目前市售鋰離子二次電池之電解質多採用有機溶劑，雖具有能量密度高、充放電速度快等優勢，然而其具有不穩定以及起火燃燒風險。因此為了提升電池安全性，以固態的電解質材料取代有機液態電解質，不僅能排除電池內部短路及液態電解質的洩露問題，還可以徹底解決鋰離子二次電池安全性隱患。然而，在全固態鋰電池中，電極與固體電解質之間的固相固相接觸相比固相液相接觸具有更高的界面接觸電阻，同時，其界面相容性和充放電穩定性也顯著影響全固態鋰電池的循環性能和庫倫性能。因此本研究將針對界面調控機理與修飾方法，進行新型之複合電極結構的開發，可獲得穩定結構及良好電化學性質，以實現高能量密度全固態鋰電池之可行性。
本研究以鋁摻雜磷酸鋁鈦 ( Li1.3Al0.3Ti1.7(PO4)3；LATP )作為固態電解質材料，而正極材料分別選用磷酸鋰鐵(LiFePO4)和鈷酸鋰(LiCoO2)進行熱化學穩定性之研究，藉以製備無機固態鋰電池性能之複合電極設計。由晶體結構分析結果顯示，LATP與LiCoO2之熱化學穩定性較差，於500oC下即有Co3O4第二相的形成；另一方面，在LATP與LiFePO4具有較佳的熱化學穩定性，在不同溫度(500-700oC)下，仍維持兩相共存且無明顯之異相生成。
本研究中當LATP/LiFePO4複合陰極比例為50 vol%：50 vol%時，可有效共燒於LATP基材上。藉由EIS量測可得知，藉由共燒溫度可有效降低介面極化阻抗，當於700oC共燒溫度時，界面極化阻值為455Ω，當三相界從電解質/電極的界面延伸到整體電極當中，提高共燒溫度可使電極燒結現象提升，進而降低界面極化阻值。由放電速率測試結果顯示，當放電速率為0.1C，可獲得140 mAh/g 之電容量，此電池之充放電循環達50圈後，其庫倫效率仍可維持95%以上。

State-of-the-art Li ion batteries use organic liquid electrolytes. Although these batteries provide high efficiency, reliability, good cycle life, they still exhibit the safety issues regarding fire and explosion. All solid-state batteries are an emerging option for next-generation traction batteries promising low cost, high performance and high safety. However, solid state Li batteries still show some problems and challenges such as low ionic conductivity, high interface polarization, low flexibility. The problems and challenges may be overcome or suppressed through better materials design and interface engineering. Thus, in this proposed work, the main objectives will be to enhance the chemistry stability of solid electrolyte; It is expected that Li batteries with proper materials design and interface engineering will show superior high-voltage, reliability, safety feature and stacking capability for many applications.
In this study, Li1.3Al0.3Ti1.7(PO4)3(LATP) was used as the solid electrolyte material, and the cathode materials were selected from lithium iron phosphate (LiFePO4) and lithium cobaltate (LiCoO2) for chemical stability. Testing to find the best composite electrode structure for development. The XRD results show that the chemical stability of LATP and LiCoO2 is poor, and the formation of Co3O4 second phase appears at 500oC. On the other hand, LATP and LiFePO4 have better chemical stability at temperatures up to 700oC.
In this study, when the proportion of LATP-LiFePO4 composite cathode is 50 vol%: 50 vol%, it can be successfully sintered on the LATP substrate. The result of discharge rate testing show that 140 mAh/g when the discharge rate is 0.1C. After 50 cycles charge/discharge, its coulombic efficiency still maintain more than 95%.

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