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•High pressure (greater than 3 MPa) on the electrode causes deterioration.•An anode failure mode caused by high pressure was established.•Severe pressure blocks electrolyte ion ...conduction in the electrode.•High polarization due to pressure causes Li metal deposition.
Pressure on electrodes in cells is crucial for improving their active material density and electronic conductivity. A single-layer pouch cell (60 mAh) was fabricated to study the electrochemical effects of external pressures ranging from 0 to 3 MPa. The high-pressure cell at 3 MPa presented poor capacity retention owing to Li plating and pore-clogging on the graphite electrode. However, the optimized pressed cell did not hinder Li-ion transport in the graphite anode and underwent 200 cycles with 82 % capacity retention. External pressure impacts the contact between the electrodes and electrolyte; however, excessive pressure makes it difficult to supplement Li ions from the electrolyte into the graphite anode, resulting in increased polarization, electrolyte side reactions, and Li-metal deposition.
The binder is an essential component in determining the structural integrity and ionic conductivity of Li‐ion battery electrodes. However, conventional binders are not sufficiently conductive and ...durable to be used with solid‐state electrolytes. In this study, a novel system is proposed for a Li secondary battery that combines the electrolyte and binder into a unified structure, which is achieved by employing para‐phenylenediamine (pPD) moiety to create supramolecular bridges between the parent binders. Due to a partial crosslinking effect and charge‐transferring structure of pPD, the proposed strategy improves both the ionic conductivity and mechanical properties by a factor of 6.4 (achieving a conductivity of 3.73 × 10−4 S cm−1 for poly(ethylene oxide)‐pPD) and 4.4 (reaching a mechanical strength of 151.4 kPa for poly(acrylic acid)‐pPD) compared to those of conventional parent binders. As a result, when the supramolecules of pPD are used as a binder in a pouch cell with a lean electrolyte loading of 2 µL mAh−1, a capacity retention of 80.2% is achieved even after 300 cycles. Furthermore, when it is utilized as a solid‐state electrolyte, an average Coulombic efficiency of 99.7% and capacity retention of 98.7% are attained under operations at 50 °C without external pressure or a pre‐aging process.
A binder‐electrolyte integrated solid‐state battery (SSB) system exploiting a new synergistic ionic conduction mechanism through supramolecular bridging with p‐phenylenediamine molecules is proposed. As such, the contact issue in SSBs can be minimized, enabling the implementation of high loading SSB systems. These achievements are expected to provide a strong foundation for the development of SSB systems with exceptional energy density.
Enhancing the incorporation of highly accessible Lewis acid sites on fillers is crucial for achieving exceptional electrochemical performances in composite solid electrolytes (CSEs). Typically, they ...can provide a vital role in improving CSEs performance by interacting with lithium salt anions and the polymer matrix through Lewis acid–base interactions. To address this technological need, in this work, a novel filler of bimetallic UiO‐66(Zr/Ti)‐ionic liquid grafted composite (BUIL) is developed to enhance its inherent electrochemical properties. The bimetallic structure, which introduces structural defects, along with the grafted ionic liquid, abundantly creates accessible Lewis acid sites. This modification of the intrinsic Lewis acidity results in a remarkable enhancement of CSEs performances. The incorporation of BUIL in CSEs leads to a significant increase in ionic conductivity (0.458 mS cm−1) and lithium‐ion transference number (0.668) at 30 °C. Furthermore, LiFePO4/CSEs/Li cells demonstrate a high specific capacity of 148.5 mAh g−1 at a current density of 1 C, which is stably maintained over 880 cycles. Overall, the innovative synthetic approach in producing multifunctional fillers for CSEs shows strong potential for enhancing the performance of advanced lithium metal batteries.
A bimetallic UiO‐66(Zr/Ti)‐ionic liquid grafted (BUIL) filler is developed to enhance the effectiveness of Lewis acid–base interactions as a filler. By incorporating the bimetallic structure and the grafted ionic liquid, the BUIL filler provides a greater number of accessible Lewis acid sites. As a result, the BUIL filler significantly increased the dissociation of lithium salt and greatly reduced the crystallinity of the polymer matrix, eventually improving the performance of composite solid electrolytes.
