Synergistic effects of carbon framework confinement and transition-metal alloy strategies on promoting lithium storage performances of germanium anode

Ge-based anodes have been considered as an alternative to graphite for lithium-ion batteries because of their high theoretical capacities. Nonetheless, their performance is still not up to the requirements of practical application. Herein, a novel Ge12Ni19 @nitrogen-doped carbon microflowers (Ge12Ni19 @NCFs) composite with subtle hierarchical structure was successfully fabricated based on carbon framework confinement and transitionmetal alloy strategies. Detailed analysis was conducted on its unique structure and composition through various characterizations. Meanwhile, control tests proved that the nitrogen-doped carbon framework can improve the cycle stability effectively. Furthermore, density functional theory (DFT) calculations reveal that alloying with Ni is conducive to accelerating electron migration and Li+ diffusion of Ge anode. Benefiting from the synergistic effects, the Ge12Ni19 @NCFs composite exhibited a remarkable lithium storage performance. After cycled 1000 times at 2 A g � 1, it still delivered a high capacity of 541 mAh g � 1 with a retention of 90%.

Automated summary

A novel Ge12Ni19 @nitrogen-doped carbon microflowers (Ge12Ni19 @NCFs) composite with a subtle hierarchical structure was successfully fabricated. The nitrogen-doped carbon framework improved the cycle stability effectively, and alloying with Ni accelerated electron migration and Li+ diffusion of Ge anode. The Ge12Ni19 @NCFs composite exhibited remarkable lithium storage performance, delivering a high capacity of 541 mAh g-1 with a retention of 90% after 1000 cycles at 2 A g-1.