Crystalline Cu-silicide stabilizes the performance of a high capacity Si-based Li-ion battery anode

Abstract

Metal-silicides have demonstrated bright prospects as advanced anodes for lithium-ion batteries (LIBs). However, their roles in volume change accommodations are still unclear to us. Here, we design and fabricate a nanoporous Si/Cu_0.83Si_0.17/Cu composite, supported with a highly crystalline Cu-silicide/Cu rigid framework, which demonstrates a high reversible capacity of 820.4 mA h g⁻¹ after 500 cycles at a current density of 3 A g⁻¹. According to the in situ TEM, there was no obvious structural damage and electrode pulverization during the initial lithiation, and a highly crystalline LiCuSi phase was observed. Furthermore, the conversion of the Cu_0.83Si_0.17/LiCuSi couple during repeated cycles is highly reversible, and the structural integrity could be well maintained. These results demonstrate that the highly crystalline Cu-silicide together with the nanoporous structure contributes to the ultrastable cycle performance and the Cu-silicide/Cu rigid framework supported the superior rate performance. The present work points out a facile but effective strategy for the engineering of alloy type anodes with superior cycle and rate properties for next generation LIBs.