| 摘要: | 傳統鋰電池通常使用液體電解質作為傳導介質，並使用多孔隔離膜來區分正極和負極。然而，這種傳統方法在製作隔離膜時需要耗費大量時間並回收相關溶劑，而且液體電解質的高易燃性引發安全疑慮。因此，本研究採用光聚合方法，能夠快速製造出無需溶劑且不需要大量電解液的固態電解質，作為製造固態鋰電池的基礎。首先，從高分子的角度來看，導電需要具有長鏈分子的擺動來進行傳導，但同時不能受結晶區的影響。因此，我們使用PEGDA和MA進行共聚合，與PEO結合形成無結晶網狀交聯型高分子，提供離子傳導的功能。為了進一步提高導電性，我們添加了SCN和LiTFSI，它們之間的晶體轉換機制可以增加導電度。實驗結果顯示，在0.5C和1C的條件下，添加30%的SCN時，具有高電容量分別為148.5 mAh/g和111.7 mAh/g，並在長時間循環中保持90%以上的電容保持率。然而，由於SCN本身不是高強度分子，添加過多會降低電解質隔膜的強度。為了解決這個問題，我們添加了LAGP形成複合電解質，結合了高分子、無機陶瓷材料和添加劑三種導電途徑。然而，在電池元件中，LAGP本身的特性會與鋰金屬發生還原反應。為避免這個負面影響，我們首先鋪平LAGP混合物，然後倒入高分子液體進行光聚合，以獲得LAGP聚集在同一側（陰極端）的複合薄膜。在進一步的實驗中，添加5%的LAGP和30%的SCN表現出良好的電性，分別在0.5C和1C條件下具有154.9 mAh/g和110.1 mAh/g的高電容量。此外，材料的強度接近未添加SCN時的數值。綜上所述，本研究成功地製備了具有快速、環保、強度、安全和電性等五個關鍵指標的複合電解質，該材料展現出優異的固態鋰電池性能。;Traditional lithium batteries typically require liquid electrolytes as a conducting medium using porous membranes to separate the positive and negative electrodes. However, this conventional method not only involves significant time and solvent recovery efforts during the production of the membrane but also raises safety concerns due to the high flammability of liquid electrolytes. Therefore, in this study, we adopted a solvent-free and electrolyte-minimized approach using photopolymerization to rapidly produce a solid-state electrolyte.
From a polymer perspective, conductivity in the solid-state electrolyte requires long-chain polymer segments for ion transport while remaining unaffected by crystalline regions. To achieve this, we utilized a co-polymerization of PEGDA and MA, combined with PEO, to form a networked crosslinked polymer matrix that provides ion conductivity and electron insulation. To further enhance the conductivity, we introduced additives such as SCN and LiTFSI, which undergo a crystalline-to-conductive transition mechanism. Experimental results demonstrated high capacity values of 148.5 mAh/g and 111.7 mAh/g at 0.5C and 1C rates, respectively, with the addition of 30% SCN. Moreover, the electrolyte maintained a capacity retention of over 90% even after numerous charge-discharge cycles. However, due to SCN′s lower molecular strength, excessive amounts led to a decline in the mechanical properties of the electrolyte membrane. To address this issue, we incorporated LAGP to form a composite electrolyte, comprising polymer, inorganic ceramic material, and additives, thereby creating three pathways for conductivity.
Nevertheless, LAGP itself undergoes reduction when it comes into contact with lithium metal. To mitigate this effect, we first applied a uniform LAGP slurry and subsequently poured the polymer liquid for photopolymerization, resulting in a composite thin film with LAGP aggregating on one side (cathode side). In further experiments, the addition of 5% LAGP and 30% SCN exhibited excellent electrochemical performance, with high capacities of 154.9 mAh/g (at 0.5C) and 110.1 mAh/g (at 1C). Additionally, the strength of the material approached values comparable to those before the addition of SCN. This study successfully developed a composite electrolyte that fulfills five key criteria: rapid production, environmental friendliness, mechanical strength, safety, and electrochemical performance for solid state lithium battery. |
