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

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 (VLS) 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 catalysed 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. 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 after 100 cycles. Voltage profiles and differential capacity plots 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.