Search Results (131)

In the framework of mean-field approximation, the influence of social contacts on the spread of an epidemic in a population of constant size is discussed. The key feature of the proposed model is that it includes two infection–transmission mechanisms depending on the physical nature of the contact between people. We separate the transfer mechanism related directly to the movement of people (the so-called transport processes) from the one occurring when the relative velocity between individuals is negligible (the so-called social contacts). Based on the developed physicochemical analogy, this approach allows us to derive, in a unified manner, expressions for the rate constants of infection–transmission of different nature. The resulting transmission rate constants are used to modify the SEIS model to examine the influence of social activity on the formation of an endemic equilibrium in the population under consideration. The frequency of social contacts is estimated using Dunbar’s approach and a direct statistical calculation based on the binomial distribution. These relations are then used to discuss the formation of quasi-stationary states, which can be interpreted as endemic equilibria. A qualitative analysis of the resulting dynamical regimes is carried out. The necessary conditions for the existence of this equilibrium, depending on both social and medical–biological factors, are also derived. The analytical results are illustrated by numerical simulations. The present results should be interpreted as a necessary step to establish a link between purely transport and social mechanisms of epidemic development. Full article

Graphite remains the predominant negative electrode material in commercial lithium-ion batteries (LIBs); however, its practical performance is increasingly limited by interface-driven degradation rather than bulk intercalation. This review examines the interconnected electrochemical, mechanical, and safety challenges associated with uncoated and coated graphite, with particular focus on how solid electrolyte interphase (SEI) formation and evolution deplete cyclable lithium, increase interfacial resistance, and induce polarization that leads to lithium plating and dendritic growth during rapid charging and low-temperature operation. Electrolyte and solvation engineering are highlighted as coating-free strategies to mitigate these issues by reducing Li⁺ desolvation barriers and directing interphase chemistry toward thinner, more ion-conductive, fluorinated SEI films that inhibit plating while maintaining high-rate capability. Coated graphite approaches are compared, including carbon, inorganic, and polymer coatings that function as artificial SEI layers to minimize direct electrolyte contact, stabilize interphase composition, and enhance mechanical durability. Key trade-offs are discussed, including decreased first-cycle coulombic efficiency (FCCE) due to increased surface area, transport limitations arising from excessively thick coatings, nonuniform coverage leading to local current hotspots, and side reactions induced by the coatings. The discussion is further extended to sodium and potassium systems, explaining how larger ion sizes, unfavorable thermodynamics, and significant lattice expansion hinder their insertion into graphite, and summarizing strategies such as interlayer expansion and alternative carbon architectures that improve reversibility for larger ions. This review concludes that achieving durable, safe, and fast-charging graphite electrodes requires an integrated interfacial design that combines optimized graphite morphology, electrode architecture, and electrolyte chemistry. Full article

This study investigates the influence of a battery’s formation process on its long-term performance and proposes a management strategy that integrates formation optimization with controlled over-discharge recovery. The results indicate that the initial formation is a critical prerequisite determining the effectiveness of subsequent capacity recovery. The proposed controlled over-discharge strategy aims to “reset” the battery degradation process by controllably oxidizing and decomposing the aged SEI and in situ reconstructing a new SEI. The efficacy of this strategy highly depends on the SEI substrate characteristics determined by the initial formation: different formation processes result in initial SEI layers with significant differences in structure and composition, which directly affect their reconstructability during over-discharge and the upper limit of performance recovery. Experiments confirm that batteries subjected to an optimized formation process achieve a maximum SOH improvement of 3.11% and a maximum cycle life extension of 19.7%. In contrast, batteries with a non-optimized formation show only a 2.01% SOH improvement and a 12.8% life extension. Therefore, optimizing the formation process is not only fundamental for enhancing the initial battery state but also a necessary prerequisite for fully unleashing the potential of subsequent recovery strategies. This study provides theoretical and technical foundations for establishing an integrated battery management strategy spanning from manufacturing formation to regeneration. Full article

The formation of lithium-ion batteries (LIBs) directly affects the properties of the solid electrolyte interphase (SEI) layer, which in turn affects cell performance, lifetime, and safety. Therefore, measurement of SEI properties during formation is a topic of great interest for LIB manufacturing. EIS has previously been applied to half-cell and three-electrode configurations for this purpose; however, these results have been questioned due to the potential non-linearity of the EIS measurement. Additionally, the limited application of the method to half cells and three-electrode cells limits the application of this method to production lines, where only two-electrode full cells are manufactured. In this work, we compare dynamic and steady-state EIS measurements during the formation cycling of NMC532/graphite coin cells. DRT analysis is used to distinguish the time constants of the two electrodes for equivalent circuit modeling. The main findings of this work are that dynamic EIS (DEIS) measurements only significantly affect the frequency response below ~30 Hz. Additionally, time constants and effective capacitance are unaffected by DEIS. We conclude that DEIS remains a promising technique for studying SEI formation in a two-electrode configuration and may be applicable on production lines for rapid diagnostics or even tracking SEI growth in real time. Full article

