Yan Yonghui, Liu Yang, Zhang Yongguang, Qin Chunling, Bakenov Zhumabay, Wang Zhifeng
School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401, China.
School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401, China.
J Colloid Interface Sci. 2021 Jun 15;592:103-115. doi: 10.1016/j.jcis.2021.02.026. Epub 2021 Feb 13.
Due to huge volume expansion and poor electrical conductivity, the commercial application of the promising Germanium (Ge) anode is restrained in lithium ion battery (LIB) field. Generally, conductive metals can improve the electron mobility in Ge. In that way, whether active materials or conductive metals account for a higher proportion in the anode is controversial in this field and needs to be clarified urgently. Herein, three Ge-based anodes with different ratios in conductive Ag are fabricated by a facile melt spinning and one-step dealloying method. It is found that Ag nanoparticles embedded three-dimensional nanoporous Ge (Ag/np-Ge) electrode with high active material ratio exhibits the best cycling stability among tested samples, delivering a high capacity of 953 mAh g after 100 cycles at a current density of 100 mA g and an excellent reversible capacity of 522 mAh g after 200 cycles even at the high current density of 1000 mA g. The enhanced cycling stability can be attributed to the synergistic effect of nanoporous network-like structure and embedded Ag nanoparticles. A dramatical increase in electrical conductivity and activity of Ge by doping of Ag is confirmed by density functional theory (DFT) calculations. The work provides us an idea to rationally design the three-dimensional structure of active materials assisting with a proper ratio of conductive metals, which may promote the development of promising Ge anodes for LIBs with excellent cycling stability.
由于体积膨胀巨大且电导率较差，具有前景的锗（Ge）负极在锂离子电池（LIB）领域的商业应用受到限制。通常，导电金属可以提高锗中的电子迁移率。因此，在该领域中负极中活性材料或导电金属占比更高存在争议，亟待澄清。在此，通过简便的熔体纺丝和一步脱合金方法制备了三种具有不同导电银比例的锗基负极。研究发现，具有高活性材料比例的嵌入银纳米颗粒的三维纳米多孔锗（Ag/np-Ge）电极在测试样品中表现出最佳的循环稳定性，在100 mA g的电流密度下循环100次后具有953 mAh g的高容量，即使在1000 mA g的高电流密度下循环200次后仍具有522 mAh g的优异可逆容量。循环稳定性的增强可归因于纳米多孔网络状结构和嵌入的银纳米颗粒的协同效应。密度泛函理论（DFT）计算证实了通过掺杂银显著提高了锗的电导率和活性。这项工作为我们提供了一个思路，即合理设计活性材料的三维结构并辅以适当比例的导电金属，这可能会促进具有优异循环稳定性的用于LIBs的有前景的锗负极的发展。
