Abstract
Germanium (Ge), as a viable candidate anode material for future sodium-ion batteries, has attracted much attention. However, such material is usually troubled by huge volume changes during charge/discharge process, leading to the rapid degradation of electrochemical performance. Notably, construction of carbon coating layers is a practical strategy to alleviate the volumetric effect of Ge. Moreover, rational design of nanosized Ge with amorphous structure can also significantly enhance its sodium-ion storage performance. Herein, amorphous Ge (a-Ge) encapsulated by nitrogen-doped carbon nanofiber (Ge@NC) was successfully prepared by facile electrostatic spinning technique and annealing treatment. Impressively, the a-Ge nanoparticles are effectively protected by the flexible nitrogen-doped carbon nanofiber (NC), contributing to faster reaction kinetics and improved cycling stability since the high electrical conductivity and buffering effect of the NC layers. In addition, the nanosized Ge with amorphous structure can offer more open framework and higher structural stability. Therefore, the integrated Ge@NC electrode displays a high capacity of 404 mAh g−1 after 300 cycles at 0.1 A g−1. More excited, the synergistic effect of amorphous structure of Ge and nitrogen-doped carbon layers endow Ge@NC with remarkable long cycle life up to 15,000 cycles at 5 A g−1.
Published Version
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