Synthesis and electrochemical performance of carbon-coated Fe2GeO4 as an anode material for sodium-ion batteries

The development of anode materials with high capacity and good cycling stability is one of the state-of-the-art objectives in the field of rechargeable sodium-ion batteries. In this work, we synthesized high-capacity spinel Fe2GeO4 using a facile hydrothermal method followed by calcination and investigated its electrochemical performance as an anode material for sodium-ion batteries. The Fe2GeO4 material delivered a high initial discharge capacity of 448.1 mAh g(-1) but it showed gradual capacity fading with a capacity retention of 67.4% after 50 cycles. Its high initial capacity originated from the high electrochemical activity of Fe caused by its multiple oxidation reactions. To enhance the cycling stability of the Fe2GeO4, carbon was coated onto the surface of Fe2GeO4 particles. The carbon-coated Fe2GeO4 (Fe2GeO4@C) exhibited an initial discharge capacity of 423.0 mAh g(-1) with good capacity retention. The sodium-ion full cell was assembled with an Fe2GeO4@C anode, and a NaCo0.5Fe0.5O2 cathode, and the results showed superior cycling performance, demonstrating that the Fe2GeO4@C can be used as a promising anode material for sodium-ion batteries.