Void Formation and Surface Roughening in Amorphous Li-Alloy Electrodes

Abstract

Lithium alloys with metallic or semi-metallic elements are attractive candidate materials for the next generation negative electrodes of lithium ion batteries due to their large specific and volumetric capacities. The key challenge with lithium alloy electrodes, especially Li/Si, has been their large volume changes during insertion and extraction of lithium. These volume changes can lead to pulverization and debonding. Recent efforts to improve the cyclability of Li-alloy based electrodes are highlighted by the utilization of nano-structured materials, including Si nanowires (NWs), crystalline-amorphous Si core-shell NWs, sealed Si nanotubes and nano-structured carbon/silicon composites. It is widely accepted that nano-sized materials provide better accommodation for diffusion-induced stress (DIS) and thus improve a battery’s cyclability.