Direct Observation of Nanoparticle Superlattice Formation by Using Liquid Cell Transmission Electron Microscopy

Park, Jungwon; Zheng, Haimei; Lee, Won Chul; Geissler, Phillip L.; Rabani, Eran; Alivisatos, A. Paul

doi:10.1021/nn203837m

Cited by 157 publications

(156 citation statements)

References 44 publications

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“…1,13 Improvements in ultrahigh spatial and energy resolutions have been accompanied by remarkable advances of in situ TEM techniques, which enable the real-time observation of the dynamic structural and chemical evolution in materials under a variety of external stimuli or battery operating conditions. The progress in this field is evident, as demonstrated by the success of in situ mechanical testing or heating while maintaining a high spatial resolution, 14,15 by the imaging of reaction processes in gases and liquids, [16][17][18][19] by the observations of reactions and phase transformations upon external biasing 20,21 and so on. In addition, the newly developed CMOS camera, which enables the direct electron detection and fast image acquisition at over 400 frames per second for 1 × 1 K images, has significantly advanced the capability to observe fast reactions in real time.…”

Section: Recent Advancements In Aem Capabilitiesmentioning

confidence: 99%

Advanced analytical electron microscopy for lithium-ion batteries

Qian

et al. 2015

NPG Asia Mater

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Lithium-ion batteries are a leading candidate for electric vehicle and smart grid applications. However, further optimizations of the energy/power density, coulombic efficiency and cycle life are still needed, and this requires a thorough understanding of the dynamic evolution of each component and their synergistic behaviors during battery operation. With the capability of resolving the structure and chemistry at an atomic resolution, advanced analytical transmission electron microscopy (AEM) is an ideal technique for this task. The present review paper focuses on recent contributions of this important technique to the fundamental understanding of the electrochemical processes of battery materials. A detailed review of both static (ex situ) and real-time (in situ) studies will be given, and issues that still need to be addressed will be discussed. NPG Asia Materials (2015) 7, e193; doi:10.1038/am.2015.50; published online 26 June 2015 INTRODUCTIONTo implement the commercialization of lithium-ion batteries in electric vehicles and smart grid systems, further improvements are required, especially with respect to the energy/power density, coulombic efficiency and cycle life. These parameters primarily depend on the diffusion of lithium-metal ions, electron transport, structure and chemical dynamics of the electrode/electrolyte materials, among others. During electrochemical cycling, significant changes in the material structure and elemental distributions occur, including ion relocation, lattice expansion/contraction, phase transition and structure/surface reconstruction. These changes could substantially influence ion and electron transport and affect the performance of the entire battery system. Understanding the structure-property relationships for each component and their synergistic behaviors during electrochemical processes is, therefore, essential for the design of new battery materials and the optimization of existing systems.Although many analysis techniques (for example, X-ray diffraction, X-ray absorption spectroscopy, neutron diffraction, nuclear magnetic resonance and so on) have been employed for such studies, most of them can acquire only spatially averaged information. Nevertheless, the structural and chemical evolution of battery materials upon electrochemical cycling can often be linked to specific nanofeatures, such as defects, interfaces and surfaces. As a result, techniques based on analytical transmission electron microscopy (AEM) are ideal tools to study these issues. The capability of AEM to precisely probe the structural/chemical evolutions at an ultrahigh spatial resolution frequently provides insight that cannot be obtained directly using macroscopic characterization methods.

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Section: Recent Advancements In Aem Capabilitiesmentioning

confidence: 99%

Advanced analytical electron microscopy for lithium-ion batteries

Qian

et al. 2015

NPG Asia Mater

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“…[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] Particle coalescence has been observed for haematite, iron oxyhydroxide, platinum-iron alloy, platinum, silver, and gold, allowing for assessment of coalescence features such as preferred particle orientations and kinetics. [12][13][14][24][25][26] When performing these experiments, care must be taken to avoid electron beam artifacts, such as specimen charging/reduction, flow effects, and bubbles, that can influence specimen behavior.…”

mentioning

confidence: 99%

Understanding the Role of Solvation Forces on the Preferential Attachment of Nanoparticles in Liquid

Welch¹,

Woehl²,

Park

et al. 2015

ACS Nano

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Optimization of colloidal nanoparticle synthesis techniques requires an understanding of underlying particle growth mechanisms. Non-classical growth mechanisms are particularly important as they affect nanoparticle size and shape distributions which in turn influence functional properties. For example, preferential attachment of nanoparticles is known to lead to the formation of mesocrystals, although the formation mechanism is currently not well understood. Here we employ in situ liquid cell scanning transmission electron microscopy (STEM) and steered molecular dynamics (SMD) simulations to demonstrate that the experimentally observed preference for end-to-end attachment of silver nanorods is a result of weaker solvation forces occurring at rod ends. SMD reveals that when the side of a nanorod approaches another rod, perturbation in the surface bound water at the nanorod surface creates significant energy barriers to attachment. Additionally, rod morphology (i.e. facet shape) effects can explain the majority of the side attachment effects that are observed experimentally.

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“…In addition, understanding the effect of the support on TEM imaging of catalyst systems is necessary to accurately distinguish such imaging artifacts from actual structural evolution occurring in supported nanoparticles under environmental conditions. In situ TEM, which enables the observation of structural changes under environments -e.g., temperature, gaseous atmosphere, liquid -approaching those of working conditions [19][20][21][22][23], faces additional imaging challenges, as the presence of liquid, gas, and/or windows from closed-cell holders can greatly reduce signal intensity.…”

Section: Introductionmentioning

confidence: 99%

Statistical analysis of support thickness and particle size effects in HRTEM imaging of metal nanoparticles

et al. 2016

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a b s t r a c tHigh-resolution transmission electron microscopy (HRTEM) examination of nanoparticles requires their placement on some manner of support -either TEM grid membranes or part of the material itself, as in many heterogeneous catalyst systems -but a systematic quantification of the practical imaging limits of this approach has been lacking. Here we address this issue through a statistical evaluation of how nanoparticle size and substrate thickness affects the ability to resolve structural features of interest in HRTEM images of metallic nanoparticles on common support membranes. The visibility of lattice fringes from crystalline Au nanoparticles on amorphous carbon and silicon supports of varying thickness was investigated with both conventional and aberration-corrected TEM. Over the 1-4 nm nanoparticle size range examined, the probability of successfully resolving lattice fringes differed significantly as a function both of nanoparticle size and support thickness. Statistical analysis was used to formulate guidelines for the selection of supports and to quantify the impact a given support would have on HRTEM imaging of crystalline structure. For nanoparticles Z1 nm, aberration-correction was found to provide limited benefit for the purpose of visualizing lattice fringes; electron dose is more predictive of lattice fringe visibility than aberration correction. These results confirm that the ability to visualize lattice fringes is ultimately dependent on the signal-to-noise ratio of the HRTEM images, rather than the point-to-point resolving power of the microscope. This study provides a benchmark for HRTEM imaging of crystalline supported metal nanoparticles and is extensible to a wide variety of supports and nanostructures.

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Direct Observation of Nanoparticle Superlattice Formation by Using Liquid Cell Transmission Electron Microscopy

Cited by 157 publications

References 44 publications

Advanced analytical electron microscopy for lithium-ion batteries

Advanced analytical electron microscopy for lithium-ion batteries

Understanding the Role of Solvation Forces on the Preferential Attachment of Nanoparticles in Liquid

Statistical analysis of support thickness and particle size effects in HRTEM imaging of metal nanoparticles

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