Sodium metal batteries (SMBs) are promising energy storage systems, yet their practical application is hindered by unstable solid electrolyte interphases (SEIs) and safety issues associated with flammable electrolytes. Although the flame-retardant solvent trimethyl phosphate (TMP) is widely used in rechargeable batteries, its application in SMBs remains constrained due to uncontrolled and accumulated parasitic reactions with sodium metal anodes. Here, we propose a novel synergistic strategy that combines a fluorinated additive (FEC) with a low-cost, high-concentration NaClO₄ to stabilize the electrode–electrolyte interface in TMP-based electrolytes. This approach enables the formation of a robust, NaF-rich SEI while restructuring the Na⁺ solvation sheath to coordinately trap TMP molecules, thereby suppressing parasitic reactions between sodium metal and TMP. As a result, the Na|Na₃(VOPO₄)₂F cell achieves exceptional cycling stability with 89.04% capacity retention over 1000 cycles at 1C. This work provides a cost-effective and practical pathway toward safe and long-lasting SMBs using non-flammable phosphate electrolytes. Full article

Response spectra (RS) provide an efficient link between earthquake ground motions and structural demand. Still, rare event screening for long-period, resonance-sensitive systems is often approximated by applying uniform multipliers to a design-basis earthquake (DBE) spectrum to represent beyond-design-basis earthquake (BDBE) levels. This paper develops critical excitation (CE) based response spectra (CE-RS) as a spectrum-format, low-overhead screening tool that makes period-local resonance sensitivity explicit while remaining anchored to code-defined hazard levels. This paper develops CE-RS as a response-spectrum-based screening tool for identifying period-local resonance sensitivity at code-defined hazard levels by using the CE framework to search, within an admissible set defined by bounded power spectral density (PSD) content and intensity constraints, for the input that maximizes structural response. Code-based target spectra are adopted as hazard anchors, consistent with the intent of probabilistic seismic hazard analysis (PSHA), at representative sites in Australia (Canberra; AS 1170.4:2024, Site Class Be) and the United States (San Francisco; ASCE/SEI 7-22, Site Class BC). For each site, a spectrum-compatible seed accelerogram is generated to reproduce the 5% damped target spectrum and to calibrate admissible-set bounds using peak ground acceleration (PGA), peak ground velocity (PGV), and Arias intensity. CE is then performed period-by-period over the long-period range to obtain CE-RS ordinates, which are compared with the DBE target and conventional BDBE-type references formed by uniform spectrum scaling. The resulting framework provides a code-comparable, site-anchored interpretation of long-period demand influenced by resonance effects, supporting rapid prioritization in preliminary design and in the screening of existing long-period-sensitive infrastructure for strengthening/rehabilitation. Full article

Although tin disulfide (SnS₂) possesses a theoretical specific capacity (645 mAh g⁻¹) significantly superior to that of commercial graphite, along with the merits of Earth abundance and cost-effectiveness, its commercial application as an anode material for lithium-ion batteries (LIBs) is severely hindered by substantial volume expansion during cycling. Herein, N-doped SnS₂ composites featuring a stacked hexagonal nanosheet architecture were synthesized via a facile one-step hydrothermal strategy. The incorporation of nitrogen significantly bolsters the long-term cycling stability of the electrode during charge/discharge processes. Electrochemical tests results reveal that the composite delivers an initial specific capacity of 500.8 mAh g⁻¹ at a current density of 0.5 A g⁻¹. Following 10 stabilization cycles, the capacity is recorded at 394.9 mAh g⁻¹, and notably, it increases to 481.66 mAh g⁻¹ after 500 cycles, corresponding to a high capacity retention of 96.17%. This superior performance is attributed to the introduced nitrogen, which provides abundant active sites and facilitates the formation of a robust solid electrolyte interphase (SEI) film. Furthermore, density functional theory (DFT) calculations demonstrate that N-doping narrows the band gap of SnS₂, thereby improving electrical conductivity and electron transport efficiency. Full article

