Improving the cycling stability of three-dimensional nanoporous Ge anode by embedding Ag nanoparticles for high-performance lithium-ion battery.

Due to huge volume expansion and poor electrical conductivity, the commercial application of the promising Germanium (Ge) anode is restrained in lithium ion battery (LIB) field. Generally, conductive metals can improve the electron mobility in Ge. In that way, whether active materials or conductive metals account for a higher proportion in the anode is controversial in this field and needs to be clarified urgently. Herein, three Ge-based anodes with different ratios in conductive Ag are fabricated by a facile melt spinning and one-step dealloying method. It is found that Ag nanoparticles embedded three-dimensional nanoporous Ge (Ag/np-Ge) electrode with high active material ratio exhibits the best cycling stability among tested samples, delivering a high capacity of 953 mAh g-1 after 100 cycles at a current density of 100 mA g-1 and an excellent reversible capacity of 522 mAh g-1 after 200 cycles even at the high current density of 1000 mA g-1. The enhanced cycling stability can be attributed to the synergistic effect of nanoporous network-like structure and embedded Ag nanoparticles. A dramatical increase in electrical conductivity and activity of Ge by doping of Ag is confirmed by density functional theory (DFT) calculations. The work provides us an idea to rationally design the three-dimensional structure of active materials assisting with a proper ratio of conductive metals, which may promote the development of promising Ge anodes for LIBs with excellent cycling stability.