Structure and electrochemical performance of Ba Li_（2-x）Na_xTi_6O_（14）（0≤x≤2） as anode materials for lithium-ion battery

• Published in: 中国科学：材料科学（英文版） Vol. 60; no. 8; pp. 728 - 738
• Main Author: Wei Tao Mao-Lian Xu Yan-Rong Zhu Qianyu Zhang Ting-Feng Yi
• Format: Journal Article
• Language: English
• Published: 2017
• ISSN: 2095-8226; 2199-4501

A series of Ba Li_（2-x）NaxTi_6O_（14）（0≤x≤2） compounds as lithium storage materials were synthesized by a facile solidstate method. X-ray diffraction Rietveld refinement shows that the Bragg positions correspond to the Ba Li_2Ti_6O_（14）, indicating a successful preparation. The Na＋ions doped Ba Li_2-Ti_6O_（14） compounds have larger unit-cell volume than the pristine one because ionic radius of Na＋ion is 55% larger than that of Li＋ion. SEM shows that the Ba Li_2-xNaxTi_6O_（14）（x=0, 0.5 and1） powders show similar irregular shaped particles between500 and 1000 nm. However, Ba Li_2-xNaxTi_6O_（14）（x=1.5 and 2）powders show similar rod-like shape. CV reveals that the passivating film is mainly formed during the first insertion process, and the solid electrolyte interface film on the surface of Ba Li_2-xNaxTi_6O_（14）（0≤x≤2） is formed below 0.7 V in the first cycle. Compared with other samples, Ba Li_0.5Na1.5Ti_6O_（14） exhibits higher reversible capacity, better rate capability and superior cyclability. Ba Li_0.5Na1.5Ti_6O_（14） delivers the delithiation capacities of 162.1 mAhg~-（1）at 50 m A g~-（1）, 158.1 mAhg~-（1）at 100 m A g~-（1）, 156.7 mAhg~-（1）at 150 m A g~-（1）, 152.2 mAhg~-（1）at 200 m A g~-（1）, 147.3 mAhg~-（1）at 250 m A g~-（1）and 142 mAhg~-（1）at 300 m A g~-（1）, respectively. An interesting thing is that Ba Na2Ti_6O_（14） as anode also shows an acceptable electrochemical performance. All these improved electrochemical performances of Ba Li_0.5Na1.5Ti_6O_（14） are attributed to the lowest polarization and the highest lithium ion diffusion coefficient among all samples.Hence, Ba Li_0.5Na1.5Ti_6O_（14） with excellent cycling performance,simple synthesis route and wide discharge voltage range can be a possible anode candidate for lithium-ion batteries.