Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
Nanoscale. 2018 Apr 26;10(16):7343-7351. doi: 10.1039/c8nr00865e.
Si/Ge core/shell nanowire heterostructures have been expected to provide high energy and power densities for lithium ion battery anodes due to the large capacity of Si and the high electrical and ionic conductivities of Ge. Although the battery anode performances of Si/Ge core/shell nanowire heterostructures have been characterized, the degradation of Si/Ge core/shell nanowire heterostructures has not been thoroughly investigated. Here we report the compositional and structural changes of the Si/Ge core/shell nanowire heterostructure over cycling of lithiation and delithiation at different charging rates. The Si/Ge core/shell nanowire heterostructure holds the core and shell structure at a charging rate of 0.8 A g-1 up to 50 cycles. On the other hand, compositional intermixing and loss of Si occur at a charging rate of 20 A g-1 within 50 cycles. The operation condition-dependent degradation provides a new aspect of materials research for the development of high performance lithium ion battery anodes with a long cycle life.
硅/锗核壳纳米线异质结构由于硅的高容量和锗的高电导率和离子电导率，有望为锂离子电池阳极提供高能量和功率密度。尽管已经对 Si/Ge 核壳纳米线异质结构的电池阳极性能进行了表征，但 Si/Ge 核壳纳米线异质结构的退化尚未得到彻底研究。在这里，我们报告了在不同充电速率下锂化和脱锂循环过程中 Si/Ge 核壳纳米线异质结构的组成和结构变化。在 0.8 A g-1 的充电速率下，Si/Ge 核壳纳米线异质结构保持核壳结构，直到 50 个循环。另一方面，在 20 A g-1 的充电速率下，在 50 个循环内发生了组成混合和 Si 的损失。这种与操作条件相关的退化提供了材料研究的一个新方面，有助于开发具有长循环寿命的高性能锂离子电池阳极。
