FIB SEM Research Articles

A Protocol for Predicting Lithium-Ion Battery Performances Reflecting the Three-Dimensional Structure of Electrodes

As social needs for higher capacity and longer life of lithium-ion batteries increase, shortening the period from research to development and commercialization of batteries has become an extremely important issue. To minimize the above period, a protocol for predicting the performances of (lithium-ion) batteries is highly urged for. Many reports have been published so far regarding the simulation technology of charge-discharge profiles of lithium-ion batteries.1,2 However, in most of simulations, the porous structure of lithium-ion battery electrodes is simplified into a 1D or 2D models. To achieve more accurate battery performance prediction, we adopted the actual 3D structure of the positive and negative electrodes of lithium-ion batteries in simulations.A plasma FIB SEM (Helious5, Thermofisher Scientific Inc.) was used to obtain the 3D structures of the positive and negative electrodes of the lithium-ion battery. The porosity and tortuosity of the electrodes were calculated by reconstructing a 3D image and performing image analysis. Based on this 3D structure, we also calculated the lithium ion conductivity in the electrode. The obtained 3D structural parameters were applied to the simulation of battery characteristics and compared with actual charge/discharge test results. We have also developed a performance prediction protocol that allows to reflect the measured physical properties of battery materials in the simulation.Figure 1 shows cross-sectional images of two different high-nickel-type positive electrodes prepared under different experimental conditions. It can be seen that the active materials are packed densely for both the electrodes, but the level of conductive carbon and binder dispersion is different. The particle size distribution of the active materials was also found to be largely different between the two samples. Structural parameters were obtained from the 3D structure by image analysis, and highly accurate performance prediction was performed. It can be predicted that the rate capability reflects the structural homogeneity. Also, the simulation revealed that the particle size distribution plays an important role for achieving favorable rate capability. Acknowledgement This work was financially supported by the NEXT Center of Innovation Program (COI-NEXT, Grant Number JPMJPF2016) of the Japan Science and Technology Agency. References (1) M Doyle , J. Newman, A. S. Gozdz, C . N. Schmts, and M. Tarascon, J. Electrochem. Soc. 1996, 143, 1890(2) G. Li and C. W. Monroe, Annu. Rev. Chem. Biomol. Eng. 2020, 11 277. Figure 1

Shale Oil–Water Two-Phase Flow Simulation Based on Pore Network Modeling

Abstract With the growing significance of shale oil in the realm of oil and gas resources, there has been a heightened focus on the impact of the indeterminate oil–water two-phase flow behavior in shale reservoirs on the effective exploitation of shale oil. The utilization of FIB–SEM scanning on shale samples enables the establishment of the real pore network structure and facilitates the analysis of pore type, pore throat size and connectivity of shale reservoirs through the implementation of two-dimensional slices. Subsequently, the gridded connectivity-based pore network model is utilized to conduct oil–water two-phase flow simulation, wherein the L–S and N–S mathematical models are incorporated to quantitatively examine the correlation between the displacement pressure and wettability and the recovery degree and remaining oil, as well as the impact of throat size on pressure loss. The research findings indicate the emergence of five distinctive pore types in shale reservoirs, namely intergranular pores, dissolution pores, intercrystalline pores, intracrystalline pores, and microfractures. In shale reservoirs with poor connectivity, a significant quantity of nanometer-scale pores are generated, wherein the seepage capacity is primarily influenced by the size and connectivity of pore throats. The smaller the throat size is, the greater the displacement pressure will be and the greater the pressure drop will be after the throat is passed through. To prevent fingering and excessive pressure drop, it is necessary to maintain reasonable control over the displacement pressure. The displacement efficiency is optimal when the wall surface is in a water-wet state. Therefore, enhancing the wettability of the surface can facilitate the efficient recovery of the remaining oil in the microscopic pore throats. The research findings offer valuable theoretical insights for the efficient exploitation of shale oil resources.

