Preparation And Characterization Of Supercapacitor Based On Water Electrolytes And Carbon Materials

Due to increasing consideration of environmental issues in recent years, electricvehicles, photovoltaic power plants, wind power generation came into being. Theinternational governments and research institutions have been actively planning andinvesting in a variety of new energy storage equipment. Supercapacitor, also known aselectric double layer capacitors, electrochemical capacitors is a new energy storagedevice based on electrochemical processes of the electrode/electrolyte interface. Ithas a series of favor features that short charging and discharging time, long life, highpower density and wide temperature ranging for many applications.Supercapacitor also known as ultracapacitor, which the capacity can be achievedas Farah level or even thousands of Farah, is differed from the conventional capacitor.It not only can be quickly charged and discharged with large power density, but alsotake up some characteristics of both conventional capacitors and rechargeable batteryand build up between them as a new device for storing electric energy. In recent years,carbon-based supercapacitors have been successfully used in electric vehicles. Tocarry out the study and application of supercapacitor is of great significance in solvingenergy and environmental issues, and the development of electric vehicles.The main contents of this paper are divided into six chapters, a brief review onthe introduction and application of the supercapacitor, exploration of coinsupercapacitor technology and test methods in laboratory and electrochemicalmeasurement of activated carbon, graphene, and carbon-molybdenum oxide et alcarbon-based materials as electrode materials for supercapacitor in water electrolyte.(1) The activated carbon after nitric acid treatment is used as electrode materialin ammonium sulfate, lithium sulfate, sodium sulfate, potassium sulfate, potassiumchloride and potassium hydroxide, six kinds of electrolyte for electrochemicalperformance studies. The results show that the processing activated carbon material in the alkaline electrolyte obtains the best performance of these supercapacitors; amongthe neutral salt electrolyte, ammonium sulfate and lithium sulfate are better, andsodium sulfate capacitive nature is of the worst, mainly because of the formation ofhydrated sodium ions in aqueous solution, the hydrated sodium ionic radius isrelatively large, resulting in the specific capacitance is relatively small, the ionmigration impedance is also the largest, but it’s the best in cycle stability of thesetypes of electrolyte.(2) In this paper, redox preparation of graphene was carried out, the studies haveshown that it could effectively make it remaining lamellar by adding a certain amountof potassium chloride during the reduction process of the graphene. Mechanism ofaction of the potassium chloride was studied, mainly because of the role of oxygenfunctional groups on the graphene oxide surface bonding with the potassium ion andthe buoyancy significantly increased after potassium chloride added to the solution,further reducing agglomeration of the graphene. The research showed that thelamellar graphene formed more effective electric double layer and came up muchlarger capacitance than the agglomerating graphene by the electrochemicalperformance testing.(3) A new type of nanorods grafted nanograins of carbon-molybdenum oxide wasprepared, and characterized the morphology and structure of the complexes, proposedthe formation mechanism of the nanorods grafted nanograins. This kind of carbidecompounds was rich in carbon rods and molybdenum dioxide nanograins,electrochemical operating voltage of1.2V, higher than the general carbon and metaloxide complexes operating voltage (≤1V). The new wide potential electrodematerials would be important in guiding significance for preparing supercapacitorelectrode materials.