LAUSR

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.