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Capacitive Properties Of Carbon-based Supercapacitor In KI Active Electrolyte

Posted on:2021-04-09Degree:MasterType:Thesis
Country:ChinaCandidate:H LiFull Text:PDF
GTID:2392330605967757Subject:Engineering
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At present,the research on the improvement of energy density of supercapacitors mainly focuses on the selection of electrode materials and the optimal design of electrolytes.Based on the construction of low-cost and excellent electrode materials,the performance of electrolytes is improved to build high-performance supercapacitors.In this paper,starting from graphene oxide?GO?,reduced graphene oxide?r GO?hydrogel and Mn CO3@r GO composite material were prepared,and separately study its supercapacitor performance in electrochemically-added KI electrolyte?sulfuric acid,sodium sulfate?.The main contents are as follows:1. Hydrothermal reaction to prepare graphene hydrogels?GEs?with 3D mesh structure.This unique 3D structure solves the disadvantage of easy stacking of graphene sheets.GEs sections soaked in electrolyte were directly used as electrode sheets,and two electrodes were assembled for testing.Different GO concentration will cause capacitance difference of electrode material.The results show that the electrochemical properties of the prepared GE5 are the best when the concentration of GO is 5 mg m L-1,and the electrochemical properties of the materials decrease with the increase of the concentration.In order to further improve the electrochemical performance of GE5,hydrazine hydrate reduced GE5 twice at different temperatures and regulated the functional groups on the surface of GE5.The results showed that the electrochemical performance of GE5-50R was the best when the reduction temperature was50oC.In H2SO4+KI electrolyte,the specific capacitance values of GE5 and GE5-50R are342.75 and 538.8 F g-1 respectively when the current density is 1 A g-1.Comparing the capacitance difference caused by different electrolyte,GE5-50R was tested in H2SO4 electrolyte.The results showed that the electrochemical performance of GE5-50R was good in the active electrolyte with KI.The specific capacitance of GE5-50R can keep 85%after 800 cyclic voltammetric tests in the electrolyte with KI added.Compared with 5%in H2SO4 electrolyte,the addition of KI can significantly improve the performance of capacitor and the cycle stability of capacitor.2. A series of MnCO3@r GO?GMs?composites were prepared by one-step hydrothermal reaction using KMn O4 and GO as precursors.For different concentrations of KMn O4,the obtained GMs electrode materials also have different electrochemical properties on the supercapacitor.With the increase of KMn O4 concentration,the capacitance performance decreases.The GM2 obtained at the concentration of 0.02 M has the best capacitance characteristics.When the current density is 0.5 A g-1,the specific capacitance of GM2 is 61.2 F g-1.In Na2SO4 electrolyte,KI was added to prepare active electrolyte,and three electrodes were assembled for electrochemical test.The electrochemical curve of the test shows the characteristic of oxidation-reduction of pseudo capacitance.When the current density is 0.5 A g-1,the specific capacitance of GM2 is 546 F g-1,and after 2000 cyclic voltammetry tests,the capacitance remained 93%of the 100th cycle.which shows that the introduction of active components in the electrolyte is an effective means to increase the electrochemical performance of supercapacitor.
Keywords/Search Tags:Supercapacitor, Electrochemical performance, Active electrolyte, Graphene hydrogel, Graphene composite material
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