| Supercapacitors are both promising energy storage devices because they have the characteristics of fast charge and discharge of capacitors and the energy storage characteristics of batteries.The performance of supercapacitors mainly depends on the electrode materials,and the research of electrode materials has been a hot topic at home and abroad.In this paper,the structure and electrochemical properties of activated carbon prepared by mixing coal,graphene residual carbon and both are systematically studied.In order to further improve the material capacity,the composite materials of sulfide and two activated carbons were prepared by hydrothermal method.The composition,structure and capacitance properties of the composites were systematically studied.It is expected to provide a theoretical basis for the design and preparation of supercapacitor electrode materials.Activated carbons with different alkali-carbon ratios were prepared at 600℃ and 800℃using anthracite as raw materials.The structural analysis showed that the activated carbon prepared by using different alkali-carbon ratios was amorphous carbon.The electrochemical performance test showed that the coal-based activated carbon prepared at a temperature of 800℃with an alkali-to-carbon ratio of 3:1 had the best comprehensive performance at 0.5 A/g current density.The lower capacity is 142.5 F/g.Taking graphene residual carbon as the research object,the effects of activation temperature,alkali-carbon ratio and carbon source ratio on the structure and electrochemical properties of carbon materials were studied.Structural analysis showed that the activated carbon obtained at different activation temperature treatments and different carbon ratios were amorphous carbon.The electrochemical performance test showed that the specific capacitance of the electrode material was 186 F/g at a current density of 1 A/g,when the ratio of graphene residual carbon to anthracite was 3:1.Different from single activated carbon,composite activated carbon material is a typical hybrid capacitor energy storage mechanism,which has both electric double layer reaction and tantalum capacitance reaction.MoS2 was prepared by hydrothermal method under different pH conditions.The structural analysis showed that the obtained MoS2 had low crystallinity and was amorphous.The electrical property test showed that the specific capacitance of MoS2 prepared at pH=3 was 185 F/g.At pH=3,a composite material of MoS2 and graphene residual carbon(MoS2/GR)was prepared.The composite with the residual carbon content of 15%had the highest specific capacitance of 312 F/g.After 1000 cycles,the capacity was maintained.The composite material of MoS2 and composite activated carbon(MoS2/C/GR)was prepared under the same conditions.At 1 A/g current density,the maximum capacity was obtained when the composite carbon content was 10%,which was 536.2 F/g.The effects of nickel acetate,thiourea and trisodium citrate on the structure and electrochemical properties of NiS were studied by hydrothermal method.Then the composite materials with graphene,coal-based activated carbon and composite activated carbon were synthesized by hydrothermal method.The structure and electrochemical properties of the materials were studied.The results show that the NiS prepared under the condition of 1:7:4 ratio of nickel acetate,thiourea and trisodium citrate has good purity,high crystallinity and flower-like structure.The capacity was at most 537.8 F/g at a current density ofl A/g,and the capacity retention was 71.3%after 1000 cycles.The composites prepared by NiS and graphene residual carbon have the best electrochemical performance among the three types of composite materials.When the residual carbon content of graphene is 5%,the specific capacitance at the current density of 1 A/g is 774 F/g.The ion diffusion resistance is the smallest,and the specific capacitance retention rate after cycling 1000 times is 77.2%.There are 133 figures,4 tables and 126 references in this dissertation. |
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