Multiphase-solid fluid inclusions in HP-LT eclogite facies rock (Zavkhan Terrane, Western Mongolia): evidence for the evolution from saline to hypersaline fluids during metamorphism in subduction zone

Fluid inclusions in high- and ultrahigh-pressure metamorphic rocks provide direct information on the composition of the fluids that evolved during metamorphism and fluid-rock interactions in deep subduction zones. We investigate the fluid inclusions in the Khungui eclogite of the Zavkhan Terrane, Central Asian Orogenic Belt. Fluid inclusions are observed in garnet and quartz in the eclogite samples that underwent metamorphism during subduction. The primary fluid inclusions in quartz are composed of liquid and vapor with high salinities (15.7–16.4 wt.% NaCl eq.), whereas the secondary fluid inclusions in quartz are classified as: relatively high salinity (Type I:12.5–16.3 wt.% NaCl eq.) and low salinity (Type II:6.7–10.6 wt.% NaCl eq.). The garnet shows compositional zoning from Ca-poor cores to Ca-rich rims, and the rims that grew during the eclogite-stage metamorphism (2.1–2.2 GPa at 580–610 °C) preferentially contain numerous primary fluid inclusions. The primary fluid inclusions in garnet are commonly bi-phases (liquid and vapor); however, some are multiphase-solid fluid inclusions composed of fluids (liquid and vapor) and combinations of several minerals (halite, quartz, apatite, calcite, biotite, chlorite, and actinolite). Bi-phase fluid inclusions preferentially occur in the inner parts of the Ca-rich garnet rim, whereas multiphase-solid fluid inclusions occur along the margins of the Ca-rich rim. We hypothesize that the multiphase-solid fluid inclusions are formed via interactions between trapped fluids, trapped minerals, and the host garnet during exhumation. By combination of FIB–SEM and synchrotron X-ray CT analyses, the detailed occurrences, volumes, and compositions of the solid phases in the fluid inclusion was analyzed. We then conduct mass balance analysis to reconstruct accurate fluid compositions using data from the FIB–SEM and synchrotron X-ray CT images of the multiphase-solid fluid inclusion. The results of these analyses reveal that (1) fluid changed from an H2O-dominated saline fluid (13–16 wt. % NaCl eq.) at the prograde to the earlier eclogite stage to H2O–CO2-dominated hypersaline fluid at later eclogite stage (~ 32 wt. % NaCl eq., 7.3 wt. % CO2 and ~ 19 molal dissolved cations); (2) a variety of mineral assemblages in multiphase-solid fluid inclusions are produced by post-entrapment reactions between the trapped hypersaline fluid, trapped minerals and the fluid host mineral. The evolution of fluids from saline to hypersaline during the eclogite facies stage is probably caused by the formation of hydrous minerals (i.e., barroisite) under a near-closed system.

Shallow burial shale gas accumulation pattern of the Wufeng–Longmaxi Formations in the northern Guizhou area, western Yangtze platform

Although continuous breakthroughs of economic shale gas exploitation have been made globally within the middle–deep buried depth (∼1500–3500 m), the shallow–buried (less than 1500 m) shales are also widely distributed, showing excellent exploration prospects. However, the shale gas accumulation (SGA) pattern of the shallow burial shale remains unknown, limiting future shale gas exploration. To investigate the SGA pattern and the exploration potential of shale gas in shallow–buried shales, experiments such as X–Ray Diffractometer, N2 and CO2 adsorption, Focused Ion Beam Scanning Electron Microscopy (FIB-SEM), total organic carbon (TOC) content, gas chromatography–mass spectrometry, and field gas content test were carried out based on three wells penetrated the Wufeng–Longmaxi Formation with the buried depths of less than 700 m in the Northern Guizhou area, western Yangtze Platform. The geochemical and mineral records indicate that the organic matter is enriched as a result of global climate and regional tectonic activity, indicating the sufficient gas generation potential. The results of low pressure N2 and CO2 adsorption, as well as images of the FIB–SEM show that the mesopores are controlled by the organic matter, and the micropores, which are associated with minerals (primarily clays), can provide much more specific surface area and pore space in shallow–buried shales. Furthermore, carbonates with low porosity and permeability from the Songkan, Jiancaogou and Baota Formations, and the shale interval with low TOC values, weak brittleness, and low porosity, can serve as good roofs and floors for the SGA. Despite the fact that multi–stage tectonic movements resulted in the formation of faults and fractures, the good preservation, adequate gas storage space, and sufficient hydrocarbon generation potential contribute to the SGA in the shallow–buried shale.

