NiSi_x/Ge核壳纳米线作为锂离子电池负极材料的电化学性能

High-performance Li-ion Batteries Using NiSi_x/Ge Core-shell NWs as Anode Materials

Ge具有约1 600mAhg-1的理论比容量,是商业化石墨材料理论容量(372mAhg-1)的4倍多,是目前较有吸引力的锂离子电池负极材料。纳米材料相比于体材料由于具有独特的物理化学特性,广泛地应用于锂离子电池领域。本文采用化学气相沉积和射频溅射的方法在泡沫镍上合成出了大量NiSix/Ge核壳纳米线,并进行了扫描电子显微镜(SEM)、X射线能谱(EDX)、透射电子显微镜(TEM)表征分析。将其作为负极材料应用于锂离子电池中,首次放电比容量约为1700mAhg-1,首次效率为70.9%。60个循环后放电比容量仍可维持在950mAhg-1以上,相比于Ni/Ge薄膜,表现出更好的锂离子电池循环性能。NiSix纳米线的优异导电性、纳米线之间的充足空间给予的缓解体积膨胀功能及膜与纳米线的优良接触在提高锂离子电池性能上起到了非常重要的作用。

Germanium can offer a high capacity of around 1 600mAhg-1 , which is four times more than of graphite, attracting more and more focus on studying it. Nanomaterials have been widely applied in Li-ion batteries due to their unique physical and chemical properties. In this paper, we employed a simple chemical vapor deposition （CVD） and subsequent RF sputtering method to synthesize the NiSix/Ge core-shell nanowires （NWs）, which were specifically characterized by field emission scanning electron microscopy （FESEM）, energy-dispersive X-ray spectrometer （EDX）, and transmission electron microscopy （TEM）. When used as anode materials for Li-ion batteries, the sample achieved a first discharge capacity of around 1 700mAhg-1 and Compared to the Ni/Ge thin film, NiSix/Ge core-shell nanowires exhibited better cycling performance, which can be attributed to the good conductivity of NiSix NWs, efficient alleviation of volume change and high quality of adhesion between Ge layer and NWs.