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The Application Of Redox Electrolyte For Activated Carbon Supercapacitor

Posted on:2016-03-22Degree:MasterType:Thesis
Country:ChinaCandidate:T T HuFull Text:PDF
GTID:2272330470964832Subject:Chemical Engineering
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Because of the rapid development of the global economy, the global population is growing, and convenient electronic device market is also growing rapidly, and the development of hybrid cars, global energy consumption is also at an alarming rate. At the current rate of consumption of global energy depletion will inevitably take place in the near future. Therefore, there have been many growing and urgent needs of development, not only requires clean, renewable, sustainable alternative energy sources(solar, wind, tidal), but also advanced, low-cost, environmentally friendly energy conversion and storage devices to meet the needs of modern society emerging ecological problems. Recently, supercapacitors as a novel electrochemical energy storage devices are widely attention, it has many advantages, such as, fast charge and discharge, long cycle life and environmental protection and other. The mainly factors affecting the performance of the supercapacitor electrode are materials and electrolyte.In this thesis, hydrochar carbon sphere were prepared by the hydrothermal carbonization of β-cyclodextrins under different reaction conditions(temperature,time, fill rate, solid-liquid ratio), and to study the carbonization and activation conditions(carbonization temperature, activation temperature, activation time) on the electrochemical properties of the activated carbon material. Besides, introducing CuSO4/FeSO4 as redox materials into 1 mol L-1 H2SO4 and added KI/I2 into 2 mol L-1KCl solution formed a high-property redox electrolytes for activated carbon supercapacitors. The main contents obtained are as follow:1. The activated carbon has been prepared by simple carbonization and activation of β-cyclodextrins hydrochar which is synthesized by the hydrothermal method. When the hydrothermal reaction condition is 200 ℃(temperature)、2 h(time)、1:5(solid-liquid ratio)、53%(fill rate) get the good dispersion and well-proportioned hydrochar. And the best carbonization and activation condition is800 ℃(carbonization temperature) 、 2 h(carbonization time) 、 450 ℃(activation temperature)、1.5 h(activation time). The specific capacitance of activated carbon was181 F g-1 in 1 mol L-1 H2SO4 electrolyte. The value was larger than the corresponding values of carbonization carbon. After 1000 cycles, the capacitance retention of 80%was observed.2. Introducing CuSO4/FeSO4 as redox materials into 1 moL L-1 H2SO4 electrolyte formed the novel redox electrolytes for activated carbon supercapacitors.In this novel electrolyte, the specific capacitance of activated carbon supercapacitor was heightened by threefold, reaching 540 F g-1. Meanwhile, the supercapacitor showed good stability with retention of the initial capacitance values of 83.3% after1000 galvanostatic cycles. Activated carbon materials in Cu2+/Fe2+/H2SO4 electrolyte system get the low equivalent series resistance(1.09 Ω) compared to the other two active electrolyte, and also has a minimum charge transport resistance.3. The influences of a redox electrolyte based on KI/I2-KCl solution on the pseudocapacitive behaviors of activated carbon supercapacitor were investigated. It is discovered that the specific capacitance of the supercapacitor in KI/I2-KCl solution is233 F g-1 at 0.5 A g-1 current density. The capacitance value is larger than the capacitance in KCl solution. Furthermore, it could be inferred that the supercapacitor reflected outstanding cyclic atability with retention of the initial capacitance values of89.7% after 1000 galvanostatic cycles. At the same time, the activated carbon in KI/I2-KCl electrolyte compared to in KCl electrolyte get a lower equivalent series resistance.
Keywords/Search Tags:β-cyclodextrins, Activated carbon, hydrothermal, Redox electrolyte, Supercapacitor
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