以溶膠凝膠法製備Li4Ti5-xVxO12與Li4Ti5O12/C之鋰鈦氧負極材料及其在鋰離子二次電池之應用

本研究主要利用溶膠凝膠法順利製備出兩系列鋰鈦氧之樣品，第一部分為-以五氧化二釩進行陽離子摻雜之鋰鈦氧Li4Ti5-xVxO12 (LTOVs)，第二部分為-以乙炔碳黑進行導電碳添加之鋰鈦氧Li4Ti5O12/C (LTO/Cs)。由於利用溶膠凝膠法進行合成，兩系列樣品LTOVs與LTO/Cs，在SEM與TEM觀察下，二次粒子都是由直徑約5 - 15 nm奈米級一次粒子所構成，有利於快速充放電。第一部分合成之釩摻雜LTOVs系列，利用ICP-OES與EA進行組成分析， XRD與XPS進行結構鑑定與各元素鍵結之了解；另由XPS檢測發現有部分Ti4+因釩之摻雜而被還原成Ti3+，進而影響電子導電度，其中LTOV06 (Li4Ti4.94V0.06O12)顯示有最佳電化學性質，在電位區間為1 - 2.5 V，其電容量為207.5 (0.2 C)、199.1 (0.5 C)、189.1 (1 C)、179.1 (2 C)、157.7 mAh g-1 (5 C)，而在電位區間為0 - 2.5 V、5 C充放電，LTOV06首圈電容量高達242.9 mAh g-1，且在250圈之電荷保持率仍有89%。第二部分所合成乙炔碳黑添加之樣品LTO/Ds系列，利用EA與BET得知其碳含量為2.51 - 5.89 wt.%與比表面積(1.43 - 3.64 m2 g-1)，顯示LTO/Ds系列具有低碳含量與低表面積之性質，其中LTO/D-2 (3.04 wt.%、3.64 m2 g-1)擁有最佳電化學性質，其倍率放電表現為238.7 (0.2 C)、231.6 (0.5 C)、221.0 (1 C)、200.8 (2 C)、156.2 mAh g-1 (5 C)。最後，LTOV06與LTO/D-2做為鋰離子二次電池負極材料之潛力將一併比較討論。

關鍵字

鋰鈦氧；鋰離子二次電池電池；負極材料；溶膠凝膠

並列摘要

In this study, two series of lithium titanate anodes, namely, vadadium-doped Li4Ti5-xVxO12 (LTOVs) and Li4Ti5O12/carbon black (LTO/Ds), were synthesized via the sol-gel method. It is demonstrated that by the sol-gel process the nano-size primary particles with diameters of 5 - 15 nm were obtained for both the LTOVs and LTO/Ds series, benifiting to the high rate charge-discharge performance of lithium battery. In partⅠ, the spinel-type V-doped Li4Ti5-xVxO12 (0 ≤ x ≤ 0.3) samples were prepared. The elemental proportions of metals and carbon in LTOVs were determined by ICP-OES and EA, respectively. The XRD and XPS results exhibited that the V-doping barely affected the lattice parameter, while varied the ratio of Ti3+ and Ti4+ oxidation states. For electrochemical analyses, LTOV06 (x = 0.06) showed the best capacity among LTOVs and its discharge capacities in the voltage range of 1 - 2.5 V wre 207.5 (0.2 C), 199.1 (0.5 C), 189.1 (1 C), 179.1 (2 C) and 157.7 mAh g-1 (5 C), respectively. Besides, in the voltage range of 0 - 2.5 V at 5 C, the initial discharge capacity of the LTOV06 electrode was 242.9 mAh g-1 and retained 89 % after 250 cycles. In partⅡ, the Li4Ti5O12/carbon black samples with various amount of carbon black (DB) as an extra carbon source were also prepared by the sol-gel method. The EA and BET results exhibited that the carbon content and surface area of LTO/Ds were as low as 2.51 - 5.89 wt.% and 1.43 - 3.64 m2 g-1, respectively. The electrochemical analyses showed that LTO/D-2 with carbon content of 3.04 wt.% and surface area of 3.64 m2 g-1 exhibited the best capacity among the LTO/Ds prepared. The discharge capacities of the LTO/D-2 electrode obtained were 238.7 (0.2 C), 231.6 (0.5 C), 221.0 (1 C), 200.8 (2 C) and 156.2 mAh g-1 (5 C), respectively. Finally, the potentials as the anode materials for ithium battery between LTOV06 and LTO/D-2 were compared.

並列關鍵字

Lithium titanate ； Lithium-ion battery ； Anode material ； Sol-gel

參考文獻

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以溶膠凝膠法製備Li4Ti5-xVxO12與Li4Ti5O12/C之鋰鈦氧負極材料及其在鋰離子二次電池之應用

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