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Cui, Yi

Publications and source records attributed to Cui, Yi.

At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Fast galvanic lithium corrosion involving a Kirkendall-type mechanism

Developing a viable metallic lithium anode is a prerequisite for next-generation batteries. However, the low redox potential of lithium metal renders it prone to corrosion, which must be thoroughly understood for it to be used in practical energy-storage devices. Here in this paper, we report a previously overlooked mechanism by which lithium deposits can corrode on a copper surface. Voids are observed in the corroded deposits and a Kirkendall-type mechanism is validated through electrochemical analysis. Although it is a long-held view that lithium corrosion in electrolytes involves direct charge-transfer through the lithium–electrolyte interphase, the corrosion observed here is found to be governed by a galvanic process between lithium and the copper substrate—a pathway largely neglected by previous battery corrosion studies. The observations are further rationalized by detailed analyses of the solid–electrolyte interphase formed on copper and lithium, where the disparities in electrolyte reduction kinetics on the two surfaces can account for the fast galvanic process.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Spatio-Temporal Characterization of Synchrophasor Data Against Spoofing Attacks in Smart Grids

“Source ID Mix” has emerged as a new type of highly deceiving attack which can alter the source information of synchrophasor data measured by multiple phasor measurement units, thereby paralyzing many wide-area measurement systems applications. To address such sophisticated cyber attacks, we have exploited the spatio-temporal characteristics of synchrophasor data for authenticating measurements’ source information. Specifically, the source authentication is performed when the measurements are subjected to three types of spoofing attacks. Some practical difficulties in applying the proposed method on real-time authentication caused by insufficient measurement data have also been solved. Experimental results with real synchrophasor measurements have validated the effectiveness of the proposed method in detecting such complicated data spoofing and improving power systems’ cyber security.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2019

In Situ Focused Ion Beam Scanning Electron Microscope Study of Microstructural Evolution of Single Tin Particle Anode for Li-Ion Batteries

Tin (Sn) is a potential anode material for high-energy density Li-ion batteries because of its high capacity, safety, abundance and low cost. However, Sn suffers from large volume change during cycling, leading to fast degradation of the electrode. For the first time, the microstructural evolution of micrometer-sized single Sn particle was monitored by focused-ion beam (FIB) polishing and scanning electron microscopy (SEM) imaging during electrochemical cycling by in situ FIB-SEM. Our results show the formation and evolution of cracks during lithiation, evolution of porous structure during delithiation and volume expansion/contraction during cycling. The electrochemical performance and the microstructural evolution of the Sn microparticle during cycling are directly correlated, which provides insights for understanding Sn-based electrode materials.

25 ENERGY STORAGE↗
DOE OSTI2019

An Interconnected Channel-Like Framework as Host for Lithium Metal Composite Anodes

Lithium (Li) metal anodes have long been counted on to meet the increasing demand for high energy, high–power rechargeable battery systems but they have been plagued by uncontrollable plating, unstable solid electrolyte interphase (SEI) formation, and the resulting low Coulombic efficiency. These problems are even aggravated under commercial levels of current density and areal capacity testing conditions. In this work, the channel–like structure of a carbonized eggplant (EP) as a stable “host” for Li metal melt infusion, is utilized. With further interphase modification of lithium fluoride (LiF), the as–formed EP–LiF composite anode maintains ≈90% Li metal theoretical capacity and can successfully suppress dendrite growth and volume fluctuation during cycling. EP–LiF offers much improved symmetric cell and full–cell cycling performance with lower and more stable overpotential under various areal capacity and elevated rate capability. Furthermore, carbonized EP serves as a light–weight high–performance current collector, achieving an average Coulombic efficiency ≈99.1% in ether–based electrolytes with 2.2 mAh cm –2 cycling areal capacity. Furthermore, the natural structure of carbonized EP will inspire further artificial designs of electrode frameworks for both Li anode and sulfur cathodes, enabling promising candidates for next–generation high–energy density batteries.

25 ENERGY STORAGE↗
DOE OSTI2019

Direct electrochemical generation of supercooled sulfur microdroplets well below their melting temperature

Significance Since the first discovery of supercooling in 1724, the study of supercooled matter has been mainly limited to varying temperature or pressure. Here we demonstrate an electrochemical approach to generate and observe supercooled sulfur. Our methodology combines dark-field microscopy, a transparent electrochemical cell, and a fast camera to visualize the process at single microdroplet with millisecond time resolution. This platform may open up opportunities for studying supercooled liquids as the droplets approach either homogeneous nucleation to the crystalline state or enter into the glass transition. Relevant to understanding lithium-sulfur battery chemistry, liquid sulfur is observed to form in the electrochemical cell and elucidates a long-debated reaction pathway for sulfur redox reaction in this environment.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Mitigation of Shuttle Effect in Li–S Battery Using a Self-Assembled Ultrathin Molybdenum Disulfide Interlayer

