Preparation And Electrochemical Performance Of Vanadium-based Cathode Materials For Aqueous Zinc-ion Batteries

Aqueous zinc-ion batteries（ZIBs）present prominent merits in the production cost,preparation efficiency and safety,but the poor service lifespan and rate performance always imped the reusability and quick-charge technology,which greatly stimulate us to stabilize the electrode structure and upraise the reaction kinetics.First,a hybrid structure composed of Mn doped V₆O₁₃ nanoribbons and N-S modified porous carbon structure（Mn VO/（SN）-C）has been designed.1D porous nanoribbon structure can form Zn²⁺diffusion channels and enable the abundant energy-storage sites,while the doping of Mn ion into V₆O₁₃ can optimize the electronic structure simultaneously.The rigid and conductive N-S modified carbon structure can not only protect the nanoribbons,but also boost the electron transport rate in the electrochemical reaction,and thus depress the huge volume expansion and ameliorate conductivity.Therefore,Zn²⁺diffusion rate and electrochemical reaction kinetics are greatly promoted,resulting the excellent cycle stability and super-rate performance of this cathode material.At the current density of 0.5 A g^-1,this electrode material can deliver favorable capacity of 414.2 m A h g^-1,and can deliver 272.4 m A h g^-1 at 10 A g^-1(67.37%retention from 1 to 10 A g^-1).It also achieves long-term cycle stability（100.1%after 1000 cycles）at 10 A g^-1.In addition,the maximum energy density of Mn VO/（SN）-C cathode is 307.3 Wh kg^-1,and the maximum power density is 5715 W kg^-1,which is higher than most of the recently reported cathode materials.Second,we use glycerol and sodium dodecylbenzene sulfonate（SDBS）as reducing agents and surfactants to modify commercial V₂O₅,and then construct composite materials by coating and reducing graphene oxide（r GO）.The addition of glycerol can not only cause structural transformation of V₂O₅ while being reduced,but also provide abundant hydrophilic groups.And SDBS can cause the material to be polymerized oriented and produce a large number of point defects at the same time,providing abundant active sites for the rapid diffusion of ions,so the synthesis of sea urchin-like VO₂-SDBS.The purpose of coating r GO is to stabilize the structure of the material and improve the conductivity of the material.The composite material is applied to cathode material for ZIBs,it can provide a reversible capacity of 417.7 m A h g^-1 after 100 cycles at a current density of 1 A g^-1;the current densities are 0.5,1.0,2.0,4.0,6.0,8.0 and 10 A g^-1,can provide 437.8,426.8,420.7,413.3,410.0,408.9and 402.8 m A h g^-1 reversible capacity,from 0.5 to 10 A g^-1,capacity retention rates up to 92.0%,showing its excellent rate performance.In addition,when the energy density is 307.3 Wh kg^-1,the power density is 7629 W kg^-1.