The discharge capacity and lifespan of zinc ion batteries currently remain impractical due to limitations in the cathode. Low -valence vanadium oxides are promising cathode material precursors that can be electrochemically converted into highly active hydrated amorphous oxides. However, the activation process itself suffers from structural instability or high local strain, due to the low electronic conductivity and the limited ion diffusion kinetics. To tackle this issue, herein, we synthesize porous carbon -coated nitrogen -doped V 2 O 3 (p-NVO@C) microparticles utilizing a nitrogen -containing vanadium -based metal - organic framework (MOF) as the precursor. The uniform N doping and carbon coating improve the electronic conductivity of the active material particles. The carbon coating also traps the active material to reduce its dissolution loss; the high porosity of the pNVO@C alleviates the stress from Zn 2 + -intercalation-induced expansion and shortens the ion transport paths. Moreover, first -principles calculations indicate that the doped N atoms in vanadium oxides generate a locally enhanced electric field, which accelerates the diffusion of Zn 2 + . Given the above advantages, the p-NVO@C particles demonstrate an outstanding specific capacity of 501 mAh/g at a current density of 0.2 A/g and a remarkable rate performance after the initial activation. The capacity retention rate remains as high as 95.7 % after 2000 cycles at a current density of 10 A/g. Ex -situ characterizations confirm the robust structural stability during phase transition cycles. This work provides an excellent solution to developing cathode materials for highperformance aqueous zinc ion batteries.

The increasing demand for flexible and wearable electronic devices has led to widespread interest in flexible electrochemical energy storage devices. However, the transformation of the battery structure from conventional to flexible presents a great challenge to the battery design. Herein, we developed a facile method for the preparation of a self-supporting composite film consisting of oxygen-vacancy rich MnO2 nanowires (NWs), few-layer graphite nanosheets (FLGs), and single-walled carbon nanotube (SWNT) bundles as the cathode of flexible zinc-ion batteries. This ternary interwoven interconnection 3D structure enhances the electrochemical performance of the battery and realizes fast charge transfer; oxygen vacancies in the MnO2 NWs caused by heat treatment (300 degrees C in Ar) allow for rapid intercalation and diffusion of Zn2+. The interwoven FLGs and SWNT bundles improve the electrical conductivity, and the robust interactions between the two carbon nanomaterials and the MnO2 NWs effectively make the composite film with excellent mechanical properties. This self-supporting flexible electrode exhibits a high specific capacity of 374 mAh/g at 0.4 A/g, maintains a Coulombic efficiency of similar to 100 % after 1600 cycles at 2 A/g, and has a high energy density of 651.5 Wh kg(-1) at 65.2 W kg(-1). Moreover, the flexible zinc ion batteries assembled with the electrode demonstrate good mechanical properties and a high reversible specific capacity of 343 mAh/g after 75 bending cycles. Based on these findings, we believe that this composite film holds great promise as a cathode material in flexible energy storage applications.

Manganese-based aqueous zinc-ion batteries (AZIBs) are considered promising cathode materials for large-scale energy storage applications due to their low cost and high safety. However, the primary constraints on achieving high specific capacity and cycling stability are the inherent low conductivity and suboptimal structural stability of the AZIB cathodes. Herein, we report a high-performance poly(3,4-ethylenedioxythiophene) (PEDOT)-coated vanadium-doped MnO2 nanorod (NR) electrode for AZIBs. First, vanadium-doped MnO2 (V-MnO2) NRs were synthesized by a simple hydrothermal synthesis method. The V-MnO2 NRs were further encapsulated with a nanolayer of PEDOT through an in situ polymerization process, which was subsequently treated with sulfuric acid to achieve a smooth surface. The V doping creates oxygen vacancies within the MnO2, allowing for the rapid embedding and diffusion of Zn2+. The PEDOT nanolayer greatly enhances the conductivity and structural stability of the V-MnO2. Benefiting from the unique features, an optimal composite NRs electrode exhibits a high specific capacity of 250 mAh g(-1) at 0.4 A g(-1), a high energy density (388 Wh kg(-1) at 151 W kg(-1)), and excellent stability over 5000 cycles at 3 A g(-1). In addition, the flexible pouch cell assembled with the electrode shows good stability under bending. Given the positive outcomes, the material holds great potential for use as a cathode in next-generation flexible energy storage systems.

The lack of suitable cathode materials greatly limits the potential applications of rechargeable aqueous zinc ion batteries (ZIBs), despite their great promise in terms of high safety, high energy density, and low cost. One promising cathode material is VOOH, which possesses high specific capacity and fast Zn2+ transport channels after a phase transition to V2O5 center dot nH2O during electrochemical cycling. However, its susceptibility to structural disintegration and aggregation during charging and discharging leads to severe capacity decay. To address this issue, we construct a composite consisting of VOOH particles and VSx microrods by a one-step hydrothermal method using a vanadium-based metal-organic framework (MIL-88B(V)) as a sacrificial template. The VOOH particles undergo electrochemical activation and transform into V2O5 center dot nH2O nanoarrays that vertically grow on the VSx microrods. This unique nano-composite effectively maintains the morphology of nanoarrays in elec-trochemical cycling, resulting in a significant enhancement of rate performance and long-term cycling stability. Moreover, the VSx itself provides considerable capacity and its high conductivity improves the rate performance of the composite. Consequently, the VOOH/VSx nanocomposite exhibits a superior capacity of 364 mA h g- 1 at 0.2 A g- 1 after activation. Notably, it maintains remarkable capacity retention of 99.6% after 700 cycles, even at a high current density of 10 A g- 1. Based on these findings, we believe that the VOOH/VSx composite holds great promise as a cathode material for aqueous ZIBs.