ion batteries. [ABSTRACT FROM AUTHOR]

Due to the presence of the hierarchical freestanding structure, outstanding MXene conductive networks and abundant oxygen vacancy, the d-NVO@MXene hybrid film exhibits excellent electrochemical properties. [Display omitted] Aqueous zinc ion batteries (AZIBs) have gained extensive attention due to the numerous advantages of zinc, such as low redox potential, high abundance, low cost as well as high theoretical specific capacity. However, the development of AZIBs is still hampered due to the lack of suitable cathodes. In this work, the freestanding defective ammonium vanadate@MXene (d-NVO@MXene) hybrid film was synthesized by simple vacuum filtration strategy. Due to the presence of the hierarchical freestanding structure, outstanding MXene conductive networks and abundant oxygen vacancy (in the d-NVO nanoribbons), the d-NVO@MXene hybrid film can not only expose more active sites but also possess outstanding conductivity and kinetics of charge transfer/ion diffusion. When the d-NVO@MXene hybrid film was directly used as the cathode, it displayed a high specific capacity of 498 mAh/g at 0.5 A/g and superior cycling stability performance with near 100 % coulomb efficiency. Furthermore, the corresponding storage mechanism was elucidated by ex situ various characterizations. This work provides new ideas for the development of freestanding vanadium-based cathode materials for AZIBs. [ABSTRACT FROM AUTHOR]

d-NHVO nanoribbons with abundant oxygen vacancies have excellent electrochemical performance. [Display omitted] Vanadium-based oxides have gained widespread attention as promising cathode materials for aqueous zinc-ion batteries (AZIBs) due to their abundant valences, high theoretical capacity and low cost. However, the intrinsic sluggish kinetics and unsatisfactory conductivity have severely hampered their further development. Herein, a facile and effective defect engineering strategy was developed at room temperature to prepare the defective (NH 4) 2 V 10 O 25 ·8H 2 O (d-NHVO) nanoribbon with plenty of oxygen vacancies. Owing to the introduction of oxygen vacancies, the d-NHVO nanoribbon possessed more active sites, excellent electronic conductivity and fast ion diffusion kinetics. Benefiting from these advantages, the d-NHVO nanoribbon as an aqueous zinc-ion battery cathode material exhibited superior specific capacity (512 mAh g−1 at 0.3 A g−1), excellent rate capability and long-term cycle performance. Simultaneously, the storage mechanism of the d-NHVO nanoribbon was clarified via comprehensive characterizations. Furthermore, the pouch battery based on the d-NHVO nanoribbon was fabricated and presented eminent flexibility and feasibility. This work provides a novel thought for simple and efficient development of high- performance vanadium-based oxides cathode materials for AZIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] Aqueous zinc-ions batteries with low cost, reliable safety, high theoretical specific capacity and eco-friendliness have captured conspicuous attention in large-scale energy storage. However, the developed cathodes often suffer from low electrical conductivity and sluggish Zn2+ diffusion kinetics, which severely hampers the development of aqueous zinc-ions batteries. Herein, we successfully prepare Mg/PANI/V 2 O 5 •nH 2 O (MPVO) nanosheets through conducting polymers (polyaniline) and metal ions (Mg2+) co-intercalated strategy and systematically explore its electrochemical performance as cathode materials for aqueous zinc-ion batteries. Benefitting from the synergistic effect of polyaniline and Mg2+ co-intercalated, the MPVO exhibits larger interlayer spacing and higher electrical conductivity than the single guest intercalation, which significantly enhances the electrochemical kinetics. As a consequence, the MPVO cathodes deliver superior specific capacity, rate capability and long-term cycling performance. Moreover, multiple characterizations and theoretical calculations are executed to expound the relevant mechanism. Therefore, this work provides a novel thought for the design of high-performance cathode materials for aqueous ZIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] Aqueous zinc-ions batteries with low cost, reliable safety, high theoretical specific capacity and eco-friendliness have captured conspicuous attention in large-scale energy storage. However, the developed cathodes often suffer from low electrical conductivity and sluggish Zn2+ diffusion kinetics, which severely hampers the development of aqueous zinc-ions batteries. Herein, we successfully prepare Mg/PANI/V 2 O 5 •nH 2 O (MPVO) nanosheets through conducting polymers (polyaniline) and metal ions (Mg2+) co-intercalated strategy and systematically explore its electrochemical performance as cathode materials for aqueous zinc-ion batteries. Benefitting from the synergistic effect of polyaniline and Mg2+ co-intercalated, the MPVO exhibits larger interlayer spacing and higher electrical conductivity than the single guest intercalation, which significantly enhances the electrochemical kinetics. As a consequence, the MPVO cathodes deliver superior specific capacity, rate capability and long-term cycling performance. Moreover, multiple characterizations and theoretical calculations are executed to expound the relevant mechanism. Therefore, this work provides a novel thought for the design of high-performance cathode materials for aqueous ZIBs. [ABSTRACT FROM AUTHOR]

