Preparation And Electrochemical Performance Of SiOC-based Anode Materials

Lithium-ion batteries,which have great potential for satisfy the demanding requirements for the development of energy storage materials,are playing an important role in our daily life.Therefore,researchers are working hard to design silicon-based anode materials with stable cycle performance and commercial prospects.Predecessors have donated themselves to explore the components of silicon-based anodes and found that silicon oxide can effectively suppress the volume expansion.What's more,the combination of silicon/carbon anode materials can enhance the transfer of electrons and help maintain the stability of electrode.Therefore,the Si-O-C composite material has great potential for commercial application.The main work of this thesis is around the SiOC composite and graphene materials.By mixing and heat-treating the SiOC composite and the graphene material to form a hierarchical structure,the SiOC-based material and the graphene material are composited together.The as prepared material shows improved electrochemical performance and stability.We describe our main contents of this paper as follows:(1)We prepared SiOC nanoparticles with Si,O,and C distributed uniformly in atom scale through the sol-gel method.Herein,the boron doping SiOC@Graphene(B-SiOC@G)hierarchical structure was fabricated by using boron doping-induced interconnection-assembly(BIIA)method.The continuous formation of the solid electrolyte interphase(SEI)film is effectively prevented by the graphene matrix.Therefore,the resulting B-SiOC@G anode shows excellent cycle stability with a 0.03%decay per cycle during 1000 at 0.5A ^g-1 and maintains a reversible capacity of 445 m A h g^-1.Such work offers a novel view of the prospect to design the structure stable Si-based anodes with long cycle life and high volumetric energy density for practical energy applications.(2)In the second part of the experiment of this paper,we prepared SiOC nanoparticles in the same way as in the previous chapter,and used citric acid and ascorbic acid as inducers and organic carbon sources,which help SiOC to anchor on graphene oxide(GO)through the interaction between hydrogen bonds.In this structure,SiOC double-coated with graphene and graphitic carbon are interconnected each other.The sample obtained in this way reduces the load of boron element and reduces the electrochemical capacity loss.On the other hand,the introduction of graphitic carbon improves the conductivity of the structure.In addition,when organic acids are used as carbon sources,SiOC can be surface modified due to the abundant carboxyl groups in the organic acids,so that the SiOC matrix can be more evenly combined with the graphene matrix and the binder when used as the anode material of lithium ion batteries.,The as prepared VC-SiOC@G electrode shows a reversible capacity of 412 m A h g^-1 after 500 cycles at a large current density of 1 A g^-1In the last part,we summarize and forecast the full text,and summarize the advantages and disadvantages of the work in this paper.