Preparation Of Supercapacitor By Doped Porous Carbon Material And Study On Its Electrochemical Properties

Supercapacitor is component that relies on electric double layer structure or redox reaction of tantalum capacitor layer to store and release charges.The main factors affecting the electrochemical performance of supercapacitors include electrode material,current collector,electrolyte and so on.The kind of electrode materials is the most important factor among them.Therefore,the development of electrode materials with excellent performance is the first priority to improve the overall performance of supercapacitors.Based on the concept of low cost,high performance and environmental protection,this thesis focuses on the development and design of new carbon-based composite hetero-element materials,and discuss on the effects of the microstructure and electrochemical properties of the obtained materials.The research contents and the primary results are as follows:（1）The carbon-based material（KACS）that has large specific surface area was obtained by calcining chitosan at high temperature and incorporating with KOH,then boron atoms were doped into carbon-based material by high-temperature hydrothermal reaction to prepare BKACS.We used the structural and morphological characterization to explore the changes on the structure of the BKACS material in the process of carbonization,alkali activation and doping of boron atoms.At the same time,the electrochemical properties of the prepared electrode materials were characterized by electrochemical workstations.BKACS material exhibited the excellent specific capacitance of 316 F g^-1(the current density was 0.2 A g^-1)in 6 M KOH electrolyte at the high current of 10 A g^-1.After 10,000 times repeated charge and discharge,the capacitance retention was 94.08%.（2）The carbon-based material KACS prepared in（1）was used as reducing agent,and KMn O₄ was selected as the manganese source.KACS and KMn O₄ were mixed in different ratios in water bath liquid phase.They were spontaneously oxidized by heating and stirring in the water bath equipment.The electrode material Mn KACS with abundant nanorods on the surface was obtained by the reduction reaction.Its structure,morphology and electrochemical properties were tested.The results showed that Mn KACS-2 material which was obtained at the optimum mixing ratio of 2:20exhibited the specific capacitance of 460 F g^-1 in 6 mol L^-1 potassium hydroxide electrolyte(the current density was 0.2 A g^-1).After 10,000 times repeated charge and discharge process at large current of 10 A g^-1,the capacitance retention rate was91.67%.（3）The carbon-based material KACS prepared as in（1）was used as substrate,and magnesium chloride was used as magnesium source.Magnesium atoms were doped into the carbon material by high-temperature hydrothermal reaction to prepare the electrode material Mg KACS.It was characterized for its morphology and structure,and its electrochemical properties were studied by electrochemical workstation.According to research,the material Mg KACS had specific capacitance effect of 293 F g^-1 at the current density of 0.2 A g^-1,and it still maintained 89.57%capacitance after repeated charging and discharging for 10,000 times at large current.