In Situ Environmental TEM in Imaging Gas and Liquid Phase Chemical Reactions for Materials Research

Abstract

Gas and liquid phase chemical reactions cover a broad range of research areas in materials science and engineering, including the synthesis of nanomaterials and application of nanomaterials, for example, in the areas of sensing, energy storage and conversion, catalysis, and bio-related applications. Environmental transmission electron microscopy (ETEM) provides a unique opportunity for monitoring gas and liquid phase reactions because it enables the observation of those reactions at the ultra-high spatial resolution, which is not achievable through other techniques. Here, the fundamental science and technology developments of gas and liquid phase TEM that facilitate the mechanistic study of the gas and liquid phase chemical reactions are discussed. Combined with other characterization tools integrated in TEM, unprecedented material behaviors and reaction mechanisms are observed through the use of the in situ gas and liquid phase TEM. These observations and also the recent applications in this emerging area are described. The current challenges in the imaging process are also discussed, including the imaging speed, imaging resolution, and data management.

Review—Promises and Challenges of In Situ Transmission Electron Microscopy Electrochemical Techniques in the Studies of Lithium Ion Batteries

“…14,55,[183][184][185][186] Pulverization is one of the most undesirable factors result in capacity fading and instability in cycling for Sn-based anode in LIBs. 183 The β-Sn NPs in the size range from 79 to 526 nm converted to crystal Li 22 Sn 5 phase without cracking or fracture after lithiation, but upon lithiation these NPs in this range of sizes could be induced and to form micrometer-sized Sn NPs where fractures were frequently observed. 183 A binder-free Sn NP/carbon nanofiber hybrid with a unique structure exhibited an improved capacity with high coulombic efficiency.…”

“…Importantly, TEM produces a window into the material's behaviors under real processing conditions, for discernible changes may occur if we remove the materials from the growth chamber and complete a post-mortem analysis. 7 Although in situ TEM has been used in many areas like material synthesis, catalysis, life sciences, and energy conversion, 22,97 and yields distinctive information, it comes at the expense of extra experimental complexity. Specially designed sample holders may be needed to offer control of the specimen's environment, 66,98 because common TEMs are not compatible with gases or liquids.…”

“…Specially designed sample holders may be needed to offer control of the specimen's environment, 66,98 because common TEMs are not compatible with gases or liquids. 22 There are three main types of TEM sample holders used for research on LIBs, that is, gas environmental (open-cell configuration), thin-windowed cell (closed liquid-cell configuration), and a whole solid-state battery. 7,99 The samples in an open-cell configuration are placed without any physical separation from the vacuum and are locally exposed to a lowpressure gas such as nitrogen.…”

“…[17][18][19][20] Achievements in the area of in situ microscopy in the past five years have brought material characterization techniques to the point where these questions may be studied. 21 Over 100 papers relating to the application of in situ TEM electrochemistry in LIB z E-mail: zhxie@cwnu.edu.cn; jzhang@gamry.com each year have been published according to an analysis by Web of Science.Typical reviews recently regarding in situ TEM in electrochemistry primarily focus on imaging of materials evolution in gas-and liquidphase chemical reactions, 22 economic production of graphene and two-dimensional (2D) transition of metal dichalcogenides (TMDCs) as well as their composites, 23 introduction of the advances and challenges of the device itself, 2,7,19 individual anode materials of LIBs such as nanoscale silicon, 24-27 tin nanoneedles, 21 Si/C hybrid nanostructures, 28 and germanium. 17 Here, we will first introduce the fundamental structure of LIBs and compare them with traditional electrochemical measurements for LIBs, especially in the aspect of quantitatively determining lithium diffusion coefficient (D Li ) on the electrode.…”

“…Typical reviews recently regarding in situ TEM in electrochemistry primarily focus on imaging of materials evolution in gas-and liquidphase chemical reactions, 22 economic production of graphene and two-dimensional (2D) transition of metal dichalcogenides (TMDCs) as well as their composites, 23 introduction of the advances and challenges of the device itself, 2,7,19 individual anode materials of LIBs such as nanoscale silicon, 24-27 tin nanoneedles, 21 Si/C hybrid nanostructures, 28 and germanium. 17 Here, we will first introduce the fundamental structure of LIBs and compare them with traditional electrochemical measurements for LIBs, especially in the aspect of quantitatively determining lithium diffusion coefficient (D Li ) on the electrode.…”