High Aspect‐ratio Germanium‐Tin Alloy Nanowires: Potential as Highly Efficient Li‐Ion Battery Anodes

Abstract

Abstract Here, the fabrication of a high aspect ratio (>440) Ge 1− x Sn x nanowires with super‐thin (≈9 nm) diameter, much below the Bohr radius, using a simple solvothermal‐like growth method under supercritical toluene conditions at a reaction temperature of 440 °C is reported. Ge 1− x Sn x nanowires are grown with varying amounts of Sn in Ge lattice, between 3.1 to 10.2 at%. The growth of the Ge 1− x Sn x alloy nanowires is achieved without any additional catalysts, and directly on current collector substrates (titanium) for application as Li‐ion battery anodes. The electrochemical performance of the binder‐free Ge 1− x Sn x nanowires as an anode material for Li‐ion batteries is investigated via galvanostatic cycling and detailed analysis of differential capacity plots. The dimensions of the nanowires, and the amount of Sn in Ge, are critical to achieving a high specific capacity and capacity retention. Ge 1− x Sn x nanowires with the highest aspect ratios and with the lowest Sn content (3.1 at%) demonstrate exceptional capacity retention of ≈90% and 86% from the 10th to the 100th and 150th cycles respectively, while maintaining a very high specific capacity value of 1176 and 1127 mAh g −1 after the 100 and 150 cycles respectively.