Nanostructured Germanium Anode Materials for High-Performance Lithium-ion Batteries

Abstract

Lithium reactive elements such as Si, Ge, Sn, and Sb have been investigated as potential high-capacity anode materials for the high-capacity Li-ion batteries. Among them, Ge demonstrates the high capacity and has a good cyclability, although the volume change similar with Si is normally observed. The analogous LixGe system has received little attention. Fully lithiated Li4.4Ge has a high theoretical capacity of 1600 mAh g-1 with a volume change of 370%. The room temperature diffusivity of Li in Ge is 400 times greater than that in Si, indicating that Ge can be more attractive electrode material for high power-rate anodes. There are several ways to overcome the volume exchange problem, such as reducing the size to nano scale, using composites with active/active of active/inactive matrixes, or using thin films or alloys. This includes the formation of an alloy with a ductile active metal so that it acts as a buffer for volume expansion. Herein the advanced nanostructured Germanium anode materials for Lithium-ion battery was presented using the template with reductive decomposition method, Kirkendall effect without template and Polyol method. In addition, a reaction mechanism of Germanium and Germanium oxides during lithation and delithiation process was proposed.