應用於固態鋰離子電池之鋰銦氯改質鈦酸鋰陽極

Abstract

隨著電動車與儲能設備快速發展，對高安全性與高能量密度之鋰離子電池需求日益提升。固態電解質因具備優異熱穩定性與阻燃性，成為液態電解質之潛在替代材料。為克服氧化還原電位不匹配與界面不穩定性問題，本研究針對鈦酸鋰進行鋰銦氯包覆處理，形成Li3InCl6@Li4Ti5O12 (LIC@LTO)複合陽極，以提升其於固態全電池中的穩定性與電化學性能。 本研究選用THF (tetrahydrofuran)作為反應溶劑進行LIC包覆，因其為非質子性極性溶劑，較不易與前驅物發生副反應，成功製備出不同含量之LIC@LTO樣品。經XRD、SEM、TEM及EDS分析證實5 wt% LIC包覆樣品具明顯包覆層，且仍保有LTO之結構。進一步以XPS與XANES光譜技術分析其化學狀態與氧化態，結果顯示5 wt% 樣品具最佳之化學性質。 電化學測試結果顯示，以THF合成之5 wt% LIC@LTO半電池於循環伏安法測試中，展現較小極化現象。將此改質陽極LIC@LTO與陰極LCO進行之全電池組裝後，其首圈放電容量達108 mAh/g，第五十圈放電容量仍可維持58 mAh/g，且電池阻抗亦明顯低於未包覆樣品，證實LIC包覆有助於降低界面阻抗與提升整體電池性能。 綜合而言，本研究證實以THF進行5 wt% Li3InCl6@Li4Ti5O12表面包覆可提升鋰離子電池陽極之界面穩定性與離子傳輸能力，為實現高性能固態鋰離子電池提供關鍵材料設計之策略。

With the rapid development of electric vehicles and energy storage systems, the demand for lithium-ion batteries with high safety and high energy density is steadily increasing. Solid-state electrolytes, known for their excellent thermal stability and flame retardancy, have emerged as promising alternatives to conventional liquid electrolytes. To address issues related to redox potential mismatch and interfacial instability, this study applies a lithium indium chloride (Li3InCl6) coating on lithium titanate (Li4Ti5O12), forming a Li3InCl6@Li4Ti5O12 (LIC@LTO) composite anode, aiming to enhance the interfacial stability and electrochemical performance of solid-state full cells. Tetrahydrofuran (THF), an aprotic polar solvent, was selected as the reaction medium for the LIC coating due to its low reactivity with precursors, enabling the successful synthesis of LIC@LTO samples with varying coating ratios. XRD, SEM, TEM, and EDS analyses confirmed that the 5 wt% LIC-coated sample exhibited a distinct coating layer while retaining the structural integrity of LTO. Further characterization using XPS and XANES techniques revealed that the 5 wt% sample possessed the most favorable chemical states and oxidation behavior. Electrochemical tests demonstrated that the 5 wt% LIC@LTO half-cell synthesized via THF exhibited reduced polarization in cyclic voltammetry. When assembled into a full solid-state cell with LiCoO2 (LCO), the LIC@LTO anode delivered an initial discharge capacity of 108 mAh/g, maintaining 58 mAh/g after 50 cycles. Moreover, the interfacial resistance of the coated sample was significantly lower than that of the uncoated LTO, confirming the beneficial role of LIC coating in reducing impedance and improving overall battery performance. In conclusion, this study confirms that a 5 wt% Li3InCl6 coating applied via THF effectively enhances the interfacial stability and lithium-ion transport capability of the LTO anode, offering a promising materials strategy for the development of high-performance solid-state lithium-ion batteries.