Na掺杂Li2-xNaxMnSiO4/C正极材料的微波辅助合成与电化学性能  

Microwave-assisted Synthesis and Electrochemical Performance of Na-Doped Cathode Materials Li2-xNaxMnSiO4/C

作　　者：马东玮 田润赛 刘振江 冯源源 丁泓宇 冯季军[1] MA Dongwei;TIAN Runsai;LIU Zhenjiang;FENG Yuanyuan;DING Hongyu;FENG Jijun(School of Chemistry and Chemical Engineering,University of Jinan,Jinan 250022,China)

机构地区：[1]济南大学化学化工学院

出　　处：《高等学校化学学报》2019年第6期1280-1287,共8页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:51102114);济南市科技发展计划项目(批准号:201401234)资助~~

摘　　要：采用溶胶-凝胶法并辅以微波热处理合成了Na掺杂改性的Li2-xNaxMnSiO4/C(x=0,0.05,0.09,0.13)复合正极材料.利用X射线衍射(XRD)、扫描电子显微镜(SEM)、恒电流充放电测试、循环伏安(CV)和交流阻抗(EIS)测试等对材料进行了表征.结果表明,经微波辐射后得到的电极材料具有Pmn21型空间结构,其碳层分布均匀,粒径细小均匀,约为15~30nm.在微波辅助原位碳包覆和Na掺杂共同作用下,复合材料的电荷转移电阻明显降低,Li+扩散速率增大,展现出优良的电化学性能.在0.1C倍率下Li1.91Na0.09MnSiO4/C样品首次放电比容量为211mA·h/g,50次循环后仍保持80mA·h/g的可逆容量;0.5C和2.0C倍率下的放电比容量分别为106和53mA·h/g,大电流下的可逆容量明显提高.Li2-xNaxMnSiO4/C( x =0, 0.05, 0.09, 0.13) composite cathode materials were synthesized with microwave assisted sol-gel method. The crystal structure, morphology and electrochemical performance were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), galvanostatic charge-discharge test, cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS). The results indicate that the as-prepared materials can be well indexed to Pmn21 space group. The particles are fine with carbon layer coated uniformity and their size are evenly distributed in the range of 15-30 nm. With the synergistic effects of Na^+ doping and microwave assisted in-situ carbon coating, the charge transfer resistance is reduced while the diffusion of Li^+ is enhanced significantly, leading to excellent electrochemical performance. The Li 1.91 Na 0.09 MnSiO 4/C exhibits an initial discharge capacity as high as 211 mA·h/g at 0.1C and retained 80 mA·h/g after 50 cycles. The reversible capacities at high rate currents are also improved obviously, with discharge capacities of 106 mA·h/g and 53 mA·h/g at 0.5C and 2.0C separately.

关 键 词：正极材料 LI2MNSIO4 微波辅助合成 原位碳包覆 钠掺杂 

分 类 号：O646[理学—物理化学]