Preparation,Characterization And Electrochemical Zinc Storage Properties Of Vanadium-Based MXene-Derived Oxides

The aspirational blueprint for achieving carbon neutrality has largely inspired the promotion of grid-scale energy storage with renewable,low-cost,and secure features.Despite lithium-ion batteries has been a great commercial success among the many energy storage systems available,their application in grid-scale energy storage has still been limited by the inevitable safety hazards and lithium scarcity.Rechargeable aqueous zinc batteries（AZIBs）are a promising alternative thanks to earth-abundant reserves and intrinsic safety.However,the practical implementation of AZIBs has been fearfully hampered by the lack of stable high-capacity cathode material candidates and severe dendrite growth of zinc-metal anodes.Vanadium-based compound cathode materials are the hottest AZIBs cathode materials in recent years,but in practical applications,it is found that they face problems such as poor conductivity,slow ion diffusion,vanadium dissolution,structural phase transition,and collapse.At the same time,as the most commonly used anode,the anode side of metal zinc is also plagued by inherent defects such as tricky dendrites,hydrogen evolution reactions,corrosion,and passivation.Only by addressing the fatal shortcomings of both parties can excellent device performance be expected.In this paper,we start with the improvement of both the positive and negative electrodes to realize high-capacity,long-life,and stable zinc-ion batteries.The specific research results are as follows:（1）Few-layer V₂CT_x MXene was used as the vanadium source,two-dimensional sheet frame structured by V₂O₃@C nanofabrication was constructed through the simple method of hydrothermal and annealing.On the one hand,carbon coating improves the conductivity of V₂O₃ as the main body of zinc storage inhibits the dissolution of elements,and stabilizes the band structure of V₂O₃ during cycling.On the other hand,the interconnection between V₂O₃@C nanowires is conducive to the rapid migration of zinc ions,and the abundant voids can buffer the volume expansion during the Zn²⁺deintercalation process.When electrochemically tested on the prepared V₂O₃@C,excellent rate performance(reversible capacity of 175.0 m Ah g^-1 at8.0 A g^-1)was exhibited.（2）A more extensive and convenient multilayer V₂CT_x MXene was selected as raw material,and the simple hydrothermal synthesis strategy was continued while introducing metal zinc salts to successfully synthesize accordion-like Zn V₂O₄@C cathode material（A-ZVO@C）.By inhibiting the"lattice respiration"of zinc atoms in the crystal structure,the capacity,magnification,and cycle performance of the A-ZVO@C cathode is improved.The prepared A-ZVO@C was tested for morphology,structural characterization,and electrochemical performance.The specific capacity is increased to 400 m Ah g^-1 at 0.2 A g^-1 current density;Even at a high current of 8.0 A g^-1,its capacity remains 200.0 m Ah g^-1,providing better rate performance.In addition,A-ZVO@C has low solubility in the electrolyte,and the prepared electrode is soaked in the electrolyte for up to six months,and it circulates 6000 times at a current density of 5.0 A g^-1,with a capacity retention rate of 85.4%.The effectiveness of MXene’s in-situ derivatization and cationic pre-embedding strategies was further verified.（3）The zinc storage performance of the modified vanadium oxide cathode material was improved,but the shortcomings of the zinc metal anode need to be further overcome to improve the overall performance of aqueous zinc-ion batteries.We prepared nitrogen-doped Zn O/C hollow spheres using zinc-based MOF as raw material,which was used as an artificial interface protective layer for zinc metal anode to alleviate the growth of negative dendrite and the occurrence of side reactions.The excellent ability of the protective layer in inducing preferential deposition of zinc uniform（002）crystal planes and inhibiting hydrogen evolution reaction was proved by in situ light microscopy,ex situ XRD,etc.,and the assembled Zn@HZCS symmetric battery was used for a cycle life of 1400 hours.The A-ZVO@C//Zn@HZCS battery assembled with this electrode has greatly improved cycle stability at high current density,and has an ultra-high capacity of 93.6%at 5.0 A g^-1 with 6000 cycles.