| 摘要: | 本研究使用醋酸纖維素(Cellulose Acetate)及雙（三氟甲基磺醯）氨基鋰（Lithium bis(trifluoromethanesulfonyl)imide, LiTFSI）混摻於聚偏二氟乙烯（Poly(vinylidene) difluoride, PVDF）高分子中，接著添加水熱法合成之Li1.3Al0.3Ti1.7(PO4)3 （LATP）陶瓷粉末形成複合型固態電解質薄膜，並且更換不同的混摻物/PVDF高分子之比例、透過溶液澆鑄法開發具有最佳性能的複合型固態電解質薄膜。由結果可以得知此種複合型固態電解質薄膜具有寬廣的電位窗（~5 V）、高溫下的熱穩定性（~250 ℃）、以及機械可撓性，而將電解質薄膜配合少量電解液 (1 M LiTFSI in TEGDME) 應用於磷酸鐵鋰（LiFePO4, LFP）正極後，也表現出優異的電化學性能。在混摻適量的CA及LiTFSI至PVDF（PVDF: CA: LiTFSI = 4: 1: 4）後，其導電率可達到3.3⨉10-4 S cm-1，而放電容量則為139.8 mAh g-1 @ 0.1 C且維持穩定的庫倫效率（~100 %）。接著，為了進一步改善熱穩定性及電化學性能，使此電解質薄膜能應用在更多極端條件，在下一階段的研究中添加不同比例條件的LATP粉末至PVDF/CA/LiTFSI高分子電解質薄膜中，可發現當LATP陶瓷粉末添加量為20 wt%時具有最佳的電化學性能。在此摻雜比例下（PVDF: CA: LiTFSI: LATP = 4: 1: 4: 2），複合型固態電解質薄膜擁有6.6⨉10-4 S cm-1的導電率，而放電容量則被提升至162.1 mAh g-1 @ 0.1 C，並保有穩定的庫倫效率（~100 %）。此研究所開發的複合型固態電解質薄膜展現出優秀的電化學穩定性、高溫下的熱穩定性、高離子導電率及放電容量，同時採用了相對具有環境友善性的材料與製程，表明其應用於鋰離子電池的潛力。;In this study, cellulose acetate (CA) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were added to poly(vinylidene) difluoride (PVDF) polymer, followed by the addition of hydrothermally-synthesized Li1.3Al0.3Ti1.7(PO4)3 (LATP) ceramic powder to form the composite solid electrolyte (CSE) membranes via solution casting method. Different dopant/PVDF ratios were investigated to develop a composite with optimal performance. From the results, it could be known that this CSE membrane had a wide potential window (~5 V), thermal stability at high temperatures (~250 °C), and mechanical foldability. The membranes showed excellent electrochemical performance after applying to LiFePO4 (LFP) cathode with a trace amount of liquid electrolyte (1 M LiTFSI in TEGDME). After mixing an appropriate amount of CA and LiTFSI into PVDF (PVDF: CA: LiTFSI = 4: 1: 4), the conductivity could reach 3.3⨉10-4 S cm-1, and the discharge capacity was 139.8 mAh g-1 @ 0.1 C and maintained stable Coulombic efficiency (~100 %). Then, to further improve the thermal stability and electrochemical performance enabled the electrolyte membrane to be used in more extreme environments, LATP powders in different weight ratios were added to the PVDF/CA/LiTFSI solid polymer electrolyte (SPE) membrane. Upon 20 wt% doping ratio (PVDF: CA: LiTFSI: LATP = 4: 1: 4: 2), the CPE membrane had a conductivity of 6.6⨉10-4 S cm-1, and the discharge capacity was enhanced to 162.1 mAh g-1 @ 0.1 C with stable Coulombic efficiency (~100 %). The CPE membrane developed in this research exhibited excellent electrochemical stability, thermal stability at high temperatures, and high ionic conductivity and discharge capacity. Also, the process and materials were relatively environmental-friendly, indicating its potential for applying for lithium-ion batteries (LIBs). |
