Based On The Cross-linked Si/C Composite Materials And The Applications Of Lithium-ion Battery Anode

Lithium-ion batteries(LIBs)play an important role in our daily life.The theoretical specific capacity of traditional commercial graphite anode is only 372mAh/g,which can no longer meet the growing market demand.Silicon material with its high specific capacity(4200mAh/g)has attracted the attention of researchers and is considered as one of the most ideal,promising,and alternative anode materials in next generation LIBs.However,the volume change of silicon hampers the practical use of silicon-based anode in lithium-ion batteries.In this paper,in order to resolve the internal drawbacks of Silicon and reduce the process cost,the submicron Si particles,recovered from the slurry kerf waste of photovoltaic industry,were used as raw materials to prepare anode for LIBs.Based on the mechanism of preparing silicon anode with cross-linked network structure modified by binder,we introduce a silane coupling agent(DAMO)and polyacrylic acid(PAA)to prepare the silicon-carbon composite material with cross-linked structure through internal grafting.The main research contents are as follows:1.The preparation of three-dimensional cross-linked net structure of submicron Si used as the high-performance anode for LIBs.In this paper,we introduce a silane coupling agent(3-2(2-Aminoethylamino)propyltrimethoxysilane)and a polyacrylic acid to prepare the Silicon/carbon composite material with cross-linking structure,named Si@DAMO,which enhances the concatenation of silicon particles.After carbonization,we acquire the Si@DAMO-900.The Si@DAMO-900 electrode exhibits a reversible capacity up to 1970.6 mAh/g after 200 charge/discharge cycles at the current density of 420 mA/g.The cross-linked net structure improves the fracture resistance of Silicon particles and promotes the reversible electrochemical reaction.2.The preparation of C/Si@DAMO composite materials as high-performance anode for LIBs.Base on the cross-linked net structure of Si@DAMO,we select polyvinyl pyrrolidone(PVP)as carbon/nitrogen source.Then,through carbonization treatment,the C/Si@DAMO composite materials with cross-linked structure were prepared.The coated with PVP can fabricate a multi-dimensional conductive network,which alleviates the huge expansion stress and makes up for the shortage conductivity of Si particles.In addition,the composite material with cross-linked network structure can improve the fracture resistance of silicon particles and guarantee the integrity of silicon electrode.When tests at the current density of 420 mA/g,the C/Si@DAMO anode delivers a capacity of 2066.7 mAh/g after 200 cycles.In this paper,the raw material of silicon is recycled from the remains of photo-voltaic industry,which reduces the environmental pollution and resource waste.And the preparation process of composite material is low-cost,simple,economical,and environmentally friendly,which has a great industrial production potential.