CAS Key Laboratory of Materials for Energy Conversion, Department of Materials Science and Engineering, University of Science and Technology of China , Hefei 230026, Anhui, China.
ACS Nano. 2014 Jul 22;8(7):7051-9. doi: 10.1021/nn501945f. Epub 2014 Jun 23.
Germanium-based materials (Ge and GeOx) have recently demonstrated excellent lithium-ion storage ability and are being considered as the most promising candidates to substitute commercial carbon-based anodes of lithium-ion batteries. Nevertheless, practical implementation of Ge-based materials to lithium-ion batteries is greatly hampered by the poor cyclability that resulted from the huge volume variation during lithiation/delithiation processes. Herein, uniform carbon-encapsulated Ge and GeOx nanowires were synthesized by a one-step controlled pyrolysis of organic-inorganic hybrid GeOx/ethylenediamine (GeOx/EDA) nanowires in H2/Ar and Ar atmospheres, respectively. The as-obtained Ge/C and GeOx/C nanowires possess well-defined 0D-in-1D morphology and homogeneous carbon encapsulation, which exhibit excellent Li storage properties including high specific capacities (approximate 1200 and 1000 mA h g(-1) at 0.2C for Ge/C and GeOx/C, respectively). The Ge/C nanowires, in particular, demonstrate superior rate capability with excellent capacity retention and stability (producing high stable discharge capacities of about 770 mA h g(-1) after 500 cycles at 10C), making them promising candidates for future electrodes for high-power Li-ion batteries. The improved electrochemical performance arises from synergistic effects of 0D-in-1D morphology and uniform carbon coating, which could effectively accommodate the huge volume change of Ge/GeOx during cycling and maintain perfect electrical conductivity throughout the electrode.
锗基材料（Ge 和 GeOx）最近表现出优异的锂离子存储能力，被认为是最有前途的替代锂离子电池商业碳基负极的候选材料。然而，锗基材料在锂离子电池中的实际应用受到严重阻碍，原因是在锂化/脱锂过程中体积变化巨大，导致循环性能不佳。在此，通过在 H2/Ar 和 Ar 气氛中分别一步热解有机-无机杂化 GeOx/乙二胺（GeOx/EDA）纳米线，合成了均匀的碳包覆 Ge 和 GeOx 纳米线。所获得的 Ge/C 和 GeOx/C 纳米线具有明确的 0D-in-1D 形态和均匀的碳包覆，表现出优异的锂离子存储性能，包括高比容量（在 0.2C 时分别约为 1200 和 1000 mA h g-1）。特别是 Ge/C 纳米线具有优异的倍率性能，具有出色的容量保持率和稳定性（在 10C 下循环 500 次后，可产生约 770 mA h g-1 的高稳定放电容量），有望成为未来高功率锂离子电池的电极候选材料。电化学性能的提高源于 0D-in-1D 形态和均匀碳涂层的协同效应，这可以有效地容纳 Ge/GeOx 在循环过程中的巨大体积变化，并在整个电极中保持完美的导电性。
