含TEMPO氧化纖維素奈米纖維基之高分子固態電解質及其界面改性應用於全固態鋰金屬電池

Abstract

為了滿足實際應用中對高能量密度的要求，鋰金屬電池（LMBs）在許多能量存儲設備中佔據重要地位。然而，鋰電池中常用的傳統有機液態電解質具有腐蝕性和熱穩定性差的特點而面臨著安全性方面的重大問題，限制了它們的應用範疇。因此，開發具有更高安全性的固態電解質已經成為電池和能量存儲設備的必要方向。值得注意的是，與具有良好導離率的無機固態電解質相同，高分子固態電解質（SPEs）由於其良好的柔韌性以及與正極/負極的兼容性成為新興的候選材料之一。 在本研究中，TEMPO氧化奈米纖維素成功地引入固態電解質中作為三維骨架，透過簡單且環保的工藝與聚環氧乙烷(Polyethylene oxide)均勻混溶，製備了具獨立自支撐特性的高分子固態電解質薄膜。除顯著提高機械強度，引入的TOCN保留了足夠的離子傳輸通道，使衍生的高分子固態電解質具有高效的離子傳輸能力。由此SPE組裝的對稱鋰電池表現出良好的電化學穩定性;同時，組裝的LiFePO4 | TP28 | Li金屬半電池也表現出優異的倍率性能，在長期循環壽命測試中，利用0.1 C下的初始比容量為151 mAh g-1，100次循環後比容量保持率為96.5%。 於此基礎上，本研究的第三章節證明了引入丁二腈作為固態增塑劑可進一步促進鋰離子傳輸外，更提高基於TOCN的高分子固態電解質薄膜的柔韌性和電化學性能。此外，透過利用PEO/LiBOB修飾NCM正極和高分子固態電解質之間的界面特性，可以提高組裝的NCM | SPE | Li半電池的電化學性能，從而提高其長期循環壽命，並使其能夠在較低工作溫度下應用於高壓NCM正極系統。簡言之，TOCN嵌入的自支撐高分子固態電解質薄膜成功得被開發了，並在實際的電池應用中展現出應用的價值與潛力。

To meet the high energy density requirements for practical applications, lithium-metal batteries (LMBs) hold a significant position in many energy storage devices. However, the conventional organic liquid-state electrolytes commonly used in lithium batteries face significant safety concerns due to their corrosive nature and thermal instability, limiting their widespread adoption. Therefore, the exploitation of solid-state electrolytes with higher safety has emerged as a necessary direction for batteries and energy storage devices. It is worthwhile noting that, similar to inorganic solid-state electrolytes, solid-state polymer electrolytes (SPEs) have become an appealing candidate due to their high flexibility and compatibility with cathodes/anodes. In this study, the TEMPO-oxidized nanocellulose has been successfully employed as a three-dimensional scaffold, which is hybridized with polyethylene oxide through a simple and environmentally friendly process to prepare a cellulose-embedded SPE. In addition to significantly enhancing the mechanical properties, TEMPO-oxidized nanocellulose (TOCN) also preserves ample ion transport channels within the derived SPE. This characteristic enables the SPE to facilitate efficient and controllable transport of lithium ions. The assembled symmetric Li-cell shows respectable electrochemical stability, while the assembled LiFePO4 | TP28 | Li half-cell demonstrates excellent rate performance, delivering a specific capacity of 151 mAh g-1 at 0.1 C, with a discharge-specific capacity retention of 96.5% after 100 cycles. Moreover, the introduced succinonitrile has also been demonstrated as a solid-state plasticizer which further enhances the tensile strength and electrochemical properties of the derived TOCN-embedded SPEs because the introduced succinonitrile creates additional conducting channels to facilitate Li-ion transport. By utilizing PEO/LiBOB to modify the interfacial properties between the NCM cathode and SPE, the performance of the assembled half-cell can be improved. This modification also enables our prepared SPEs to apply for high-voltage NCM cathode systems at lower operating temperatures. In conclusion, the TOCN-embedded solid-state polymer electrolyte membranes have been successfully developed, which exhibit promising potential for practical applications.