Search NASA⌕ Search

SEARCH · Search NASA

Results for “Visualization & Storage”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Cameco Corporation's Approach to Legacy and Ongoing Waste Management Within the Fuel Services Division - 19124

Since 2011, a Fuel Services Division (FSD) employee has been dedicated to oversee divisional waste management with the goal of accelerating the recycle/disposal of accumulated legacy radioactive wastes stored at its Ontario operations in Blind River and Port Hope. The Blind River Refinery (BRR) and Port Hope Conversion Facility (PHCF) were previously owned by the federal Crown Corporation, Eldorado Nuclear, becoming part of Cameco in 1988 and Cameco Fuel Manufacturing (CFM), previously known as Zircatec Precision Industries, becoming part of Cameco in 2006. Accumulated legacy radioactive waste is stored at each of the facilities. This radioactive waste has accumulated from operations beginning in the 1930's in Port Hope and the 1980's in Blind River. Due to minimal commercially available outlets for the disposal and/or treatment of these wastes, the waste was managed onsite by storage in underutilized space in buildings, trailers and/or in the secured yard. This relatively low-cost practice meant that over decades, the inventory increased at an unsustainable rate until available space became a limiting factor. During this time, the labelling, inventory records, characterization details and other history of many of the waste materials was not maintained adequately. Due to the volume of waste that had accumulated, campaigns to address these deficiencies in information were not considered feasible, sustaining the issue of accumulation of low-level radioactive waste. Since 2011, FSD has completed annual campaigns to address the accumulated legacy waste, which has included processing of material for decontamination to meet the unrestricted release criteria under the Canadian Nuclear Substance and Radiation Devices Regulations (NSRDR), disposal of marginally contaminated wastes (<500 ppm uranium) at a permitted landfill in the United States, processing of contaminated materials to reduce the volume of low-level radioactive waste and disposal at a designated facility in Port Hope. In addition FSD has undertaken significant changes to radioactive waste management practices at each of the facilities. Multiple characterization techniques, including visual observation, review of process and other historical records, laboratory analysis and radiation scanning have been utilized in campaign planning to identify the scope and appropriate waste management technique(s) to reduce the inventory of stored material. This divisional waste management program has resulted in a significant change to how radioactive waste is generated, inventoried, characterized and managed within FSD and has increased the visibility within the leadership team of the opportunities and challenges of waste management, such as alignment with decommissioning planning, project planning and budgeting. The heightened awareness has led to better financial and physical resource planning to execute waste projects with a current projected elimination of the legacy waste within FSD by 2025. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

In‐operando crystallization study of zinc nitrate hexahydrate using zinc oxide nucleators

Abstract Supercooling (∆T Sup ) is one of the crucial problems in utilizing a phase change material (PCM), which has been attempted to overcome using nucleators possessing small lattice disregistry without comprehensive understanding of the nucleation phenomenon. Here, this work studies the interactions between nucleators and PCM via in‐operando direct visualization for the first time, to the best of our knowledge, to better understand the crystallization process during freezing of a PCM using zinc nitrate hexahydrate (ZNH) and a zinc oxide (ZnO) nucleator. According to our in‐operando study, freezing was randomly initiated by only a fraction of the nucleator particles during each thermal cycling. However, previously unresponsive nucleators also suddenly crystalized PCM when the propagating crystal encountered them, improving the crystal initiation and thereby ∆T Sup . Consequently, for equal wt% of ZnO, better nucleation behavior was obtained using uniformly distributed small nucleator particles throughout the PCM, as compared to either large or poorly distributed aggregated nucleators. DSC results using ZnO‐needle as nucleator confirmed a 38% and 33.3% lower ∆T Sup upon employing 5 wt% small (individual) particles (~4 μm on average), as compared to using equal wt% of small (aggregated) particle clusters (~200 μm) and large particles (~46 μm), respectively. Crystallization of ZNH caused additional hair‐like ZnO growth preferentially decorated along lateral faces of the original nucleator particles. The in‐operando studies are valuable tools to correlate inherent crystallization phenomena to the practical thermal energy storage properties of the system.

