| The widely used fossil energy has caused more and more pollutions to the environment,such as acid rain,greenhouse effect,smog,etc..Therefore,developing clean energy is imperative,among which the development of energy storage equipments has been paid great attention.To meet the increasing needs of energy storage devices with high capacity,high power density and long service life,electrode materials are believed to be the key to high-performance energy storage devices.Carbon materials(CMs)owing to unique properties,such as high specific surface area,chemical stability,good electrical conductivity and so on,have widely being used in the energy field.In the present,CMs are usually obtained by carbonation of the natural products or polymers.The difficulty in tailoring the carbon structures and the tedious activation process make it unsuitable for production of CMs with desired high performance.Researchers have been looking for simple,improved synthetic methods to prepare CMs with excellent properties.In this thesis,we focused on the preparation of carbon-based materials by using simple,easy-to-operate,highly safe methods and environmentally friendly precursors.Their structure and morphology were characterized by PXRD,Raman,SEM,TEM and other technologies.Their properties in supercapacitors and lithium-ion batteries were also studied.This thesis includes the following three chapters:Chapter 1,Introduction.This chapter presents a brief introduction on the development and the research background of carbon-based materials.The research status and application prospects of carbon-based materials in the fields of supercapacitors,lithium-ion batteries,and metal-free catalysts are also discussed.Chapter 2,Facile synthesis of microporous nitrogen-doped carbon materials and its application in energy storage properties.We report a simple one-pot method to produce nitrogen-doped carbon materials(NCMs)by reacting N-bromosuccinimide with calcium carbide at high temperature.The texture properties of NCMs varied with the preparative temperature.The NCM prepared at 700°C possessed dual micropores(7 ? and 12 ?)and mesopores with the largest specific surface area of 1436 m2 g-1.The obtained porous carbon material was used in a supercapacitor,exhibiting a specific capacity of 214 F g-1 at a current density of 0.2 A g-1.The capacitance retention rate was about 96% after 5000 cycles at a current density of 5 A g-1.This work provides a simple way to synthesize N-containing carbon materials with excellent charge storage properties,which may be used to synthesize other tailored carbon materials with various properties.Chapter 3,Synthesis of composite carbon-silicon material and its performance as anode materials for Li-ion batteries.Here we report a simple method to silicon-carbon composite material by using the reaction of small molecule NBS and silicon Zintl salt magnesium silicide,taking advantage of the easy dissociation of NBS to remove the magnesium and the remaining groups to form polymeric carbon shell onto the silicon particles at high temperature.In the lithium ion battery test,the composite material displayed a specific capacity of 656 m Ah g-1 at a current density of 0.1 A g-1 and good cycle stability.The synthetic procedure is simple and easy to operate,and reducing many cumbersome steps in conventional preparations,providing possibilities for large-scale synthesis of silicon-carbon composite materials for using in lithium-ion batteries and other applications. |
