掺杂与表面包覆对尖晶石型LiMn_2O_4电化学性能的影响  

Effect of doping and surface coating on the electrochemical properties of spinel LiMn_2O_4

作　　者：胡拥军[1] 李义兵 吴四贵 

机构地区：[1]湖南城市学院化学与环境工程系,湖南益阳413000 [2]巴彦淖尔紫金矿业有限公司,内蒙古临河015000

出　　处：《化工进展》2007年第4期563-566,576,共5页Chemical Industry and Engineering Progress

基　　金：湖南省教育厅科研基金资助项目(No.04C161)

摘　　要：用固相法制备了Cr3+和F-同时掺杂的尖晶石型LiMn2O4正极材料,并对掺杂材料进行氧化铝表面包覆改性,用扫描电子显微镜和X射线衍射研究了材料的表面形貌和晶体结构,用充放电实验和交流阻抗技术测试了材料的电化学性能。结果表明:LiMn2O4在掺杂Cr3+和F-及表面包覆氧化铝后仍为尖晶石型结构,随掺杂和包覆量的增加,材料首次放电容量降低,但循环性能明显改善,其中未掺杂、掺杂量为0.10和表面包覆0.3%的氧化铝的材料室温首次放电容量分别为125.3 mA·h/g、117.5 mA·h/g和113.7 mA·h/g,循环25次后容量保持率分别为82.7%、91.5%和93.6%,而55℃下25次循环后放电容量及其保持率以表面包覆氧化铝的最佳,分别达到104.2 mA·h/g和92.1%。Spinel LiMn2O4 cathode material doped with Cr^3＋ and F- was prepared by solid-state reaction, and the material was modified by coating Al2O3 on its surface. The morphology and structure were characterized with scanning electron micrograph and X-ray diffraction, and the electrochemical properties were studied with charging-discharging test and A.C impedance test. The results showed that both materials doped with Cr^3＋ and F- and coated with Al2O3 had a spinel structure. With increasing level of doping and coating, their initial discharging capacity reduced, but their cycling performance was greatly improved. The 1st discharging capacities of LiMn2O4, LiMn1.9Cr0.1O3.9F0.1 and LiMn1.9Cr0.1O3.9F0.1/coated 0.3%Al2O3 were 125.3, 117.5 and 113.7mA · h · g^-1 respectively, after 25 cycles, their capacity retentions were 82.7%, 91.5% and 93.6% respectively. When cycling at 55℃, the electrochemical properties of the material coated with Al2O3 was the best, its discharging capacity and capacity retention after 25 cycles were 104.2 mA· h · g^-1 and 92.1% respectively.

关 键 词：锂离子电池 正极材料 LIMN2O4 尖晶石型结构 掺杂 

分 类 号：TM912.9[电气工程—电力电子与电力传动]