高能球磨辅助固相法制备Zr掺杂的钛酸锂

Synthesis of Zr Doped Li4Ti5O12 by a High-Energy Ball-Milling Modified Solid-State Method

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

Abstract:

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·g-1, 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.