Study On Nitrogen-doped Carbon Microspheres As Anode Materials For Lithium Ion Batteries

Among many secondary battery systems,lithium ion battery(LIB)has become the most widely used battery because of its high specific energy,good cycle performance,low self discharge and no memory effect.Lithium ion battery is mainly composed of positive and negative electrode materials,electrolyte and separator.In terms of anode material,graphite is the main anode material for commercial lithium-ion batteries,and graphite is the main commercial anode material used in the currently available lib,However,due to the structural characteristics of graphite itself,the development of graphite anode materials has also encountered bottlenecks,such as the specific capacity(372m Ah/g)has reached the limit,and it can not meet the continuous high current discharge capacity required by large power batteries.In order to make carbon anode materials display excellent electrochemical performance such as high power density and high energy density,In this paper,cetyltrimethylammonium bromide(CTAB)was used as template,phenolic resin(resorcinol and formaldehyde)as carbon source,TEOS as auxiliary pore forming agent,ammonia as catalyst and melamine as nitrogen source,Nitrogen doped carbon microspheres were prepared by hydrothermal reaction and high temperature carbonization.The structure of the composite was analyzed by SEM,XRD and EDS.the electrochemical performance of the composite was tested by constant current charge discharge and electrochemical workstationBy controlling the amount of ammonia,nitrogen dosage and carbonization temperature of catalyst,the nitrogen doped carbon microsphere composite with better performance was prepared.The results show that the first discharge specific capacity of nitrogen microspheres is811.6m Ah/g,the first coulomb efficiency is 54%,and the capacity can reach 360 m Ah/g after100 cycles,It has a high capacity retention rate,which indicates that heteroatom n destroys the electrical neutrality and integrity of pure carbon materials and creates a large number of defects and vacancies,which further increase the active sites of carbon materials and improve the electrochemical performance of carbon materials.At 0 ℃,the first discharge capacity of the material is 201.9m Ah/g.After 20 cycles,it can be concluded that heteroatom n can destroy the electrical neutrality and integrity of pure carbon materials and create a large number of defects and vacancies,The first discharge capacity is 367.1m Ah/g at-20℃ and 166.8m Ah/h after 20 cycles.By controlling the amount of nitrogen doping,nitrogen doped carbon microsphere composites with better properties were prepared.The results show that the current density is100 m A/g,the first discharge capacity is 607.7m Ah/g and the first coulomb efficiency is 36.1%when the nitrogen doping is 1.5g and 1.5g nitrogen doping.After 150 cycles,the specific discharge capacity reaches 314.4m Ah/g.There are 33 pictures,9 tables and 72 references.