Chakraborty, Anirban↗
DOE OSTI2020

Chemo‐mechanical Alterations Induced From CO 2 Injection in Carbonate‐Cemented Sandstone: An Experimental Study at 71 °C and 29 MPa

Abstract Carbon capture, utilization, and storage may lead to mechanical degradation of the subsurface reservoir from fluid‐rock interaction, which could lead to wellbore instability or reservoir compaction. To better understand potential relationship between mechanical degradation with various carbonate cement textures and compositions in sandstone reservoirs, six flow‐through experiments were conducted. Formation water (TDS = 5,390 mg/L) enriched with CO 2 flowed through two types of Pennsylvanian Morrow B Sandstone: an ankerite‐siderite‐cemented sandstone (disseminated cement texture) and a calcite‐cemented sandstone (poikilotopic cement texture). The experiments produced little change in permeability in the ankerite‐siderite‐cemented sandstone, but permeability increased up to more than 1 order of magnitude in the calcite‐cemented sandstone. Ultrasonic measurements and cylinder‐splitting tests (also known as Brazilian tests) suggested negligible mechanical degradation of the ankerite‐siderite‐cemented sandstone. Variable changes, with significant mechanical degradation in the static moduli, were observed in the calcite‐cemented sandstone. Thus, dissolution of the disseminated ankerite‐siderite cement (0.28–0.30%) had minimal impact on modifying the flow network and the mechanical integrity of the sandstone, whereas dissolution of the poikilotopic calcite cement (0.89–1.13%, quantified with fluid chemistry and visualized with X‐ray microcomputed tomography) impacted the mechanical strength of the sandstone by disconnecting framework grains. With the high water‐to‐rock mass ratios (7.3–8.2) and number of pore volumes (147–675) employed in these experiments, potential risks are most relevant to regions near injection wells. Ultimately, the chemo‐mechanical effects induced by CO 2 injection are strongly influenced by the cement texture and composition and the burial history of the reservoir rock.

Wu, Z.↗
DOE OSTI2023

A reactive wetting strategy improves lithium metal reversibility

The cycling of lithium metal (Li 0 ) anode is often accompanied by irregular lithium plating/stripping, leading to poor Li 0 reversibility, and posing a grand challenge to constructing reliable Li 0 batteries. Hereby, we report a reactive wetting strategy to enable conformal and highly reversible Li 0 plating/stripping through a lithium-reactive substrate. In this study, the reactive wetting, smooth nucleation, and conformal growth behaviors of Li 0 are visualized through in-situ transmission electron microscopy, ex-situ scanning electron microscope, and in-situ optical microscope characterizations. Based on the reactive wetting substrate, high average Coulombic efficiencies (99.0% at 0.5 mA cm -2 for 400 cycles) are realized for Li 0 anodes. By pre-plating Li 0 into the reactive wetting substrate as anodes and leveraging LiFePO 4 as cathodes, high capacity retention (76.0% after 200 cycles in low N/P ratio conditions) is also achieved in the as-constructed Li 0 full cells. This work establishes a fundamental understanding of reactive wetting dynamics of Li 0 and provides a drop-in solution to improving Li 0 reversibility.

25 ENERGY STORAGE↗
DOE OSTI2018

Insights into the Interconnection of the Electrodes and Electrolyte Species in Lithium–Sulfur Batteries Using Spatially Resolved Operando X-ray Absorption Spectroscopy and X-ray Fluorescence Mapping

The lithium–sulfur (Li–S) battery chemistry has attracted great interest in the last decade because of its outstanding theoretical gravimetric energy density compared to the state-of-the-art lithium-ion battery technology. However, practically achieved energy density is still far below the theoretical value, even in small laboratory-scale batteries. The problems seen in laboratory-scale batteries will inevitably increase during scale-up to large application-format cells, as the electrolyte to active material (AM) ratio will need to be reduced in these cells to achieve high gravimetric energy density on cell-level basis. Our paper shows the unique possibility of X-ray fluorescence (XRF) mapping to visualize the spatial distribution of the AM inside operating Li–S batteries in all cell components [working electrode (WE), separator, and counter electrode (CE)]. Through a combination of operando XRF mapping and X-ray absorption spectroscopy, we show that unless self-discharge is efficiently prevented, the AM can completely dissolve and distribute throughout the cell stack within a time frame of 2 h, causing poor capacity retention. Finally, using a polysulfide diffusion barrier between the WE and the CE, we successfully suppress these processes and thereby establish a tool for examining the sealed cathode electrode compartment, enabling sophisticated studies for future optimization of the WE processes.