Electric field distribution around asymmetric agglomerate model reconstructed from FIB–SEM images of epoxy nanocomposite

AbstractThis study focussed on determining the electric field distribution formed by asymmetric agglomerates in order to elucidate the mechanism by which large agglomerates reduce the dielectric breakdown strength of nanocomposites. Epoxy nanocomposite sample was prepared by adding 2.5 vol% of TiO2nanoparticles with a primary particle size ranging from 30 to 50 nm. The three‐dimensional (3D) structure of the epoxy nanocomposites with a thickness of 5 μm was analysed via focussed ion beam and scanning electron microscopy. The 3D reconstruction was performed using 250 observation images, and a 3D model of the particle in the observational range was obtained. The electric field distribution for the 3D model of the agglomerate with the largest size was determined using the finite element method. In addition, we constructed a calculation model that effectively accommodate changes in the direction of the applied electric field. Subsequently, we examined the changes in the maximum electric field intensity around the agglomerate.

Pulsed laser ablation of cutting edge geometries in alumina and zirconia composites at 200 fs and 2 ps

In this study, the feasibility of lasermachining cutting edges into mixed oxide ceramics such as alumina toughened zirconia (ATZ) and zirconia toughened alumina (ZTA) is evaluated. A simplified standard wedge geometry is machined into cylindrical samples by combining orthogonal and quasi-tangential laser machining strategies. For the experiments a laser source emitting a wavelength of 515 nm is applied and the pulse duration is varied between 0.2 and 2 ps. As target parameters the cutting edge radius and Sa value of the rake face are analyzed. The heat affected zone is analyzed by FIB SEM. An edge radius of 6.7±1.6μm at an Sa value of 0.115μm in the case of ZTA and an edge radius of 4.9±0.3μm at an Sa value of 0.125μm in the case of ATZ can be achieved. The results are promising for the application of laser ablation towards the manufacturing of cutting edges in oxide ceramics such as ATZ and ZTA.

(Invited) Anode-Free Sodium Metal Batteries

Sodium-ion batteries (SIBs) have been regarded as one of the most promising alternatives to lithium-ion batteries (LIBs) due to their analogous working mechanism but greater abundance. The cost-effectiveness of Na batteries is expected to overtake that of LIBs in terms of electromobile applications if their energy densities can reach 200 Wh kg-1. In an anode-free configuration, all active sodium is stored in the cathode while anode only contains current collector with zero excess sodium, therefore achieving maximized energy density, significantly reduced cost, and simplified manufacture procedures. However, the anode-free batteries often suffer rapid capacity decay due to the absence of a reservoir to replenish the Na loss during cycling. In this work, we employed repeated cold rolling and folding to fabricate a metallurgical composite of sodium-antimony-telluride Na2(Sb2/6Te3/6Vac1/6) dispersed in electrochemically active sodium metal, termed “NST-Na”. This new intermetallic has a vacancy-rich thermodynamically stable fcc structure and enables state-of-the-art electrochemical performance in widely employed carbonate and ether electrolytes. NST-Na achieves 100% depth-of-discharge (DOD) in 1 M NaPF6 in G2, with 15 mAh cm-2 at 1 mA cm-2 and CE of 99.4%, for 1000 hours of plating/stripping. Sodium metal batteries (SMB, NMB) with NST-Na and Na3V2(PO4)3 (NVP) or sulfur cathodes give significantly improved energy, cycling and CE (> 99%). Anode-Free battery with NST collector and NVP obtains 0.23% capacity decay per cycle. Imaging and tomography using (cryo-)FIB sectioning, (cryo-)SEM, and (cryo-)TEM imaging indicate that sodium metal fills the open space inside the self-supporting sodiophilic NST skeleton, resulting in dense (pore-free and SEI-free) metal deposits with flat surfaces. The baseline Na deposit consists of filament-like dendrites and Dead Metal, intermixed with pores and SEI. Density functional theory (DFT) calculations show that uniqueness of NST lies in the thermodynamic stability of Na atoms (rather than clusters) on its surface that leads to planar wetting, and in its own stability that prevents decomposition during cycling. Figure 1

