Department of Materials Science and Engineering, ‡Department of Chemistry and Biochemistry, §Department of Physics and Astronomy, and ⊥California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States.
ACS Nano. 2017 Aug 22;11(8):7995-8001. doi: 10.1021/acsnano.7b02589. Epub 2017 Aug 7.
The high theoretical energy density of alloyed lithium and germanium (LiGe), 1384 mAh/g, makes germanium a promising anode material for lithium-ion batteries. However, common alloy anode architectures suffer from long-term instability upon repetitive charge-discharge cycles that arise from stress-induced degradation upon lithiation (volume expansion >300%). Here, we explore the use of the two-dimensional nanosheet structure of germanane to mitigate stress from high volume expansion and present a facile method for producing stable single-to-multisheet dispersions of pure germanane. Purity and degree of exfoliation were assessed with scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. We measured representative germanane battery electrodes to have a reversible Li-ion capacity of 1108 mAh/g when cycled between 0.1 and 2 V vs Li/Li. These results indicate germanane anodes are capable of near-theoretical-maximum energy storage, perform well at high cycling rates, and can maintain capacity over 100 cycles.
合金锂和锗（LiGe）的理论能量密度很高，达到 1384mAh/g，这使得锗成为锂离子电池有前途的阳极材料。然而，常见的合金阳极结构在经过多次充放电循环后会因嵌锂时的应力诱导降解而长期不稳定（体积膨胀>300%）。在这里，我们探索了使用锗烷的二维纳米片结构来缓解高体积膨胀带来的应力，并提出了一种制备纯锗烷稳定单分散到多分散体的简便方法。使用扫描电子显微镜、透射电子显微镜和拉曼光谱评估了纯度和剥离程度。我们测量了具有代表性的锗烷电池电极，当在 0.1 到 2V 相对于 Li/Li 之间循环时，其可逆锂离子容量为 1108mAh/g。这些结果表明，锗烷阳极能够实现接近理论最大能量存储，在高循环速率下表现良好，并且可以在 100 次循环以上保持容量。
