Structural Design And Regulation Of Ptcda-based Energy Storage New Materials And Study On The Electrochemical Performance

The design and development of high-performance new energy materials and devices based on electrochemical energy storage are of great significance for mitigating environmental pollution and solving energy crisis.Supercapacitors are a class of new electrochemical energy storage devices with high power density and fast charge and discharge rates.However,low energy storage density has always been a bottleneck that limits their development and application.The optimization of the pore structure of carbon materials or the introduction of heteroatom doping to improve their capacitance performance as electrode materials,or by matching carbon electrodes with pseudocapacitive or battery-type electrodes to improve the energy density of supercapacitor devices is currently the main reseach hotspot.In recent years,due to the designable framework structure,which can effectively control the pore structure and introduce heteroatoms or metal centers,porous framework compounds such as porous organic frameworks?POFs?and metal organic frameworks?MOFs?have become an kind of important precursor for doped porous carbon,metal oxides or sulfides electrode materials,which has been paid much attention.3,4,9,10-perylenetetracarboxylic dianhydride?PTCDA?,is a dye intermediate,and its imide derivatives are important perylene dyes.PTCDA has the characteristics of condensed ring?conjugated skeleton and abundant active groups,which has good application prospects in organic solar cells,nanoelectronics,and organic electrode materials for lithium/sodium ion batteries.However,based on the high requirements for rapid charge and discharge mechanism,supercapacitors demand good conductivity of the electrode material.But the semiconductor properties of PTCDA and its derivatives limit its application in supercapacitors.In view of the structural characteristics of PTCDA,the use of PTCDA as a monomer or ligand to form porous framework compounds of POFs or MOFs is of great significance for expanding its application in the field of new energy materials and basic research on the application of high value-added dyes.However,there are few reports on related researches.There are still few methods and theories for the design and structural control of PTCDA-based porous frameworks and their derived materials.To explore the controllable fabrication method of directional construction of target functional porous materials,to explore the control methods of high specific area of materials,hierarchical pore structure and reasonable pore size distribution,and the structure-effect relationship with energy storage capacity have become urgent topics in this field.Based on the large conjugated molecular structure of dye intermediate PTCDA and its imide derivatives,this thesis designs and prepares PTCDA-based POFs and MOFs and their derivative materials.And heteroatoms or metal centers are introduced by constructing porous frameworks to enhance specific capacitance of electrode materials and energy of density devices.The main innovative work is as follows:1.Using PTCDA,nitrogen/oxygen-containing monomer 2,6-diaminoanthraquinone?DAAQ?and triformylresorcinol?TFP?as the main raw materials,PTCDA and DAAQ are firstly polymerized to produce a polyquinone imine?PQI?with a rigid structure.Then the PQI and TFP are polymerized to Schiff base polymerization and suffered from the subsequent heat treatment by melted salt method in one step.N,O-doped POFs-based porous carbon framework HPCFs are in-situ constructed.The main mechanism of the formation of HPCFs by conjugated Schiff base POFs at higher temperatures is explored.The effect of high temperature treatment conditions on the microporous structure and the doping content of nitrogen and oxygen heteroatoms in HPCFs is discussed.The relationship between the pore effect and in-situ doping and its electrochemical energy storage performance is studied.The experimental results show that the HPCF-500 prepared at a synthesis temperature of 500 exhibits a higher specific capacitance(at a current density of 1 A g^-1 the specific capacitance is 286.5 F g^-1,and at 125.0 F g^-1 at 10 A g^-1),and has good cycling stability.When the power density is 0.9 kW kg^-1,the two-electrode system HPCF-SC assembled based on ionic liquid EMIMBF₄ as electrolyte has an energy density up to 237.1 Wh kg^-1.The energy storage mechanism study illustrates that in the pore structure of HPCFs,the pore structure larger than 5?is effective for the formation of electric double layer capacitance.The heteroatom-doped quaternary nitrogen N-Q is conducive to the electron transfer occurring in the electrode material,while the pyrrole nitrogen N-5,pyridine nitrogen N-6 and quinone-based oxygen O-I can introduce into the pseudocapacitance and increase the total capacitance.The one-step construction of POFs-derived porous carbon by the molten salt method has the characteristics of relatively simple raw materials and methods and short preparation processes,which has good application prospects in the controllable preparation and industrialization of high-performance porous carbon materials.2.Based on the design of generalized"one for two",PTCDA and PQI are used as ligands to coordinate with respective metal ions through solvothermal synthesis to synthesize Zn-PQI-MOFs and NiCo-PTCDA-MOFs,which act as precursors for derived carbon and metal sulfide materials.In the structural design of Zn-PQI-MOFs,PQI as a ligand combines the rigid structure of the conjugated skeleton of PTCDA and the advantages of nitrogen and oxygen heteroatoms in DAAQ,resulting in an ultra-high specific surface area(1381.4 m² g^-1)and micro-and meso-porous hierarchical pore structure for the N,O-doped carbon.It shows a high specific capacity and rate capability(at a current density of 1 A g^-1,the specific capacity is 240.6 C g^-1,210.0 C g^-1 at 10 A g^-1).NiCo-PTCDA-MOFs-based porous NiCo₂S₄ also has a high specific surface area(95.5 m² g^-1),with mesopores as the main pore structure,and excellent capacity performance(805.1 C g^-1 at 1A g^-1).The prepared MOF-based N,O-doped carbon material and porous NiCo₂S₄ are assembled into a battery-supercapacitor hybrid device?BSC?.When the power density is 0.8 kW kg^-1,the energy density is 52.0 Wh kg^-1.Compared with the corresponding symmetric devices?porous NiCo₂S₄//porous NiCo₂S₄ system and N,O-doped carbon//N,O-doped carbon system?,the energy storage performance has been significantly improved.Through the"one for two"strategy,positive and negative electrode materials with matching energy storage performance are developed,which provides a simple and feasible method for achieving high energy density and high power density of electrochemical energy storage devices.3.Using solvothermally synthesized Zn-PTCDA-MOFs particles and lignin extraction components as raw materials,Zn-PTCDA-MOFs are embedded in the lignin-based spinning nanofibers by electro spinning technology.After heat treatment,hierarchical pore distribution is formed in the hollow carbon nanofibers HCNFs.The introduction of Zn-PTCDA-MOFs particles plays a key role in the formation of mesopores in HCNFs.By controlling the activation temperature,the pore structure of HCNFs can be adjusted.The prepared HCNF-1000 electrode not only has a high specific capacitance(229.6 F g^-1 at a current density of 2 A g^-1),and good rate performance(176.8 F g^-1 at 10 A g^-1,99.1 F g^-1 at 30 A g^-1).The HCNF-SC,a two-electrode symmetrical system assembled based on 6 M KOH as an electrolyte,has an energy density of 5.1Wh kg^-1 when the power density is 0.5 kW kg^-1.HCNF-1000-based solid-state supercapacitor HCNF-FSC shows good electrochemical performance even in different folded states,and has excellent cycling stability.The initial capacitance is still maintained at 90.3%after 10000 cycles of charge-discharges.PTCDA-based MOFs are embedded in biomass-based electrospinning nanofibers to construct hollow carbon nanofibers,which provides a new design strategy for the development of a self-supporting flexible electrode material with environmentally friendly and excellent energy storage performance,which displays the potential application value for the development of portable wearable devices.