离子液体中锂离子电池锡基合金负极材料的电化学制备及其储锂性能研究

发布时间：2018-05-01 16:39

本文选题：Reline离子液体 + Sn基合金　；参考：《湘潭大学》2017年硕士论文

【摘要】：锡基负极材料有高理论比容量(994 mAh g-1)和安全性能好等优点,在锂电科研领域备受青睐。锡基负极材料的商业化应用,需要解决循环稳定性差这一难题。锡在嵌锂的时候会发生较大的体积膨胀,随着循环次数的增加,活性材料锡在嵌锂时形成Li4.4Sn的量增多,体积膨胀也越严重,使电极材料的活性成分发生粉化和脱落,可逆比容量便会大幅度下降。本文以Reline离子液体为溶剂,运用操作时间短、环保的电化学沉积法,在铜箔上电沉积制备Sn基合金负极材料。运用SEM、EDS和XRD表征和分析合金材料的表面形貌、物相及组成,同时运用CV和恒流充放电测试电化学性能。对比探索了溶液中溶质的配比、溶液中不同类型的溶质、电沉积时间和电流密度对Sn基合金材料的电化学性能方面的影响,期望锡基材料的电化学性能得到改善,为此,在以下三个方面开展了研究工作。1.Reline离子液体中电化学沉积Sn-Co合金负极材料探讨了溶液中溶质的配比、溶液中不同的溶质、电沉积时间和电流密度对Sn基合金材料的电化学性能方面的影响。结果表明,溶液中溶质的配比为Sn2+:Co2+=1:1,电沉积时间和电流密度分别设为20 min和2 mA cm-2以及溶液中的溶质都为硫酸盐化合物的条件下,制得的Sn-Co合金负极材料表面存在许多纳米级孔洞,表现出最好的电化学性能。0.2 C下首次放电比容量为874 mAh g-1,首次充电比容量为716 mAh g-1,60次循环后的充放电比容量分别为892 mAh g-1和912 mAh g-1,除首次外的60次循环库仑效率都在97%以上,首次库仑效率为81.9%。2.Reline离子液体中电化学沉积Sn-Ni合金负极材料探讨了溶液中溶质的配比以及溶液中不同的溶质对Sn基合金薄膜电极电化学性能的影响。结果表明,溶液中溶质的配比为Sn2+:Ni2+=2:1以及溶液中的溶质都为硫酸盐化合物的条件下,制得的Sn-Ni合金负极材料表面形貌较分散且存在气孔,表现出最好的电化学性能。0.5 C下首次放电比容量为580 mAh g-1,160次循环后放电比容量为451 mAh g-1,除首次外的160次循环库仑效率在97%以上。3.Reline离子液体中电化学沉积Sn-Co-Zn合金负极材料探讨了沉积电流密度和溶液中溶质的配比对Sn基合金材料的电化学性能方面的影响。结果表明,电沉积电流密度设置为20 mA cm-2,溶液中溶质的配比为Sn2+:Co2+:Zn2+=2:1:2下电沉积的Sn-Co-Zn合金负极材料,有很特别的表面形貌,表面颗粒为“杨桃型类八面体”结构,0.5 C下首次放电比容量为666 mAh g-1,前58次循环后,达到最大的放电比容量为977 mAh g-1。首次库仑效率为77.5%,除首次外的80次循环库仑效率在97%以上,是电化学性能较好的材料。
[Abstract]:Tin based anode material has many advantages, such as high theoretical specific capacity (994 mAh g-1) and good safety performance, so it is very popular in the field of lithium electric research. The commercial application of tin-based anode materials needs to solve the problem of poor cyclic stability. With the increase of cycle times, the amount of Li4.4Sn formed by tin in lithium intercalation increases, and the volume expansion becomes more serious, which causes the active composition of the electrode material to be powdered and shedding. The reversible specific capacity will be greatly reduced. Sn-base alloy anode materials were prepared by electrodeposition on copper foil using Reline ionic liquid as solvent and electrochemical deposition method with short operating time and environmental protection. The surface morphology, phase and composition of the alloy were characterized and analyzed by means of SEM-EDS and XRD. The electrochemical properties of the alloy were measured by CV and constant current charge-discharge. The effects of solute ratio in solution, different types of solute in solution, electrodeposition time and current density on the electrochemical properties of Sn based alloy materials were compared and explored. The electrochemical properties of tin based alloy materials were expected to be improved. 1. Electrochemical deposition of Sn-Co alloy negative electrode materials in Reline ionic liquids the proportion of solutes in solution, different solutes in solution, The effects of electrodeposition time and current density on the electrochemical properties of Sn-based alloys. The results show that the ratio of solute in the solution is Sn2: CO2 / 1: 1, the electrodeposition time and current density are 20 min and 2 Ma cm-2, respectively, and the solute in the solution is sulfate compound. There are many nanoscale holes on the surface of the Sn-Co alloy negative electrode material. The first discharge specific capacity is 874 mAh g-1 at 0.2C, and the charge-discharge specific capacity is 892 mAh g -1 and 912 mAh g -1 after 60 cycles of 716 mAh g -1, respectively. The Coulomb efficiency of 60 cycles except for the first time is above 97%. The first Coulomb efficiency was electrochemical deposition of negative electrode material of Sn-Ni alloy in 81.9%.2.Reline ionic liquid. The effects of solute ratio in solution and different solutes in solution on electrochemical properties of Sn-based alloy thin film electrode were investigated. The results show that when the solute ratio is Sn2: Ni2 / 2: 1 and the solutes in the solution are sulfate compounds, the surface morphology of the Sn-Ni alloy anode material is dispersed and there are pores. The first discharge specific capacity is 580 mAh g-1160 cycles and the discharge specific capacity is 451 mAh g-1. The Coulomb efficiency of 160 cycles except for the first time is over 97%. 3. Electrochemical deposition of Sn-Co-Zn alloy negative in Reline ionic liquid. The effects of deposition current density and the ratio of solute in solution on the electrochemical properties of Sn based alloy were investigated. The results show that the electrodeposition current density is 20 Ma / cm ~ (-2) and the ratio of solute in the solution is Sn2: Co _ 2: Zn _ 2: Zn _ 2: 1: 2. The electrodeposition of Sn-Co-Zn alloy negative electrode material has a very special surface morphology. The initial discharge specific capacity of the surface particles is 666 mAh g-1 under the structure of "caramon-like octahedron" 0.5C, and the maximum discharge specific capacity is 977 mAh g-1 after the first 58 cycles. The first Coulomb efficiency is 77.5%, and the Coulomb efficiency of 80 cycles except for the first time is more than 97%, so it is a material with good electrochemical performance.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O646;TM912

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