可快速充放電之鋰離子電池在使用的方便上不言可喻，而其對於電動車的應用而言更是關鍵，因此鋰離子電池在動力及儲能等方面的應用前景吸引了越來越多的關注。在電池負極的選擇上，與目前商業化的石墨碳相比，單斜晶二氧化鈦(TiO2(B))因其嵌鋰容量大、毒性小且能耗低、循環穩定性好、安全性能佳，被廣泛的認為具高功率電池潛力。
本研究以P25與氫氧化鈉利用水熱法方式製備TiO2(B)奈米片，透過參數的改變探討奈米片的成長及組成之影響，並探討其電化學行為的影響。由TEM、BET結果顯示，藉由水熱法方式在180 oC進行12 h反應，在6 M濃度可以獲得比表面積為100 m2 g-1的TiO2(B)奈米片。並由電性量測顯示在25次0.1C量測環境下，有良好的電容量維待率為96%、其可逆電容量為209 mAh g-1。
此外，利用低溫化學水浴法將SnO2修飾於TiO2(B)奈米片上，合成TiO2(B)/SnO2複合材料，並藉由XRD、TEM、ICP-MS及充放電測試等對材料進行了研究。結果顯示，經由水浴法可將SnO2奈米顆粒成長於TiO2(B)表面，並藉循環伏安法、充放電循環測試來了解複合材料的特性。從結果知，加入適量的SnO2所得複合材料，可以有效地提升鋰離子電池的電容量，並具有優良的循環壽命，其中SnO2添加量為21.44 wt %時，在1~3 V電壓區間，充放電流為0.1 C時，在50次測試下可維持651 mAh g-1可逆電容量及92 %良好的庫倫效率。
除了上述TiO2(B)負極材料受到矚目之外，Li4Ti5O12也受到注意。尖晶石(Spinel)結構之Li4Ti5O12，具有穩定的晶體結構，充放電所導致的體積變化率小，因此循環壽命極優，且嵌鋰電位為1.5 V，不會和電解液反應形成SEI膜，電池內阻抗不會上升。
本研究以鈦酸四丁酯與氫氧化鋰作為前驅物，利用水熱法製備Li4Ti5O12奈米片，並再藉由熱處理透過參數的改變探討奈米片的成長及組成之影響，並探討其電化學行為的影響。由XRD、TEM、BET結果顯示，在2 M氫氧化鋰及550 oC後熱處理可獲得的Li4Ti5O12奈米片並具有較高比表面積為94 m2 g-1，由電化學的量測顯示，這具備高比表積的Li4Ti5O12材料在20 C高倍率性能有優良的特性，且電容量可維持有150 mAh g-1。
為改善Li4Ti5O12導電性不佳問題並簡化製程流程，以鈦酸四丁酯與氫氧化鋰直接藉由熱處理方法製備Li4Ti5O12奈米材料。透過XRD、SEM、CV、EA及電化學性能量測結果顯示，在2 M氫氧化鋰及450 oC熱處理反應，可以成功獲得尖晶石Li4Ti5O12奈米粒材料，並具有最佳的電化學性能，在0.1 C倍率下首次充放電電容量可達200 mAh g-1，當電流增大到20 C，充放電電容量仍然保持在170 mAh g-1，經XAS分析可知，在低溫450 oC熱處理，獲得Ti3+的生成，改善了Li4Ti5O12的導電性，提升其電化學性能。
關鍵字：鋰離子電池、單斜晶二氧化鈦、鈦酸鋰、奈米負極材料

TiO2(B) nanosheets exhibit a surface area of 100 m2 g-1, which is larger than those obtained by solid-state reaction. The capability of lithium-ion battery could be strongly enhanced by TiO2(B) nanosheets to yield a discharge capacity higher than 200 mAh g-1, even upon 25 cycles of 0.1 C discharge-charge operations, showing highly reversible capacity and good cycling stability with excellent capacity retention of 96% with water-based binder. The TiO2(B)/SnO2 composites show a higher reversible capacity and better durability than that of the pure TiO2(B) for use as a battery anode. The composite electrodes exhibiting a high initial discharge capacity of 2239 mAh g-1 and a discharge capacity of more than 869 mAh g-1 could be maintained after 50 cycles at 0.1 C in a voltage range of 1.0 - 3.0 V at room temperature. Li4Ti5O12 nanosheets obtained by a hydrothermal method with 2 M LiOH and a followed heat treatment at 550 oC exhibit an outstanding stable capacity of 150 mAh g-1 at 20 C.
Keywords: TiO2(B) nanosheets, Li4Ti5O12, Hydrothermal synthesis, Li-ion batteries

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