Twisted nanocolumns for LIBs via phi-sweep method in ion assisted e-beam deposition

Abstract

In this work, twisted nanostructured silicon-copper (with 19%at. copper) thin film is fabricated by glancing angle deposition phi-sweep process of ion beam assisted electron beam evaporation method. The thin film delivers 977 mAh g(-1) after 100 cycles, when cycled with 100 mA g(-1) rate and performs 280 mAh g(-1) at 2.5 A g(-1) rate. The morphological and the compositional particularities of the electrode might govern this noticeable cycle performance: Gaps among the nanostructures accommodate large volume changes and provide easy access to lithium ions for reacting with silicon to deliver high capacity. Plus, the direct connection of nanostructures to the current collector displays short lithium travelling distance promoting lithiation kinetic. Moreover, small intermetallics creating electronic conductive pathways enhance the reversibility. And finally, 5 min ion assisted deposition increases the adhesion of the film while avoiding possible delamination, hence quick failure of the electrode in the early stages of cycling.