Preparation Of Porous Carbon Materials By Molten Salt Method And Its Electrochemical Energy Storage Characteristics

Supercapacitors have the advantages of high power density,long cycle life and fast charging and discharging rates,However,its energy density is low compared to secondary batteries,which in turn limits its further application.Electrode material is the main factor affecting the electrochemical performance of supercapacitors,In contrast,carbon materials as electrodes have cheap and easy access,high conductivity,high specific surface area and special structure,such characteristics facilitate ion transport and provide more active sites.Therefore,simple and efficient preparation of carbon materials for electrochemical energy storage is a recent hot topic of research.In this thesis,a mixed molten salt method is used to prepare porous carbon materials,and the microstructure of porous carbon is better controlled by adjusting the type of mixed molten salt.Aqueous zinc ion electrochemical energy storage devices can be a good alternative to lithium ion batteries from the cost and safety point of view.Meanwhile,zinc ion battery-capacitor hybrid devices（ZIBCHDs）integrate the advantages of high energy density of zinc ion batteries（ZIBs）and high power density of zinc ion hybrid capacitors（ZICs）and are expected to become a good energy storage device for the next generation.The main research of this thesis includes the synthesis of porous carbon materials with controllable morphology and adjustable pore size distribution using molten salt and molten salt-assisted chemical activation methods and the study of their related electrochemical energy storage properties.Details of the work are as follows:（1）Using sodium carboxymethyl cellulose as the precursor,more microporous and mesoporous pores can be produced in carbon materials by mixing molten salts.A graphene-like nanoporous carbon material with a high specific surface area of 1739.5 m²g^-1was prepared using the Cs Cl-Na Cl mixed molten salt method.it was used as a cathode material for zinc ion hybrid capacitors（ZICs）.At a current density of 0.1A g^-1,the specific capacity is as high as169.1 m Ah g^-1,while at a power density of 16 k W g^-1,It can reach an energy density of 62.24 Wh kg^-1and has a capacity retention rate of 91.7%after 10,000 cycles of stability testing.（2）Three-dimensional carbon skeleton structures with N-doped nanosheets were prepared by Na Cl molten salt-assisted potassium hydrogen tartrate （KHC₄H₄O₆）activation method using polyacrylamide as the precursor.It was shown that Na Cl molten salt can promote the activation ability of KHC₄H₄O₆, which results in more nanopores.This porous carbon material with abundant pore size and unique microstructure can be a good carrier of iodine.Its assembled ZIBCHDs exhibit battery-level specific capacity and energy density.At the same time,its charging and discharging efficiency and cycling stability can be comparable to supercapacitors.