Lithium ion battery (LIB) has been interesting in a variety of applications especially for electric vehicles (EV), and hybrid electric vehicles (HEV). Commercialized graphite is used for a representative anode material but has still problems which are the formation of solid electrolyte interphase (SEI) layer and some decomposition in low flat potential. Therefore, SEI is attributed to decrease a capacity of cycle in first few cycle as well as not to transfer lithium ion for high C rate.[1] Due to the lack of potential candidates, TiNb₂O₇ (TNO) has been investigated as one of the promising next candidates since first proposed as a novel anode material by Goodenough in 2011.[2] TNO anodes display an operational potential larger than 1.0 V (versus Li/Li⁺), which should avoid the formation of the SEI layer.[2-5] Herein, we reported that wrapping reduced graphene oxide (rGO) around micron sized TiNb₂O₇ is designed for enhancing the electrochemical properties owing to the greatly conductive material and micro-sized structure. The reduced graphene oxide-wrapped TiNb₂O₇ microspheres (rGO-TNO MS) have been synthesized by adding formic acid for fabricating microspheres and then wrapped by rGO using cetyltrimethylammonium bromide (CTAB). The formic acid is desirable as an acid catalyst and when tested as an anode material for lithium ion batteries, the rGO-TNO MS shows a high reversible capacity of 242.97 mAh g^{-1 ­}at 0.1C (38.7mAh g^-1) and 93.33% of the coulombic efficiency of rGO-TNO MS. Moreover, rGO-TNO MS is specialized for high C rate (100 C) and sustain long cycle stability after 500cycle indicating that is a promising candidates for application in high rate lithium ion storage systems.

References

[1] B. Guo, X. Yu, X.-G. Sun, M. Chi, Z.-A. Qiao, J. Liu, Y.-S. Hu, X.-Q. Yang, J.B. Goodenough, S. Dai,  Energ. Environ. Sci., 7 (2014) 2220-2226.

[2] J.-T. Han, Y.-H. Huang, J.B. Goodenough, Chem. Mater., 23 (2011) 2027-2029.

[3] K. Tang, X. Mu, P.A. van Aken, Y. Yu, J. Maier, Adv. Energy Mater., 3 (2013) 49-53.

[4] X. Lu, Z. Jian, Z. Fang, L. Gu, Y.-S. Hu, W. Chen, Z. Wang, L. Chen,  Energ. Environ. Sci., 4 (2011) 2638-2644.

[5] L. Fei, Y. Xu, X. Wu, Y. Li, P. Xie, S. Deng, S. Smirnov, H. Luo, Nanoscale, 5 (2013) 11102-11107.