scholarly journals Towards an Understanding of the SEI Formation and Lithium Preferential Plating on Copper

2020 ◽  
Author(s):  
Svetlana Menkin ◽  
Christopher A. O'Keefe ◽  
Anna B. Gunnarsdottir ◽  
Sunita Dey ◽  
Federico Pesci ◽  
...  
Keyword(s):  
Coulombic Efficiency ◽  
Current Collector ◽  
Practical Implementation ◽  
Reaction Products ◽  
Interface Composition ◽  
Safety Issues ◽  
Air Atmosphere ◽  
Ionic Conducting ◽  
Potential Safety ◽  
Rest Time

<div>‘Anode-free’ batteries present a significant advantage due to their substantially higher energy density and ease of assembly in a dry air atmosphere. However, potential safety issues due to lithium (Li) dendrite growth rather than smooth Li metal plating on the Cu current collector, and low cycling coulombic efficiency during their operation are delaying their practical implementation. To understand the interplay between Cu surface chemistry and the morphology of the plated Li, we studied the SEI formation on Cu and the preferential plating of Li using ssNMR, insitu NMR, XPS, ToF-SIMS, SEM and EIS.</div><div>A native interphase layer (N-SEI) is formed instantaneously on copper current collectors upon their immersion in LiPF6-based electrolyte. The nature of the N-SEI is affected by the copper interface composition, homogeneity and formation time. In addition to the typical SEI components, it contains CuxO and its reaction products. Parasitic semi-reversible electrochemical reactions were observed with in-situ NMR measurements of Li plating efficiency during the first five cycles. The morphology of the plated lithium is affected by the SEI homogeneity, current density and rest time in the electrolyte before the plating. The preferential plating of Li is governed by the distribution of ionic conducting compounds rather than electronic conducting compounds.</div>

scholarly journals Towards an Understanding of the SEI Formation and Lithium Preferential Plating on Copper

2020 ◽  
Author(s):  
Svetlana Menkin ◽  
Christopher A. O'Keefe ◽  
Anna B. Gunnarsdottir ◽  
Sunita Dey ◽  
Federico Pesci ◽  
...  
Keyword(s):  
Coulombic Efficiency ◽  
Current Collector ◽  
Practical Implementation ◽  
Reaction Products ◽  
Interface Composition ◽  
Safety Issues ◽  
Air Atmosphere ◽  
Ionic Conducting ◽  
Potential Safety ◽  
Rest Time

<div>‘Anode-free’ batteries present a significant advantage due to their substantially higher energy density and ease of assembly in a dry air atmosphere. However, potential safety issues due to lithium (Li) dendrite growth rather than smooth Li metal plating on the Cu current collector, and low cycling coulombic efficiency during their operation are delaying their practical implementation. To understand the interplay between Cu surface chemistry and the morphology of the plated Li, we studied the SEI formation on Cu and the preferential plating of Li using ssNMR, insitu NMR, XPS, ToF-SIMS, SEM and EIS.</div><div>A native interphase layer (N-SEI) is formed instantaneously on copper current collectors upon their immersion in LiPF6-based electrolyte. The nature of the N-SEI is affected by the copper interface composition, homogeneity and formation time. In addition to the typical SEI components, it contains CuxO and its reaction products. Parasitic semi-reversible electrochemical reactions were observed with in-situ NMR measurements of Li plating efficiency during the first five cycles. The morphology of the plated lithium is affected by the SEI homogeneity, current density and rest time in the electrolyte before the plating. The preferential plating of Li is governed by the distribution of ionic conducting compounds rather than electronic conducting compounds.</div>

scholarly journals Fine-grained lineage for safer notebook interactions

2021 ◽  
Vol 14 (6) ◽  
pp. 1093-1101
Author(s):  
Stephen Macke ◽  
Hongpu Gong ◽  
Doris Jung-Lin Lee ◽  
Andrew Head ◽  
Doris Xin ◽  
...  
Keyword(s):  
Static Analysis ◽  
Intermediate State ◽  
Data Science ◽  
Safety Issues ◽  
Fine Grained ◽  
Potential Safety

