Immobilization of GeS2 on exfoliated graphite sheet for high-capacity lithium-ion battery anodes

Abstract

Among germanium-based composites, GeS2 has attracted increasing concerns owning to its high theoretical capacity when applied to lithium-ion batteries (LiBs) as anode materials. Nevertheless, the intrinsic poor conductivity and volume expansion issues of GeS2 hindered its practical applications. Herein, we report a ball milling-assisted solid-state reaction approach to simultaneously smash GeS2 particles and exfoliate graphite powder. In this way, the GeS2 was pulverized and well anchored in exfoliated graphite sheets. When used as anode electrode for LiBs, the graphite sheets not only served as electron transfer layers, but also helped alleviating the volume shrinkage/expansion of GeS2 during the repeated lithiation/de-lithiation processes. The well designed GeS2-coated graphite sheet structure endow the hybrid GeS2/graphite (GeS2/C) anode with high reversible capacity. For instance, the GeS2/C anode powder delivered specific capacities of 823.3 and 395.3 mAh g-1 at 100th and 200th cycle under 0.1 and 1.5 A g-1, respectively, these values were higher than that of the neat GeS2 anode (corresponding to 453.1 and 81.0 mAh g-1). This study offers a facile and economical strategy to settle the drawbacks of GeS2 for LiBs anode, which shed some light on guiding the preparation of various types of graphite-supported electrodes with improved integral electrochemical performance.