Graphene-supported cubic hollow carbon shell-coated germanium particles as high-performance anode for lithium-ion batteries

Germanium-based materials are considered to be an alternative material for high energy density lithium-ion battery anodes due to their superior theoretical capacity. However, the severe volume expansion during the lithium insertion and the easily agglomerated tendency of Ge nanoparticles become the key obstacles to the stable cycle and capacity retention of Ge anodes. Herein, we designed a double-layered protective structure in which the cubic hollow Ge@C hybrids are uniformly dispersed on reduced graphene oxide sheets (Ge@C-rGO) through conventional dopamine-coated precursor and subsequent carbothermal reduction processes. In the synthesized Ge@C-rGO hybrids, the large-area rGO sheets cooperate with the amorphous carbon layer to accommodate and buffer the volume expansion of Ge particles, and to ensure that the Ge nanoparticles are in a separated state to the utmost extent. The Ge@C-rGO electrode which is employed in lithium-ion battery owns the reversible capacities of 1183 mAh.g(-1) at the specific current of 100 mAg(-1) and 710 mAh.g(-1) at 1 A g(-1) for 200 cycles. In addition, it exhibited good cycle stability, rate reversibility and electronic conductivity, and is a potential anode material with high performance and long-cycle capability.