The Preparation And Characterization Of Activated Carbon And MXene

Recent years, the application of electric vehicles and development of periodic clean energy(such as solar energy, water energy, wind energy, tidal energy) makes an increasing demand of the energy storage equipment. For all energy storage equipment, supercapacitor and lithium-ion battery possesses promised future. Carbon based supercapacitors own extremely excellent cycle performance and rate capability. Unfortunately, in practice, that kind of supercapacitor is limited by their low energy density can be used in certain domains which allow the devices to get charged and discharged frequently. Otherwise, MXene based Li-ion batterys own good rate performance but also limited by its low gravitational specific capacity which makes it can not meet our need. Therefore, this article is carried out in two aspects: i, preparation of high capacitance supercapacitor electrode materials; ii, synthesis of MXene based electrode materials with high Li-ion battery performace. The main research methods and results are as follows:(1) Sodium alginate derived activated carbons are prepared by chemical activation method from sodium alginate. By changing the sintering temperature and use level of NaOH,different activated carbons are prepared. The structure and electrochemical characterization indicates that in aqueous electrolyte the electrochemical properties of the activated carbon are mainly affected by the specific surface area. In addition, the oxygen content in the activated carbon can effectively reduce the hydrophobicity of the material and hence improve its electrochemical performance, but material with high oxygen content will also undergo low conductivity and poor rate performance.(2) Delaminated MXene(d-MXene) and graphene oxide(GO) dispersions were used as precursors to prepare MXene and three-dimensional graphene(3DG) composite by hydrothermal method. After the hydrothermal, the products were proofed to be a kind of TiO2@3DG composite which implies that the MXene have been oxidized. These oxide particles can effectively inhibit the collapse of the pore structure and make these products with better performance after drying. And the tests of non-dried electrodes proof that the forming of titanium oxide can improve the reduction degree of the materials, and thus improve the rate performance of the material.(3) D-MXene and manganese oxide(MnOx) dispersions were used as precursors to prepare MXene and MnOx composite by cold quenching method. By adjusting the pH of the mixture dispersion, MXene nano-scrolls(MNS) has been produced. By comparing the electrochemical properties of MnOx@MXene and MnOx@MNS, it proofs that MnOx@MNS possesses better cycle performance. Then, the MnOx@MNS was annealed at different temperatures in order to study the reduction effect of MNS upon MnOx, as well as thechanging of the crystal structure and valence state of MnOx. The electrochemical characterization of the products after annealing shows that the cycle performance and rate performance of the products were greatly improved after annealing. The structure characterization also proofs that the crystal structure, valence state and the electrochemical performance of the product was closely related to the annealing temperature.