矽奈米結構之合成及其在鋰離子電池上之應用

Abstract

在眾多的電池能源技術中，鋰離子電池因有高能量密度的特性，因此被廣泛的研究。在其中，矽材由於他在地球上的含量多且具有相當高的理論電容值 (3579 mAh g-1)，因此被視為鋰離子電池中最有潛力的陽極材料之一。 在本研究中，我們利用氣固相反應在較低溫的環境下合成出高結晶性的純矽材料。接著將其作為陽極活性材料以應用於鋰離子電池上。當應用於鋰離子電池之陽極時，似奈米線狀結構的陽極活性材料，在420 mA g-1的充放電速度下經過50次循環充放電後有391 mAh g-1 (以EC/DEC作為電解液)及561 mAh g-1 (以EC/DMC/EMC作為電解液)的電容表現。相較於使用商業用的矽粉以及其它以發表的純矽材料文獻，有較高的電容表現以及穩定性。結果顯示此純矽材料是有潛力做為鋰離子電池之陽極活性材料。此外，我們使用兩種不同電解液配方，得到顯著不同的電化學性能結果，以顯示電解液於鋰電上的重要性。

Among the various battery technologies, lithium ion batteries stand out because of the facilitating design of storage systems with high energy density. Silicon is a promising candidate for electrodes in lithium ion batteries due to its high theoretical lithium storage capability (3579 mAh g-1) and the numerous natural abundance. Here, we report that via a simple vapor-solid reaction growth (VSRG) method, highly crystalline silicon materials can be synthesized at relatively low temperatures. The as-fabricated Si samples were applied for lithium-ion battery anodes. The half cells consisted of Si nanowire-like (NW) structures demonstrated a reversible capacity 391 and 561 mAh g-1 in EC/DEC and EC/DMC/EMC electrolytes, respectively, after 50 discharge/charge cycles at a current density of 420 mA/g. In contrast to commercial Si particles, the results showed that the Si nanowire-like (NW) structures exhibited much higher reversible capacity and better cyclic stability, promising candidates for anode of lithium-ion battery. Furthermore, we compared two electrolytes which exhibit dramatically different electrochemical performance to show the important role of the electrolytes.