Computational notebooks have emerged as the platform of choice for data science and analytical workflows, enabling rapid iteration and exploration. By keeping intermediate program state in memory and segmenting units of execution into so-called "cells", notebooks allow users to enjoy particularly tight feedback. However, as cells are added, removed, reordered, and rerun, this hidden intermediate state accumulates, making execution behavior difficult to reason about, and leading to errors and lack of reproducibility. We present nbsafety, a custom Jupyter kernel that uses runtime tracing and static analysis to automatically manage lineage associated with cell execution and global notebook state. nbsafety detects and prevents errors that users make during unaided notebook interactions, all while preserving the flexibility of existing notebook semantics. We evaluate nbsafety's ability to prevent erroneous interactions by replaying and analyzing 666 real notebook sessions. Of these, nbsafety identified 117 sessions with potential safety errors, and in the remaining 549 sessions, the cells that nbsafety identified as resolving safety issues were more than 7X more likely to be selected by users for re-execution compared to a random baseline, even though the users were not using nbsafety and were therefore not influenced by its suggestions.

scholarly journals Fluorine-donating electrolytes enable highly reversible 5-V-class Li metal batteries

2018 ◽  
Vol 115 (6) ◽  
pp. 1156-1161 ◽  
Author(s):  
Liumin Suo ◽  
Weijiang Xue ◽  
Mallory Gobet ◽  
Steve G. Greenbaum ◽  
Chao Wang ◽  
...  
Keyword(s):  
Coulombic Efficiency ◽  
High Surface ◽  
Solid Electrolyte Interphase ◽  
Current Collector ◽  
Wide Bandgap ◽  
Fluorine Concentration ◽  
Metal Anode ◽  
Key Factor ◽  
Significant Loading ◽  
Fluoroethylene Carbonate

Lithium metal has gravimetric capacity ∼10× that of graphite which incentivizes rechargeable Li metal batteries (RLMB) development. A key factor that limits practical use of RLMB is morphological instability of Li metal anode upon electrodeposition, reflected by the uncontrolled area growth of solid–electrolyte interphase that traps cyclable Li, quantified by the Coulombic inefficiency (CI). Here we show that CI decreases approximately exponentially with increasing donatable fluorine concentration of the electrolyte. By using up to 7 m of Li bis(fluorosulfonyl)imide in fluoroethylene carbonate, where both the solvent and the salt donate F, we can significantly suppress anode porosity and improve the Coulombic efficiency to 99.64%. The electrolyte demonstrates excellent compatibility with 5-V LiNi0.5Mn1.5O4 cathode and Al current collector beyond 5 V. As a result, an RLMB full cell with only 1.4× excess lithium as the anode was demonstrated to cycle above 130 times, at industrially significant loading of 1.83 mAh/cm2 and 0.36 C. This is attributed to the formation of a protective LiF nanolayer, which has a wide bandgap, high surface energy, and small Burgers vector, making it ductile at room temperature and less likely to rupture in electrodeposition.

Crowd Planning and Preparation

2019 ◽  
Author(s):  
William O’Toole ◽  
Dr Stephen Luke ◽  
Travis Semmens ◽  
Dr Jason Brown ◽  
Andrew Tatrai
Keyword(s):  
Life Safety ◽  
Contingency Planning ◽  
Practical Implementation ◽  
Military Operations ◽  
Safety Issues ◽  
Crowd Management ◽  
Planning Methods ◽  
Risk Areas ◽  
Two Phases ◽  
And Control

This chapter reviews planning methods and practices. Significant work has been published and used for long periods on planning methods. Preplanning is essential due to the life safety factors that a crowd can develop in situ. Planning can be considered in two phases. Information and background planning essential to communicate facts and identify risk areas in crowd management and operational planning. This then provides resourcing and contingency planning once the operation is in place. Like military operations both phases are important, however in many crowd situations operational and contingency planning is given less scrutiny. This is because the plans are normally scrutinised by authorities, councils, government, venue or land owners and they are more comfortable with pre-information type plans that inform them of the context background and communication flows. How the crowds are managed by security contractors is not usually an area they are experienced in, hence less attention is paid to these areas. The aim of this chapter is to provide enough knowledge for all event stakeholders to review and discuss practical implementation issues in security deployment and control. Planning and preparation requires an increased focus for crowd management because the emerging behaviour from the collective requires more options to be considered and prepared for. As crowds can cause life safety issues and because agents and systems can interact to exaggerate interactions and responses quickly, preparation and contingency planning is vital. Crowd risk assessments have to be conducted to understand and communicate the magnitude of the problems that can occur. If the consequences of the crowd activity are significant to the risk appetite of the organiser then response methods and measures should be developed and implemented. An example of this would be preparing additional signage, barriers and guards to divert pedestrians away or around potential bottlenecks when the flow becomes too congested.