Trace amounts of H₂O are inevitably introduced during lithium battery manufacturing processes, which induces the hydrolysis of LiPF₆, leading to HF formation, which triggers a cascade of deleterious reactions that degrade the solid electrolyte interphase (SEI) and corrode electrode materials. In this work, a water-scavenging electrolyte was constructed by employing a boroxine-linked covalent organic framework (COF) as the suspended phase. The ring-opening reaction of the boroxine ring units in COFs can effectively capture H₂O, thereby suppressing the hydrolysis of PF₆⁻ and mitigating electrode corrosion caused by HF. Consequently, a Li-metal battery with a high-nickel cathode retained 73% of its initial capacity after 500 cycles at 1 C, and a silicon-based lithium-ion battery with a high-nickel cathode sustained stable cycling over 500 cycles at a high rate of 10 C. This suspension strategy, leveraging a boroxine-linked COF with dual H₂O-scavenging capability, offers a scalable and versatile platform for electrolyte engineering toward practical next-generation lithium batteries. Full article

Silicon-based materials offer exceptional theoretical capacity for lithium-ion batteries (LIBs), but their practical application remains severely hindered by large volume expansion, low electrical conductivity, and unstable solid electrolyte interphase (SEI) formation during cycling. Herein, a binder-free silicon-containing carbon composite anode (denoted as CP-Si@C-4, where CP represents the conductive carbon paper substrate) is designed: carbon constitutes the structural and conductive framework, while silicon nanoparticles serve as a functional alloying component contributing characteristic lithiation/delithiation behavior. This framework comprises a conductive carbon paper (CP) scaffold, a resin-derived carbon matrix for homogeneous silicon dispersion, an interconnected carbon nanotube (CNT) network enabling long-range electron transport, and a conformal chemical vapor deposition (CVD) carbon layer for interfacial stabilization. Rather than simply increasing the overall carbon content, a series of control electrodes with distinct carbon configurations are deliberately designed to decouple the respective roles of bulk stress buffering and particle-level interfacial stabilization during cycling. The results indicate that functionally differentiating and coordinately regulating these two functions is critical for achieving durable binder-free silicon-containing carbon composite anodes. Benefiting from this cooperative multidimensional carbon architecture, the optimized CP-Si@C-4 anode delivers an initial Coulombic efficiency (ICE) of 86.3% and maintains a reversible capacity of ~990 mA h g⁻¹ at 2 A g⁻¹ after 1000 cycles. This work provides a structural design concept for improving long-term stability in binder-free silicon-containing carbon composite anodes. Full article

The electrochemical reuse of spent graphite from the negative electrodes of lithium-ion batteries is influenced by regeneration-induced changes in near-surface chemical and defect states. These states govern solid electrolyte interphase (SEI) re-formation, particularly when bulk contaminants are suppressed. Acidic malic-acid leaching and ethylenediaminetetraacetic acid chelation under alkaline conditions (pH 8.7) were compared under similar operating parameters to isolate the role of the leaching environment. This was followed by heat treatment at 1200 °C to decouple chemical cleaning from structural restoration. Both methods reduced the total impurities from 217.85 ppm to ~1.8 ppm, approaching that of commercial graphite. Despite the comparable bulk purity, depth-resolved X-ray photoelectron spectroscopy after formation cycling revealed distinct outermost surface states relevant to SEI re-formation: acidic processing yielded a more oxygenated carbon signature and higher LiOH fraction at the outermost surface (~16%), whereas alkaline chelation produced a more graphitic, carbonate-dominated surface with lower LiOH (~7%). Electrochemical and impedance measurements were consistent with these differences, suggesting that after the bulk impurities were minimized, resistance development was largely governed by the leaching-conditioned near-surface state, which biased the SEI composition. The comparison under matched conditions linked the regeneration environment to SEI-relevant surface speciation and provided a mechanistic basis for selecting regeneration routes to reuse spent graphite as a negative-electrode active material. Full article

Silicon oxide/graphite (SiO_x/Gr) anodes are promising candidates for high energy-density lithium-ion batteries. However, their complex multiphysics degradation mechanisms pose challenges for accurately interpreting and predicting capacity fade behavior. In particular, existing multiphysics models typically treat gas generation and solid electrolyte interphase (SEI) growth as independent or unidirectionally coupled processes, neglecting their bidirectional interactions. Here, we develop an electro–thermal–mechanical–gaseous coupled model to capture the dominant degradation processes in SiO_x/Gr anodes, including SEI growth, gas generation, SEI formation on cracks, and particle fracture. Model validation shows that the proposed framework can accurately reproduce voltage responses under various currents and temperatures, as well as capacity fade under different thermal and mechanical conditions. Based on this validated model, a mechanistic analysis reveals two key findings: (1) Gas generation and SEI growth are bidirectionally coupled. SEI growth induces gas release, while accumulated gas in turn regulates subsequent SEI evolution by promoting SEI formation through hindered mass transfer and suppressing it through reduced active surface area. (2) Crack propagation within particles is jointly governed by the magnitude and duration of stress. High-rate discharges produce large but transient stresses that restrict crack growth, while prolonged stresses at low rates promote crack propagation and more severe structural degradation. This study provides new insights into the coupled degradation mechanisms of SiO_x/Gr anodes, offering guidance for performance optimization and structural design to extend battery cycle life. Full article

