Quantifying the Morphology Evolution of Lithium Battery Materials Using Operando Electron Microscopy

Abstract

With the increase in dependence on renewable energy sources, interest in energy storage systems has increased, particularly with solar cells, redox flow batteries, and lithium batteries. Multiple diagnostic techniques have been utilized to characterize various factors in relation to the battery performance. Electrochemical tests were used to study the energy density, capacity, cycle life, rate, and other related properties. Furthermore, it is critical to correlate the information collected from the characterization of materials to its properties while functioning for advanced batteries. In situ and operando electron microscopy methods are specifically designed to conduct such characterization, and analysis was found to be the best method to achieve that objective. However, the characterization information collected varies according to the types of electron microscopy techniques. Also, the use of complementary analytical techniques further provides a more comprehensive study of these different characterizations, giving insights into the morphology-performance relationship of battery materials and interfaces. Within this review, the focus is on in situ and operando electron microscopy characterization of battery materials, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), cryogenic transmission electron microscopy (Cryo-TEM), and three-dimensional (3D) electron tomography. This review aims to cover both advanced electron microscopy imaging techniques and their applications in the characterization of battery materials involving cathode, anode, and separator and solid electrolyte interphase (SEI). The review discusses a range of advanced electron microscopy techniques, including TEM, SEM, and atomic force microscopy, as well as associated analytical techniques such as energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy. The use of these techniques has led to significant advances in our understanding of battery materials, including the identification of new phases and structures, the study of interface properties, and the characterization of defects and degradation mechanisms. Future perspectives on these advanced electron microscopy techniques and opportunities are also discussed. Overall, this review highlights the importance of electron microscopy in battery research and the potential for these techniques to drive future advancements in the field.

Towards stable electrode–electrolyte interphases: Regulating solvation structures in electrolytes for rechargeable batteries

“…[ 103 ] For interphasial properties, since Peled first introduced the concept of SEI on Li metal anode, the research history of SEI has been accompanied by the development of battery technologies in the past five decades. [ 35,104,105 ] Conventional methods, such as X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), Raman, nuclear magnetic resonance (NMR), high‐resolution transmission electron microscopy (HRTEM), and so forth, have successfully provided primary information of ingredients, structures, and morphologies of EEI layers. However, the understanding of EEI is still insufficient in batteries.…”

“…Surging interest in the study of solvation structures of electrolytes and publications in this area have been rapidly increasing in the past decade (Figure 1B). Besides, the development of advanced characterization methods such as cryoelectron microscopy, [ 33 ] synchrotron radiation techniques, [ 34 ] and various in situ spectroscopy methods [ 7,35 ] have greatly benefited the understanding of the formation of EEI layers and the origin of their functions in batteries.…”

Revealing microscopic dynamics: in situ liquid-phase TEM for live observations of soft materials and quantitative analysis via deep learning

“…Taking advantage of its ability to achieve remarkable temporal and spatial precision while immersed in a liquid medium, liquid cell TEM technology offers a valuable means to explore diverse phenomena. These include the nucleation, growth, 7–9 and etching mechanisms of individual nanoparticles, 6,10–14 dynamic motion of nanoparticles in liquids, 15–18 electrochemical deposition and lithiation of electrode materials, 19–23 as well as imaging of biomaterials in liquid environments. 24–26 As in situ liquid-cell TEM techniques continue to mature and their application scope expands, there has also been a gradual emergence of studies focusing on soft matter.…”

Atomic-Scale Characterization of Microscale Battery Particles Enabled by a High-Throughput Focused Ion Beam Milling Technique

“…Commonly used material characterization techniques for cathode materials in LIBs include X-ray diffraction to assess their crystallinity and transmission electron microscopy (TEM) to assess their nanoscale features and their composition. In addition, the use of in situ or operando TEM techniques can be used for material characterization under operating conditions . A primary challenge with utilizing TEM techniques is the thickness of the sample, which must be sufficiently thin for electrons to be transmitted through the sample (e.g., nominally ≤100 nm). , Due to this size restriction, the analysis of microscale particleswhere the particle diameter is >1 μmby TEM is challenging due to the inability of electrons to be transmitted through the sample.…”

“…In addition, the use of in situ or operando TEM techniques can be used for material characterization under operating conditions. 22 A primary challenge with utilizing TEM techniques is the thickness of the sample, which must be sufficiently thin for electrons to be transmitted through the sample (e.g., nominally ≤100 nm). 23 , 24 Due to this size restriction, the analysis of microscale particles—where the particle diameter is >1 μm—by TEM is challenging due to the inability of electrons to be transmitted through the sample.…”