Analysis of copper pillar bump interconnects for RF-filters

Surface Acoustic Wave (SAW) RF-filters are essential components for wireless communication. Miniaturization and cost reduction are the main driving forces for the development of these components. Up to now the dominant technology to connect the miniaturized filters are solder bumps. For further miniaturization a technology to fabricate copper pillar bumps (CPB) on SAW RF-filters was developed and the second level reliability of the components was tested. In this paper the physical analysis of CPB interconnects with a high resolution FIB SEM and EDX will be explained in detail. We will also show results of this analysis including the formation of the intermetallic phases and the structure and the degradation of the Ni barrier layers.

Utilization of FIB–SEM nanotomography to visualize early HCoV-229E virus-mediated endocytosis nanoscale interactions

Utilization of FIB–SEM nanotomography to visualize early HCoV-229E virus-mediated endocytosis nanoscale interactions

Failure mechanism of 4H-SiC junction barrier Schottky diodes under harsh thermal cycling stress

The concern in the long-term reliability of the SiC power devies is raised lately in power electronic field due to its brief history and limited data. In this work, discrete 1200 V/20A SiC JBS diodes have been intensively investigated by HTRB, HAST, and TCT. 2 % samples have failed in the harsh thermal cycling test, showing that the failure mechanism is attributed to field-oxide cracking. The electrical and physical failure analysis pointed out that a gradual degradation occurred at the termination structure, causing non-recoverable damages and provoking a significant increase in the leakage current. The FIB cut and SEM analysis showed the delamination existence between field oxide layer and silicon carbide layer in the degraded devices. The observed leakage current after the TCT could be well correlated with the formation of the delamination, which created a current leaking path between active and termination region. These findings emphasize the importance of SiO2/SiC interface quality in the long-term highly reliable SiC power devices, and indicate further optimized design of SiO2 passivation layer or other alternative materials is urgently needed to overcome this structural weakness.

Effect of Environmental pH on Mineralization of Anaerobic Iron-Oxidizing Bacteria.

Freshwater lakes are often polluted with various heavy metals in the Anthropocene. The iron-oxidizing microorganisms and their mineralized products can coprecipitate with many heavy metals, including Al, Zn, Cu, Cd, and Cr. As such, microbial iron oxidation can exert a profound impact on environmental remediation. The environmental pH is a key determinant regulating microbial growth and mineralization and then influences the structure of the final mineralized products of anaerobic iron-oxidizing bacteria. Freshwater lakes, in general, are neutral-pH environments. Understanding the effects of varying pH on the mineralization of iron-oxidizing bacteria under neutrophilic conditions could aid in finding out the optimal pH values that promote the coprecipitation of heavy metals. Here, two typical neutrophilic Fe(II)-oxidizing bacteria, the nitrate-reducing Acidovorax sp. strain BoFeN1 and the anoxygenic phototrophic Rhodobacter ferrooxidans strain SW2, were selected for studying how their growth and mineralization response to slight changes in circumneutral pH. By employing focused ion beam/scanning electron microscopy (FIB–SEM) and transmission electron microscopy (TEM), we examined the interplay between pH changes and anaerobic iron-oxidizing bacteria and observed that pH can significantly impact the microbial mineralization process and vice versa. Further, pH-dependent changes in the structure of mineralized products of bacterial iron oxidation were observed. Our study could provide mechanical insights into how to manipulate microbial iron oxidation for facilitating remediation of heavy metals in the environment.

