本研究透過簡易的兩階段水熱法合成鋅鈷硫化物(ZnCo2S4)，利用改變硫化時間(第一系列)和改變硫的添加量(第二系列)形成ZnCo2S4鈴鐺型奈米球體結構(Yolk-shell nanosphere structure)。在材料的部分，選用ZnCo2S4三元過渡金屬硫化物(Ternary transition metal sulfide)作為活性物質，其相較於二元金屬硫化物或是傳統的金屬氧化物，具備較高的導電性、更豐富的價態和優異的電化學性質；在結構的部分，鈴鐺型結構除了可以提高材料的比表面積，增加電解質和活性物質之間的反應活性位點，藉此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高電流密度下的比電容量和穩定性。
將ZnCo2S4奈米粉體製備成漿料並塗佈於泡沫鎳上作為工作電極，進行三電極電化學量測。由CV曲線可得知，ZnCo2S4-18h和ZnCo2S4-0.4g不但顯示出贗電容器的氧化還原峰之特徵，且對稱的氧化還原峰表明良好的氧化還原可逆性，而在高電位掃速時(30 mV s-1)，皆擁有最大的積分面積(29.7、36.2)，並透過比電容量公式計算GCD曲線在各電流密度之放電時間，可得知ZnCo2S4-18h和ZnCo2S4-0.4g在大電流密度下仍然具有最佳之比電容量(1250.1 F g-1 at 15 A g-1、1457.0 F g-1 at 15 A g-1)。
為了近一步了解ZnCo2S4電極在實際應用中的儲能性質，因此將ZnCo2S4當作正極材料與負極為活性碳材料組裝成不對稱超級電容器，進行二電極電化學量測。由CV曲線可得知，ZCS-18h//AC和ZCS-0.4g//AC不對稱超級電容器同時具備贗電容和電雙層電容的特性，並擁有近似於等腰三角形的典型超級電容器充放電曲線。ZnCo2S4-18h//AC不對稱超級電容器，在高功率密度18000.0 W kg-1下，還是能保有良好的能量密度65.3 Wh kg-1，而在大電流密度15 A g-1下進行2000圈多次充放電後，其比電容維持率仍可達到75%；ZnCo2S4-0.4g//AC不對稱超級電容器，當功率密度為2397.9 W kg-1時，具有最佳之能量密度106.6 Wh kg-1，且在高功率密度17860.2 W kg-1下，還是能保有良好的能量密度70.3 Wh kg-1，而在大電流密度15 A g-1下進行2000圈多次充放電後，其電荷傳輸電阻從3.22Ω下降至0.84Ω。

In this study, zinc-cobalt sulfide (ZnCo2S4) was synthesized by a two-stage hydrothermal method, and ZnCo2S4 yolk-shell structure can be obtained by increasing the sulfidation 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, the yolk-shell structure can effectively increase the specific capacitance and stability at a high current density. The ZnCo2S4 nano-powder slurry was coated onto the nickel foam as the positive electrode and activated carbon as the negative electrode of the asymmetric supercapacitor. Through electrochemical measurement, it is found that ZnCo2S4-18h//AC exhibits the best electrochemical properties. The asymmetric supercapacitor exhibits the characteristics of both pseudocapacitor and electric double-layer capacitor based on the CV curve, and ZnCo2S4-18h//AC has the largest integral area at different scan rates. 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, and ZnCo2S4-18h//AC has the longest discharging time at different current densities. The energy density can reach about 65.3 Wh Kg-1 at a high power density of 18000.0 Wh kg-1. The cyclic stability remained 75% after charging and discharging of 2000 cycles at a large current density of 15 A g-1.

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