25 ENERGY STORAGE↗
DOE OSTI2017

Wallula Basalt Pilot Demonstration Project: Post-injection Results and Conclusions

Deep underground geologic formations are emerging as a reasonable option for long-term storage of CO 2 , including large continental flood basalt formations. At the GHGT-11 and GHGT-12 conferences, progress was reported on the initial phases for Wallula Basalt Pilot demonstration test (located in Eastern Washington state), where nearly 1,000 metric tons of CO 2 were injected over a 3-week period during July/August 2013. The target CO 2 injection intervals were two permeable basalt interflow reservoir zones with a combined thickness of ~20 m that occur within a layered basalt sequence between a depth of 830-890 m below ground surface. During the two-year post-injection period, downhole fluid samples were periodically collected during this post-injection monitoring phase, coupled with limited wireline borehole logging surveys that provided indirect evidence of on-going chemical geochemical reactions/alterations and CO 2 disposition. A final detailed post-closure field characterization program that included downhole fluid sampling, and performance of hydrologic tests and wireline geophysical surveys. Included as part of the final wireline characterization activities was the retrieval of side-wall cores from within the targeted injection zones. These cores were examined for evidence of in-situ mineral carbonization. Visual observations of the core material identified small globular nodules, translucent to yellow in color, residing within vugs and small cavities of the recovered basalt side-wall cores, which were not evident in pre-injection side-wall cores obtained from the native basalt formation. Characterization by x-ray diffraction identified these nodular precipitates as ankerite, a commonly occurring iron and calcium rich carbonate. Isotopic characterization (δ 13 C, δ 18 O) conducted on the ankerite nodules indicate a distinct isotopic signature that is closely aligned with that of the injected CO 2 . Both the secondary mineral nodules and injected CO 2 are measurably different from the isotopic content of basalt, injection zone groundwater and for naturally occurring calcite. Final post-injection wireline geophysical logging results also indicate the presence of free-phase CO 2 at the top of the two injection interflow zones, with no vertical migration of CO 2 above the injection horizons. Furthermore, these findings are significant and demonstrate the feasibility of sequestering CO 2 in a basalt formation.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

A High Energy–Density, Cobalt–Free, Low–Nickel LiNi 0.7 Mn 0.25 Al 0.05 O 2 Cathode with a High–Voltage Electrolyte for Lithium–Metal Batteries

Cobalt-free cathode materials have garnered increased attention for applications in next-generation batteries for electric vehicles, as cobalt is considered to have at a high supply chain risk. Here, the use of a localized saturated electrolyte (LSE) to enable stable cycling of a cobalt-free, low-nickel layered-oxide cathode LiNi 0.7 Mn 0.25 Al 0.05 O 2 (NMA-70) to higher voltages (4.6 V) in a lithium-metal battery is demonstrated. Compared to the baseline LP57 electrolyte, the LSE extends the cycle life from ≈100 cycles to ≈400 cycles before reaching 80% capacity retention. Visual indicators of cell degradation, such as product deposition, are observed on electrodes cycled in LP57. It is shown that cycling NMA-70 in LSE reduces the overall active material loss and overpotential growth during extended cycling. This is attributed to the formation of a beneficial fluorinated interphase layer, a lower degree of rock-salt phase formation, and a reduction in the gas evolution from the cathode surface. The decrease in gas evolution from the cathode cycled in LSE reflects a lower degree of electrolyte reactivity and an overall improvement in the safety characteristics of the cell. Furthermore, this study highlights the importance of a stable electrolyte to enable the high-voltage cycling of alternative, lower nickel, and cobalt-free cathodes.

25 ENERGY STORAGE↗
DOE OSTI2022

Artificial neural network approach for multiphase segmentation of battery electrode nano-CT images

The segmentation of tomographic images of the battery electrode is a crucial processing step, which will have an additional impact on the results of material characterization and electrochemical simulation. However, manually labeling X-ray CT images (XCT) is time-consuming, and these XCT images are generally difficult to segment with histographical methods. We propose a deep learning approach with an asymmetrical depth encode-decoder convolutional neural network (CNN) for real-world battery material datasets. This network achieves high accuracy while requiring small amounts of labeled data and predicts a volume of billions voxel within few minutes. While applying supervised machine learning for segmenting real-world data, the ground truth is often absent. The results of segmentation are usually qualitatively justified by visual judgement. We try to unravel this fuzzy definition of segmentation quality by identifying the uncertainty due to the human bias diluted in the training data. Further CNN trainings using synthetic data show quantitative impact of such uncertainty on the determination of material’s properties. Nano-XCT datasets of various battery materials have been successfully segmented by training this neural network from scratch. We will also show that applying the transfer learning, which consists of reusing a well-trained network, can improve the accuracy of a similar dataset.