Disaster Prevention Strategies: A Study on Underground Commercial Street

2016 ◽  
Vol 41 (3) ◽  
pp. 38-43
Author(s):  
Qin Yan ◽  
Yin Pan
Keyword(s):  
Open Space ◽  
Underground Space ◽  
Disaster Prevention ◽  
Prevention Strategies ◽  
Air Defense ◽  
Safety Issues ◽  
Potential Safety ◽  
Evacuation Routes ◽  
The City ◽  
Commercial Street

Planning for underground spaces has become an effective way to use central areas in cities given the steady economic growth in China. The development of underground spaces in mountainous cities has satisfied the needs of the diversification of the city commercial areas and pedestrian movement. Safety issues exist because these underground spaces were originally used for civil air defense. This study was based on the underground commercial street in Chongqing, which is a typical mountainous city. Based on the results of combined fieldwork and survey, this paper summarized current safety issues, which include the not-fully-open exit, the imbalanced exit location, blocked evacuation routes, and the poor awareness of the potential safety issues. This paper proposed a framework of the safety factors for the underground space and synopsized prevention strategies that are specific to potential disasters in the underground environment. The framework comprises ensuring that the exits are fully open, the underground corridors are kept unblocked, the open space on the street is increased for disaster prevention, and equipment security is maintained and managed. At last, This paper summarized disaster prevention strategies, which include ensuring unimpeded exits, balancing the locations of the exits, avoiding blocks, increasing the disaster prevention square area in the underground space, maintaining and managing the security of the equipment.

Generic Issues Program Overview and Update

2008 ◽  
Author(s):  
Jack W. Foster ◽  
John V. Kauffman
Keyword(s):  
Effective Means ◽  
Cost Effective ◽  
Nuclear Regulatory Commission ◽  
The United States ◽  
The Body ◽  
Safety Issues ◽  
Potential Safety ◽  
Construction Operation ◽  
Regulatory Commission ◽  
Available Information

The United States Nuclear Regulatory Commission (NRC) has a Generic Issues Program (GIP) to address Generic Issues (GI). A GI is defined as “a regulatory matter involving the design, construction, operation, or decommissioning of several, or a class of, NRC licensees or certificate holders that is not sufficiently addressed by existing rules, guidance, or programs.” This rather legalistic definition has several practical corollaries: First, a GI must involve safety. Second, the issue must involve at least two plants, or it would be a plant-specific issue rather than a GI. Third, the potential safety question must not be covered by existing regulations and guidance (compliance). Thus, the effect of a GI is to potentially change the body of regulations and associated guidance (e.g., regulatory guides). The GIP was started in 1976, thus it is a relatively mature program. There have been approximately 850 issues processed by the program to date. More importantly, even after 30 years, new GIs continue to be proposed. The entire set of Generic Issues (GIs) is updated annually in NUREG-0933, “A Prioritization of Generic Safety Issues.” GIs tend to involve complex questions of safety and regulation. The efficient and effective means of addressing these issues is very important for regulatory effectiveness. If an issue proves to pose a genuine, significant safety question, then swift, effective, enforceable, and cost-effective action needs to be taken. Conversely, if an issue is of little safety significance, the issue should be dismissed in an expeditious manner, avoiding unnecessary expenditure of resources and regulatory burden or uncertainty. This paper provides an overview of the 5-stage program, from identification through the regulatory assessment stage. The paper also includes a discussion of the program’s seven criteria, sources of proposed GIs, recent improvements, publicly available information, historical performance, and status of current GIs.

scholarly journals Potential Adverse Drug Events and Drug–Drug Interactions with Medical and Consumer Cannabidiol (CBD) Use

2019 ◽  
Vol 8 (7) ◽  
pp. 989 ◽  
Author(s):  
Joshua Brown ◽  
Almut Winterstein
Keyword(s):  
Drug Interactions ◽  
Sleep Disturbances ◽  
Adverse Drug Events ◽  
Alternative Therapy ◽  
Consumer Products ◽  
Medical Cannabis ◽  
Biological Targets ◽  
Safety Issues ◽  
Treatment Regimens ◽  
Potential Safety

