Germanium nanoparticles supported by 3D ordered macroporous nickel frameworks as high-performance free-standing anodes for Li-ion batteries

Germanium-based materials are gaining increasing attention as promising anodes for Li-ion batteries (LIBs) due to their high specific capacity, good cycling stability and excellent rate performance. Similarly to Si, Ge-based anodes undergo a huge volume expansion and contraction during Li intercalation and deintercalation, causing a rapid and irreversible capacity decay. In this work, Ge nanoparticles are uniformly attached to a 3D ordered macroporous (3DOM) Ni framework (Ge/3DOM-Ni) via a facile drop-coating technique in order to address the volume expansion and stability issues plaguing Ge anodes. The 3D ordered macroporous Ni frameworks with high porosity act not only as highly conductive current collectors but also as a robust porous support for the formation of a thin layer of Ge nanoparticles. The three-dimensional porous network facilitates the penetration of the electrolyte and lithium ions. The possible alloy interface generated among the Ge nanoparticles and Ni framework during the calcination process ensures good electric contact among the nanoparticles and the 3D ordered macroporous Ni framework. When used as self-supporting binder-free anodes for lithium ion batteries, the Ge/3DOM-Ni electrode shows high rate performance and excellent structural and cycling stability. This work provides a facile and effective strategy for improving the electrochemical performance of Ge-based anodes.