Li4Ti5(1-x)M5xO12 (M = Al or Mg, and 0 ≤ x ≤ 0.09 )鋰離子電池負極材料的製備與特性研究

Preparation and characterization of Li4Ti5(1-x)M5xO12 (M = Al or Mg, and 0 ≤ x ≤ 0.09 ) anode materials for Li- ion batteries

陳宥霖(You-lin Chen)

指導教授 ： 吳溪煌

大同大學/工程學院/材料工程學系所/碩士(2011年)

摘要

以溶膠-凝膠法合成尖晶石結構的Li4Ti5O12 及Li4Ti5(1-x)M5xO12 (M= Mg or Al, 0 ≤ x ≤ 0.09)粉末，探討熱處理溫度(800~1000oC)、Mg2+及Al3+部分取代Ti4+對合成之Li4Ti5O12 基負極材料電化學特性之影響。分別以XRD, ICP-OES, SEM 探討合成粉末之晶體結構、成分組成及表面形貌。並以循環充放電測試、循環伏安分析探討合成粉末之化學特性。發現合成粉末都為尖晶石相，Li4Ti5O12 粉末之晶格常數隨熱處理溫度上升而略有增大，但隨Mg2+或Al3+取代量增加則分別有顯著增大及減小。Li4Ti5O12 粉末平均粒徑由800oC 下合成粉末的350 nm增加至1000oC 下合成粉末的550nm，而Mg2+或Al3+部分取代對平均粒徑的影響則不顯著。在不同溫度下合成的Li4Ti5O12 粉末中，以經850oC 下熱處理的樣品具有較高之初充放電電容量。在由850oC 下合成的Li4Ti5(1-x)M5xO12 (M = Mg 或Al, 0 ≤ x ≤ 0.09)中，鎂取代在x = 0.01的樣品表現最佳，在0.5 至2.5V 的充放電截止電壓下，經循環30 圈循環充放電都有較高之可逆電容量，在0.1 ,1 及 5C 時初始電容量分別為196、170 及146 mA h g-1。

關鍵字

尖晶石結構 ； Li4Ti5O12 ； 負極材料 ； 陽離子取代

並列摘要

Spinel Li4Ti5O12 and Li4Ti5(1-x)M5xO12 (M = Mg or Al, 0 ≤ x ≤ 0.09) samples were prepared via a sol-gel method followed by heat-treatment at various temperatures (800~ 1000oC). The crystal structure, composition, and morphology of the synthesized samples were investigated with XRD, ICP-OES, and SEM, respectively. The electrochemical properties of synthesized samples were also studied with capacity retention study and cyclic voltammetry. The XRD patterns showed spinel Li4Ti5O12 formed exclusively in the prepared sample. The calculated lattice parameter of spinel changes slightly with increasing heat-treating temperature, however, it increases/decreases with increasing amount of Mg2+/Al3+-substitution, respectively, for Li4Ti5(1-x)M5xO12 samples prepared at 850oC. The average particle size increases from 350 nm in 800oC prepared sample to 550 nm in 1000oC sample, though the variation in average particle size with amount of Mg2+ or Al3+-substitutions can be ignored. Among the Li4Ti5O12 samples prepared at various temperatures, 850oC prepared sample manifests the most promising initial charge/discharge capacities with cutoff voltages of 0.5 and 2.5 V. So the temperature was used for preparing Li4Ti5(1-x)M5xO12 powders. The samples with x = 0.01 for both Mg2+ and Al3+-substitutions exhibit the most promising cycling performance among the prepared Li4Ti5(1-x)M5xO12 samples with initial discharge capacities of 196, 170, and 146 mAh/g at 0.1, 1, and 5C rates, respectively.

並列關鍵字

Li4Ti5O12 ； Spinel structure ； cation substitution. ； anode material

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