27 research outputs found
Fluoroethylene Carbonate-Based Electrolyte with 1 M Sodium Bis(fluorosulfonyl)imide Enables High-Performance Sodium Metal Electrodes
No full textSodium (Na) metal
anodes with stable electrochemical cycling have
attracted widespread attention because of their highest specific capacity
and lowest potential among anode materials for Na batteries. The main
challenges associated with Na metal anodes are dendritic formation
and the low density of deposited Na during electrochemical plating.
Here, we demonstrate a fluoroethylene carbonate (FEC)-based electrolyte
with 1 M sodium bis(fluorosulfonyl)imide (NaFSI) salt for the stable
and dense deposition of the Na metal during electrochemical cycling.
The novel electrolyte combination developed here circumvents the dendritic
Na deposition that is one of the primary concerns for battery safety
and constructs the uniform ionic interlayer achieving highly reversible
Na plating/stripping reactions. The FEC–NaFSI constructs the
mechanically strong and ion-permeable interlayer containing NaF and
ionic compounds such as Na2CO3 and sodium alkylcarbonates
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No full textDepartment of Energy Engineering (Battery Science and Technology)Aprotic electrolyte based lithium-oxygen batteries are of considerable interest due to its ultrahigh theoretical specific energy density (1675 mAh per gram of oxygen) against the present lithium-ion battery. In spite of the attractiveness of its high theoretical capacity, there is a number of drawbacks such as instability of electrochemical reaction of electrode and electrolytes. In order to overcome these parasitic reactions, significant efforts have been devoted to developing the key materials such as carbon-free air cathodes and high concentrated electrolytes. However, the CO2 evolution during the charging process and low ionic conductivity limit the ideal electrochemical reaction in aprotic electrolytes.
In this thesis, we applied the molten electrolyte based on nitrate-based electrolyte (Li/Na/K/Cs/Ca-NO3). The molten electrolyte, which has a eutectic point of 65???, has the advantages of high stability and high-temperature operation, thereby preventing detrimental solvent byproducts in lithium-oxygen batteries. We examined the Oxygen Evolution Reaction (OER) and Oxygen Reduction Reaction (ORR) on operating temperature using in situ pressure drop and gas analyses, Differential Electrochemical Mass Spectrometry (DEMS). Our results demonstrated that the Li2O2, a discharge product, formed a stable hexagonal morphology in the lithium-oxygen battery upon discharge process by scanning electron microscopy and X-ray diffraction techniques. Also, it leads to improved oxygen mobility at high temperature since a molten salt was used as the electrolyte in lithium-oxygen batteries. In addition, we found that kinetics are improved with increasing operating temperature in molten salt electrolyte cells.ope
Unsymmetrical fluorinated malonatoborate as an amphoteric additive for high-energy-density lithium- ion batteries
No full textHigh-capacity Si-embedded anodes and Li-rich cathodes are considered key compartments for post lithium-ion batteries with high energy densities. However, the significant volume changes of Si and the irreversible phase transformation of Li-rich cathodes prevent their practical application. Here we report lithium fluoromalonato(difluoro)borate (LiFMDFB) as an unusual dual-function additive to resolve these structural instability issues of the electrodes. This molecularly engineered borate additive protects the Li-rich cathode by generating a stable cathode electrolyte interphase (CEI) while simultaneously tuning the fluoroethylene carbonate (FEC)-oriented solid electrolyte interphase (SEI) on the Si-graphite composite (SGC) anode. The complementary electrolyte design utilizing both LiFMDFB and FEC exhibited an improved capacity retention of 85%, a high Coulombic efficiency of ???99.5%, and an excellent energy density of ???400 W h kg−1 in Li-rich/SGC full cells at a practical mass loading after 100 cycles. This dual-function additive approach offers a way to develop electrolyte additives to build a more favorable SEI for high-capacity electrodes
Biomimetic Superoxide Disproportionation Catalyst for Anti-Aging Lithium???Oxygen Batteries
