Silicon-Copper Helical Arrays for New Generation Lithium Ion Batteries.

The helical array (with 10 atom % Cu) exhibits 3130 mAh g(-1) with 83% columbic efficiency and retains 83% of its initial discharge capacity after 100th cycle. Homogeneously distributed interspaces between the helical arrays accommodate high volumetric changes upon cycling and copper atoms form a conductive network to buffer the mechanical stress generated in the electrode while minimizing electrochemical agglomeration of Si. Also, ion assistance is believed to enhance the density of the helices at the bottom thus increasing the adhesion.