电化学法制备锂离子电池锡—镍薄膜负极及性能的研究

【作者】 刘凯；

【导师】 李晶泽；

【作者基本信息】 电子科技大学 ， 材料科学与工程， 2012， 硕士

【摘要】 目前商品化的锂离子电池负极主要是石墨材料,但其理论比容量较低(372mAh/g)。金属锡作为锂离子电池负极材料时具有较高的理论比容量(994mAh/g)而受到广泛关注。但是含锡的负极材料在充放电过程中,由于发生合金化反应导致体积膨胀,多次充放电循环后活性物质粉化脱落,使得电接触变差,进而容量急剧衰减,所以限制了其在锂离子电池中的应用。本论文通过多孔氧化铝模板电化学法制备了镍线／管、锡线／管阵列纳米结构化薄膜,用扫描电子显微镜(SEM)、X-射线衍射(XRD)分析了薄膜的形貌与组成,并研究了锡管阵列薄膜负极的电化学性能；本论文还采用氢气泡动态模板电化学法制备了多孔型锡-镍复合薄膜,用恒电流充放电法(CD)、循环伏安法(CV)测试了多孔复合薄膜电极的电化学行为,主要内容如下：(一)通过自制及商品化的氧化铝多孔模板,制备了镍(Ni)、锡(Sn)纳米线／管阵列,通过SEM、XRD对金属纳米线／管的形貌及组成进行了表征。SEM显示：当沉积速度加快或者沉积电量增加时,管阵列会演化成线阵列,通过自制与商品模板制备的金属阵列平均直径分别为50nm、200nm左右,XRD分析表明镍线具有(111)晶向的择优生长。最后探索了锡管阵列作为负极的电化学行为。(二)采用电化学法制备了四个系列多孔复合电极。首先是多孔镍系列复合电极,包括：Ni(多孔)/Sn(致密)、Ni(多孔)/Sn(致密)/Ni(致密)、Ni(多孔)／SnNi合金(致密),其中,第三种电极循环性能最好,第2至30次循环平均容量损失只有0.02%；之后,研究了Sn(多孔)、SnNi合金(多孔)镀层分别复合不同厚度致密镍层系列电极的电化学性能,充放电测试表明：复合的镍层越厚,充放电循环中容量保持率越好;最后,初步研究了多孔型CuSnNi三元合金与普通型三元合金的电化学行为,结果表明：多孔型三元合金的性能较好。更多还原

【Abstract】 The anode of the commercial lithium ion battery is mainly using graphite. However, its theoretical specific capacity is low (372mAh/g). Tin is a kind of attractive anode materials, because it has a higher theoretical specific capacity (994mAh/g). Unfortunately, tin anode has large volume change in the process of alloy and de-alloy with lithium, which leads to a poor cycle performance. As a result, pure tin can not be applied as the anode for the commercialized lithium ion battery.Here, we prepared thin films of nickel (Ni), tin (Sn) nanowire and nanotube arrays through AAO template-assisted electrochemical deposition. We analysed the morphologies and compositions of the samples by scanning electron microscopy (SEM), X-ray diffraction (XRD). Following that, we explored the electrochemical properties of tin tube arrays thin film. Atternatively, we prepared porous tin-nickel composite film by hydrogen bubble dynamic template-assisted electrochemical method. The electrochemical properties of porous tin-nickel composite film were characterized with CD (constant current charge-discharge test) and CV (cyclic voltammetry) methods. The main contents of this work were listed as below:(1) Through home-made and commercial AAO template, we prepared Ni, Sn nanowire/tube arrays. The morphology and composition of samples were characterized by SEM and XRD. The SEM images displayed that the average diameter of nickel wires was50nm and200nm through home-made and commercial AAO template respectively. When the deposition rate or the amount of the charge was increased, hollow tube became into solid wire. The XRD analysis showed that the nickel wire had a preferential growth direction along (111) facet. The electrochemical behavior of tin tube array thin film was investigated.(2) We fabricated composite film electrodes by electrochemical method. Firstly, porous nickel series, included:Ni (porous)/Sn (dense), Ni (porous)/Sn (dense)/Ni (dense), Ni (porous)/SnNi alloy (dense), of which, the third electrode had the best cyclic performance (average capacity loss from2nd to30th cycle only0.02%/per cycle). Secondly, Sn (porous) and SnNi alloy (porous) layers were combined with dense nickel layer at different thickness. The electrochemical performance showed that the thicker nickel layer could provide the better capacity retention rate. Finally, we preliminarily studied electrochemical performance of a porous CuSnNi alloy film, showing longer cycle lifetime with respect to that of the plain alloy film.更多还原