Templated Synthesis of SiO₂ Nanotubes for Lithium-Ion Battery Applications: An In Situ (Scanning) Transmission Electron Microscopy Study

Abstract

One of the weaknesses of silicon-based batteries is the rapid deterioration of the charge-storage capacity with increasing cycle numbers. Pure silicon anodes tend to suffer from poor cycling ability due to the pulverization of the crystal structure after repeated charge and discharge cycles. In this work, we present the synthesis of a hollow nanostructured SiO 2 material for lithium-ion anode applications to counter this drawback. To improve the understanding of the synthesis route, the crucial synthesis step of removing the ZnO template core is shown using an in situ closed gas-cell sample holder for transmission electron microscopy. A direct visual observation of the removal of the ZnO template from the SiO 2 shell is yet to be reported in the literature and is a critical step in understanding the mechanism by which these hollow nanostructures form from their core−shell precursors for future electrode material design. Using this unique technique, observation of dynamic phenomena at the individual particle scale is possible with simultaneous heating in a reactive gas environment. The electrochemical benefits of the hollow morphology are demonstrated with exceptional cycling performance, with capacity increasing with subsequent charge−discharge cycles. This demonstrates the criticality of nanostructured battery materials for the development of next-generation Li + -ion batteries.

Advances and Opportunities in Closed Gas-Cell Transmission Electron Microscopy

“…One of the challenges with silicon-based batteries is the poor cycling performance of a pure silicon anode, often due to the fragmentation of its crystal structure after repeated charge–discharge cycles. Ronan et al address this issue by introducing a hollow nanostructured SiO 2 material for use as a lithium-ion anode . To elucidate the growth mechanism of SiO 2 nanotubes, they employ in situ closed gas-cell TEM to directly observe the process of removing the internal ZnO core template under a 5% H 2 atmosphere (Figure a).…”

“…Ronan et al address this issue by introducing a hollow nanostructured SiO 2 material for use as a lithium-ion anode. 41 To elucidate the growth mechanism of SiO 2 nanotubes, they employ in situ closed gas-cell TEM to directly observe the process of removing the internal ZnO core template under a 5% H 2 atmosphere (Figure 3a). This unique technique allows simultaneous observation of dynamic phenomena at the single-particle scale during heating in an active gas environment.…”

“…Applications of gas-cell TEM on low-dimensional nanomaterials (a) In situ TEM reveals the synthesis process of SiO 2 nanotubes . (b) Precise identification of the active phase of a cobalt catalyst for the growth of carbon nanotubes by in situ TEM .…”

“…(d) Oxidative degradation of BP nanoflakes in a humid environment with O 2 and H 2 O . (a) Reprinted with permission from ref . Copyright 2022 The Authors.…”