石墨烯/尖晶石LiMn_2O_4纳米复合材料制备及电化学性能  

Synthesis and Electrochemical Performance of Graphene Modified Nano-Spinel LiMn_2O_4 Cathode Materials

作　　者：崔永丽[1] 徐坤[1] 袁铮[1] 谢仁箭[1] 朱光林[1] 庄全超[1] 强颖怀[1] 

机构地区：[1]中国矿业大学材料科学与工程学院,徐州221116

出　　处：《无机化学学报》2013年第1期50-56,共7页Chinese Journal of Inorganic Chemistry

基　　金：中央高校基本科研业务费专项基金(No.2010LKHX03;2010QNB04;2010QNB05);江苏高校优势学科建设工程资助项目

摘　　要：采用溶胶凝胶法和还原氧化石墨法制备尖晶石LiMn2O4纳米晶和石墨烯纳米片,并采用冷冻干燥法制备了石墨烯/尖晶石LiMn2O4纳米复合材料,利用XRD、SEM、AFM等对其结构及表面形貌进行表征;利用CV、充放电、EIS研究纳米复合材料的电化学性能和电极过程动力学特征。结果表明:纳米LiMn2O4电极材料及其石墨烯掺杂纳米复合材料的放电比容量分别为107.16 mAh.g-1,124.30 mAh.g-1,循环100周后,对应容量保持率为74.31%和96.66%,石墨烯可显著改善尖晶石LiMn2O4电极材料的电化学性能,归结于其良好的导电性。纳米复合材料EIS上感抗的产生与半导体尖晶石LiMn2O4不均匀地分布在石墨烯膜表面所造成局域浓差有关,并提出了感抗产生的模型。Nano-LiMn2O4 and graphene nanosheets were synthesized by sol-gel route and reduction of exfoliated graphite oxides method respectively. Graphene modified spinel LiMn2O4 cathode nanocomposites were synthesized by freeze-drying method. The structure, morphology and electrochemical performance of the synthesized materials were characterized by X-ray diffraction （XRD）, atomic force microscopy （AFM）, scanning electron microscopy （SEM）, cyclic voltammetry （CV）, electrochemical impedance spectroscopy （EIS） and galvanostatic charge- discharge techniques. The graphene modified spinel LiMn2O4 nanocomposites exhibited a high discharge capacity of 124.30 mAh·g^-1 at 0.1C, while spinel LiMn2O4 only delivered 107.16 mAh-gq at the same rate. Compared with pure LiMn2O4, the graphene modified LiMn2O4 exhibited excellent cycle ability, with a capacity retention of 96.66% after 100 cycles versus about 74% for pure LiMn2O4. The improved electrochemical performance was attributed to the excellent conductivity of graphene nanosheets. The inductive loop observed in the impedance spectra of the graphene modified LiMn2O4 electrode was attributed to the formation of nano-LiMn2O4 local concentration cell from which current flows in opposition to Li de-intercalation into cathode, consistent with the conditions for the generation of an inductive loop. Consequently a model was proposed to explain the inductive loop response of composites electrode for lithium ion batteries.

关 键 词：锂离子电池 石墨烯 尖晶石LiMn2O4纳米复合材料 电化学性能 电化学阻抗谱 感抗 

分 类 号：O613.71[理学—无机化学]