Study On The Preparation And Energy Storage Performance Of Conductive Polymer/MOF Composites And Their Derivatives

Supercapacitor is an emerging energy storage device,which has the advantages of high-power density,fast charge and discharge,and excellent cycle stability.However,the lower energy density limits the large-scale applications of supercapacitors in the commercial field.The shape and structure of electrode materials play a key role in the performance of supercapacitors.Therefore,it is of paramount importance to reasonably design advanced electrode materials to promote efficient electron transmission and rapid ion diffusion to improve the performance of supercapacitors.In recent years,metal-organic frameworks(MOF)with high specific surface area and low density are considered to be promising new-generation electrode materials.Nanostructured porous electrode materials(such as metal oxides,sulfides,hydroxides,and porous carbon)can be obtained by simple heat treatment of MOF,which can well retain the original MOF morphology and structure and improve the energy storage performance of the materials.Unfortunately,due to the low conductivity of most MOF,the shortcomings of poor rate performance and capacity decay with the cycle have greatly hindered their practical application.As a kind of electrode material with high conductivity and low cost,conductive polymers have attracted sustaintial attention.Therefore,compositing conductive polymers with MOF and their derived materials as electrode materials will make full use of their synergistic effects,expose more active sites,promote rapid ion transport,and provide better supercapacitive performance.Therefore,this thesis designed and synthesized conductive polymer/MOF and its derived composite to improve the electrochemical performance of electrode materials.The specific work of this paper is as follows:1.Ni-MOF nanosheet arrays grown on PANI decorated Ni foam(Ni-MOF/PANI/NF),which was directly used as electrode of supercapacitors.The as-prepared Ni-MOF/PANI/NF exhibites a high areal capacitance(3626.4 m F cm^-2 at 2 m A cm^-2)and good rate capacity(71.3%).Moreover,an asymmetric supercapacitor(ASC)device used Ni-MOF/PANI/NF and activated carbon(AC)can delivered high energy density of 45.6 W h kg^-1 and excellent cycling stability(maintain 81.6%of initial capacity after 10000 cycles).2.A hierarchical 2D PANI/Ni₃S₂ nanosheet arrays on NF with open network was successfully developed by the grown of Ni₃S₂ nanosheet arrays derived from 2D Ni-MOF templates followed by the electrodeposition of a layer of PANI nanoflakes.The optimized PANI/Ni₃S₂/NF-100 electrode exhibited a high areal capacity(1.56 m A h cm^-2 at 5 m A cm^-2),which significantly better than a single PANI/NF or Ni₃S₂/NF electrode.Furthermore,an ASC fabricated can delivered high energy density of 48.3 W h kg^-1 and outstanding durability(maintain 85.7%of initial capacity after 15000cycles).It superior electrochemical performance can be attributed to the unique hierarchical PANI/Ni₃S₂ nanosheet arrays structure.3.ZIF-67 derived Co₃S₄ hollow nanocages(HNCs)were embedded in polypyrrole(PPy)tubes to form a mixed“Co₃S₄-to-PPy-to-Co₃S₄”conductive networks.The synthesized Co₃S₄-HNCs@PPy has excellent electrochemical activity(1706.0 F g^-1 at 1 A g^-1)and high rate capability(72.5%).ASC based on Co₃S₄-HNCs@PPy can provide high energy density of 50.5 W h kg^-1 and has excellent cycle stability(maintain 82.8%of initial capacity after 10000 cycles).This excellent electrochemical performance can be attributed to the synergy of the intertwined“Co₃S₄-to-PPy-to-Co₃S₄”conductive networks,including abundant active sites,shortened charge transport pathways and enhanced charge transfer capabilities mechanical stability.Comprehensive research contents above,we have successfully prepared with different morphology and structure of conductive polymers/MOF composite electrode materials and its derivatives,and showed excellent electrochemical performance,it can be used in areas such as energy storage and conversion,and for the development of high-performance conductive polymer/MOF composite materials and its derivatives in preparation of electrode materials provides a new way of thinking and strategy.