Effects of Cu current collector as a substrate on electrochemical properties of Li/Si thin film cells
Effects of Cu current collector as a substrate on electrochemical properties of Li/Si thin film cells
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DOI：
10.1007/s10853-005-2656-6
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发表时间：
2006
影响因子：
4.5
通讯作者：
Cho Gyu Bong;Lee Bong Ki;Sin Won Chul;C. K. Koo;A. Jun;Nam Tae Hyun;Kim Ki Won
中科院分区：
文献类型：
--
作者：
Cho Gyu Bong;Lee Bong Ki;Sin Won Chul;C. K. Koo;A. Jun;Nam Tae Hyun;Kim Ki Won
金属硅，基于Li4的形成，理论容量达到4200mAh/g。 4Si（Li222Si5）相是一种有前途的锂微电池负极材料[1]。然而，当Si应用于锂电池时，会形成Li4。 4Si伴随着电极的大体积膨胀，导致容量快速衰减。因此，许多实验和理论工作都集中在减少硅电极的结构变化上。铜箔已被用作锂电池的商业集流体，并用作薄膜电池的基板。最近，一些研究使用机械粗糙化的铜箔基板实现了高容量锂/非晶硅薄膜电池的延长寿命[2, 3]。基材的粗糙表面增强了活性材料和集流体之间的粘附力。因此，衬底表面粗糙度是提高Li/Si薄膜电池循环性能的重要因素。然而，商业铜箔的制造工艺对其微观结构和表面粗糙度有很大影响。当电池以微型尺寸制造时，必须认真对待这些因素。不过，目前还没有任何报道澄清他们之间的关系。因此，研究作为集流体的基底的微观结构和粗糙度之间的关系对于理解薄膜微电池的电化学性能具有重要意义。在这项研究中，采用滚压工艺使铜箔表面粗糙化并改变其微观结构。众所周知，剪切带的形成会导致横向粗糙度地形出现峰和谷（沟槽）[4-6]。本研究的目的是检查不同处理的铜箔的结构和表面特征，并阐明这些因素对锂/硅薄膜电池电化学性能的影响。
Metallic Si, whose the theoretical capacity reaches to 4200 mAh/g based on the formation of Li4. 4Si (Li222Si5) phase, is a promising anode material for the Li microbatteries [1]. However, when Si is applied to the Li batteries, the formation of Li4. 4Si is accompanied with a large volume expansion of electrode and leads to a rapid capacity fade. Thus, much of the experimental and theoretical effort has been focused on reducing structural change in the Si electrode.Cu foil has been used as a commercial current collector for Li batteries and applied as a substrate for thin film batteries. Recently, some studies achieved a prolonged lifetime of Li/amorphous Si film cell with high capacity using a mechanically roughened Cu foil substrate [2, 3]. The rough surface of substrate enhanced the adhesive force between an active material and a current collector. Therefore, surface roughness of substrate is an important factor to improve the cycleability of Li/Si film cell. However, the manufacturing processes of the commercial Cu foil influence strongly on its microstructure as well as surface roughness. Those factors must be significantly treated, when batteries are fabricated at micro scale. Nevertheless, there was no report on clarifying relationship between them. Thus, the investigation of the relationship between microstructure and roughness of substrate as a current collector is important to understand the electrochemical properties of thin film microbatteries. In this study, a rolling process is applied to roughen the surface of Cu foil and to change its microstructure. It was well known that the formation of shear bands causes peaks and valleys (trenches) in the roughness topography running in the transverse direction [4–6]. The objectives of this study are to examine the structure and the surface feature of differently treated Cu foils and to clarify effects of those factors on the electrochemical properties of Li/Si film cell.