Lithium iron phosphate (LiFePO₄, LFP) batteries dominate grid-scale energy storage, yet their cycle life is capped by its capacity fade issues. Conventional failure workflows suffer from redundant tests, high cost, and long turnaround time because the underlying mechanisms remain unclear. Herein, multi-scale characterization coupled with electrochemical tests have been quantitatively established to reveal four synergistic fade modes of LFP: active-Li loss, FePO₄ secondary-phase formation, SEI rupture, and particle fracture. A two-tier “screen–validate” protocol is proposed to accurately and efficiently disclose its mechanism. In the screening tier, capacity, cyclic voltammetry, electrochemical impedance spectroscopy, low-magnification scanning electron microscopy, and snapshot X-ray diffraction (XRD) rapidly flag the most probable failure cause. The validation tier then deploys mechanism-matched in situ/ex situ tools (operando XRD, TEM, XPS, ToF-SIMS, etc.) to build a comprehensive evidence chain of dynamic structural evolution, materials loss tracking, and quantitative proof. The streamlined workflow preserves scientific rigor and reproducibility while cutting analysis time and cost, offering a closed-loop route for fast failure diagnosis and targeted optimization of next-generation LFP batteries. Full article

High temperatures during charge–discharge cycles pose a significant threat to the safety and capacity of lithium-ion batteries by accelerating solid–electrolyte interphase (SEI) growth. Conversely, elevating the temperature during charging enhances Li-ion transport and suppresses lithium plating, suggesting an asymmetric temperature modulation (ATM) strategy in which cells are charged at elevated temperatures and discharged at room temperature to mitigate degradation under extreme fast-charging conditions. In this study, a one-dimensional electrochemical model incorporating key side reactions—SEI formation, lithium plating, and lithium stripping—is developed to analyse the ageing behaviour of plug-in hybrid electric vehicle (PHEV) cells under ATM operation. Within the present modelling framework and for the investigated temperature and current ranges, lithium plating is found to exert only a modest influence on the SEI growth rate, and the capacity degradation associated with SEI formation at a given temperature follows a unique time dependence that shows only a weak sensitivity to the charging rate. A phenomenological hill-shaped dependence of plating reversibility on the state of charge (SOC) is implemented based on experimental observations. The simulation results show good agreement with experimental data for PHEV cells operated under ATM, reproducing a capacity retention of about 80% after 1000 cycles at a charging temperature of 49 °C. Full article

As electronic technologies continue to advance, the demand for high-performance and safe batteries has steadily increased. However, silicon-based anode materials experience severe volume expansion and poor structural stability during cycling, which limits their practical application. In this study, we synthesized hollow mesoporous silica to develop an anode material with long-term cycling stability. Electrochemical analysis revealed that the material exhibited low-capacity decay, decreasing from 125 mA·h·g⁻¹ to 120 mA·h·g⁻¹ at a C-rate of 20 C, and retained a 49 mA·h·g⁻¹ after 500 charge–discharge cycles at a C-rate of 10 C. Furthermore, electrochemical impedance spectroscopy and Scanning Electron Microscopy analysis confirmed that the hollow mesoporous silica structure is long-term cycling stability in the anode. Full article

Flavoromics and metabolomics were used to evaluate the effects of selenium-enriched yeast (SEY) in hen feed on the volatile flavor and nutritional quality indicators in the resulting chicken meats. Volatile organic compounds (VOCs) were analyzed using GC-MS and odor activity value calculations. Ninety-eight VOCs were identified. The treatment group had more abundant VOCs, with mainly increased fat, mushroom, fruit, and vanilla odor. Modulating the nutritional profile of chicken meat through SEY feed can reduce saturated fatty acid levels, increase unsaturated fatty acid levels, and significantly reduce cholesterol levels in Dongxiang green-shell chicken (DX). Metabolomics analysis has elucidated the potential mechanisms, whereby adding SEY to the diet of DX reduces cholesterol levels through secondary bile acid biosynthesis pathways. Its related metabolic changes may also directly or indirectly promote the formation of key substances that give meat its flavor. Adding SEY to the diet of Jingfen laying hens affects the muscle metabolism environment via the propanoate metabolism pathway, increasing the grassy notes of chicken meat while reducing its gamey taste. Full article