Scalable synthesis of hierarchical porous Ge/rGO microspheres with an ultra-long cycling life for lithium storage

The hierarchical porous germanium/reduced graphene oxide (Ge/rGO) microspheres are synthesized through an industrially scalable spray drying technique using commercial germanium dioxide (GeO2) as raw material. The Ge/rGO microspheres architecture with Ge nanoparticles homogeneously embedded in the three-dimensional (3D) interconnected conductive rGO network. When employed as anode for lithium ion batteries (LIBs), the as-obtained Ge/rGO microspheres exhibit excellent electrochemical performance with a high reversible capacity (811 mAh g(-1) after 1000 cycles), ultra-long cycling life (over 80% capacity retention from the 6th to 1000th cycles at 1 C), and high rate capability (380 mAh g(-1) at 20 C). In addition, the full cell consisting of Ge/rGO-2 anode and LiFePO4 cathode also delivers good cycling stability with high energy density. The 3D conductive rGO network provides the pathway for electron transportation and promotes to form stable solid electrolyte interphase (SEI) layer. Furthermore, the void space deduced from the porous structure can effectively accommodate volume changes and enhance the structural integrity of Ge/rGO microspheres. This facile and scalable synthetic strategy is beneficial for large-scale production of Ge-based electrode materials for further application in high energy and power density LIBs.