Y. Yang, J. Li, X. He, J. Wang (State Key Lab of Physical Chemistry of Solid Surfaces), D. Sun (Bluestone Global Technology, Inc.), and J. Zhao (State Key Lab of Physical Chemistry of Solid Surfaces)
Recent studies showed that Li
3VO
4 intercalates Li-ions mainly between 0.5 ~ 1.0 V versus Li
+/Li, lower than Li
4Ti
5O
12, and at the same time can deliver a much higher theoretical capacity (~394 mAh g
-1) than Li
4Ti
5O
12 (~175 mAh g
-1).
[1] Therefore, Li
3VO
4 might be a better anode candidate for higher energy-density cell than Li
4Ti
5O
12 as well as better safety cell than graphite.
[2] However, its low electrode kinetics and poor electronic conductivity results in large resistance polarization and poor rate performance, preventing it from being widely used.
[3, 4] In this study, we developed a method to solve these two issues simultaneously. The unique hollow spherically structured Li
3VO
4/C (H-LVO/C) composite was synthesized via a facile spray drying process and subsequent heat treatment (as shown in Figure 1a). TEM images (Figure 1b and c) clearly reveal the hollow structure of LVO/C microspheres, and the LVO particles are coated with a layer of carbon with thickness about 5 nm.
The surfaced coated carbon layer can enhance the electronic conductivity. Meanwhile, the hollow spherical geometry of the particles is effective for increasing the wetting area for electrolyte and decreasing the Li-ion diffusion length, both are beneficial for fast charge transport. Consequently, the composite exhibits exceeding rate capability (a stable capacity of 125 mAh g-1 even at 80 C) and long-life performance with a capacity retention of 97 % (a reversible capacity of 275 mAh g-1) after 3000 cycles at 10 C.
Figure captions
Figure 1 (a) The formation mechanism of hollow spherical LVO/C composite. (b) The TEM image and (c) the HRTEM image of the H-LVO/C. (d) Long-term cycling performance of the H-LVO/C at 10 C.
References
[1] C. K. Zhang, H. Q. Song, C. F. Liu, Y. G. Liu, C. P. Zhang, X. H. Nan, G. Z. Cao, Adv. Funct. Mater. 2015, 25, 3497.
[2] H. Li, X. Liu, T. Zhai, D. Li, H. Zhou, Advanced Energy Materials 2013, 3, 428.
[3] Q. Li, J. Sheng, Q. Wei, Q. An, X. Wei, P. Zhang, L. Mai, Nanoscale 2014, 6, 11072.
[4] Z. Jian, M. Zheng, Y. Liang, X. Zhang, S. Gheytani, Y. Lan, Y. Shi, Y. Yao, Chem. Commun. 2015, 51, 229.
