| Silicon-based materials have an unparalleled specific capacity(?4200 mAh g-1),environmental friendliness and low-cost make it one of the most promising anode candidate materials for applications in next-generation LIBs.However,the commercial application of silicon-based materials is limited by some drawbacks including low ion transport rate and conductivity,as well as large volume expansion(-400%)during charge and discharge.This article summarizes the research and development of silicon-based materials at home and abroad,based on this,in view of the problem of silicon as the anode of lithium ion batteries,combined with electrospinning and dyeing and finishing technology,a new type of composite carbon nanofiber negative electrode material is developed to obtain High energy density lithium-ion battery.This paper starting from improving the ion/electronic conductivity of silicon-based materials and assisting in reducing volume expansion,researched of flexible Si@SiOx composite acrylic-based carbon nanofibers(Si@SiOx-CACNF),Si/TiO2/Ti2O3 composite carbon nanofibers(STTC)and its applications of the lithium-ion battery.Chapter 1 introduces the development of lithium-ion batteries,then introduces the development of anode materials,and focuses on the problems facing the development of Si-based anode materials.Finally,it discusses the combination of Si-based anode materials with electrostatic spinning technology.Based on the current status of development,the research significance and content of this article are put forward.In chapter 2,the silicon nano-powder(?60 nm)was subjected to high-energy ball milling to obtain Si@SiOx powder,using civil acrylic as a carbon source and zinc acetate(Zn(Ac)2)as an additive,Si@SiOx-CACNF was prepared through electrostatic spinning,pre-oxidation,and carbonization.Comparing the morphology of the particles before and after ball milling,it was found that an amorphous SiOx layer with a thickness of?S nm was obviously formed on the surface of the particles after ball milling,Si@SiOx-CACNF was used as the anode electrode of lithium ion battery,at a current density of 0.1 A g-1,after 100 cycles,the battery exhibits a specific capacity of 1359 mAh g-1,and the average coulomb efficiency is>98%.Through in-situ EIS and modeling,analysis of its mechanism reveals that the amorphous SiOx layer has a high ion/electron transmission rate,and that it can relieve the volume expansion of the silicon core during the Li+intercalation/extraction process.Carbon nanofibers provide a good conductive network,Which further improves the electrochemical performance of the battery.However,due to the limited thickness of the SiOx layer,the cycle stability of the battery is not good and needs to be improved.In chapter 3,in view of the limited thickness of the SiOx layer formed by the Si particles in the previous chapter,a high-energy ball milling of TiO2 and Si was introduced to prepare a Si/TiO2 mixed powder,and Si was placed in a disordered frame of TiO2,using PAN as a carbon source,Si/TiO2/Ti2O3-CNF(STTC)was prepared by electrospinning and carbonization(atmosphere was hydrogen).During the carbonization process,the combined action of hydrogen and carbon causes TiO2 to be partially reduced to Ti2O3.According to theoretical calculations,Ti2O3 has high lithium ion conductivity and can be used as an ion transmission bridge between silicon and carbon nanofibers.As a result of electrochemical performance tests,the material was used as the anode electrode of a lithium ion battery.At a current density of 0.2 A g-1,after 200 cycles,it had a high specific capacity of 1449 mAh g-1.After 500 times,there is still a specific capacity of 924 mAh g-1,and the average coulomb efficiency is>99%.Finally,in chapter 4,we systematically summarize the research results of this article and put forward future development directions and suggestions. |
PDF Full Text Request