Investigation of fluoroethylene carbonate effects on tin-based lithium-ion battery electrodes.
Investigation of fluoroethylene carbonate effects on tin-based lithium-ion battery electrodes.
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DOI：
10.1021/am508593s
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发表时间：
2015-03
影响因子：
9.5
通讯作者：
Zhenzhen Yang;A. Gewirth;L. Trahey
中科院分区：
文献类型：
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作者：
Zhenzhen Yang;A. Gewirth;L. Trahey
采用在铜箔（2-D）和泡沫（3-D）上化学镀锡的方法来制备无碳和无粘合剂的薄膜，用于固体电解质界面（SEI）性能的研究。当在纽扣电池中相对于锂金属进行电化学循环时，由于电极曲率，泡沫电极表现出比平面电极更好的循环性能。发现添加剂/共溶剂氟代碳酸亚乙酯（FEC）的作用显著提高了电池的容量保持率和库仑效率。2%FEC的添加量足以在慢（C/9）循环速率下在电池中获得益处。采用现场电化学石英晶体微天平（EQCM-D）研究了锡薄膜电极在含和不含FEC添加剂电解液中的界面性质。电解质在电极表面的分解过程和Li与Sn的合金化/脱合金化过程在分子水平上由表面质量变化定量表征。在初始还原扫描中，含FEC的电解质沉积少于不含FEC的电解质，但在几个循环伏安循环后增加了SEI的总厚度/质量。EQCM-D研究表明，在不同的电压范围内，每摩尔电子累积的质量（mpe）是不同的，这表明有/没有FEC的电解质的还原产物是不同的。
Electroless plating of tin on copper foil (2-D) and foams (3-D) was used to create carbon- and binder-free thin films for solid electrolyte interphase (SEI) property investigation. When electrochemically cycled vs lithium metal in coin cells, the foam electrodes exhibited better cycling performance than the planar electrodes due to electrode curvature. The effect of the additive/cosolvent fluoroethylene carbonate (FEC) was found to drastically improve the capacity retention and Coulombic efficiency of the cells. The additive amount of 2% FEC is enough to derive the benefits in the cells at a slow (C/9) cycling rate. The interfacial properties of Sn thin film electrodes in electrolyte with/without FEC additive were investigated using in situ electrochemical quartz crystal microbalance with dissipation (EQCM-D). The processes of the decomposition of the electrolyte on the electrode surface and Li alloying/dealloying with Sn were characterized quantitatively by surface mass change at the molecular level. FEC-containing electrolytes deposited less than electrolyte without FEC on the initial reduction sweep, yet increased the overall thickness/mass of SEI after several cyclic voltammetry cycles. EQCM-D studies demonstrate that the mass accumulated per mole of electrons (mpe) was varied in different voltage ranges, which reveals that the reduction products of the electrolyte with/without FEC are different.