Atomic-scale combination of germanium-zinc nanofibers for structural and electrochemical evolution.

Song, Gyujin; Cheong, Jun Young; Kim, Chanhoon; Luo, Langli; Hwang, Chihyun; Choi, Sungho; Ryu, Jaegeon; Kim, Sungho et al. · Nat Commun · 2019

basic_science · Level V

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Abstract

Alloys are recently receiving considerable attention in the community of rechargeable batteries as possible alternatives to carbonaceous negative electrodes; however, challenges remain for the practical utilization of these materials. Herein, we report the synthesis of germanium-zinc alloy nanofibers through electrospinning and a subsequent calcination step. Evidenced by in situ transmission electron microscopy and electrochemical impedance spectroscopy characterizations, this one-dimensional design possesses unique structures. Both germanium and zinc atoms are homogenously distributed allowing for outstanding electronic conductivity and high available capacity for lithium storage. The as-prepared materials present high rate capability (capacity of ~ 50% at 20 C compared to that at 0.2 C-rate) and cycle retention (73% at 3.0 C-rate) with a retaining capacity of 546 mAh g<sup>-1</sup> even after 1000 cycles. When assembled in a full cell, high energy density can be maintained during 400 cycles, which indicates that the current material has the potential to be used in a large-scale energy storage system.