石榴石型固態電解質材料具有高離子導電度，是具有潛力應用於鋰金屬電池的固態電解質材料；然而，石榴石型固態電解質與鋰金屬之間的界面問題會影響電池的性能及壽命，因此本研究使用金屬氟化物對固態電解質進行表面改質，以提高其與鋰金屬的契合度和穩定性。首先，以固態合成法合成具有優異離子電導率的石榴石型固態電解質Li7−xLa3Zr2−xTaxO12 (LLZTO)；接著對合成的固態電解質以氟化亞錫與氟化銀進行了表面披覆改質，再將改質後的固態電解質進行材料分析，從材料特性研究結果顯示，隨著鉭添加量愈多，造成主峰角度會往高角度方向產生偏移，造成分子間的間距變小，另外透過固態電解質表面與橫截面形貌的觀察，能夠證明金屬氟化物成功地披覆在固態電解質上，在電化學性能測試中，改質後的固態電解質能夠降低了固態電解質與鋰金屬之間的界面阻抗，氟化銀的晶界阻抗為800歐姆而氟化錫的晶界阻抗為706歐姆，顯示出添加氟化亞錫相較氟化銀有更低的晶界阻抗，因此，金屬氟化物不僅提高了固體電解質的電導率，而且形成了穩定的界面層。在全電池電容量測試方面，結果顯示，添加氟化亞錫的首圈從原本的31.3mAh/g提升到210.8 mAh/g，且初始庫倫效率從77％ 提升到95.8％ ，充放電性能在高電壓和高溫條件下可提升電容量和初始庫倫效率。金屬氟化物表面改質對鋰金屬固態電池的性能和安全性發揮關鍵作用，有利固態電池技術應用發展。

Garnet-type solid electrolyte materials have high ionic conductivity and are potential solid electrolyte materials for use in lithium metal batteries; however, the interface problem between garnet-type solid electrolytes and lithium metal limits their performance in practical applications. In this study, the metal fluoride was used to modify the surface of solid electrolyte, which can improve its fit and stability with lithium metal. First, a garnet-type solid electrolyte Li7−xLa3Zr2−xTaxO12 (LLZTO) with superior ionic conductivity was synthesized by a solid-state synthesis method. Subsequently, the surface of the synthesized solid-state electrolyte was modified through coating with the metal fluorides including tin fluoride and sliver fluoride . The modified solid electrolyte was analyzed and electrochemical performance tested. The surface and cross-sectional morphologies of the solid-state electrolyte can be confirmed that the metal fluoride is successfully coated on the solid-state electrolyte. Through the assembly of lithium-lithium symmetric electrodes and full cells, the modified solid-state electrolyte can reduce the interface impedance between solid electrolyte and lithium metal. Therefore, the metal fluoride not only improves the conductivity of the solid electrolyte, but also forms a stable interface layer. In terms of full cell testing, the results showed the great cycle stability and safety for the charge-discharge performance. The Metal fluoride surface modification have played a key role in the performance and safety of lithium metal solid-state batteries, which is beneficial to the application of lithium metal solid-state battery.

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