Enhanced electrochemical properties of carbon coated Zn2GeO4 micron-rods as anode materials for sodium-ion batteries

- Zn2GeO4 micron-rods with diameter of 200-500 nm were prepared via hydrothermal method.
- Dopamine-derived carbon acts as coating layer to improve the electronic conductivity.
- Zn2GeO4@C micron-rods exhibit good cycle stability and rate performance.

Germanium-based composites are a series of potential anode materials for sodium-ion batteries owing to the alloying reaction between Ge and Na to form NaGe, which is beneficial to achieve a high specific capacity. However, the significant volume change and sluggish kinetics during the electrochemical process restrict the application of such materials. Herein, a dopamine-derived carbon-coated ternary germanium oxide, Zn2GeO4@C with micron-rod morphology, is successfully synthesized by a facile hydrothermal method and its sodium storage behavior is examined between 0.01 and 3.0 V. Zn2GeO4@C micron-rods deliver a specific capacity of 317 mA h g−1 at a current density of 100 mA g−1 and an excellent rate capability of 150 mA h g−1 at high applied current density of 2 A g−1, which is superior to the bare Zn2GeO4 micron-rods. Both the synthesis strategy and materials design obtained from this study provide new perspective for the development of novel anode materials for sodium-ion batteries.

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