25 ENERGY STORAGE↗
DOE OSTI2021

Operando video microscopy of Li plating and re-intercalation on graphite anodes during fast charging

Despite the demand for fast-charging lithium (Li)-ion batteries, high-energy-density batteries with thick graphite anodes are limited by Li plating when charging at >4C rates. In this work, plan-view operando video microscopy is applied on >3 mA h cm –2 calendared graphite electrodes to study the dynamic evolution of local state-of-charge (SoC) and Li plating during fast charging. This technique allows for visualization of the spatial heterogeneity in SoC across the electrode, nucleation and growth of Li filaments, Li re-intercalation into graphite, “dead Li” formation, and SoC equilibration. The operando microscopy analysis is complemented by ex situ imaging of through-plane gradients in SoC to gain a three-dimensional visualization of spatial heterogeneity. We demonstrate that (1) Li plating preferentially nucleates on the graphite particles that lithiate fastest during fast charging; (2) the onset of Li plating correlates with the local minimum of the graphite electrode potential; (3) galvanic corrosion currents are responsible for Li re-intercalation, dead Li formation, and SoC re-equilibration after fast charging; and (4) electrochemical signatures during OCV rest or discharge are associated with Li re-intercalation into graphite. Furthermore, this work provides insight into the Li–graphite interactions at the composite electrode level and can be used to inform strategies to diagnose and mitigate Li plating during fast charging.

25 ENERGY STORAGE↗
DOE OSTI2020

Multimodal Nanoscale Tomographic Imaging for Battery Electrodes

Accurate representations of the 3D structure within a lithium-ion battery are key to understanding performance limitations. However, obtaining exact reconstructions of electrodes, where the active particles, the carbon black and polymeric binder domain, and the pore space are visualized is challenging. In this work, it is shown that multimodal imaging can be used to overcome this challenge. High-resolution ptychographic X-ray computed tomography are combined with lower resolution but higher contrast transmission X-ray tomographic microscopy to obtain 3D reconstructions of pristine and cycled graphite-silicon composite electrodes. This cross-correlation enables quantitative analysis of the surface of active particles, including the heterogeneity of carbon-black and binder domain and solid-electrolyte interphase coverage. Capturing the active particles as well as the carbon black-binder domain allows using these segmented structures for electrochemical simulations to highlight the influence of the particle embedding on local state of charge heterogeneities.

25 ENERGY STORAGE↗
DOE OSTI2018

Localized concentration reversal of lithium during intercalation into nanoparticles

Nanoparticulate electrodes, such as Li x FePO 4 , have unique advantages over their microparticulate counterparts for the applications in Li-ion batteries because of the shortened diffusion path and access to nonequilibrium routes for fast Li incorporation, thus radically boosting power density of the electrodes. However, how Li intercalation occurs locally in a single nanoparticle of such materials remains unresolved because real-time observation at such a fine scale is still lacking. We report visualization of local Li intercalation via solid-solution transformation in individual Li x FePO 4 nanoparticles, enabled by probing sub-angstrom changes in the lattice spacing in situ. The real-time observation reveals inhomogeneous intercalation, accompanied with an unexpected reversal of Li concentration at the nanometer scale. The origin of the reversal phenomenon is elucidated through phase-field simulations, and it is attributed to the presence of structurally different regions that have distinct chemical potential functions. Furthermore, the findings from this study provide a new perspective on the local intercalation dynamics in battery electrodes.

25 ENERGY STORAGE↗
DOE OSTI2018

Understanding the Dynamics of Primary Zn-MnO 2 Alkaline Battery Gassing with Operando Visualization and Pressure Cells

The leading cause for safety vent rupture in alkaline batteries is the intrinsic instability of Zn in the highly alkaline reacting environment. Zn and aqueous KOH react in a parasitic process to generate hydrogen gas, which can rupture the seal and vent the hydrogen along with small amounts of electrolyte, and thus, damage consumer devices. Abusive conditions, particularly deep discharge, are known to accelerate this “gassing” phenomena. In order to understand the fundamental drivers and mechanisms for such gassing behavior, the results from multiphysics modeling, ex-situ microscopy and operando measurements of cell potential, pressure and visualization have been combined. Operando measurements were enabled by the development a new research platform that enables a cross-sectional view of a cylindrical Zn-MnO 2 primary alkaline battery throughout its discharge and recovery. A second version of this cell can actively measure the in-cell pressure during the discharge. It is shown that steep concentration gradients emerge during the cell discharge through a redox electrolyte mechanism, leading to the formation of high surface area Zn deposits that experience rapid corrosion when the cell rests to its open circuit voltage. Such corrosion is paired with the release of hydrogen and high cell pressure – eventually leading to cell rupture.

