Fabrication And Electrochemical Performance Of Free-standing 3D-rGO/Sn Anode Material

Metallic Sn is a promising alternative anode material,because it not only has high theoretical capacity(991 m Ah g^-1) for Li_4.4Sn) and electronic conductivity but also has moderate operating voltage which can improve the safety of LIBs during the charge/discharge process.However,the practical application of metallic Sn as anode material for LIBs suffers from the dramatic volume expansion during lithium-ion alloying processes,leading to the severe pulverization which causes electrical disconnection of the active materials from current collector and instability of solid electrolyte interface?SEI?.We report a facile and safe technique of preparing a high performance,Sn metal anode material for lithium ion batteries?LIBs?,using a three-dimensional?3D?self-assembly of graphene oxide as a conductive frame.In this well-designed architecture,the three-dimensional reduced graphene oxide?3D-r GO?structure with excellent flexibility can efficiently refrain the encapsulated Sn from dispersing into the electrolyte directly and sustain the stabilization of Sn nanoparticles.We studied the effect of three parameters,time,temperature,and tin content.As a consequence,we find that 3D-r GO/Sn anode,annealed in H₂ atmosphere at 600?for 4 h,exhibits the most excellent cycling stability performance(1089.4 m Ah g^-1at first cycle and remain589.0 m Ah g^-1at 100^thcycle in 200 m A g^-1)and best rate performance.In order to further explore the influence of three-dimensional porous network structure the Sn anode,we add carbon nanotubes into three-dimensional graphene structure,in which one-dimensional carbon nanotubes and Two-dimensional graphene are interwovened and laminated.As the result,3D-r GO-CNTs loading with tin nanoparticles are prepared.It was found that the carbon nanotubes after treated with strong oxidizing acid can effectively improve the electrochemical performance of 3D-r GO/Sn material.Nevertgless,the material containing 15 wt%acidified carbon nanotubes had the best electrochemical performance.The discharge specific capacity is still 625.9 m Ah g^-1 after 100 cycles at 200 m A g^-1 current density,which indicates that the acidified carbon nanotubes can further improve the porous structure of the three-dimensional graphene.It is beneficial to improve the electrochemical stability of three-dimensional graphene/Sn anode material.