Preparation of nanostructured Ge/GeO2 composite in carbon matrix as an anode material for lithium-ion batteries

•A simple and direct method to fabricate Ge/GeO2/C composite materials is reported.•In situ XRD analysis shows a complex reaction of conversion reaction as well as Li-Ge alloy reaction.•The composite exhibited superior electrochemical performance as a LIB anode.•The improved electrochemical performance arises from synergistic effect.

A Ge/GeO2 composite embedded in a carbon matrix (Ge/GeO2/C) is synthesized using a one-step mechanical ball-milling method, and its potential as a Li-ion battery anode material is evaluated. Characterization using scanning electron microscopy and transmission electron microscopy reveal that the uniformly distributed germanium and oxygen elements are embedded in the carbon matrix. In situ X-ray diffraction analysis provides insight into the complex conversion reaction as well as the Li–Ge alloy reaction. The Ge/GeO2/C composite exhibits a fairly high capacity of 915 mAh g−1 up to 50 cycles (with good cycling and a high rate capability). The improvement in the electrochemical performance arises from the synergistic effects of the reduced particle size, conductive carbon matrix, and catalytic function of Ge to mitigate mechanical strain and provide an efficient network for electron transfer.