- 學位論文
新穎尖晶石金屬硫化物於鋰離子電池負極材料之應用
Applications of Novel Spinel-based Metal Sulfide Anode Materials for Lithium-ion Battery
摘要
近年來，隨著科技蓬勃發展，市場對於通訊設備和電動汽車市場的需求遽增，因此鋰離子電池在這20多年中得到廣泛的發展與研究，鋰離子電池不僅需要高能量密度，還需要高理論電容量，才可以為電子設備提供高容量並減少充電時間，因此我們成功開發新穎的儲能負極材料並應用於鋰離子電池。 在這項研究中，我們主要透過溶劑熱法成功製備CuIn2S4並且透過高能球磨技術製備出CuIn2S4/C複合材料作為鋰離子電池的負極材料，使用X光繞射儀（X-ray diffraction, XRD）、掃描式電子顯微鏡（Scanning electronic microscopy, SEM）和高解析穿透式電子顯微鏡（High-resolution transmission electron microscopy, HR-TEM）對CuIn2S4和CuIn2S4/C複合材料的晶體結構和表面形貌進行分析，在電化學之表現CuIn2S4的可逆電容量在0.2 A/g和1 A/g的電流密度下分別為349 mAh/g和176 mAh/g，而經過高能球磨後，CuIn2S4/C複合材料的高速率充放電能力和可逆容量分別提高到在0.2 A/g的電流密度下為717 mAh/g和1 A/g的電流密度下591 mAh/g，另外，CuIn2S4的循環穩定性也成功被改善，CuIn2S4/C複合材料在5 A/g的電流密度下進行500次充放電循環之後還可以保有376 mAh/g。為了了解電化學反應機理，進行充放電過程中對CuIn2S4極板進行非原位以及原位的XRD測量。 接著，透過溶劑熱法成功製備MgIn2S4，並且使用奈米碳管進行複合，製備出CNT-MgIn2S4複合材料作為鋰離子電池的負極。當CNT的添加量為1 wt.%時具有較佳的電化學性能，在0.5 A/g的電流密度下充放電200次循環後，電容量仍有184 mAh/g，而過多的CNT會產生團聚現象，導致電化學性能不佳，隨著CNT的添加量增加，在交流阻抗分析中，阻抗值也隨之增加。最後，我們針對不同黏著劑對於此材料在電性上的表現進行探討，當使用水性黏著劑CMC/SBR時具有較佳的電化學表現，0.5 A/g的電流密度下充放電200次循環後，保有215 mAh/g的可逆電容量。
並列摘要
The corresponding lithium-ion batteries (LIBs) technology have been widely developed in more than 20 years because of the needing for mobile devices and electric vehicles market. LIBs required not only high energy density but also high specific capacity, therefore providing high capacity and decreased recharge time for electric devices. In this study, we focused on CuIn2S4/C composite as anode materials for Li-ion batteries by using hydrothermal reaction and subsequently high energy ball-milling technique. The crystal structure and surface morphology of as-synthesized CuIn2S4 and CuIn2S4/C composite were characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM). The reversible capacity of pristine CuIn2S4 sample displays 349 mAh/g and 176 mAh/g at current density of 0.2 A/g and at 1 A/g, respectively. After introducing high energy ball milling with carbon black, the rate capability and reversible capacity of CuIn2S4/C composite anode dramatically improved to 717 mAh/g at 0.2 A/g and 591 mAh/g at 1 A/g, respectively. In addition, the cycle stability of CuIn2S4 is also enhanced. The as-synthesized CuIn2S4/C composite demonstrates as high as 376 mAh/g under 5 A/g for more than 500 cycles without fading. In order to understand reaction mechanism, ex-situ XRD and in-situ XRD measurement of CuIn2S4 anode are carried out during charge and discharge processes. In the second part, we focused on MgIn2S4 by hydrothermal method and used carbon nanotubes to prepare CNT-MgIn2S4 composite material as anode material for lithium-ion battery. When the CNT addition amount is 1 wt.%, it has better electrochemical performance. After 200 cycles, CNT1-MgIn2S4 displays 184 mAh/g at current density of 0.5 A/g. Adding too much CNTs will cause agglomeration, and then lead electrochemical performance not good. With increase the content of CNTs, the impedance also increases. Lastly, we focused on the electrochemical performance of MgIn2S4 involve the use of non-aqueous (PVDF) and aqueous (CMC+SBR) binders. With the aid of CMC+SBR, MgIn2S4 obtained a reversible capacity of 215 mAh/g after 200 cycles at a current density is 0.5 A/g. However, the capacity of the PVDF electrode is 77.3 mAh/g after 200 cycles at a current density is 0.5 A/g. It can be seen that when CMC+SBR is used as the binder, the electrode can still maintain a certain capacity at higher current density, and will not be destroyed.