电沉积制备锂离子电池Sn-Cu合金负极材料及电化学性能研究

发布时间：2018-03-05 05:08

本文选题：锂离子电池　切入点：负极材料　出处：《广西大学》2014年硕士论文　论文类型：学位论文

【摘要】：金属锡作为新型锂离子电池负极材料,以其较高的比容量日益引起人们的广泛关注。然而由于金属锡电极在充放电过程中体积膨胀大,造成电极表面开裂、活性物质脱落等现象严重,大大降低了它的循环稳定性,从而限制了金属锡电极的实际应用。解决此问题的方法主要有将锡与其他元素组合,形成锡基合金、锡基氧化物或复合物。本论文以石墨为阳极,铜箔为阴极,在焦磷酸盐电解液体系中分别用直流电沉积和脉冲电沉积技术制备了Sn-Cu合金负极材料,并用X-射线衍射(XRD)、扫描电子显微镜(SEM)、循环伏安(CV)、交流阻抗(EIS)和恒流充放电测试等手段研究了电沉积过程工艺因素对材料的组成结构、微观形貌和电化学性能的影响。在直流电沉积过程中添加不同种类的氨基酸表面活性剂,可提高Sn-Cu合金负极材料的循环稳定性和比容量。其中以氨基乙酸为添加剂,在电沉积时间4min和电流密度5mA·cm-2条件下,制备的合金电极0.1C的放电比容量为678.8mAh·g-1,0.5C的放电比容量为485.2mAh·g-1,循环50次后容量保持率为81.4%。脉冲电沉积法制备Sn-Cu合金负极材料的条件：脉冲频率10Hz,电流密度20mA·cm-2,占空比20%,脉冲时间5min(实际电沉积时间)。在此条件下,合金电极的0.1C的放电比容量为821.8mAh·g-1，，0.5C的放电比容量为494.5mAh·g-1,50次循环后容量保持率为66.0%。
[Abstract]:As a new type of anode material for lithium ion battery, metal tin has attracted more and more attention due to its high specific capacity. However, due to the large volume expansion of the metal tin electrode during charge and discharge, the surface of the electrode is cracked. The phenomenon of active substance shedding is serious, which greatly reduces its cycle stability and limits the practical application of metal tin electrode. The main solution to this problem is to combine tin with other elements to form tin base alloy. Tin based oxides or complexes. In this paper, Sn-Cu alloy anode materials were prepared by direct current electrodeposition and pulse electrodeposition in pyrophosphate electrolyte system with graphite as anode and copper foil as cathode. The effects of electrodeposition process factors on the composition, microstructure and electrochemical properties of the materials were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), AC impedance spectroscopy (EIS) and constant current charge-discharge measurements. The cyclic stability and specific capacity of Sn-Cu alloy negative electrode materials can be improved by adding different kinds of amino acid surfactants in the process of DC electrodeposition, in which aminoacetic acid is used as additive, and the electrodeposition time is 4 minutes and the current density is 5 Ma 路cm-2. The specific discharge capacity of the alloy electrode 0.1C is 678.8 mAh 路g-1C, the discharge capacity of 0.5C is 485.2mAh 路g-1.The capacity retention rate of the alloy electrode is 81.4 after 50 cycles. The conditions for the preparation of Sn-Cu alloy anode materials by pulse electrodeposition are as follows: pulse frequency 10 Hz, current density 20 Ma 路cm -2, duty cycle 20, pulse time 5 min. The specific discharge capacity of the alloy electrode 0.1 C is 821.8mAh 路g-1C, the discharge specific capacity is 494.5mAh 路g-1C after 50 cycles, the capacity retention rate is 66.0.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM912

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