In Situ and Operando Morphology Study of Germanium–Selenium Alloy Anode for Lithium-Ion Batteries

Selenium-doped germanium (GeSe) micrometer-sized particles have been reported with good cycling performance and rate capability due to a Li–Se–Ge network formed during the first lithiation that provides a Li-ion fast pathway. To understand the effect of the Li–Se–Ge network at a high cycling rate, we monitored the morphology change of both pure Ge and GeSe particles during cycling with an in situ/operando focused-ion beam-scanning electron microscope method. Our results showed that the proposed inactive Li–Se–Ge network can provide fast Li-ion transport and also buffer volume variation, resulting in homogeneous volume change and uniform microstructural evolution.