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Title: 天然礦石二硫化鐵作為室溫鈉硫電池正極之電化學反應機制研究
The electrochemical reaction mechanism of pyrite FeS2 as Cathode for Room Temperature Sodium-Sulfur Battery
Authors: 陳家俊
Chen, Chia-Chun
Chang, Po-Chia
Keywords: 二硫化鐵
Iron disulfide(nature pyrite)
Room temperature sodium-sulfur batteries
Issue Date: 2015
Abstract: 為了尋找比傳統廣泛使用的鋰離子電池具有高能量密度及較低的成本,常溫鈉硫電池是具有淺力的候選之一,此種新型電池不但大大的降低成本,也解決了高溫鈉硫電池在工作時安全性的問題,但以硫為正極材料的常溫鈉硫電池仍存在一些困難,像是導電性不足使材料反應性不佳,以及硫在鈉離子嵌入後所形成可溶性多硫化鈉溶解於電解液…等,這些因素會導致電池的電容量衰退以及較低的庫倫效率,所以本篇論文,以尋找合適的電極材料來改善目前的鈉硫電池之問題。 本研究是將天然礦石二硫化鐵材料應用在室溫鈉硫電池之正極。我們發現二硫化鐵材料在電流密度約50mAg-1條件下其第一圈放電電容量為1360 mAhg-1,而充電電容量約為1086 mAhg-1,其不可逆電容量約為20%,循環50圈後電容量約還有745 mAhg-1。而在快速充放電的測試中,我們以電流密度約8920 mAg-1的大電流下進行充放電測試,其電容量仍表現相當高的520 mAhg-1。最後,我們發現單純以微米大小之二硫化鐵應用在鈉硫電池的正極上,搭配適當的電解液和選擇合適的電位範圍,可得到穩定的循環表現、良好的庫倫效率以及快速充放電下可保持一定之電容量。
Efficient electrical energy storage has attracted intense attention due to power demend in next generation of electric vehicles and stationary applications. Rechargeable battery has viewed as good approach for energy storage. To aspire the higher energy density than traditional lithium ion battery used wildly, room temperature sodium-sulfur batteries (RT Na-S batteries) are especially attractive because of their high specific energy. In this thesis, a iron pyrite FeS2 material was investigated as sulfur source in the cathode electrode of RT Na-S battery. We found that iron disulfide as cathode materials (FeS2/Na-S battery) exhibited first discharge and charge capacity of 1360 mAhg-1 and 1086 mAhg-1 at a current density of 50 mAg-1 with a suitable electrolyte and potential range. The irreversible capacity at first cycle is approximately 20%. The capacity of FeS2 still remained 745 mAh g-1 after 50th cycles. During rapid charge - discharge test, FeS2/Na-S battery showed a high capacity of 520 mAh g-1 at a current density of 8920 mAg-1. In the detailed characterization by Raman and X-ray absorption spectra, we found that No polysulfide was formed by sulfur in FeS2 reacting with sodium and dissolved in electrolyte, resulting in remaining good capacity retention. Overall results indicated that The FeS2 cathode materials used in RT Na-S battery exhibited long cycle performance, high Coulombic efficiency and good capacity retention at high charge-discharge rate.
Other Identifiers: G060242085S
Appears in Collections:學位論文

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