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The safety of Li-ion batteries (LIBs) has long been a critical issue for their widespread application. The ever-increasing requirements for large-scale applications such as electric ...vehicles and stationary energy storage systems have spurred great interest in ensuring high standards of safety, which requires an understanding of the thermal runaway features of cells and modules. In this study, we evaluated the thermal runaway of pouch-type LIB cells with cell capacities of 33–3300mAh by using accelerated rate calorimetry (ARC) and lab-made hotbox ramping measurements. The large-capacity cells (1000 and 3300mAh) exhibited distinct stage behaviors of the self-heating rate in the ARC profiles and large exothermic reactions accompanied by an abrupt open-circuit voltage drop (internal short circuit) in the ramping test. The small-capacity cell (33mAh) showed an incomplete thermal runaway feature. These findings were attributed to the large proportion of inactive components relative to the active components, which is discussed in terms of the heat capacity. The data sensitivity factor is also suggested as a reliable measure of thermal runaway evaluation of LIB cells.
Abstract Despite the proposal of numerous advanced materials for batteries, there remains a notable lack of comprehensive assessment protocols that facilitate direct comparisons between ...laboratory-scale research and industrial trials. Here, we introduce a standardized method coined as extremely lean electrolytic testing (ELET), designed as a uniform framework for evaluating the performance across different battery systems. This approach replicates the cycling behaviour of larger pouch cells within the more manageable format of coin cells under ELET conditions. Employing ELET, we develop quantitative models to create contour maps that standardize cell performance metrics. To demonstrate the ELET efficacy, we explore the mitigation of electrolyte decomposition in lithium-ion batteries through applying polydopamine coatings on silicon/carbon composite anodes, achieving a 150% decrease in electrolyte decomposition compared to uncoated ones. Additionally, we employ the ELET method to compare the performance of various post-secondary and commercial batteries, demonstrating its full utility in battery evaluation.
Introduction:
High resolution vessel wall MRI (VW-MRI) has enabled to characterize intracranial atherosclerosis (ICAS). We studied to identify the factors for enhancement of ICAS in VW-MRI in ...patients with acute ischemic stroke.
Methods:
Consecutive patients with acute ischemic stroke or TIA who underwent VW-MRI between January 2017 and December 2017 were included. Enhancement on VW-MRI was defined as an increase in intensity on contrast-enhanced T1-weighted sequence. We compared the clinical and the radiologic findings between patients with wall enhancement and those without wall enhancement.
Results:
Of the 48 patients with ICAS, 28 patients revealed enhancement on VW-MRI. Patients with enhancement were more likely to have severe stenotic lesions and higher levels of total cholesterol, triglycerides, low-density cholesterol, Apo (b), and Apo (b)/Apo (a) lipoprotein ratio (
p
< 0.05). Multivariable analysis demonstrated that total cholesterol (OR: 5.378, 95% CI, 1.779–16.263), triglycerides (OR: 3.362, 95% CI, 1.008–11.209), low density lipoprotein cholesterol (OR: 4.226, 95% CI, 1.264–14.126), Apo (b) lipoprotein (OR: 3639.641, 95% CI, 17.854–741954.943) levels, and Apo (b)/Apo (a) lipoprotein ratio (OR, 65.514; 95% CI, 1.131–3680.239) were independently associated with enhancement of ICAS. High-density lipoprotein cholesterol and Apo (a) lipoprotein levels were not significantly different between the patients with wall enhancement and those without wall enhancement.
Conclusions:
The presence and severity of enhancement of ICAS was significantly associated with dyslipidemic conditions. These results suggest that strict lipid modification should be achieved for the management of ICAS.
In a dynamically changing environment, the manager of a maintenance and remodeling (M/R) program is confronted with an increasing complexity of coordinating and cooperating multi-resource constrained ...multiple projects. Uncertainty and interdependence are sources of the complexity, and cause an internal disruption of an activity and chain reactions of disturbance propagation that deteriorate the stability and manageability of the program. This paper evaluates previous endeavors to apply production control and management techniques to the construction industry, and investigates the possibility of applying other production concepts and theories to organizational program management. In particular, this paper proposes a buffer allocation strategy by which periodic buffers are allocated in the flows of program constraint resources (PCRs) to stabilize a master construction schedule instead of protecting individual activities. Comparative experiments by Monte Carlo simulations illustrate better performance of the proposed strategy in terms of program goals: productivity, flexibility, and long-term stability.
