Cu3Ge coated by nitrogen-doped carbon nanorods as advanced sodium-ion battery anodes

The sodium storage performance of Ge-based materials suffers from poor cycling stability caused by the volume variation and collapse of the structure during cycling process. In this work, Cu 3 Ge coated by nitrogen-doped carbon (Cu 3 Ge-NC) nanorods are prepared by annealing the mixture of CuGeO 3 nanowires and polyacrylonitrile which acts as nitrogen and carbon source. As anode materials for sodium ion batteries, the outside carbon shell inhibits the serious volume change caused by Na + insertion/extraction, and the Cu 3 Ge alloy enhances the sodiation capacity with rapid electron transfer and fast reaction kinetics. Corresponding kinetic analysis indicates pseudocapacitive behaviors play a dominant role in the total capacity at high rates. Hence, the Cu 3 Ge-NC exhibits favorable rate capability and cycling stability, which delivers a reversible capacity of 160 mAh g −1 for 500 cycles at a current density of 100 mA g −1 .