Facile synthesis of sandwiched Zn2GeO4–graphene oxide nanocomposite as a stable and high-capacity anode for lithium-ion batteries

Abstract

Traditional metal anode materials in lithium-ion batteries are plagued by instability upon discharge–charge cycling. We report that a unique sandwiched Zn₂GeO₄–graphene oxide nanocomposite has been synthesized on a large scale through a simple ion-exchange reaction, whereby Zn₂GeO₄ nanorods with lengths of 600 nm and widths of 40 nm are homogeneously sandwiched into the graphene oxide matrix. Compared with bare Zn₂GeO₄ nanorods, a dramatic improvement in the electrochemical performance of the resulting nanocomposite has been achieved. In the voltage window of 0.001–3 V, the electrode of the Zn₂GeO₄–graphene oxide nanocomposite delivers a specific capacity as high as 1150 mA h g⁻¹ at 200 mA g⁻¹ after 100 discharge–charge cycles. Even at a high current density of 3.2 A g⁻¹, a capacity of 522 mA h g⁻¹ can be retained. The unusual electrochemical performance including highly reversible capacity and excellent rate capability arise from synergetic chemical coupling effects between Zn₂GeO₄ and graphene oxide.