共濺鍍銅矽薄膜負極電化學特性之研究

The electrochemical proporties of co-sputtered Cu5Si thin film anodes

周宛瑱(Wan-Tien Chou)

指導教授 ： 林新智

國立臺灣大學/工學院/材料科學與工程學研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.01435

摘要

近年來可攜性電子產品的使用率越來約高，如何減輕可攜式電子產品的重量，電池就成了關鍵性的元素，而目前常見的電池當中以鋰離子電池最具發展性，因為鋰離子電池不論是在單位體積或單位重量都具有較高的電容量，然而如何突破現有的電容量，使其具有更高的使用效率，鋰離子電池內部電極材料就佔了不可或缺的因素。
本研究主要探討鋰離子電池負極材料部份，藉由雙靶磁控共濺渡沉積銅矽薄膜，並藉由調整工作壓力以及改變基材的粗糙度來改善鍍膜內應力以及附著性，藉此減緩鍍膜在充放電的過程中所造成的崩裂，以大幅提升薄膜的電化學性能。研究中發現，當工作壓力較小時，鍍膜較不易產生微小顆粒，且此鍍膜具有較大的壓應力，在充放電測試中，具有較大的放電電容量。在改變基材粗糙度方面，當不鏽鋼基板經1000號砂紙研磨後，沉積的鍍膜經過10次充放電後，能有效地減緩裂縫的產生，鍍膜較不易脫離基板，故可降低不可逆電容量。另外添加微量的非活性銅元素，以形成Cu5Si合金，此合金不會參與反應，亦可緩衝充放電時的體積變化，在循環壽命測試中，添加微量銅元素，展現了極佳的循環能力。

關鍵字

雙靶共濺鍍 ； 非晶矽 ； 工作壓力 ； 表面粗糙度 ； 非活性元素

並列摘要

In the portable electronics industry, the recent trend has been toward smaller and more powerful devices. This requires batteries made from materials with very high energy densities. However, to meet the ever-increasing energy demands of modern devices, researchers are seeking new materials that will lead to smaller, lighter, and longer-lasting batteries.
Cu5Si/Si thin-film anodes have been prepared using radio frequency driven magnetron sputtering. With appropriate working pressure during deposition, film residual stress and surface morphology can be well controlled. Field-emission scanning electron microscopy and bending beam apparatus were used to characterize the surface morphology and residual stress, respectively. Cu5Si/Si thin-film anodes deposited with low working pressure can develop smooth surface morphology and large compressive stress. The electrochemical properties of the thin-film anodes deposited under various conditions were measured and compared. The Cu5Si/Si thin-films deposited at a working pressure of 1 mTorr demonstrated that the first charge and discharge capacities of the materials were about 2518 mAh/g and 2343 mAh/g, respectively, with 93% of the first cycle efficiency. The cycle life performance of this material showed that the initial discharge capacity of 2343 mAh/g could be maintained up to 86% after 50 cycles. The cycling performance of the Cu5Si/Si thin-film anodes were improved significantly.

並列關鍵字

Co-sputter ； Amorphous Si ； Working pressure ； Roughness ； Inactive metal

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