25 ENERGY STORAGE↗
DOE OSTI2015

Kelvin Probe Force Microscopy in liquid using Electrochemical Force Microscopy

Conventional closed loop-Kelvin probe force microscopy (KPFM) has emerged as a powerful technique for probing electric and transport phenomena at the solid-gas interface. The extension of KPFM capabilities to probe electrostatic and electrochemical phenomena at the solid–liquid interface is of interest for a broad range of applications from energy storage to biological systems. However, the operation of KPFM implicitly relies on the presence of a linear lossless dielectric in the probe-sample gap, a condition which is violated for ionically-active liquids (e.g., when diffuse charge dynamics are present). Here, electrostatic and electrochemical measurements are demonstrated in ionically-active (polar isopropanol, milli-Q water and aqueous NaCl) and ionically-inactive (non-polar decane) liquids by electrochemical force microscopy (EcFM), a multidimensional (i.e., bias- and time-resolved) spectroscopy method. In the absence of mobile charges (ambient and non-polar liquids), KPFM and EcFM are both feasible, yielding comparable contact potential difference (CPD) values. In ionically-active liquids, KPFM is not possible and EcFM can be used to measure the dynamic CPD and a rich spectrum of information pertaining to charge screening, ion diffusion, and electrochemical processes (e.g., Faradaic reactions). EcFM measurements conducted in isopropanol and milli-Q water over Au and highly ordered pyrolytic graphite electrodes demonstrate both sample- and solvent-dependent features. Finally, the feasibility of using EcFM as a local force-based mapping technique of material-dependent electrostatic and electrochemical response is investigated. The resultant high dimensional dataset is visualized using a purely statistical approach that does not require a priori physical models, allowing for qualitative mapping of electrostatic and electrochemical material properties at the solid–liquid interface.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Understanding the Role of Overpotentials in Lithium Ion Conversion Reactions: Visualizing the Interface

Oxide conversion reactions are known to have substantially higher specific capacities than intercalation materials used in Li-ion batteries, but universally suffer from large overpotentials associated with the formation of interfaces between the resulting nanoscale metal and Li 2 O products. Here we use the interfacial sensitivity of operando X-ray reflectivity to visualize the structural evolution of ultrathin NiO electrodes and their interfaces during conversion. We observe two additional reactions prior to the well-known bulk, three-dimensional conversion occurring at 0.6 V: an accumulation of lithium at the buried metal/oxide interface (at 2.2 V) followed by interfacial lithiation of the buried NiO/Ni interface at the theoretical potential for conversion (at 1.9 V). To understand the mechanisms for bulk and interfacial lithiation, we calculate interfacial energies using density functional theory to build a potential-dependent nucleation model for conversion. These calculations show that the additional space charge layer of lithium is a crucial component for reducing energy barriers for conversion in NiO.

25 ENERGY STORAGE↗
DOE OSTI2015

Characterization of the Uranium-Bearing Products of the Ammonia Injection Remediation Method - 15707

