Structure Design And Electrochemical Performance Of Porous Tin-based Anode Materials For Lithium-ion Batteries

As a promising candidate,Sn-based alloy anode material,such as Sn or SnO2,are as promising candidates for lithium ion battery due to its intrinsic merits of environmental benignity,abundance,and high theoretical capacity.However,Sn-based anode materials undergo huge volume change in the repeated lithiation/delithiation cycles,poor electric conductivity,formation of unstable solid electrolyte interface(SEI)film,which hinder its commercial application.In this paper,the introduction of porous structure and carbon conductive network have been proposed to solve the above-mentioned problems.Three kinds of different Sn-based porous anode compsite have been designed and prepared to acquire high performance anode for Li-ion battery.Firstly,the porous SnO2/Sn/carbon composite(p-SnO2/Sn/C)has been fabricated by one-pot hydrothermal method with pluronic F127 as soft template and subsequent carbonization.The 5 nm SnO2/Sn nanoparticles were embedded in ordered carbon framework,which can buffer huge volume change of SnO2/Sn nanoparticles and provide 3D channels for Li ion extraction and insertion during repeated cycling.In addition,the orderd porous carbon framework structure can also improve the electronic conductivity of the whole electrode and ensure formation of more stable SEI film to enhance the electrochemical stability of SnO2/Sn.As a result,the p-SnO2/Sn/C composite displays excellent long cycling performace.Secondly,SnO2/carbon nanotube-graphene composite(SnO2/CNT-GN)has been prepared by one-pot hydrothermal process with subsequent freeze drying and heating treatment.The CNT and GN form 3D interconnected framework in SnO2/CNT-GN,which can suppress the volume expansion of whole electrode for the synergistic effect of flexibility GN and high mechanical property of CNT.Moreover,the CNT-GN conductive framework can also offer faster charge transfer pathways to help electron to the surface of SnO2.Therefore,the SnO2/CNT-GN exhibits the more superior cycling performance and higher rate capability.Thirdly,one dimensional coaxial polyaniline@tin dioxide@multi-wall carbon nanotube composite(PANI@Sn02@MWCNT)has been designed and fabricated by self-assembling SnO2 on MWCNT and subsequently in-situ growing PANI flexible layer.The flexible PANI,the buffer MWCNT and the pores structure can effectively accommodate the volume expansion of SnO2 during charge/discharge process.Meanwhile,the Li-ion and electronic conductivity of the whole PANI@SnO2@MWCNT electrode can be significantly increased by the synergistic effect of PANI and MWCNT.Thus,the PANI@SnO2@MWCNT anode shows excellent cycling stability and brilliant rate capability.