Electrochemical Synthesis And Properties Research Of Tin Based Alloy Film Anodes Electrodeposited In Ionic Liquid Electrolyte For Lithium-ion Batteries

The tin-based anode material has the advantages of high theoretical specific capacity(994 mAh g-1)and good safety performance.Therefore,it's drawn a lot of attentions in the research field of lithium ion battery.In order to get commercial development,the problem of poor cycle stability of tin-based anode material should be solved.When tin embed in lithium,there will be a larger volume expansion.Along with the increasing of cycles,the active tin increasingly change to Li4.4Sn alloy,and the volume expansion turn to more serious,led to the active material occurs pulverization and fall off of the electrode,so the capacity would be reduced significantly.In this paper,Sn-based alloy anode materials were deposited on the copper foil by the electrochemical deposition,with Reline ionic liquids as solvents.The microstructure and phase composition of the alloy were characterized by SEM,EDS and XRD,and the electrochemical performance were tested by CV and constant current charge and discharge test.It is expected to improve the electrochemical properties of the tin-based materials,the effects of electrodeposition time,deposition current density,ratio of solvent and solute and different solutes in solution for the electrochemical properties of Sn-based alloy thin films were investigated.The research work is carried out in the following three aspects:1.Electrolytic deposition Sn-Co Alloy Anode Materials from Reline Ionic LiquidsThe effects of electrodeposition time,deposition current density,solute ratio in solution and the effect of different solutes for the electrochemical properties that Sn-based alloy thin films were discussed.When the electrodeposition time is 20 minutes,deposition current density is 20 mA cm-2,the ratio of the solute in the solution is Sn2+: Co2+ = 2:1,and the solute of solution is all of sulfate compound,the surface microstructure of the Sn-Co alloy anode material is dispersed and the electrochemical properties are the best.The first charge specific capacity is 716 mAh g-1 and discharge specific capacity is 874 mAh g-1 under 0.2 C,the first coulomb efficiency is 81.9%,the charge-discharge capacity is 892 mAh g-1 and 912 mAh g-1 after 60 cycles respectively,the coulomb efficiency is more than 97% in all 60 cycles except for the first.2.Electrolytic deposition Sn-Ni Alloy Anode Materials from Reline Ionic Liquids.The effects of the solute ratio in the solution and the different solutes in the solution for the electrochemical properties that the Sn-based alloy thin film electrode were discussed.The results show,when the ratio of the solute in the solution is Sn2+: Ni2+ = 2: 1,and the solute of solution is all of sulfate compound,the surface micro structure of the Sn-Ni alloy anode material is dispersed and the electrochemical properties are the best.The first discharge capacity is 580 mAh g-1 under 0.5 C,the discharge capacity is 451 mAh g-1 after 160 cycles.The coulomb efficiency is more than 97% in all 160 cycles except for the first.3.Electrolytic deposition Sn-Co-Zn Alloy Anode Materials from Reline Ionic Liquids.The effects of the solute ratio in the solution and the different solutes in the solution for the electrochemical properties that the Sn-based alloy thin film electrode were discussed.The results show,when the ratio of the solute in the solution is Sn2+: Co2+:Zn2+=2:1:2,the deposition current density is 20 mA cm-2,the obtained Sn-Co-Zn Alloy Anode Materials has special surface micro structure,Surface particles for the "caramel-type octahedron" structure,the first discharge specific capacity is 666 mAh g-1 under 0.5 C,the maximum discharge capacity in all 58 cycles is 977 mAh g-1.The first Coulomb efficiency is 77.5%.The coulomb efficiency is more than 97% in all 80 cycles except for the first,so it can be served as a good electrode material.