摘要
以氢氧化锂、乙酸锰、硝酸镁和钛酸丁酯为原料,以柠檬酸为螯合剂,采用溶胶-凝胶法制备了二价镁离子与四价钛离子等摩尔共掺杂的尖晶石型锂离子电池正极材料Li Mn1.9Mg0.05Ti0.05O4.采用热重分析(TGA),X射线衍射(XRD),扫描电子显微镜(SEM),透射电子显微镜(TEM)和电化学性能测试(包括循环伏安(CV)和电化学交流阻抗谱(EIS)测试)对所得样品的结构、形貌及电化学性能进行了表征.结果表明:780°C下煅烧12 h得到了颗粒均匀细小的尖晶石型结构的Li Mn1.9Mg0.05Ti0.05O4材料,该材料具有良好的电化学性能,在室温下以0.5C倍率充放电,在4.35-3.30 V电位范围内放电比容量达到126.8 m Ah·g-1,循环50次后放电比容量仍为118.5m Ah·g-1,容量保持率为93.5%.在55°C高温下循环30次后的放电比容量为111.9 m Ah·g-1,容量保持率达到91.9%,远远高于未掺杂的Li Mn2O4的容量保存率.二价镁离子与四价钛离子等摩尔共掺杂Li Mn2O4,改善了尖晶石锰酸锂的电子导电和离子导电性能,使其倍率性能和高温性能都得到了明显的提高.
An Mg（II） and Ti（IV）, iso-molar, co-doped cathode material LiMn1.9Mg0.05Ti0.05O4 for lithium-ion batteries was successful y synthesized via a sol-gel method, using lithium hydroxide, manganese acetate, magnesium nitrate, and butyl titanate as raw materials, and citric acid as a chelating agent. The as-prepared materials were characterized using thermogravimetric analysis （TGA）, X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and electrochemical tests （including cyclic voltammetry （CV） and electrochemical impedance spectroscopy （EIS） measurements）. The results demonstrated that the cathode material LiMn1.9Mg0.05Ti0.05O4, which was obtained after calcination at 780 °C for 12 h, exhibited a fine microstructure and good electrochemical performance. When cycled at 4.35-3.30 V at room temperature, LiMn1.9Mg0.05Ti0.05O4 delivered a discharge specific capacity of 126.8 mAhg^-1 at 0.5C rate, and maintained a capacity of 118.5 mAhg^-1 after 50 cycles;the capacity retention of this material reached 93.5%. This material showed a discharge-specific capacity of 111.9 mAhg^-1 at 0.5C rate after 30 cycles, when it was cycled at 55 °C;under these conditions the capacity retention reached 91.9%, far superior to the capacity retention of undoped LiMn2O4. The iso-molar co-doping of LiMn2O4 with Mg（II） and Ti（IV） ions led to significant modification of the electronic and ionic conductivity, and increased the rate properties and electrochemical performance of the spinel lithium manganate at elevated temperatures.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2014年第12期2283-2290,共8页
Acta Physico-Chimica Sinica
基金
国家自然科学基金(21071026)
电子科技大学杰出人才引进项目(08JC00303)资助~~
