Formation, lithium storage properties, and mechanism of nanoporous germanium fabricated by dealloying.

Germanium (Ge) has become a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity and decent electron/ion conductivity, but it exhibits inferior lifespan caused by dramatic volume variations during the (de)lithiation process. Herein, hierarchically, nanoporous Ge (np-Ge) was fabricated by the combination of selective phase corrosion with chemical dealloying. As an anode for LIBs, the np-Ge electrode exhibits marvelous cycling stability with capacity retentions of 1060.0 mA h g-1 at 0.2 A g-1 and 767.1 mA h g-1 at 1 A g-1 after 100 cycles. Moreover, the electrode shows excellent rate capability with a capacity retention of 844.2 mA h g-1 at 5 A g-1. Noticeably, the (de)lithiation mechanisms of np-Ge and porous Si-Ge (p-Si6Ge4) were unveiled by operando X-ray diffraction.