Han Xiang, Chen Huixin, Li Xin, Lai Shumei, Xu Yihong, Li Cheng, Chen Songyan, Yang Yong
Semiconductor Photonics Research Center, Department of Physics, Xiamen University , Xiamen 361005, People's Republic of China.
State Key Laboratory for Physical Chemistry of Solid Surfaces, Department of Chemistry, Xiamen University , Xiamen 361005, People's Republic of China.
ACS Appl Mater Interfaces. 2016 Jan 13;8(1):673-9. doi: 10.1021/acsami.5b09783. Epub 2015 Dec 24.
Conductive metal nanowire is a promising current collector for the Si-based anode material in high-rate lithium-ion batteries. However, to harness this remarkable potential for high power density energy storage, one has to address the interfacial potential barrier that hinders the electron injection from the metal side. Herein, we present that, solely by inserting ultrathin amorphous germanium (a-Ge) (∼5 nm) at the interface of NiSix/amorphous Si (a-Si), the rate capacity was substantially enhanced, 477 mAh g(-1) even at a high rate of 40 A g(-1). In addition, batteries containing the NiSix/Ge+Si anodes cycled over 1000 times at 10 A g(-1) while the capacity retaining more than 877 mAh g(-1), which is among the highest reported. The excellent electrochemical performance is directly correlated with the significantly improved electrical conductivity and mechanical stability throughout the entire electrode. The potential barrier between the NiSix and a-Si was modulated by a-Ge, which constructs an electron highway. Besides, the a-Ge interlayer enhances the interfacial adhesion by reducing void fraction and the inhomogeneous strain of the Li-Ge and Li-Si stacking structure was accommodated through the bending and twist of relatively thin NiSix, thus ensures a more stable high-rate cycling performance. Our work shows an effective way to fabricate metal/a-Si nanowires for high-rate lithium-ion battery anodes.
导电金属纳米线是高倍率锂离子电池中硅基负极材料极具潜力的集流体。然而，要利用这种在高功率密度储能方面的显著潜力，必须解决阻碍电子从金属侧注入的界面势垒问题。在此，我们展示了，仅通过在NiSix/非晶硅（a-Si）界面插入超薄非晶锗（a-Ge）（约5纳米），即使在40 A g(-1)的高倍率下，倍率容量也大幅提高，达到477 mAh g(-1)。此外，含NiSix/Ge+Si负极的电池在10 A g(-1)下循环超过1000次，同时容量保持超过877 mAh g(-1)，这是已报道的最高值之一。优异的电化学性能与整个电极显著提高的电导率和机械稳定性直接相关。a-Ge调节了NiSix和a-Si之间的势垒，构建了一条电子通道。此外，a-Ge中间层通过降低孔隙率增强了界面附着力，并且通过相对较薄的NiSix的弯曲和扭曲来适应Li-Ge和Li-Si堆叠结构的不均匀应变，从而确保了更稳定的高倍率循环性能。我们的工作展示了一种制备用于高倍率锂离子电池负极的金属/a-Si纳米线的有效方法。