No full textReactive oxygen species or superoxide (O2???), which damages or ages biological cells, is generated during metabolic pathways using oxygen as an electron acceptor in biological systems. Superoxide dismutase (SOD) protects cells from superoxide-triggered apoptosis by converting superoxide to oxygen and peroxide. Lithium???oxygen battery (LOB) cells have the same aging problems caused by superoxide-triggered side reactions. We transplanted the function of SOD of biological systems into LOB cells. Malonic acid-decorated fullerene (MA-C60) was used as a superoxide disproportionation chemocatalyst mimicking the function of SOD. As expected, MA-C60 as the superoxide scavenger improved capacity retention along charge/discharge cycles successfully. A LOB cell that failed to provide a meaningful capacity just after several cycles at high current (0.5 mA cm???2) with 0.5 mAh cm???2 cutoff survived up to 50 cycles after MA-C60 was introduced to the electrolyte. Moreover, the SOD-mimetic catalyst increased capacity, e.g., more than a 6-fold increase at 0.2 mA cm???2. The experimentally observed toroidal morphology of the final discharge product of oxygen reduction (Li2O2) and density functional theory calculation confirmed that the solution mechanism of Li2O2 formation, more beneficial than the surface mechanism from the capacity-gain standpoint, was preferred in the presence of MA-C60
Biodegradable ??-Chitin as a binder material for Li-O2 Battery
No full textHigh capacity Li-O2 batteries are of interest due to its exceptional theoretical energy density (3840 mAh/g) against the present Li-ion technology. To make Li-O2 cell more attractive secondary battery as future energy storage device, there are still number of drawbacks such as parasitic reaction on carbon cathodes, aprotic electrolyte decomposition, high over potential and low OER/ORR ratio. Although significant effort has been devote to develop the key materials such as a highly porous gold electrode, separators and organic electrolytes. Cathode binders are rarely studied because of their limited diversity. Here, we demonstrated the new type of biodegradable chitin material as a binder component for Li-O2 battery. The result clearly exhibited that the carbon cathode with chitin binder shows decent chemical stability toward oxygen species and exceptional electrochemical performances in Li-O2 battery
Interactive diversity promotes the evolution of cooperation in structured populations
No full textEvolutionary games on networks traditionally assume that each individual adopts an identical strategy to interact with all its neighbors in each generation. Considering the prevalent diversity of individual interactions in the real society, here we propose the concept of interactive diversity, which allows individuals to adopt different strategies against different neighbors in each generation. We investigate the evolution of cooperation based on the edge dynamics rather than the traditional nodal dynamics in networked systems. The results show that, without invoking any other mechanisms, interactive diversity drives the frequency of cooperation to a high level for a wide range of parameters in both well-mixed and structured populations. Even in highly connected populations, cooperation still thrives. When interactive diversity and large topological heterogeneity are combined together, however, in the relaxed social dilemma, cooperation level is lower than that with just one of them, implying that the combination of many promotive factors may make a worse outcome. By an analytical approximation, we get the condition under which interactive diversity provides more advantages for cooperation than traditional evolutionary dynamics does. Numerical simulations validating the approximation are also presented. Our work provides a new line to explore the latent relation between the ubiquitous cooperation and individuals' distinct responses in different interactions. The presented results suggest that interactive diversity should receive more attention in pursuing mechanisms fostering cooperation.National Natural Science Foundation (China) (Grants 61375120 and 61533001).China Scholarship Council (201406010195
Evaluation of Control Systems Sales and Receivables Accounts Receivable in Relation to Efficiency (Case Studies In PT Cahaya Sakti Multi Intraco)
No full textSales and accounts receivable control systems are important in the trading business. Control of accounts receivable is made to prevent the control of bad debts. Receivables need to be managed effectively and efficiently to the target of credit sales system is achieved.
The purpose of this study was to evaluate the system and controlling the sale of receivables in a manufacturing company do credit sales. Evaluation conducted to determine the system of sales and accounts receivable control of the company has been efficient or not, judging from the calculation of the ratios of receivables, such as age of accounts receivable, accounts receivable collection, accounts receivable turnover. Research on the author is in the PT Cahaya Sakti Multi Intraco.
