Ge nanoparticles uniformly immobilized on 3D interconnected porous graphene frameworks as anodes for high-performance lithium-ion batteries

Abstract

Germanium (Ge), an alloy-type anode material for lithium-ion batteries (LIBs), possesses many advantages such as high theoretical capacity and decent electrical conductivity. Nevertheless, its application is restricted by tremendous volume variation and tardy reaction kinetic during discharge/charge process. In this paper, the Ge/3DPG composites with Ge nanoparticles uniformly dispersed in 3D interconnected porous graphene (3DPG) skeleton are successfully prepared using a template-assisted in-situ reduction method. The unique 3D interconnected porous graphene can not only enhance the electronic conductivity and reaction kinetics of the materials, but also provide sufficient buffer space to effectively mitigate the volume expansion during cycling and strengthen the structural integrity. Moreover, the small-sized Ge nanoparticles in close conjunction with the 3D graphene can boost the surface-controlled reaction of the electrode, which contributes to a fast charge–discharge rate capability. The Ge/3DPG composite with optimized Ge/graphene mass ratio delivers high reversible specific capacity (1102 mAh g−1 after 100 cycles at 0.2 C), outstanding rate capability (494 mAh g−1 at 5 C), and admirable cycling stability (85.3% of capacity retention after 250 cycles at 0.5 C). This work provides a significant inspiration for the design and fabrication of advanced Ge-based anode materials for next-generation high-performance LIBs.