Cannabidiol (CBD) is ubiquitous in state-based medical cannabis programs and consumer products for complementary health or recreational use. CBD has intrinsic pharmacologic effects and associated adverse drug events (ADEs) along with the potential for pharmacokinetic and pharmacodynamic drug–drug interactions (DDIs). Given CBD use among patients with complex conditions and treatment regimens, as well as its expanded consumer use, awareness of potential safety issues with CBD is needed. Prescribing information for federally approved products containing CBD were reviewed. Data on ADEs and DDIs were extracted and summarized. Nearly one-half of CBD users experienced ADEs, which displayed a general dose-response relationship. Common ADEs include transaminase elevations, sedation, sleep disturbances, infection, and anemia. Given CBD effects on common biological targets implicated in drug metabolism (e.g., CYP3A4/2C19) and excretion (e.g., P-glycoprotein), the potential for DDIs with commonly used medication is high. General clinical recommendations of reducing substrate doses, monitoring for ADEs, and finding alternative therapy should be considered, especially in medically complex patients. CBD is implicated as both a victim and perpetrator of DDIs and has its own ADE profile. These effects should be considered in the risk-benefit assessment of CBD therapy and patients and consumers made aware of potential safety issues with CBD use.

scholarly journals The Influence of Micro-Structured Anode Current Collectors in Combination with Highly Concentrated Electrolyte on the Coulombic Efficiency of In-Situ Deposited Li-Metal Electrodes with Different Counter Electrodes

Batteries ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 20 ◽  
Author(s):  
Fabian Heim ◽  
Tina Kreher ◽  
Kai Peter Birke
Keyword(s):  
Coulombic Efficiency ◽  
Chemical Separation ◽  
Current Collector ◽  
Cycle Performance ◽  
Zinc Alloy ◽  
Counter Electrodes ◽  
Current Collectors ◽  
Copper Zinc ◽  
Two Measures

This paper compares and combines two common methods to improve the cycle performance of lithium metal (Li) electrodes. One technique is to establish a micro-structured current collector by chemical separation of a copper/zinc alloy. Furthermore, the use of a highly concentrated ether-based electrolyte is applied as a second approach for improving the cycling behavior. The influence of the two measures compared with a planar current collector and a 1 M concentrated carbonate-based electrolyte, as well as the combination of the methods, are investigated in test cells both with Li and lithium nickel cobalt manganese oxide (NCM) as counter electrodes. In all cases Li is in-situ plated onto the micro-structured current collectors respectively a planar copper foil without presence of any excess Li before first deposition. In experiments with Li counter electrodes, the effect of a structured current collector is not visible whereas the influence of the electrolyte can be observed. With NCM counter electrodes and carbonate-based electrolyte structured current collectors can improve Coulombic efficiency. The confirmation of this outcome in experiments with highly concentrated ether-based electrolyte is challenging due to high deviations. However, these results indicate, that improvements in Coulombic efficiency achieved by structuring the current collector’s surface and using ether-based electrolyte do not necessarily add up, if both methods are combined in one cell.

A Model-Based Failure Identification and Propagation Framework for Conceptual Design of Complex Systems

2012 ◽  
Author(s):  
Hoda Mehrpouyan ◽  
David C. Jensen ◽  
Christopher Hoyle ◽  
Irem Y. Tumer ◽  
Tolga Kurtoglu
Keyword(s):  
System Architecture ◽  
Early Identification ◽  
Mitigation Strategies ◽  
Functional Requirements ◽  
Environmental Disturbances ◽  
Safety Issues ◽  
Model Based ◽  
Potential Safety ◽  
Failure Propagation ◽  
Failure Identification

In this paper, a model-based failure identification and propagation (MFIP) framework is introduced for early identification of potential safety issues caused by environmental disturbances and subsystem failures within a complex avionic system. The MFIP framework maps hazards and vulnerability modes to specific components in the system and analyzes failure propagation paths. Block definition diagrams (BDD) are used to represent system functional requirements in the form of demonstrating the relationships between various requirements, their associations, generalizations, as well as dependencies. These concept models help to identify hazardous factors and the relationships through which their detrimental effects are transferred through-out the proposed system architecture. As such, the approach provides the opportunity to reduce costs associated with redesign and provide important information on design viability. Using this technique, designers can examine the impacts of environmental and subsystem risks on the overall system during the early stages of design and develop hazard mitigation strategies.

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