Controlled Preparation Of Functional Carbon Materials And Their Performance Regulation

As a new generation of energy storage devices,lithium-ion capacitors（LICs）rationally combine high energy density and high power density,providing an alternative solution for multi-functional electronic equipment and state grid systems.Electrode materials are the key factors affecting the performance of lithium ion capacitors.The energy density of the lithium-ion capacitor is mainly determined by the capacitive cathode material and the power density is mainly determined by the battery anode material.Therefore,the key to the development of lithium ion capacitors is to develop suitable anode and cathode materials with high capacity and good kinetic matching.Porous carbon materials are promising electrode materials due to their large surface area,good electrical conductivity,excelent cycling stability,and superior rate performance,and it is easy to prepare the required carbon materials through experimental regulation.The template method is one of the most mature approaches to preparing porous carbons.Using the structure guidance function of the template,the controllable synthesis of materials can be carried out by changing the space size,shape and structure order of the template,or adjusting the assembly mode of the template.In addition,transition metals also affect the morphology and electrochemical properties of carbon materials.The design idea of this paper is to use ethylenediamine tetraacetic acid series metal salts as raw materials,by changing the coordination metal elements and adjusting the calcination temperature,the morphology and electrochemical properties of carbon materials can be adjusted,and then suitable high-performance anode and anode materials for lithium ion capacitors can be obtained.The advantage of choosing this material is that ethylenediamine tetraacetic acid metal sodium salts have a similar structure.During the process of calcination,the material decomposition to produce a large amount of gas.At the same time,due to the presence of transition metals（copper,cobalt,iron）,the morphology and structure of the materials have different changes.The controllable preparation of functional carbon materials can be achieved by controlling the temperature and raw materials.Firstly,high nitrogen doped porous carbon materials were prepared by one-step carbonization using ethylenediamine tetraacetic acid disodium salt as raw material at 600°C,700°C and 800°C respectively,and the maximum nitrogen content of porous carbon material is 10.7 at.%,then the electrochemical performance of the materials obtained by calcining at the three temperatures was tested.Using the materials with the best performance as the anode and cathode of the LICs,the hybrid devices with a wide voltage window of 0.5-4.0 V were obtained.The energy density of LICs was 158 Wh kg^-1 at a power density of 225 W kg^-1,and 56 Wh kg^-1 at the high power density of 10.5 W kg^-1.Then,copper-catalyzed nitrogen doped porous carbon materials were prepared by one-step carbonization using Ethylenediaminetetraacetic acid copper disodium salt as raw material.The precursors were calcined at 600°C,700°C and 800°C to investigate the influence of temperature on the structural morphology and electrochemical properties of the materials.Compared with the previous chapter,it is found that copper catalyzes the conversion of sp² C.Using the materials with the best performance as the anode and cathode of the LICs,the hybrid devices with a wide voltage window of 0.5-4.0 V were obtained.The energy density of LICs was 158 Wh kg^-1 at a power density of 225 W kg^-1,and 60 Wh kg^-1 at the high power density of 10.5 W kg^-1.Finally,high graphitization nitrogen doped porous carbon materials were prepared by using Ethylenediaminetetraacetic acid disodium cobalt and Ethylenediaminetetraacetic Acid Ferric Sodium Salt as raw materials respectively.For Ethylenediaminetetraacetic acid disodium cobalt salt,by comparing three kinds of materials calcined at different temperatures,it was found that the presence of cobalt element can catalyze the graphitization transformation of materials,and the higher the temperature,the more obvious the catalytic effect was.For Ethylenediaminetetraacetic Acid Ferric Sodium Salt,the presence of iron can also catalyze the graphitization of materials,but the catalytic effect was not as strong as that of cobalt,which requires a higher temperature.The electrochemical properties of the materials calcined at600°C,700°C and 800°C were tested.And the materials calcined at 700°C showed the best performance,whether as anode or cathode.At the same time,as the anode and cathode of lithium ion capacitors,they can work in the voltage window of 0.5-4.0V and show good electrochemical performance.The energy density of LICs can reach 193 Wh kg^-1 at a power density of 225 W kg^-1,and 50 Wh kg^-1 at the high power density of 22.5 W kg^-1.