Influence of Carbon Matrix Dimensions on the Electrochemical Performance of Germanium Oxide in Lithium-Ion Batteries

Germanium dioxide (GeO2) has recently demonstrated high theoretical capacity and is being considered as the most promising candidate to substitute commercial carbon-based anodes of lithium-ion batteries. Nevertheless, practical application of GeO2 materials to lithium-ion batteries is greatly hampered by the huge volume variation during cycling. Herein, the GeO2 dispersions in different carbon matrices (i.e., 0D mesoporous carbon microspheres, 1D carbon nanotube, 2D reduced graphene oxide) are prepared by a simple route. In a comparison of these three composites, GeO2 embedded in 0D mesoporous carbon microspheres (denoted as GeO2@MCS) shows the best electrochemical performance regarding cyclability (852 mA h g(-1) at a rate of 0.5 A g(-1) after 100 cycles) and rate capability (269 mA h g(-1) at 10 A g(-1) after 50 cycles). The improved electrochemical performance arises from the novel structure that combines a variety of advantages: easy access of electrolyte and short transport path of Li+, and high conductivity transport of electrons through the 3D interconnected channels of MCS matrix. What is more, the 3D interconnected pores of MCS could effectively accommodate the huge volume change of GeO2 during cycling and maintain perfect electrical conductivity throughout the electrode.