GeO2 Encapsulated Ge Nanostructure with Enhanced Lithium‐Storage Properties

Germanium (Ge)‐based nanostructures, especially those with germanium dioxide (GeO₂), have drawn great interest for applications in lithium (Li)‐ion batteries due to their ultrahigh theoretical Li⁺ storage capability (8.4 Li/Ge). However, GeO₂ in conventional Ge(s)/GeO₂(c) (where (c) means the core and (s) means the shell) composite anodes with Ge shell outside GeO₂ undergoes an irreversible conversion reaction, which restricts the maximum capacity of such batteries to 1126 mAhg^?1 (the equivalent of storing 4.4 Li⁺). In this work, a porous GeO₂(s)/Ge(c) nanostructure with GeO₂ shell outside Ge cores are successfully fabricated utilizing the Kirkendall effect and used as a lithium‐ion battery anode, giving a substantially improved capacity of 1333.5 mAhg^?1 at a current density of 0.1 Ag^?1 after 30 cycles and a stable long‐time cycle performance after 100 cycles at a current density of 0.5 A g^?1. The enhanced battery performance is attributed to the improved reversibility of GeO₂ lithiation/delithiation processes catalyzed by Ge in the properly structured porous GeO₂(s)/Ge(c) nanostructure.