本研究採用熱壓方式製備 Li6.75La3Zr1.75Ta0.25O12 (LLZTO)陶瓷電解質，並且利用離子液體(LiFSI/PMPFSI)作為修飾劑，形成富含 LiF 且穩定的固態電解質界面(Solid electrolyte interphase, SEI)，進而提升循環穩定性。吡咯烷離子液體中陽離子部分的非極性脂肪鏈能夠產生疏鋰現象，使鋰金屬沉積均勻，避免有優選位點的發生而造成鋰枝晶形成，而陰離子部分的 FSI-離子中的 S-F 鍵能夠輕易的被破壞，進而形成 LiF，而此化合物已被證實能夠穩定 Li 金屬，在此也量測 LiFSI/PMPFSI 的離子導率，約為 3.29×10-3 S/cm，具有良好的離子導率能在界面傳輸。本研究比較未經修飾的 LLZTO 及使用液態修飾劑(碳酸酯類電解液、丁二腈基電解液、吡咯烷離子液體)修飾後的電化學性質，在長時間充放電循環中，利用傳統碳酸酯基液態電解質修飾的界面極不穩定，不僅電壓上升急劇，拆解電池後也發現固態電解質上具有蜘蛛網狀的鋰枝晶分佈，而使用 LiFSI/PMPFSI 修飾之電池，能夠持續循環 150小時以上。透過 XPS 分析，證明經由離子液體修飾的 SEI 膜具有 LiF、Li3N成份，這種液態修飾的 SEI 顯示了與固態電解質 LLZTO 兼容的界面，同時也是優異的電子阻擋層，能阻止固態電解質被鋰金屬還原，此項研究對於固態鋰電池(SSLMB, Solid-state lithium metal battery )至關重要。 ;This study utilized hot-pressed Li6.75La3Zr1.75Ta0.25O12 (LLZTO) ceramic electrolyte and employed an ionic liquid (LiFSI/PMPFSI) as a modifier to form a stable SEI (solid-electrolyte interphase) rich in LiF, thereby enhancing cycling stability. The S-F bond of FSI- ions in the ionic liquid can be easily broken,leading to the formation of LiF. This compound has been proven to stabilize Li metal. The ionic conductivity of LiFSI/PMPFSI was also measured and found to be approximately 3.29×10-3 S/cm, exhibiting good ion conductivity for interfacial transport. Additionally, the non-polar fatty chains in the pyrrolidinium-based ionic liquid can create a “lithiophobic effect”, promoting uniform deposition of lithium metal and preventing the formation of preferential nucleation sites and lithium dendrites. This study compared unmodified LLZTO with LLZTO modified using liquid modifiers (conventional electrolyte, SN-based electrolyte, ionic liquid) and measured the critical current density(CCD). During long-term charge-discharge cycling, it was observed that the interface modified with the conventional carbonate-based liquid electrolyte was highly unstable. Not only did the voltage rise sharply, but post-disassembly of the battery revealed a spiderweb-like distribution of lithium dendrites on the solid-state electrolyte. In contrast, batteries modified with LiFSI/PMPFSI were able to cycle continuously for over 150 hours. XPS analysis confirmed the presence of LiF and Li3N components in the SEI film modified by the ionic liquid, demonstrating the compatibility of the interface with the solid-state electrolyte LLZTO. This research underscores the critical importance of such interfaces for Solid-State Lithium Metal Batteries (SSLMB).