Hierarchical accordion-like manganese oxide@carbon hybrid with strong interaction heterointerface exhibits outstanding electrochemical performance. [Display omitted] Aqueous zinc ion batteries have attracted extensive concern as a promising candidate for large-scale energy storage because of their high theoretical specific capacity, low cost and inherent safety. However, the lacking of applicable cathode materials with outstanding electrochemical performance have severely hindered the further development of aqueous zinc ion batteries. Herein, we report a hierarchical accordion-like manganese oxide@carbon (MnO@C) hybrid with strong interaction heterointerface and comprehensively inquire into its electrochemical performance as cathode materials for aqueous zinc ion batteries. The unique hierarchical accordion-like layered structure coupling with strong interaction heterointerface between small MnO and carbon matrix efficaciously improve the ion/electron transfer process and enhance structure stability of the MnO@C hybrid. Benefitting from these unique advantages, the MnO@C hybrid bestows excellent specific capacity of 456 mAh g−1 at 50 mA g−1. Impressively, the MnO@C hybrid presents distinguished long-term cycling stability with fairly low decay rates of only 0.0079 % per cycle even over 2000 cycles at 2000 mA g−1. Moreover, comprehensive characterizations are executed to elucidate the mechanism involved. Therefore, this work affords a new idea for developing outstanding performance manganese-based cathode materials for aqueous zinc ion batteries. [ABSTRACT FROM AUTHOR]

The hierarchical 3D a-V 2 O 5 @Ti 3 C 2 T x microsphere with impressive Zn2+ storage ability is prepared by a simple spray drying method. [Display omitted] • The hierarchical 3D a-V 2 O 5 @Ti 3 C 2 T x microsphere was prepared by a simple spray drying method. • The amorphous V 2 O 5 endows abundant active sites for Zn2+ storage and alleviates Ti 3 C 2 T x MXene nanosheets restacking. • The presence of outstanding conductivity MXene framework enhances the conductivity and reaction kinetics. • The 3D a-V 2 O 5 @Ti 3 C 2 T x exhibits ultrahigh reversible capacity, superior rate performance and splendid cycling stability. As candidates of the next generation batteries, aqueous zinc-ion batteries (ZIBs) have drawn widespread attention owing to the advantages of environmental friendliness, low cost and ultrahigh theoretical capacity. In order to obtain superior zinc ions (Zn2+) storage ability, the cathode materials with eminent electrochemical property are placed great expectations. Herein, the hierarchical 3D a-V 2 O 5 @Ti 3 C 2 T x microsphere is prepared by a simple spray drying process. In the heterostructure, the amorphous V 2 O 5 not only endows abundant active sites for Zn2+ storage but also effectively alleviates Ti 3 C 2 T x MXene nanosheets restacking. Meanwhile, the presence of conductive Ti 3 C 2 T x MXene framework significantly enhances the conductivity and reaction kinetics of the electrode material. As a result, the 3D a-V 2 O 5 @Ti 3 C 2 T x exhibits an impressive Zn2+ storage ability, including the high reversible capacity (604 mAh g−1 at 0.5 A g−1), the superior rate performance and the splendid cycling stability. Furthermore, the relevant mechanism is illustrated via various characterizations. Moreover, the as-fabricated pouch ZIBs based on the 3D a-V 2 O 5 @Ti 3 C 2 T x displays a potential practical application prospect as flexible energy storage devices. Hence, this work may provide an inspiration for the rational design of high performance ZIBs cathode materials. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous zinc-ion batteries are emerged as fascinating "beyond Li-ion" battery technologies for large-scale energy storage due to low cost, high theoretical capacity, high safety and environmental friendliness. However, developing cathode materials with outstanding electrochemical performance are prerequisites. Herein, the a-V 2 O 5 @Ti 3 C 2 T x heterostructure is prepared by in situ incorporating amorphous V 2 O 5 with Ti 3 C 2 T x MXene to enhance the rechargeable aqueous Zn-ion batteries performance. Benefitting from the distinctive amorphous structure of a-V 2 O 5 , outstanding conductivity of Ti 3 C 2 T x MXene and the strong synergistic effect between two components, the a-V 2 O 5 @Ti 3 C 2 T x heterostructure presents isotropic ion diffusion paths, plentiful ion storage sites and splendid conductivity. As a consequence, the a-V 2 O 5 @Ti 3 C 2 T x heterostructure displays excellent specific capacity of 544 mAh g−1 at 0.5 A g−1 and outstanding rate performance. Particularly, even at a fairly high current density of 30 A g−1, the a-V 2 O 5 @Ti 3 C 2 T x heterostructure shows an impressive specific capacity of 135 mAh g−1 along with about 100% coulombic efficiency after 1000 cycles. Furthermore, the mechanism related is expounded via comprehensive characterizations. Therefore, this work offers a way for developing high-performance vanadium-based cathode materials for aqueous zinc-ion batteries. [Display omitted] • Amorphous V 2 O 5 @Ti 3 C 2 T x was fabricated via a simple in situ synthetic method. • Synergistic effect amorphous V 2 O 5 and Ti 3 C 2 T x endows fascinating properties. • The cathode presents outstanding specific capacity and cycling stability. • The mechanisms involved were elucidated via comprehensive characterizations. [ABSTRACT FROM AUTHOR]