Lithium–sulfur batteries are promising for low-cost and high-energy storage, but their applications are still limited by poor cycling stability owing to soluble lithium polysulfide shuttling during battery operation. Avoiding shuttle effect is challenging but it is essential to avoid active material loss and prevent performance decay. We use an ultrathin layer of MoS 2 with thickness of 10–40 nm, which is 1–2 orders of magnitude thinner than conventional interlayers, for Li–S batteries to mitigate polysulfide shuttling. The MoS2 layer formed by exfoliated nanoflakes is deposited by the scalable liquid-based self-assembly method. With less than 1% of additional weight in the cathode, the MoS 2 interlayer with complete coverage inhibits polysulfide diffusion across the separator and therefore remarkably improves the battery performances. Reversible specific capacity reaches 1010 and 600 mA h g –1 at 0.5 and 2C rates, respectively, which decay slowly over 400 cycles (0.11% per cycle). Moreover, the MoS 2 films with high density of catalytic active flake edges enable high areal sulfur loading up to 10 mg cm –2 and areal capacity up to 9.7 mA h cm –2 at a current density of 3.2 mA cm –2 .

25 ENERGY STORAGE↗
DOE OSTI2018

Nanostructural and Electrochemical Evolution of the Solid-Electrolyte Interphase on CuO Nanowires Revealed by Cryogenic-Electron Microscopy and Impedance Spectroscopy

Battery performance is critically dependent on the nanostructure and electrochemical properties of the solid-electrolyte interphase (SEI)—a passivation film that exists on most lithium-battery anodes. However, knowledge of how the SEI nanostructure forms and its impact on ionic transport remains limited due to its sensitivity to transmission electron microscopy and difficulty in accurately probing the SEI impedance. Here, we track the voltage-dependent, stepwise evolution of the nanostructure and impedance of the SEI on CuO nanowires using cryogenic-electron microscopy (cryo-EM) and electrochemical impedance spectroscopy (EIS). In carbonate electrolyte, the SEI forms at 1.0 V vs Li/Li + as a 3 nm thick amorphous SEI and grows to 4 nm at 0.5 V; as the potential approaches 0.0 V vs Li/Li + , the SEI on the CuO nanowires forms an 8 nm thick inverted multilayered nanostructure in ethylene carbonate/diethyl carbonate (EC/DEC) electrolyte with 10 vol % fluoroethylene carbonate (FEC) and a mosaic nanostructure in EC/DEC electrolyte. Upon Li deposition, the total SEI thickness grows to 16 nm, and significant growth of the inner amorphous layer takes place in the inverted multilayered nanostructure, indicating that electrolyte permeates the SEI. Using a refined EIS methodology, we isolate the SEI impedance on Cu and find that the SEI nanostructure directly correlates to macroscopic Li-ion transport through the SEI. The inverted layered nanostructure decreases the interfacial impedance upon formation, whereas the mosaic nanostructure continually increases the interfacial impedance during growth. Furthermore these structural and electrochemical findings illustrate a more complete portrait of SEI formation and guide further improvements in engineered SEI.

25 ENERGY STORAGE↗
DOE OSTI2018

Practical Challenges and Future Perspectives of All-Solid-State Lithium-Metal Batteries

The fundamental understandings and technological innovations in lithium-ion batteries are essential for delivering high energy density, stable cyclability, and cost-effective energy storages with the growing demands in the applications of electrical vehicles and smart grid. Solid-state electrolytes (SSEs) are more promising than organic liquid electrolyte in terms of excellent safety in developing lithium-metal anode as well as other high-capacity cathode chemistries, such as sulfur and oxygen. Considerable efforts have been made to give birth to the superionic conductors with ionic conductivities higher than 10 –3 S cm –1 at room temperature. Furthermore, the high interfacial impedances from the poor compatibility of SSEs with electrodes limit their practical applications, which are discussed in this review. Furthermore, the recent advances and critical challenges for all-solid-state lithium-metal batteries based on the cathode materials of lithium-intercalation compounds, sulfur, and oxygen are overviewed, and their future developments are also prospected.

25 ENERGY STORAGE↗
DOE OSTI2018

Improving a Mg/S Battery with YCl 3 Additive and Magnesium Polysulfide

In the originally published version of this article, the SEM image in Figure 4B inadvertently features the wrong sample. The correct Figure 4B is shown below. The authors declare that this correction does not affect the description, interpretation, or the original conclusions of the manuscript. The authors regret the inconvenience this error may have caused.

25 ENERGY STORAGE↗
DOE OSTI2018

Reversible and selective ion intercalation through the top surface of few-layer MoS 2

Electrochemical intercalation of ions into the van der Waals gap of two-dimensional (2D) layered materials is a promising low-temperature synthesis strategy to tune their physical and chemical properties. It is widely believed that ions prefer intercalation into the van der Waals gap through the edges of the 2D flake, which generally causes wrinkling and distortion. Here we demonstrate that the ions can also intercalate through the top surface of few-layer MoS 2 and this type of intercalation is more reversible and stable compared to the intercalation through the edges. Density functional theory calculations show that this intercalation is enabled by the existence of natural defects in exfoliated MoS 2 flakes. Furthermore, we reveal that sealed-edge MoS 2 allows intercalation of small alkali metal ions (e.g., Li + and Na + ) and rejects large ions (e.g., K + ). Lastly, these findings imply potential applications in developing functional 2D-material-based devices with high tunability and ion selectivity.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Impact of lithiated cobalt oxide and phosphate nanoparticles on rainbow trout gill epithelial cells

