The quantum transport properties of silicon nanowires are affected upon lithiation

Lithiated silicon nanowires show huge potential as anodes in lithium-ion batteries. The nanostructured silicon wires can potentially improve battery performance while driving down the material cost due to the abundant nature of silicon.

Dominik Bauer and Mathieu Luisier studied the anticipated effect stemming from surface roughness and disorder on the electrical and thermal characteristics of lithiated silicon nanowires. These factors have previously been known to increase scattering, resulting in a decrease in thermal and electrical transport properties.

“It is important to understand the influence of the lithium concentration on these characteristics as a poor thermal conductivity could, for example, lead to overheating effects in lithium-ion batteries using silicon nanowires as their anode material,” said Bauer.

Through density functional theory and reactive-force-field methods, the authors found that the electrical performance of the silicon nanowires remains good even though they are greatly affected by the lithium induced disorder. The authors theorize that this is due to the metallic characteristic of the nanowires when the lithium concentration increases. In contrast, the random distribution of the lithium atoms corresponded with a reduction in thermal conductivity because the phonon propagation through the nanowire is disturbed.

“The next step will consist of coupling the electron and thermal transport properties so that the temperature distribution of Si nanowires used as battery anodes can be precisely determined and the presence of local hot spots identified,” said Bauer.

The authors acknowledged that moving forward there are challenges to be addressed to improve the heat dissipation from the active region of the battery.

Source: “Influence of disorder and surface roughness on the electrical and thermal properties of lithiated silicon nanowires,” by Dominik Bauer and Mathieu Luisier, Journal of Applied Physics (2020). The article can be accessed at https://doi.org/10.1063/5.0002980 .