Germanium tin alloy nanowires as anode materials for high performance Li-ion batteries

Abstract

The combination of two active Li-ion materials (Ge and Sn) can result in improved conduction paths and higher capacity retention. Here we report for the first time, the implementation of Ge1–xSnx alloy nanowires as anode materials for Li-ion batteries. Ge1−xSnx alloy nanowires have been successfully grown via vapor–liquid–solid technique directly on stainless steel current collectors. Ge1−xSnx (x = 0.048) nanowires were predominantly seeded from the Au0.80Ag0.20 catalysts with negligible amount of growth was also directly catalyzed from stainless steel substrate. The electrochemical performance of the the Ge1−xSnx nanowires as an anode material for Li-ion batteries was investigated via galvanostatic cycling and detailed analysis of differential capacity plots (DCPs). The nanowire electrodes demonstrated an exceptional capacity retention of 93.4% from the 2nd to the 100th charge at a C/5 rate, while maintaining a specific capacity value of ∼921 mAh g−1 after 100 cycles. Voltage profiles and DCPs revealed that the Ge1−xSnx nanowires behave as an alloying mode anode material, as reduction/oxidation peaks for both Ge and Sn were observed, however it is clear that the reversible lithiation of Ge is responsible for the majority of the charge stored.