矽材相關的負極已被眾多的研究發展，其優異的比容量與合適的工作電壓能讓鋰離子電池在性能上有所突破。此外，其豐富的資源與製程技術成熟更是利於大規模的生產。然而在充放電過程中，體積劇烈的變化會導致破裂產生，脫離集流器，使壽命銳減；而本質的低導離度、導電度會降低快速充放電的輸出。為了成功導入商業，以上的問題必須被克服。
本研究使用銀奈米粒子作為增加導電率、導離率的添加物，並增益矽薄膜的倍率性質。導入的方法則是將銀奈米粒子夾於兩層矽膜之間，形成矽/銀/矽的三明治結構，並調控銀粒子於界面的分布去找尋最佳的條件以及探討增益的機制。本實驗透過SEM、TEM技術進行形貌的分析；結晶性透過XRD以及Raman圖譜進行確認，而銀奈米粒子則需藉由TEM-nanobeam繞射技術以得到精確的資訊。在電化學分析上，組裝半電池進行壽命循環、倍率性質、循環伏安法(CV)與電化學交流阻抗分析(EIS)。本實驗中，最佳改質試片D_SiAg3在10C的高速充放電下能維持於低速運作(0.2C)電容量的46%，而純矽薄膜只能維持21%。在比容量方面，10C的測試下，D_SiAg3更是具有約1250mAh/g的比容量，而純矽薄膜則是500mAh/g。在CV測試結果，能發現D_SiAg3具有較低的過電壓，以及能在快速掃描下(0.8mv/s)維持完整的鋰化以及去鋰化的反應。最後，利用EIS進行機制的探討，並引入鋰離子濃度梯度以及電力線密度的假說，嘗試解釋銀奈米粒子所帶來的優異倍率表現。
綜合所有電化學分析，D_SiAg3被證明具有最佳的導電度及導離率，因此表現良好的倍率性質。在本研究中，銀奈米粒子與多層結構的應用被系統性的測試，提供鋰離子薄膜電池矽負極全新的解決辦法。

Silicon-based anodes have attracted much attention lately due to the high specific capacity for Lithium ion battery (LIB). Unfortunately, these materials face several challenges, such as low electrical and ionic conductivity and extreme volume change during lithiation/delithation leading to pulverization and delamination, which hinders Si anodes from commercialization.
In this research, Si anodes were prepared in thin films targeting for micro-LIBs to be integrated with nanoelectronics. To enhance the rate capability of such thin film LIBs, attempts are taken to incorporate Ag nanoparticles (NPs) into Si thin films as Si/Ag NPs/Si multilayer structure by varying Ag NPs density within a fixed film thickness. The successful preparation of such multilayers was verified by scanning and transmission electron microscopy analysis, while crystalline and bonding structure were studied by X-ray diffraction and Raman spectroscopy analysis. Cycling life, rate capability, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed for electrochemical testing. The results show that the highest Ag NPs density in the multilayer structure of Si/Ag/Si, named as D_SiAg3, exhibits the best capacity retention of 46% at 10 C relative to 0.2 C, reaching specific discharge capacity of about 1250mAh/g. D_SiAg3 demonstrates excellent improvement by comparing to the pristine one, possessing only 21% retention for 500mAh/g specific discharge capacity. From the CV tests, D_SiAg3 presents a lower overpotential than the pristine one indicating Ag NPs facilitate lithium ion diffusion. Finally, through EIS along with equivalent circuit simulations, the mechanism accounting for the enhancement in rate capability is proposed where Li ionic concentration gradient is promoted by the concentrated electrical line density around Ag NPs. These results prove that D_SiAg3 has better electric and ionic conductivity than the pristine one, and the multilayer can provide a new strategy for the rational engineering of advanced thin film LIBs.

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