LAUSR

Abstract Germanium telluride (GeTe) with a layered structure and a GeTe nanocomposite modified by amorphous carbon (GeTe/C) are prepared via a simple solid-state synthesis, and their electrochemical performance for sodium-ion batteries is evaluated. To determine the electrochemical sodiation/desodiation mechanism of the GeTe and GeTe/C, various ex situ analytical methods are employed. During sodiation, GeTe in both electrodes is converted into NaGe and Na2Te phases. By contrast, during desodiation, the converted NaGe and Na2Te phases in the only GeTe/C are completely recombined into the original GeTe phase. Because of the repeated conversion/recombination reactions during sodiation/desodiation, GeTe/C displays outstanding Na-ion storage characteristics, such as a high reversible first volumetric capacity of 662 mAh cm−3, a stable capacity retention of 98.5% up to after 100 cycles, and rapid rate capabilities of 704 mAh cm−3 at 1C and 630 mAh cm−3 at 3C. Therefore, the GeTe/C is expected to perform well as a high–capacity anode in rechargeable sodium-ion batteries.