The results showed that PT Cahaya Sakti Multi Intraco SOP has made a pretty good sales. Control accounts can not be controlled. To ensure the accounts have been inefficient or not, can be calculated through the age of accounts receivable, accounts receivable collection, accounts receivable turnover of the company. From the data described in the discussion section, look no relationship between the efficiency of sales to accounts receivable system. Although sales have increased, not by itself increase Arto, this is due to the average percentage increase in accounts receivable are much higher than the percentage increase in sales. Companies must implement control measures more appropriate accounts and tighter so that the average accounts receivable could be better than the target than the credit period granted to customers. Should at least be in accordance with the credit period granted to customers. (Credit Term)
Evolutionary dynamics of general group interactions in structured populations
No full textThe evolution of populations is influenced by many factors, and the simple classical models have been developed in a number of important ways. Both population structure and multiplayer interactions have been shown to significantly affect the evolution of important properties, such as the level of cooperation or of aggressive behavior. Here we combine these two key factors and develop the evolutionary dynamics of general group interactions in structured populations represented by regular graphs. The traditional linear and threshold public goods games are adopted as models to address the dynamics. We show that for linear group interactions, population structure can favor the evolution of cooperation compared to the well-mixed case, and we see that the more neighbors there are, the harder it is for cooperators to persist in structured populations. We further show that threshold group interactions could lead to the emergence of cooperation even in well-mixed populations. Here population structure sometimes inhibits cooperation for the threshold public goods game, where depending on the benefit to cost ratio, the outcomes are bistability or a monomorphic population of defectors or cooperators. Our results suggest, counterintuitively, that structured populations are not always beneficial for the evolution of cooperation for nonlinear group interactions
Environment-Invariant Curriculum Relation Learning for Fine-Grained Scene Graph Generation
No full textThe scene graph generation (SGG) task is designed to identify the predicates
based on the subject-object pairs.However,existing datasets generally include
two imbalance cases: one is the class imbalance from the predicted predicates
and another is the context imbalance from the given subject-object pairs, which
presents significant challenges for SGG. Most existing methods focus on the
imbalance of the predicted predicate while ignoring the imbalance of the
subject-object pairs, which could not achieve satisfactory results. To address
the two imbalance cases, we propose a novel Environment Invariant Curriculum
Relation learning (EICR) method, which can be applied in a plug-and-play
fashion to existing SGG methods. Concretely, to remove the imbalance of the
subject-object pairs, we first construct different distribution environments
for the subject-object pairs and learn a model invariant to the environment
changes. Then, we construct a class-balanced curriculum learning strategy to
balance the different environments to remove the predicate imbalance.
Comprehensive experiments conducted on VG and GQA datasets demonstrate that our
EICR framework can be taken as a general strategy for various SGG models, and
achieve significant improvements.Comment: ICCV2023. arXiv admin note: text overlap with arXiv:2203.11654 by
other author
One step memory of group reputation is optimal to promote cooperation in public goods games
No full textIndividuals' change of social ties has been observed to promote cooperation under specific mechanism, such as success-driven or expectation-driven migration. However, there is no clear criterion or information from players' instinctive memory or experience for them to consult as they would like to change their social ties. For the first time we define the reputation of a group based on individual's memory law. A model is proposed, where all players are endowed with the capacity to adjust interaction ambience involved if the reputation of their environment fails to satisfy their expectations. Simulation results show that cooperation decays as the increase of player's memory depth and one step memory is optimal to promote cooperation, which provides a potential interpretation for that most species memorize their reciprocators over very short time scales. Of intrigue is the result that cooperation can be improved greatly at an optimal interval of moderate expectation. Moreover, cooperation can be established and stabilized within a wide range of model parameters even when players choose their new partners randomly under the combination of reputation and group switching mechanisms. Our work validates the fact that individuals' short memory or experience within a multi-players group acts as an effective ingredient to boost cooperation. Copyright (c) EPLA, 2013http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000323984500007&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Physics, MultidisciplinarySCI(E)14ARTICLE3null10
