Sodium-ion batteries (SIBs) are considered to be a promising low-cost alternative to common lithium-ion batteries. Several electrochemical studies have been carried out on anode nanomaterials of TiO₂ and good cyclability and high rate capability has been reported for Li-ion batteries [1]. Recently, its possible application in Na-ion batteries has put it forward as a promising candidate [2,3]. Simulated armorphization and recrystallization technique has been employed to generate nano-architectures of TiO₂ [4].

Herein, we present a detailed simulated synthesis for nanospheres of lithiated and sodiated TiO₂ where amorphous precursors were crystallised. Mixed polymorphs consisting mainly of brookite, rutile were observed from microstructures and XRDs. Crystallised nanospheres were lithiated and sodiated up to high concentrations to imitate the charging process and related volume expansions were predicted. Structural aspects were deduced from radial distribution functions and differences associated with lithiation and sodiation are quite obvious. Calculated XRDs are generated and compared with experimental results where available. Microstructures of the resulting models are analysed and a wealth of crystallographic defects (i.e. grain boundaries and point defects) were captured and their resulting influence on Li-ion and Na-ion transport are discussed.

 References

[1] J. Wei, J.X. Liu, Y.C. Dang, K. Xu, Y.A. Zhou, Adv. Mater. Res. (2013), 750−752, 301.

[2] K.T. Kim, G. Ali, K.Y. Chung, C.S. Yoon, H. Yashiro, Y-K. Sun, J. Lu, K. Amine, and S-T. Myung, Nano Lett. (2014), 14, 416.

[3] L. Wu, D. Bresser, D. Buchholz, G.A. Giffin, C.R. Castro, A. Ochel , and S. Passerini, Adv. Energy. Mater. (2015), 5, 1401142

[4] M.G. Matshaba, D.C. Sayle, T.X.T. Sayle and P.E. Ngoepe, J. Phys. Chem. C, (2016), 120, 14001.