臨場振動光譜和X光光譜於鋰金屬電池材料之應用

In situ vibrational spectroscopy and X-ray spectroscopy studies of Li metal battery materials

近年來能源需求以及經濟活動的快速增長，發展具有高效能的新世代電池系統越來越受到關注。由於電池材料的電化學性能和穩定性受到材料結構以及其材料界面反應影響，因此理解電池材料的反應機制可以為設計新穎電池材料提供更有效的資訊。臨場X光光譜和振動光譜技術如X光吸收光譜和拉曼光譜是研究電池材料結構和固液界面反應中間體的重要量測技術。本篇文章將介紹X光光譜和拉曼光譜在鋰金屬電池中負極和正極材料的研究，並簡述臨場量測技術的基本原理及實驗設計。首先我們發現具有垂直奈米通道的中孔二氧化矽薄膜可以改變電鍍時的電流密度分布和鋰金屬電鍍過程，生成具有良好結晶性的Li(110)。接著我們利用臨場X光吸收光譜在線氣相層析來詳細研究富鋰層狀氧化物正極的局部電子結構變化以及氧氣生成機制。最後我們利用臨場拉曼光譜和S K-edge X光吸收光譜來研究Li-S電池中硫正極的反應機制，不同孔洞結構的碳材對活性物質氧化還原反應以及其動力學的影響。這些對電池材料反應機制和動力學的討論將有助於開發新世代電池材料。

The development of battery materials has received great attention, mainly due to the rapid increase in energy demand. Since the geometric and electronic structures of materials play crucial roles in controlling the performance and stability of battery materials, understanding the reaction mechanism of battery materials can provide insightful information into the material design. In situ X-ray spectroscopy and vibrational spectroscopy techniques such as X-ray absorption spectroscopy (XAS) and Raman spectroscopy are the powerful tools for examining the electronic structure of battery materials and the reaction intermediates on the solid-liquid interfaces. In this study, we report on our use of X-ray spectroscopy and Raman spectroscopy to investigate the structure of electrodeposited Li metal anode and various cathode materials in Li metal batteries. Grazing-incidence wide-angle X-ray scattering results suggest that mesoporous silica thin films with perpendicular nanochannel regulate the Li electrodeposition process and lead to the formation of Li(110). By combining operando XAS with online gas chromatography, the effect of the local electronic structure on the reaction mechanism of Li-rich layered oxide cathodes is studied in detail. Operando Raman and S K-edge XAS spectroscopy are used to examine the sulfur chemistry in Li-S batteries. The role of designed porous carbon in the sulfur redox reaction is systematically investigated at high C rates. The obtained insights into the reaction mechanism and kinetics of battery material provide a better understanding and control of Li metal batteries.