Redox Organic Molecules Modified Nanocarbon Electrodes For Energy Storage

Redox organic molecules have been widely used in energy storage due to their rich redox active sites and structural designability.However,its inherent low conductivity and solubility in electrolyte have been criticized.In order to solve these drawbacks,we improve the utilization rate and fast kinetics of redox organic molecules through molecular design and structural optimization.In recent years,supercapacitors designed and prepared by low-dimensional carbon nanomaterials have been favored because of their high cycle stability and controllability.Hence,this paper combines redox organic molecules with low-dimensional nano-carbon materials through clever structural design to form functional organic-inorganic composite electrode materials.This thesis aims to combine the advantages of organic and inorganic electrode active materials,and the two synergistically enhance the electrochemical properties of the target electrode materials.The detailed contents are elaborated as below:(1)We designed a free-standing flexible redox molecule modified carbon electrode by interweaving ono-step etherificated 5-hydroxy-1,4-naphthoquinone(Juglone)hydroxyl onto carboxylated single-walled carbon nanotubes(CNTs)and bacterial cellulose(BC)nanofibers.The electrode material was fully characterized in terms structure,morphology,electrochemical properties.The electrochemical storage performance was further evaluated.Suspended Juglone molecules promote the charge transfer of CNTs like a highway through electron hopping between adjacent Juglone molecules.By adjusting the feeding ratio of Juglone,the best J₁₁-CNT-BC nanocomposite has the highest specific surface area,electrical conductivity,and tensile strength.J₁₁-CNT-BC self-standing electrode exhibits a significantly improved specific capacitance of 461.8 F g^-1 at 0.5 A g^-1.Assembled with activated carbon into ASCs,the ASC delivers a maximum energy density of 41.9 Wh kg^-1 at 1.0 k W kg^-1 power density.(2)We for the first time use the nitro-rich aromatic molecule 3Qn as a monomer.The covalent organic framework organic electrode material(3Qn-COF)was prepared by a one-step solvothermal method and?-?stacked with the two-dimensional nano-carbon material graphene(r GO).The composite electrode material(3Qn-COF/r GO)with C=N and N=N dual redox active sites,large conjugated structure,large specific surface area and short ion transport channel is formed.The trinitro substituted molecules spontaneously connect to form a rigid hexagonal skeleton,which effectively suppresses the solubility of 3Qn.In the three-electrode system,the 3Qn-COF/r GO electrode exhibits a significantly improved specific capacitance of847.8 F g^-1 at 1A g^-1,and a high capacitance retention of 99.1%after 50 000 cycles at 50 A g^-1.In short,the collision of redox organic molecules and low-dimensional carbon nanomaterials not only solve the common problems of organic molecules in molecular design,but also the abundant redox active sites provided by the prepared organic-inorganic composite electrode materials are sufficient to contribute a larger ratio capacitance.This work will open up a new window for the reasonable design of high-performance supercapacitors.