@article{Yi2019, 
author = {Zheng Yi and Ning Lin and Tieqiang Li and Ying Han and Yang Li and Yitai Qian},
title = {Meso-porous amorphous Ge: Synthesis and mechanism of an anode material for Na and K storage},
year = {2019},
journal = {Nano Research},
volume = {12},
number = {8},
pages = {1824-1830},
keywords = {sodium-ion batteries, amorphous Ge, K storage, in-situ Raman spectrum},
url = {https://www.sciopen.com/article/10.1007/s12274-019-2442-4},
doi = {10.1007/s12274-019-2442-4},
abstract = {Crystalline Ge is a highly active anode material for Li storage but inactive for Na storage because of high diffusion barrier. By in-situ Raman spectrum, we explore that the Na could reversibly alloy/dealloy with the amorphous Ge, but does not with the crystalline Ge. Herein, the amorphous Ge is fabricated by an acid-etching Zintl phase Mg2Ge route at room temperature, which shows a mesoporous architecture with a Brunauer-Emmett-Teller (BET) surface area of 29.9 m2·g-1 and a Barrett-Joyner-Halenda (BJH) average pore diameter of 7.6 nm. This mesoporous architecture would enhance the Na-ion/electron diffusion rate and buffer the volume expansion. As a result, the as-prepared amorphous Ge shows superior Na-ion storage performance including high reversible capacity over 550 mA·h·g-1 at 0.2 C after 50 cycles, good rate capability with a capacity of 273 mA·h·g-1 maintained at 5.0 C, and long-term cycling stability with capacities of 450 mA·h·g-1 at 0.4 C after 200 cycles. For the K-ion storage, the amorphous Ge is also more active than the crystalline counter and maintains a capacity of 210 mA·h·g-1 after 100 cycles at 0.2 C.}
}