碳包覆对LiNi_(0.5)Mn_(1.5)O_4电化学性能的影响  

Effect of C-coating on Electrochemical Performances of LiNi_(0.5)Mn_(1.5)O_4

作　　者：何则强[1,2] 熊利芝[1,2] 梁凯[1] 李菊香[1] 

机构地区：[1]吉首大学化学化工学院,湖南吉首416000 [2]中南大学化学化工学院,湖南长沙410083

出　　处：《精细化工》2009年第12期1145-1148,1214,共5页Fine Chemicals

基　　金：国家自然科学基金(20376086);中国博士后科学基金(2005037700);湖南省自然科学基金(07JJ3014);湖南省教育厅科学研究项目(07A058);中南大学博士后科学基金(2004107)~~

摘　　要：以蔗糖为碳源,采用溶液沉积-真空热解法制备了LiNi_(0.5)Mn_(1.5)O_4/C复合材料。用热重与差热分析、X射线衍射分析、扫描电镜分析及电化学测试等手段对LiNi_(0.5)Mn_(1.5)O_4/C的微观结构、表面形貌和电化学性能进行了研究。结果表明,蔗糖热分解后在LiNi_(0.5)Mn_(1.5)O_4颗粒的表面包覆形成了一层无定形碳。无定形碳可以有效阻止LiNi_(0.5)Mn_(1.5)O_4颗粒的聚集,增加电极的导电面积,降低电池极化,从而改善LiNi_(0.5)Mn_(1.5)O_4的电化学性能。与未包覆的LiNi_(0.5)Mn_(1.5)O_4粉末相比,LiNi_(0.5)Mn_(1.5)O_4/C复合材料具有更高的可逆容量、更稳定的循环性能和更好的倍率性能。0.2C放电时,LiNi_(0.5)Mn_(1.5)O_4/C复合材料的首次放电容量达到144.8mA.h.g-1,经60次循环后平均每次循环的容量损失仅为0.0081%。而1.0C和2.0C放电时,LiNi_(0.5)Mn_(1.5)O_4/C复合材料的首次放电容量分别保持在131.9mA.h.g-1和122.4mA.h.g-1。LiNi0.5Mn1.5O4/C composite was prepared by the solution deposition- vacuum pyrolysis method using LiNi0.5Mn1.5O4 and sucrose as raw materials. The microstructure, surface morphology and electrochemical properties were characterized by various electrochemical methods in combination with thermogravimetric （TG） analysis and differential thermal analysis （ DTA）, X - ray diffraction （XRD） and scanning electron microscope （SEM）. It was found that the amorphous carbon layer is coated on the surface of LiNi0.5Mn1.5O4 due to the pyrolysis of sucrose. The amorphous carbon can prevent the LiNi0.5Mn1.5O4 particles from aggregation, increase the conductive area of electrode, decrease the polarization of cell and improve the electrochemical properties of LiNi0.5Mn1.5O4 effectively. Compared to LiNi0.5Mn1.5O4, the LiNi0.5Mn1.5O4/C composite has increased the reversible capacity, stabilized the cycling performance and improved the rate performance. The first discharge capacity of LiNi0.5Mn1.5O4/C is more than 144. 8 mA ·h·g^-1 and the capacity loss per cycle is only 0. 008 1% after cycling 60 times at 0. 2 C. While the first discharge capacity of LiNi0.5Mn1.5O4/C keeps at 131.9 mA·h·g^-1 and 122.4 mA ·h·g^-1 respectively even cycling at 1.0 C and 2. 0 C.

关 键 词：LINI0.5MN1.5O4 蔗糖 包覆 溶液沉积 真空热解 功能材料 

分 类 号：TQ050.43[化学工程]