Seok Woo Lee, Hyun-Wook Lee, Ill Ryu, William D. Nix, Huajian Gao& Yi Cui

Nature Communications 6, Article number: 7533 doi:10.1038/ncomms8533
Received 16 February 2015 Accepted 18 May 2015 Published 26 June 2015

Following an explosion of studies of silicon as a negative electrode for Li-ion batteries, the anomalous volumetric changes and fracture of lithiated single Si particles have attracted significant attention in various fields, including mechanics. However, in real batteries, lithiation occurs simultaneously in clusters of Si in a confined medium. Hence, understanding how the individual Si structures interact during lithiation in a closed space is necessary. Here, we demonstrate physical and mechanical interactions of swelling Si structures during lithiation using well-defined Si nanopillar pairs. Ex situ SEM and in situ TEM studies reveal that compressive stresses change the reaction kinetics so that preferential lithiation occurs at free surfaces when the pillars are mechanically clamped. Such mechanical interactions enhance the fracture resistance of lithiated Si by lessening the tensile stress concentrations in Si structures. This study will contribute to improved design of Si structures at the electrode level for high-performance Li-ion batteries.





http://www.nature.com/ncomms/2015/150626/ncomms8533/full/ncomms8533.html