摘要
采用改进的高温固相法合成Zr4+掺杂的Li4Ti5O12,研究了原位包覆技术、高能球磨和金属元素掺杂对其晶型、相结构、颗粒形貌以及电化学性能的影响。结果表明:改进后的高温固相法能有效阻止颗粒团聚、提升颗粒的均匀分散度;Zr4+掺杂能降低电极极化、提升锂离子扩散系数,从而改善电化学性能。所得Li4Ti4.95Zr0.05O12在0.5 C倍率下首次放电比容量达176 mAh·g-1,在40 C高倍率下仍达52 mAh·g-1。另探讨了不同离子半径的Zr4+和Ce4+对掺杂效果的影响,结果表明较小离子半径的元素掺杂效果较好。
Zr4＋ doped Li4Ti5O12 was synthesized from Li2CO3, ZrO2 and tetrabutyl titanate by a modified solid-state method. The effects of the in-situ coating, high energy ball-milling and Zr-doping on crystalline structure, particle size, morphology and electrochemical performance of Li4Ti5O12 were investigated. The samples were tested by XRD, SEM and electrochemical workstation. The results show that the in-situ coating and ball-milling can decrease the particle size and prevent the aggregation of nanoparticles. Zr-doping obviously improves the rate capability of Li4Ti5O12 via the generation of less electrode polarization and higher Li＋ diffusion coefficient. Li4Ti4.95Zr0.05O12 exhibits an excellent rate capability and cycling stability. At the charge-discharge rate of 0.5 and 40C, its discharge capacities are 176 and 52 mAh.gl, respectively. After 10 cycles, there is less than 0.5% reduction in reversible capacity at 1, 2, 5, 10, 20 and 40 C. Compared to Ce-doping, it also shows better crystallization and electrochemical performance due to its smaller ionic radius.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2014年第9期2237-2241,共5页
Rare Metal Materials and Engineering
基金
国家自然科学基金(21171116)
国家国际科技合作专项(2012 DFG11660)
关键词
高能球磨
固相法
负极材料
钛酸锂
Zr4+掺杂
high-energy ball-milling
solid-state method
anode materials
Li4Ti5O12
Zr-doping
