本實驗以固態反應法製備固態電解質Li7La3Zr2O12應用於鋰離子電池為主軸，探討摻雜不同元素、燒結溫度對材料性質和電化學特性之關聯。 實驗分為兩部分，第一部分為探討不同元素摻雜對於固態電解質Li7La3Zr2O12的影響。於900°C~1200°C的燒結溫度範圍內，由XRD顯示在摻雜鋁、鎵的情況下，900°C即可獲得純Cubic相，Cubic相Li7La3Zr2O12和Tetragonal相相比，擁有較高的離子導電率，1200°C時顯示較低的孔隙率，因此鋰離子導離子率相較其他燒結溫度更佳，鎂摻雜無法在900°C時獲得Cubic相，需加溫至1200°C時Tetragonal相才開始轉換至Cubic相，因此雜相La2Zr2O7與Li2ZrO3更容易生成，導離子率也無法與鎵摻雜相比。 本實驗第二部分探討鋰鹽LiTFSI與poly(ethylene oxide)對固態陶瓷電解質在鋰離子電池的電化學表現，相對於錠狀陶瓷固態電解質Li6.25Ga0.25La3Zr2O12，PEO與鋰鹽及Li6.25Ga0.25La3Zr2O12粉末合成的固態電解質薄膜擁有較高的鋰離子導離子率，這是因為其厚度較薄，和正負極間的介面阻抗也較錠狀固態電解質小，因此能有較佳的電池電化學表現。 ;In this study, we synthesized the pure phase Li7La3Zr2O12 solid electrolyte material by solid state reaction and the influences of different doping elements (Al, Ga, Mg) to the Li7La3Zr2O12 were investigated. Specific doping can reduce the phase transformation temperature, i.e. the generation of cubic phase in this study. For Gallium and Aluminum doping, we can obtain the cubic phase at 900°C. However, magnesium doping needed to sinter at 1200°C to attain cubic phases instead of tetragonal phases. When the phase transformation temperature is higher, the impurity is easy to produce because of the lithium evaporation at higher temperature. Therefore, the Mg-LLZO is easy to produce impurity La2Zr2O7 and Li2ZrO3 because of higher phases transformation temperature. Compared with magnesium and aluminum doping, Gallium doping shows the highest conductivity and crystallinity because there are no impurity in the phase when we sinters the Li7La3Zr2O12 at 1200°C.
We prepare solid hybrid electrolyte by Ga-LLZO, LiTFSI and poly(ethylene oxide). Compared with Li7La3Zr2O12 pellet electrolyte, hybrid solid electrolyte shows lower thickness and higher lithium ion conductivity. In addition, the lithium metal battery shows lower resistances after using solid hybrid electrolytes. Therefore, the hybrid electrolyte battery shows better electric performance compared with inorganic ceramic pellet electrolytes.
