Study On Preparation And Electrochemical Properties Of Carbon/Cobalt Tetroxide Composites

Electrochemical energy storage material and technology has attracted much attention due to its high energy efficiency and environmental friendliness.Among them,supercapacitors have become the focus of research due to their fast charging and discharging.Many electrochemically active materials have been discovered so far,and Co₃O₄ is one of the excellent choices that can be used as electrode materials for supercapacitors.However,Co₃O₄ used as an electrode material has disadvantages such as low conductivity and poor structural stability,which limits its application in high-performance supercapacitors.Carbon materials have good conductivity,combining them with Co₃O₄ can effectively improve the structural stability and conductivity of Co₃O₄.In this paper,a fast,convenient and environment-friendly synthesis method was used to synthesize carbon/Co₃O₄ composite materials,which effectively improved the electrochemical performance of Co₃O₄.The main work of this paper is as follows:1.Using peanut shells as the carbon source,the carbonization-activation method is used to convert it into activated carbon with high specific surface area,and the Co₃O₄ is compounded onto the activated carbon by a simple calcination method.It can be observed by scanning electron microscope that Co₃O₄ is evenly distributed on the surface of activated carbon.The electrochemical test of the three-electrode system shows that the activated carbon/Co₃O₄ composite delivering a specific capacitance(582 F/g@1 A/g)and cycle stability(66%@3000 cycles).The electrochemical test of an asymmetric supercapacitor(ASC)assembled using activated carbon/Co₃O₄ composite material and commercial activated carbon delivering a specific capacitance of 58.2 F/g at a current density of 1A/g.In addition,ASC's excellent power density(8964.7 W/kg)and energy density(12.7 Wh/kg)show its practical significance.2.Using glucose as the carbon source and urea as the nitrogen source,the N-doped carbon net was synthesized by the template method.The N-doped carbon/Co₃O₄ composite material was prepared by adding Co precursor during the process of carbon synthesis and calcining.The obtained carbon/Co₃O₄ composite material exhibits excellent electrochemical performance.In the three-electrode system,the specific capacitance of the electrode made of the carbon/Co₃O₄ composite material is 1115.4 F/g at 1 A/g.The ASC device assembled based on the carbon/Co₃O₄ composite material can reach an excellent energy density of 16.4 Wh/kg at a power density of 400 W/kg.3.Polyacrylonitrile was used as carbon source,Co source was added in the process of preparing spinning solution,and carbon fiber/Co₃O₄ composites with different morphologies and electrochemical properties were synthesized by electrospinning and calcination.Electrochemical tests show that the three-electrode system and the ASC system achieve specific capacitances of 713.7 F/g and 47.5 F/g respectively at a current density of1 A/g,and after 5000 charging and discharging cycles,the initial specific capacitance can be maintained at 63.9%and 74.8%,respectively.When the power density reaches 8042.6W/kg,the energy density can still be maintained at 10.5 Wh/kg,indicating that the prepared carbon fiber/Co₃O₄ composite material has a certain practical value.