► In this study, we suggested an effective buffer allocation strategy to stabilize a master construction schedule. ► The suggested strategy transforms the internal uncertainty of activity disturbance to stability and manageability of the multiple M/R projects. ► From the results of the Monte Carlo experiments, we concluded that the suggested buffer allocation strategy performed better than the IBA (Individual buffer allocation) in terms of average completion days and complete lateness.
AbstractOil prices may continue to rise indefinitely until alternative fossil fuels or renewable energies are commercialized. In this sense, general contractors who have the responsibility of ...delivering construction materials should select an optimized alternative that needs the least oil among the various combinations of truck types of logistic companies, routes, and suppliers. In this context, the objective of this paper was to develop a genetic-algorithm (GA)-based fuel-efficient transfer path selection model (GAFETPSM) for delivering construction materials with minimum fuel consumption. A GAFETPSM considers the truck type, road type, and fuel-efficiency variation by load, and the constraints of capacity, number of trucks, and total load to be delivered. Finally, a case study showed that GAFETPSM is superior to the simulated-annealing (SA)-based model in terms of fuel consumption in delivering the same weight of construction materials. It is expected that GAFETPSM could contribute to reduce the carbon-dioxide emission by using less oil.
•Solvent-free electrode manufacturing process using polytetrafluoroethylene binder.•Dry-processed graphite anodes with high loading of active material.•Low tortuosity of dry-processed anode to enable ...better C-rate capability.•Excellent capacity retention during cycle life.•Preventing the lithium metal deposition during high C-rate charging.
The electric vehicle (EV) market now requires advanced graphite anodes that can enable both high loading and quick charging. However, meeting these requirements simultaneously is challenging because of uneven electrochemical reactions and Li-plating on the surface of graphite anodes during fast-charging. In this study, high current density graphite anodes (≈6 mA cm−2) were fabricated through a solvent-free dry-electrode process using homogeneously dispersed polytetrafluoroethylene fibrils (2.0 wt% in electrode). This approach significantly improved the mechanical properties and electrochemical performance of graphite anodes during charge/discharge cycles. Dry-processed graphite anodes outperformed conventional wet-processed electrodes in terms of rate performance and capacity retention. Furthermore, LiNi0.6Co0.2Mn0.2O2 (NCM)/graphite coin-type full cells are rapidly charged at a 3C-rate to induce Li-plating on the graphite surface. Thus, dry-processed graphite anodes exhibited less Li-plating than wet-processed anodes, implying that dry-processed electrodes are capable of fast-charging even under high-loading conditions. In addition, dry-processed graphite anodes retain 88.2 % capacity retention after 300 cycles, indicating a stable full-cell operation. Consequently, this research highlights the dry-electrode process as an innovative technique for electrode manufacturing, with the potential to reduce battery production costs while improving electrochemical performance during fast-charging.
In this study, a new process for preparation of CdS/polymer nanocomposite films using a new amphiphilic oligomer chain (Urethane Acrylate Nonionomer: UAN) is presented. UAN chains have hydrophilic ...polyethylene oxide segments and polypropylene oxide-based hydrophobic segments as part of the same backbone. In addition, these chains also have reactive vinyl groups at their hydrophobic segments. For the preparation of CdS nano-colloid solutions, UAN chains acted as a stabilizer for CdS nanoparticles dispersed in a solvent. For the fabrication of CdS/polymer nanocomposite films, UAN chains in CdS nano-colloid solutions were polymerized through reactions between their vinyl groups, resulting in the formation of CdS nanoparticle dispersed films swollen by the solvent. The nature of the solvent used strongly influenced the size of the CdS nanoparticles, which was confirmed by UV absorption spectra, PL emission spectra and TEM images. Smaller sized CdS nanoparticles were formed in higher polar solvents such as DMAc and methanol, which can be explained by the higher solubility of UAN chains and the more effective dissociation and stabilization of cadmium salts and CdS nanoparticles by UAN chains in the polar solvent.
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