Construction Of High-Performance Zinc Ion Hybrid Capacitors Based On Materials Derived From Metal Organic Frameworks

Research and development of new electrochemical energy storage devices with high energy density,high power output and long cycle life is one of the effective ways to promote efficient and renewable energy storage.As a new type of electrochemical energy storage device,metal ion hybrid capacitor has attracted much attention because of its combination of the advantages of traditional supercapacitors and secondary rechargeable batteries.Among them,zinc ion hybrid capacitors（ZIHCs）have come to the fore among many energy storage devices due to their rich reserves,low price,non-toxicity and good compatibility in aqueous,which have become a research hotspot.However,due to the problem of zinc dendrites and the low specific capacitance of capacitor-type materials,the practical application of zinc ion hybrid capacitors is hindered,designing capacitor-type materials with high specific surface area,hierarchical porous structure and heteroatom doping,as well as design and synthesis battery-type materials that can effectively and quickly insert/desorb zinc ions are effective measures to improve the performance of zinc ion hybrid capacitors.Herein,a series of capacitor-type and battery-type materials with stable structure and excellent electrochemical performance are prepared by using metal-organic framework（MOFs）as precursor combining the carbonization process and the chemical activation method.Optimize the assembly process to construction of a series of high-performancea queous zinc-ion hybrid supercapacitors（ZIHCs）.The specific research content of this paper is as follows:（1）A series of hierarchical porous carbon materials（MPC）with high specific surface area were prepared by ssing metal-organic frameworks（MIL-47（V））as precursor combing the chemical activation method,and the effect of KOH dosage on the specific surface area and porosity of the derived carbon materials was systematically studied.Analyze the influence of different pore structures on the capacitance performance of the materials,and select out the carbon material with the best capacitance performance,using it as the capacitor-type electrode of the zinc ion hybrid capacitor,the metal zinc foil as the battery-type electrode to assemble high-performance ZIHC devices.The energy density is as high as 130.1 W h kg^-1,and the maximum power output is 7.8 k W kg^-1.At a current density of 10 A g^-1 for 10000 cycles,the capacity retention rate was96.7%,showing excellent cycle stability.（2）The porous nanorod material M-V₂O₅/C with high specific surface area were prepared by annealing of MIL-47（V）precursor.The zinc storage performance of the materials in different electrolytes were systematically studied.At the same time,the kinetic behavior of energy storage and the zinc ion diffusion coefficient of the cathode material were systematically studied.Due to its stable structure,rich pore structure and developed conductive network,M-V₂O₅ has a fast dynamic behavior.It is used as a battery-type electrode,and MIL-47（V）derived porous carbon（MPC）is used as a capacitor-type electrode.By optimizing the mass ratio of the cathode and anode,the ZIHC device was successfully assembled.The device exhibits excellent rate performance and good cycle stability,and can achieve a high energy density of 26.6 W h kg^-1 and a high power output of 16 k W kg^-1.After cycling for 5 000 cycles at a current density of 5 A g^-1,the capacity retention rate was 71%,showing good cycle stability.（3）A sheet of V₂O₅ was prepared by hydrothermal method,and nitrogen-containing metal organic framework（ZIF-8）was designed to grow on its surface,the nitrogen-doped carbon composite ZnV₂O₄/NC materials were prepared by annealing of this precursor.The effect of different annealing temperatures on the crystal structure,specific surface area,pore structure and other microstructures and energy storage performance of the materials were studied,select the best preparation conditions for the material.Through ex-situ XRD methods to study the energy storage mechanism of material zinc ions,detailed analysis of the material’s energy storage kinetic behavior,calculation of zinc ion diffusion coefficient,and a systematic understanding of the material’s energy storage characteristics.Using it as battery-type cathode,and MIL-47（V）-derived porous carbon as capacitor-type anode.By optimizing the mass ratio of the cathode and anode,the constructed ZIHC device exhibits good electrochemical performance,which can achieve a high energy density of 22.3 Wh kg^-1 and a high power output of 8 k W kg^-1,showing excellent cycle performance(after 4 000 cycles at a current density of 5A g^-1,the capacity retention rate is 82.7%).