利用水熱法製備ZnCo_2S_4鈴鐺型結構之形成機制和超級電容性能之研究

Formation Mechanism and Supercapacitor Performance of ZnCo_2S_4 Yolk-shell Structure Prepared by Hydrothermal Method

邱雅雲(Y.Y. Chiou) ； 向性一(H.I. Hsiang) ； 鍾昇恆(S.H. Chung)

《鑛冶：中國鑛冶工程學會會刊》 65卷2期 (2021/06) Pp. 55-63

https://doi.org/10.30069/MM.202106_65(2).06

摘要

三元金屬硫化物相較於二元硫化物或是傳統的金屬氧化物具備較高的導電性和優異的電化學性質，在超級電容的應用上極具開發的潛力。本研究透過水熱法合成鋅－鈷硫化物（ZnCo_2S_4），利用增加硫化時間形成ZnCo_2S_4鈴鐺型（Yolk-shell）結構，鈴鐺型結構除了可以提高材料的比表面積，增加活性物質與電解液和電極的活性位點，提供豐富的路徑讓離子和電子傳輸，同時，可以有效的改善材料在離子和電子遷移過程中體積膨脹和結構變形的問題。將ZnCo_2S_4奈米粉末製備成漿料後，塗佈於泡沫鎳上作為超級電容之工作電極，通過電化學量測，發現硫化18小時的ZnCo_2S_4在掃速30mV s^(-1)具有最大的積分面積和最高的氧化峰及還原峰，在大電流密度10 A g^(-1)下具有最高之比電容量1339 F g^(-1)。將硫化18小時ZnCo_2S_4作為正極與負極為活性碳材料組裝成不對稱超級電容器，通過電化學量測，由CV曲線可得知，不對稱超級電容器同時具有贗電容和電雙層電容的特性，且由GCD曲線得知，近似於等腰三角形的充放電曲線為典型的超級電容器充放電曲線特徵。其在能量密度為71.2 Wh Kg^(-1)時，功率密度高達2396.9 W Kg^(-1)，而在大電流密度15A g^(-1)下進行2000圈多次充放電長循環量測，保持率達到75%。

關鍵字

ZnCo_2S_4 ； 鈴鐺型結構 ； 超級電容 ； 奈米球體

並列摘要

Compared with binary sulfides or traditional metal oxides, ternary metal sulfides have higher conductivity and excellent electrochemical properties, and have great potential for the application of supercapacitors. In this study, zinc-cobalt sulfide (ZnCo_2S_4) was synthesized by hydrothermal method, and ZnCo_2S_4 yolk-shell structure can be obtained by increasing the sulfidization time. Yolk-shell structure can not only increase the specific surface area of the active material, but also increase the active sites of the electrolyte and the electrode providing abundant migration paths for ions and electrons. At the same time, yolk-shell structure can effectively inhibit the volume expansion and structural deformation of the active material during ions and electrons migration. The ZnCo_2S_4 nano-powder slurry was coated onto the nickel foam as the working electrode of supercapacitor. The ZnCo_2S_4 synthesized by sulfidization for 18 h had the largest integral area and the highest oxidation potential and reduction potential of the CV curve at a scan rate of 30 mV s^(-1), and also had the highest specific capacitance of 1339 F g^(-1) at a high current density of 10 A g^(-1). An asymmetric supercapacitor was assembled by using ZnCo_2S_4 sulfidization for 18 h as the positive electrode and activated carbon material as the negative electrode. The asymmetric supercapacitor has the characteristics of both pseudocapacitance and double-layer capacitance based on the CV curve. The GCD curve shows that the charge-discharge curve displays an isosceles triangle, which is the characteristic of a typical charge-discharge curve of the supercapacitor. The power density can reach about 2396.9 W Kg^(-1) at energy density of 71.2Wh kg^(-1). The retention rate remained 75% after charging and discharging of 2000 cycles at a large current density of 15 A g^(-1).

並列關鍵字

ZnCo_2S_4 ； Yolk-shell structure ； Supercapacitor ； Nanosphere