Preparation Of MOFs Materials And Application In Supercapacitors

Metal-organic framework(MOFs)materials have become one of the research hotspots of supercapacitors due to their diverse and adjustable structures.However,their poor conductivity limits their applications.In this thesis,aiming at the problem of poor conductivity of MOFs,three kinds of electrode materials(Ni-MOF_BDC,Ni/Co-MOF_BTCand Ni-MOF_BDC@C)have been synthesized through surfactant sassisted.And their morphology,structure and electrochemical behavior have been studied.The specific content is as follows:1.Using solvothermal method,a nano flower-like Ni-MOF_BDC(S160)has been prepared by using nickel acetate as the metal source and terephthalic acid as the ligand,under the assistance of anionic surfactant sodium dodecyl sulfate(SDS).Comparing with the P160 prepared polyvinypyrrolidone(PVP)assisted and N160 prepared without surfactant,the S160 prepared the SDS assisted has the highest specific capacity;that is the specific capacity of S160 is 1036.8 F g^-1at 1 A g^-1.This good electrochemical performance is attributed to S160 assisted by SDS hold a nano-flower shape,its ultra-thin sheet shortens the path of ion migration,and the self-supporting hierarchical frame provides space for ion transportation and storage.2.Under the assistance of surfactant SDS,a sea anemone-like Ni/Co-MOF_BTC(NiCo₂₁)has been prepared by using nickel acetate and cobalt acetate as the metal sources and terephthalic acid as the ligand.The effect of the molar ratio of Ni to Co on electrochemical performance of Ni/Co-MOF_BTChas been studied.The results show that NiCo₂₁,which is prepared as the molar ratio of Ni to Co is equal to 2:1,holds the highest specific capacity in the prepared samples,namely its specific capacity reaches to 1560.3 F g^-1at the current density of 1 A g^-1.The value is better than that of single metal Ni-MOF(NiCo₄₀,1318.7 F g^-1)and Co-MOF(NiCo₀₄,618.8 F g^-1).Meanwhile,the energy density of an asymmetric device assembled by NiCo₂₁is 54.8 Wh kg^-1at power of 822.4 W kg^-1.The excellent electrochemical property of NiCo₂is belongs to the synergistic effect of bimetallic,and the sea anemone-like structure composed of nanorods.3.On the basis of the 2^ndchapter,a flower-like porous Ni-MOF_BDC@C(MOFs@C_SP)has been synthesized successfully by using carbon homemade(QK)as substrate material with the help of two surfactants(SDS and PVP).SEM results show that the MOFs@C_SPis the porous material that bends and folds into flower shape of Ni-MOF nanosheets grown with orientation on the carbon materials.The results also illustrate that the carbon material plays the role of template and conductive reinforcing agent.Under the action of carbon and double surfactant,the MOFs@C_SPhas the highest specific capacity and the lowest resistance of charge transfer,that is the specific capacity of MOFs@C_SPis 1350.1 F g^-1at 1A g^-1,corresponding to resistance of charge transfer of 0.3?.This is obviously higher than the electrochemical properties of MOFs@C_P,MOFs@C_Sand Ni-MOF_BDC.However,the energy density of the asymmetric device assembled by MOFs@C_SPis 42.9 Wh kg^-1under813.1 W kg^-1.