Fabrication Of Sn/C Composite Anode Materials For Lithium Ion Batteries By Electrospinning

Solving the volume effect of the electrode materials with high theoretical specific capacity,suchas Si,Sn or 3d transition metal oxide,is one of the key issues to develop the next generation lithium-ion electrode material with high energy density and high-rate cycling stability.One of strategies is using electrospinning technique to fabricate metal/carbon composite structure.By using nanoparticles for electrospinning directly,the dissolving out of the metal salt precursorcan be avoided and the poor dispersion of the nanoparticles can be improved.In this study,the Sn-SnSb/C composite nanofibers were fabricated by electrospinning with wet ATO slurry which exhibits a high dispersion.The prepared Sn-SnSb/C nanofibers exhibits a high reversible capacity and stable cycle performance when used as anode materials for lithium-ion batteries.The improved electrochemical performance can be attributed to the uniform dispersion of Sn-SnSb nanoparticles in the carbon nanofibers?CNFs?.The carbon nanofibers can also provide a continuous conductive network and meanwhile buffer the volume change of electrode materials.This research mainly about:1.By using ATO and PVP for electrospinning,the Sn-SnSb/C hybrid nanofiberswere fabricated after preoxidation and carbonization,and there is no agglomeration and dissolving out of the Sn and SnSb nanoparticles in the CNFs.The properties of the samples prepared with different carbonizing temperature and different content of ATO have been studied.When the carbonizing temperature is 700°C,the hybrid nanofibers showed a best electrochemical performance.It exhibited a reversible discharge specific capacity of 832 mAh·g^-1 in a current density of 50 mA·g^-1and maintained a specific capacity of 523mAh·g^-1 after1200 cycles in 1 A·g^-1.The excellent electrochemical performance can be attributed to the uniform dispersion of the Sn and SnSb nanoparticles in the CNFs whichavoid the direct contact of the nanoparticles with electrolyte and the CNFs provide a continuous conductive network.The stable solid electrolyte interface?SEI?films also improve the cycle performance of the electrode.2.Usingmulticomponent polymers of PAN/PVP for electrospinning with ATO,the porous carbon nanofibers?PCNFs?loading with Sn and SnSb nanoparticles can be obtained by water treatment and carbonization.Comparing with the hybrid nanofibers which haven't treated with water,it exhibited a higher specific capacity of 975 mAh·g^-1 in a current density of 50 mA·g^-1 and maintained a specific capacity of692 mAh·g^-1 after 250 cycles in 0.5 A·g^-1.The improvement of capacity mainly due to the porous structure which not only improve the specific surface area of the hybrid nanofibers andfacilitate the transfer of ions and electrons,but also buffer the volume change of Sn and SnSb nanoparticles during discharge/charge processes.3.Giving a pressure by using silica glass during carbonization can fabricatefree-standing nanofibers anodes.And we studied the electrochemical performance of the free-standing nanofibers anodes with different thickness and calculated the specific volumetric capacity of these anodes.The PVP/SnCl₂nanofibers can be used to fabricate free-standing anode which is flexible and this anode haven't been destroyed after repeated bending.Comparing these free-standing anodes,we found that the anode which has a uniform structure anda higher porosity exhibited a better electrochemical performance.