Microstructure Evolution of Lithium‐Ion Battery Separator under Compressive Loading: In Situ Experiments and Image‐Based Finite Simulations

The separator is the weakest mechanical part of a lithium‐ion battery. The displacement load formed by the expansion of an electrode induces the microstructure evolution of the separator, such as decreasing porosity and increasing tortuosity, which affects its ability to transport Li+ and degrades battery performance. Herein, an in situ mechanical loading device combined with focused ion beam–scanning electron microscopy (FIB–SEM) is designed to reveal the real microstructure evolution of a separator under displacement loading. An image‐based finite‐element model is tailored to investigate the microstructure evolution and its nonuniformities of the separator at different deformation levels. The quantitative relationship between the separator porosity and external displacement load is presented based on the experimental and simulation results. Herein, new insight into the degradation mechanisms of commercial lithium‐ion batteries is provided.

Recent Developments in Femtosecond Laser-Enabled TriBeam Systems

Streams of multimodal three-dimensional (3D) and four-dimensional (4D) data are revolutionizing our ability to design and predict the behavior of a broad array of advanced materials systems. Over the last 10 years, a new 3D imaging platform consisting of a femtosecond (fs) pulsed laser coupled with a focused ion beam scanning electron microscope (FIB SEM) has been developed by UC Santa Barbara in collaboration with Thermo Fisher Scientific (formerly FEI). The femtosecond-laser-enabled FIB SEM, called the TriBeam, has become one of the only 3D serial sectioning methods available that can gather millimeter-scaled multimodal datasets at sub- $$\mu $$ m voxel resolutions; these length scales are critical for many materials problems. Multimodal chemical, crystallographic, and morphological information can be gathered rapidly on a layer-by-layer basis and reconstructed in 3D. Large (gigabyte to terabyte scale) 3D datasets have been generated for a broad array of materials systems, including metallic alloys, ceramics, biomaterials, polymer- and ceramic-matrix composites, and semiconductors. The research tasks performed have resulted in a completely new design, operating with a dual-wavelength femtosecond-pulsed laser on a plasma focused ion beam (PFIB) platform.

Degradation Behavior of Solid Oxide Fuel Cells Operated at High Fuel Utilization

High energy conversion efficiency in solid oxide fuel cell (SOFC) systems can be achieved by improving the fuel utilization. However, an operation at high fuel utilizations negatively affects Ni-based cermet anodes; the downstream part of the anode is exposed to high P(O2) atmospheres due to the depletion of fuel and the high steam concentration. At this stage, no reports dealt with the degradation phenomena of the anode under such severe conditions. In this study, we aimed to clarify degradation phenomena at the downstream part of practical cells operated at high fuel utilizations by using bottom cells. Fuel gases simulated severe conditions were supplied to single cells. The change in electrochemical properties was monitored during discharge operation, and the microstructural evolution of the anode was quantitatively analyzed by the focused ion beam–scanning electron microscope (FIB–SEM) technique.

Characterization of the growth plate-bone interphase region using cryo-FIB SEM 3D volume imaging

The interphase region at the base of the growth plate includes blood vessels, cells and mineralized tissues. In this region, cartilage is mineralized and replaced with bone. Blood vessel extremities permeate this space providing nutrients, oxygen and signaling factors. All these different components form a complex intertwined 3D structure. Here we use cryo-FIB SEM to elaborate this 3D structure without removing the water. As it is challenging to image mineralized and unmineralized tissues in a hydrated state, we provide technical details of the parameters used. We obtained two FIB SEM image stacks that show that the blood vessels are in intimate contact not only with cells, but in some locations also with mineralized tissues. There are abundant red blood cells at the extremities of the vessels. We also documented large multinucleated cells in contact with mineralized cartilage and possibly also with bone. We observed membrane bound mineralized particles in these cells, as well as in blood serum, but not in the hypertrophic chondrocytes. We confirm that there is an open pathway from the blood vessel extremities to the mineralizing cartilage. Based on the sparsity of the mineralized particles, we conclude that mainly ions in solution are used for mineralizing cartilage and bone, but these are augmented by the supply of mineralized particles.

