单斜层状LiMn0.97Al0.03O2-xPO4x材料的合成及其电化学性能  

Synthesis and Electrochemical Properties of Monoclinic Layered Structure LiMn_(0.97)Al_(0.03)O_(2-x)(PO_4)_x Materials

作　　者：粟智[1] 徐茂文[1] 叶世海[2] 王永龙[2] 

机构地区：[1]新疆师范大学生命科学与化学学院,乌鲁木齐830054 [2]南开大学化学学院,新能源材料化学研究所,天津300071

出　　处：《高等学校化学学报》2010年第2期247-252,共6页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:20773070);新疆高校科研计划重点项目(批准号:XJEDU2009I28)资助

摘　　要：以Na2CO3,(CH3CO2)2Mn.4H2O,Al2O3,Na3PO4.12H2O和CH3COOLi.2H2O为原料,通过2次高温固相法和一步水热离子交换法得到一系列铝和磷掺杂的LiMn0.97Al0.03O2,LiMnO1.99(PO4)0.01和LiMn0.97Al0.03O2-x(PO4)x(x=0.01,0.03,0.05)化合物.用X射线衍射(XRD)表征了前驱体及交换产物的晶体结构,用扫描电镜(SEM)测定了晶体的形貌.通过X射线光电子能谱(XPS)、傅里叶红外光谱及恒电流充放电测试,研究了掺杂离子对合成材料结构及电化学性能的影响.研究结果表明,Al-PO4复合掺杂综合了Al3+掺杂提高材料的电化学反应活性和减低材料的电化学反应阻抗以及PO43-掺杂增大材料的晶胞体积的特点,提高材料中Li+的扩散能力,有效地抑制了材料由于Jahn-Teller效应引起的结构畸变,改性后的LiMnO2正极材料既保持了较高的容量又获得了良好的电化学循环性能.Layered lithium manganese bronze LiMn0.97Al0.03O2,LiMnO1.99（PO4）0.01 and LiMn0.97Al0.03O2-x·（PO4）x（x-=0.01,0.03,0.05） with a monoclinic structure were synthesized by the two-step high temperature solid state reaction and a hydrothermal ion exchange method,using Na2CO3,（CH3COO）2Mn·2H2O,Na3PO4·12H2O and Al2O3 as the starting materials.XRD and SEM were used to characterize the structures and morphology of the precursors and products by the ion exchange reaction.The effect of the doping ions on the structure and the electrochemical performances of the samples was investigated by X-ray photoelectron spectroscopy（XPS）,Fourier transform infrared spectroscopy（FTIR）,electrochemical impedance spectroscopy（EIS） and chronoamperometry techniques.The results showed the co-doping of Al-PO4 combined the advantages of the improvement of the electrochemical reactivity and the decrease of the electrode reaction resistance by the Al3＋ doping,as well as enlarging the unit-cell volume by the PO3-4 doping.It benefits for the Li＋ diffusion in the cathode and the suppression of Jahn-Teller distortion.Comparing the pristine one,the Al-PO4-co-doped LiMnO2 cathode exhibits higher discharge capacity and better cyclic stability.

关 键 词：单斜层状LiMnO2 正极材料 复合掺杂 水热离子交换 电化学性能 

分 类 号：P611.3[天文地球—矿床学]