Commissioned in 1943, the Hanford Site is the home of the world's first full-scale nuclear production facility. After more than 40 years of processing, improper discharge and failed storage tanks have resulted in the contamination of the Hanford vadose zone with radiologically contaminated waste. Remediation methods considered for the area include sequestration of the mobile uranium by injection of ammonia (NH{sub 3}) gas. Injection of this reactive gas increases the pore water pH, promoting the dissolution of soil minerals; a subsequent re-establishment of natural conditions is believed to result in the recrystallization of those soil minerals and the co-precipitation of uranium phases. Characterization of the precipitates formed when the ammonia (NH{sub 3}) injection method, proposed for the Hanford vadose zone, is applied to synthetic pore water on a laboratory scale. This involves: Identification of the uranium-bearing phases; A study of the effect of pore water constitution on the phases produced. Synthetic pore water solutions were prepared to mimic selected constituents of the pore water from the Hanford 200 Area: Varying constituent concentrations; Observations led to modifications to increase relative uranium content: 200 ppm → 500 ppm U; Substituted sodium silicate for silicic acid. Dried samples were analyzed by SEM-EDS and powder X-ray diffraction (XRD). A suspension in ethanol was prepared and analyzed by Transmission Electron Microscope (TEM) with Selective Area Electron Diffraction (SAED). Studied and applied geochemical modeling software (Visual Minteq and Geo-chemist's Workbench) for speciation and prediction of potential species formed. Discussion/Conclusions: - SEM-EDS Analysis: Scanning electron microscopy revealed areas of high average atomic weight which would be confirmed to be uranium-rich by energy dispersive spectroscopy analysis. The samples prepared with a more than two-fold increase in uranium concentration did not show the crystal-like forms spotted in the lower [U] samples. The samples prepared with silicic acid substituted in showed little to no uranium precipitation [not shown]. - Diffraction Analysis: Powder XRD analysis of the low [U] samples confirmed the presence of repeating crystalline patterns in the precipitate samples. Nitratine (NaNO{sub 3}) showed a massive presence, potentially obscuring significant peaks in the low [U] samples. Though it was not predicted, there was a tentative match for cejkaite (Na{sub 4}(UO{sub 2})(CO{sub 3}){sub 3}). Elevated uranium samples showed none of the needle-like crystalline shapes [diffraction data pending]. TEM - SAED confirmed the presence of a polycrystalline phase. Data analysis is complex but a comparison of average d-spacings with those of reference minerals could further support a match with cejkaite. - Geochemical Modeling: The system conditions were input into geochemical modeling software to predict the forms present throughout the reaction process. The model was used to demonstrate that the pH of the system could be increased using [NH{sub 4}{sup +}] in solution to better represent the system. Using the [NH{sub 4}{sup +}] increase, the changes in significant species with increasing pH were observed. Future Work: Repeat samples will be prepared and analyzed to bolster any potential identification. Promising samples will be submitted to the PNNL's EMSL facility, which is better equipped to perform the required analyses. An expanded study on the impact of carbonate (CO{sub 3}{sup 2-}) on the phases produced.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Visualization of lithium-ion transport and phase evolution within and between manganese oxide nanorods

Multiple lithium-ion transport pathways and local phase changes upon lithiation in silver hollandite are revealed via in situ microscopy including electron diffraction, imaging and spectroscopy, coupled with density functional theory and phase field calculations. Here, we report unexpected inter-nanorod lithium-ion transport, where the reaction fronts and kinetics are maintained within the neighbouring nanorod. Notably, this is the first time-resolved visualization of lithium-ion transport within and between individual nanorods, where the impact of oxygen deficiencies is delineated. Initially, fast lithium-ion transport is observed along the long axis with small net volume change, resulting in two lithiated silver hollandite phases distinguishable by orthorhombic distortion. As a result, a slower reaction front is observed, with formation of polyphase lithiated silver hollandite and face-centred-cubic silver metal with substantial volume expansion. Our results indicate lithium-ion transport is not confined within a single nanorod and may provide a paradigm shift for one-dimensional tunnelled materials, particularly towards achieving high-rate capability.

25 ENERGY STORAGE↗
DOE OSTI2018

Lithium metal stripping beneath the solid electrolyte interphase

Lithium stripping is a crucial process coupled with lithium deposition during the cycling of Li metal batteries. Lithium deposition has been widely studied, whereas stripping as a subsurface process has rarely been investigated. Here we reveal the fundamental mechanism of stripping on lithium by visualizing the interface between stripped lithium and the solid electrolyte interphase (SEI). We observed nanovoids formed between lithium and the SEI layer after stripping, which are attributed to the accumulation of lithium metal vacancies. High-rate dissolution of lithium causes vigorous growth and subsequent aggregation of voids, followed by the collapse of the SEI layer, i.e., pitting. We systematically measured the lithium polarization behavior during stripping and find that the lithium cation diffusion through the SEI layer is the rate-determining step. Nonuniform sites on typical lithium surfaces, such as grain boundaries and slip lines, greatly accelerated the local dissolution of lithium. As a result, the deeper understanding of this buried interface stripping process provides beneficial clues for future lithium anode and electrolyte design.

25 ENERGY STORAGE↗