The Kinetics of Li+ Electrodeposition on Sn Substrate for Li Rechargeable Battery

Sn can form alloy phase with Li with a theoretical specific capacity of 994mAh·g^-1, which is more than twice of the graphite. Due to this property, Li-Sn alloy has been considered as one of the most appealing anode materials. In order to make this material to meet the requirements of real application, huge efforts have been devoted to the research of this material ^[1-3]. In this work, the kinetics of electrodeposition of Li⁺on Sn substrate is studied, and this can provide theoretical basis on improving the electrochemical properties of Li-Sn alloy anode materials.

Galvanostatic pulse method is used for the study of the kinetics of Li⁺ electrodeposition on Sn metal and Li-Sn alloy with different Li contents which is formed instantaneously with the deposition of Li. The polarization resistance of Li-Sn alloy electrodes with different Li contents is evaluated by EIS method. Meanwhile, the kinetics of Li⁺ electrodeposition on Li metal and Cu metal substrates are compared. Some conclusions can be drawn: firstly, Li⁺ electrodeposition on Sn substrate is a process with continuing change in exchange current density and polarization resistance. Secondly, Li content in Li-Sn alloy has great impact on the kinetics of Li⁺ electrodeposition, in which the Li-Sn alloy substrate containing highest Li content is the most beneficial one among them. Thirdly, the Li⁺ deposition performance on Li-Sn alloy substrate containing highest Li content is much better than on Li metal and Cu metal substrates.

References:

[1] M. Winter, J. O. Besenhard. Electrochimica. Acta, 45 (1999) 31-50.

[2] M. Inaba, T. Uno, A. Tasaka. J. Power Sources, 146 (2005) 473–477.

[3] S. C. Chao, Y. C. Yen, Y. F. Song, Y. M. Chen, H. C. Wu, N. L. Wu. Electrochemistry Communications, 12 (2010) 234–237.

Statement:

The novelty of this work is that, it is found that as the deposition of Li⁺ on Sn surface proceeds, the alloy of Li-Sn is formed with increase of Li content in the alloy. The exchange current density of Li⁺ deposition on the alloy is changed with the Li content. This feature could affect the overall kinetics Li⁺ deposition and the cycleability of Li metal anode.

Relating topic: electrode materials (Li battery anodes)