Electrochemical Characteristics of SOFC Anodes Operated at High Fuel Utilization

High energy conversion efficiency in solid oxide fuel cell (SOFC) systems can be achieved by improving the fuel utilization. However, when the SOFCs are operated under high fuel utilization, the downstream part of the anode is exposed to high steam concentration and hence high P(O2) atmospheres, and this has a negative impact on the stability of Ni-based cermet anodes. At this stage, no reports dealt with the degradation phenomena of the anode under such severe conditions. In this study, we aimed to clarify degradation phenomena at the downstream part of practical cells operated at high fuel utilizations by using bottom cells. Fuel gases that simulated severe conditions were supplied to single cells. The change in electrochemical properties was monitored during discharge operation, and the microstructural evolution of the anode was quantitatively analyzed by the FIB–SEM technique.

Changes in Microstructure of NiCo-Dispersed SDC Hydrogen Electrodes for the Improvement of Durability via Reversible Cycling Operation Between SOEC and SOFC-Modes

We have examined changes in microstructure of double-layer hydrogen electrodes for solid oxide cells, consisting of a samaria-doped ceria (SDC) scaffold with highly dispersed Ni–Co nanoparticles as the catalyst layer (CL) and a thin current collecting layer of Ni–YSZ cermet, whose durability we recently found to undergo a remarkable improvement via reversible cycling operation between electrolysis and fuel cell-modes. The lower parts of many Ni‒Co particles were found to be anchored tightly on the SDC support after the cycling operation, probably due to a strong interaction between Ni‒Co and SDC. It was demonstrated by focused ion beam–scanning electron microscopy (FIB–SEM) that the Ni content in the CL was nearly fully maintained by the cycling operation, compared with a significant depletion of Ni after SOEC single-mode operation. Such a stabilization of the microstructure is proposed to contribute to the improved durability.

Characterizing coal pore space by gas adsorption, mercury intrusion, FIB–SEM and µ-CT

Understanding multiphase flow properties is essential for assessing and exploiting coals. These properties depend on the 3D pore space information, i.e. geometry and topology. However, determining the geometric and topological properties in coals are still challenging due to the complicated pore structures comprising several length scales. Studying pore scale structures in coals in a continuous range across over several length scales and integrating these information are necessary to increase the understanding of the role of pore structure on transport properties. Most of the current modeling methods are usually based on one or two experimental methods with limited and insufficient information. In this work, CO2 adsorption, N2 adsorption, MIP, X-ray µ-CT and FIB–SEM are used to study the pore structure characteristics of coal samples cored from the No. 9 coal seam of upper Permian Longtan formation at the Longfeng mine, China. The porosity, pore surface area, pore size distribution, connectivity and pore shapes measured by different methods are analyzed. We show that a combination of these techniques provides a richer picture of pore structure in coals. The obtained 3D pore structure can be applied to predict transport properties which are important to capture coal mine methane (CMM) and optimize field development. The results will also be helpful for the gas control in coal mines.

Biointerfaces: Probing the Ultrastructure of Spheroids and Their Uptake of Magnetic Nanoparticles by FIB–SEM (Adv. Mater. Technol. 3/2020)

Biointerfaces: Probing the Ultrastructure of Spheroids and Their Uptake of Magnetic Nanoparticles by FIB–SEM (Adv. Mater. Technol. 3/2020)

Probing the Ultrastructure of Spheroids and Their Uptake of Magnetic Nanoparticles by FIB–SEM

AbstractSpheroids are 3D cellular systems largely adopted as model for high‐throughput screening of molecules and diagnostics tools. Furthermore, those cellular platforms also represent a model for testing new delivery carries for selective targeting. The coupling between the 3D cell environment and the nanovectors can be explored at the macroscale by optical microscopy. However, the nanomaterial‐cell interplay finds major action at the single cell and extracellular matrix level with nanoscale interactions. Electron microscopy offers the resolution to investigate those interactions; however, the specimen preparation finds major drawbacks in its operation time and preciseness. In this context, focused ion beam and scanning electron microscopy (FIB–SEM) allows for fast processing and high resolution of the cell‐nanomaterial interface. Here, in fact, a novel approach is shown to prepare large‐area 3D spheroid cell culture specimens for FIB–SEM. Sectioning procedures are explored to preserve the peculiar structure of spheroids and their interaction with magnetic nanovectors. The results pave the way for advanced investigations of 3D cellular systems with nano and micromaterials relevant to tissue engineering, bioelectronics, and diagnostics.