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 Ge_1–xSn_x alloy nanowires as anode materials for Li-ion batteries. Ge_1−xSn_x alloy nanowires have been successfully grown via vapor–liquid–solid technique directly on stainless steel current collectors. Ge_1−xSn_x (x = 0.048) nanowires were predominantly seeded from the Au_0.80Ag_0.20 catalysts with negligible amount of growth was also directly catalyzed from stainless steel substrate. The electrochemical performance of the the Ge_1−xSn_x 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 Ge_1−xSn_x 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.