Metal oxide and phosphate nanoparticles (NPs) are ubiquitous in emerging applications, ranging from energy storage to catalysis. Cobalt-containing NPs are particularly important, where their widespread use raises questions about the relationship between composition, structure, and potential for environmental impacts. To address this gap, we investigated the effects of lithiated metal oxide and phosphate NPs on rainbow trout gill epithelial cells, a model for environmental exposure. Lithium cobalt oxide (LCO) NPs significantly reduced cell viability at 10 µg/mL, while a 10-fold higher concentration of lithiated cobalt hydroxyphosphate (LCP) NPs was required to significantly reduce viability. Exposure to Li+ and Co2+ alone, at concentrations relevant to ion released from the NPs, did not reduce cell viability and minimally impacted reactive oxygen species (ROS) levels. Both LCO- and LCP-NPs were found within membrane-bound organelles. However, only LCP-NPs underwent rapid and complete dissolution in artificial lysosomal fluid. Unlike LCP-NPs, LCO-NPs significantly increased intracellular ROS, could be found within abnormal multilamellar bodies, and induced formation of intracellular vacuoles. Increased p53 gene expression, measured in individual cells, was observed at sub-toxic concentrations of both LCO- and LCP-NPs, implicating both in inductions of cellular damage and stress at concentrations approaching predicted environmental levels. Our results implicate the intact NP, not the dissolved ions, in the observed adverse effects and show that LCO-NPs significantly impact cell viability accompanied by increase in intracellular ROS and formation of organelles indicative of cell stress, while LCP-NPs have minimal adverse effects, possibly due to their rapid dissolution in acidic organelles.

Melby, Eric S.↗
DOE OSTI2018

An electrochemical thermal transistor

Abstract The ability to actively regulate heat flow at the nanoscale could be a game changer for applications in thermal management and energy harvesting. Such a breakthrough could also enable the control of heat flow using thermal circuits, in a manner analogous to electronic circuits. Here we demonstrate switchable thermal transistors with an order of magnitude thermal on/off ratio, based on reversible electrochemical lithium intercalation in MoS 2 thin films. We use spatially-resolved time-domain thermoreflectance to map the lithium ion distribution during device operation, and atomic force microscopy to show that the lithiated state correlates with increased thickness and surface roughness. First principles calculations reveal that the thermal conductance modulation is due to phonon scattering by lithium rattler modes, c -axis strain, and stacking disorder. This study lays the foundation for electrochemically-driven nanoscale thermal regulators, and establishes thermal metrology as a useful probe of spatio-temporal intercalant dynamics in nanomaterials.

42 ENGINEERING↗
DOE OSTI2018

Flexible and stable high-energy lithium-sulfur full batteries with only 100% oversized lithium

Lightweight and flexible energy storage devices are urgently needed to persistently power wearable devices, and lithium-sulfur batteries are promising technologies due to their low mass densities and high theoretical capacities. Here we report a flexible and high-energy lithium-sulfur full battery device with only 100% oversized lithium, enabled by rationally designed copper-coated and nickel-coated carbon fabrics as excellent hosts for lithium and sulfur, respectively. These metallic carbon fabrics endow mechanical flexibility, reduce local current density of the electrodes, and, more importantly, significantly stabilize the electrode materials to reach remarkable Coulombic efficiency of >99.89% for a lithium anode and >99.82% for a sulfur cathode over 400 half-cell charge-discharge cycles. Furthermore, the assembled lithium-sulfur full battery provides high areal capacity (3 mA h cm –2 ), high cell energy density (288 W h kg –1 and 360 W h L –1 ), excellent cycling stability (260 cycles), and remarkable bending stability at a small radius of curvature (<1 mm).

25 ENERGY STORAGE↗
DOE OSTI2018

Shell-Protective Secondary Silicon Nanostructures as Pressure-Resistant High-Volumetric-Capacity Anodes for Lithium-Ion Batteries

Here, the nanostructure design of a prereserved hollow space to accommodate 300% volume change of silicon anodes has created exciting promises for high-energy batteries. However, challenges with weak mechanical stability during the calendering process of electrode fabrication and poor volumetric energy density remain to be solved. Here we fabricated a pressure-resistant silicon structure by designing a dense silicon shell coating on secondary micrometer particles, each consisting of many silicon nanoparticles. The silicon skin layer significantly improves mechanical stability, while the inner porous structure efficiently accommodates the volume expansion. Such a structure can resist a high pressure of over 100 MPa and is well-maintained after the calendering process, demonstrating a high volumetric capacity of 2041 mAh cm–3. In addition, the dense silicon shell decreases the surface area and thus increases the initial Coulombic efficiency. With further encapsulation with a graphene cage, which allows the silicon core to expand within the cage while retaining electrical contact, the silicon hollow structure exhibits a high initial Coulombic efficiency and fast rise of later Coulombic efficiencies to >99.5% and superior stability in a full-cell battery.

25 ENERGY STORAGE↗