This study aims to reduce dependence on copper while enhancing the energy density of lithium-ion batteries. Plastic-based current collectors (PBCCs) offer a promising approach to replace copper, minimize the proportion of inactive material, and ultimately increase the energy density of lithium-ion batteries. A key challenge involved the synergistic optimization of the PBCC's conductive framework and its interfacial surface properties. Herein, a PI-CNT-Cu composite membrane was constructed by depositing copper onto electrospun PI fibers containing CNTs. This hierarchical architecture coupled the intrinsic longitudinal conductivity of the CNT network within the fibers with the transverse conductivity of the continuous copper layer, resulting in a composite membrane with a volumetric conductivity of 5.6 × 103 S cm-1. In the electrochemical performance evaluations, graphite anodes employing PI-CNT-Cu CCs exhibited a capacity retention of 95.29% after 190 cycles at 0.5C. The performance enhancement could be attributed to the markedly rougher surface of the PI-CNT-Cu CC (Sa = 2.668 µm) relative to copper foil (Sa = 0.938 µm). This morphology enhanced the contact area and adhesion with the electrode layer, which was crucial for maintaining the structural integrity of the electrode during long-term cycling. In contrast to copper foil, the PI-CNT-Cu CC, with its fiber-woven structure, exhibited a significantly lower areal density with identical thickness values. The capacity of the anode electrode, was calculated based on the total mass including active materials and CCs. Utilizing PI-17%CNT-Cu exhibited significantly higher discharge capacities of 81.7 mA h g-1 at the same rates compared to the Cu foil at 35.08 mA h g-1.

A unified treatment of two-dimensional adhesive contact on a power-law graded elastic half-plane

An extended bearing area model and stickiness criterion for adhesive contact of layered materials

Abstract We perform a dimension reduction analysis for a coupled rate-dependent/rate-independent adhesive-contact model in the setting of visco-elastodynamic plates. We work with a weak solvability notion inspired by the theory of (purely) rate-independent processes, and accordingly term the related solutions “semistable energetic”. For semistable energetic solutions, the momentum balance holds in a variational sense, whereas the flow rule for the adhesion parameter is replaced by a semistability condition coupled with an energy-dissipation inequality. Prior to addressing the dimension reduction analysis, we show that semistable energetic solutions to the three-dimensional damped adhesive contact model converge, as the viscosity term tends to zero, to three-dimensional semistable energetic solutions for the undamped corresponding system. We then perform a dimension reduction analysis, both in the case of a vanishing viscosity tensor, and in the complementary setting in which the damping is assumed to go to infinity as the thickness of the plate tends to zero. In both regimes, the presence of adhesive contact yields a nontrivial coupling of the in-plane and out-of-plane contributions. In the vanishing-viscosity case, we additionally confine the analysis to the case in which also inertia is neglected: in the vanishing-thickness limit, we thus obtain purely rate-independent evolution for the adhesive contact phenomenon, still formulated in terms of the semistable energetic solution concept. In the second, undamped scenario, inertia is instead encompassed; thus the limiting evolution retains a mixed rate-dependent/rate-independent character, and is again given in terms of an energy-dissipation inequality and a semistability condition.

Although the idea of employing cell membrane biomimetic technologies for detecting circulating tumor cells (CTCs) promises paradigm-shifting advances in cancer diagnostics, its wide application is restricted by CTCs phenotypic variations. Current improvements primarily focus on optimizing biomimetic coatings to enhance capture efficiency, but there remains a significant gap between existing strategies and the practical demands of CTCs detection. Herein, a novel method considering the perspective of tumor cell modification was proposed, which involved concurrently modulating cellular chemical and mechanical properties. Specifically, the strategy employed metabolic glycoengineering to selectively remold tumor cells, thereby introducing artificial receptors into the tumor cell membrane. Additionally, Cytochalasin D, a drug that can interfere with the cytoskeleton, was used to alter the mechanical properties of the cell membrane, softening it and thereby significantly enhancing the contact area and adhesion ability between target cells and the substrate surface. To cope with the complex application environment, a visual biomimetic detection system was developed, leveraging the homologous targeting properties of the tumor cell biomimetic layer in combination with advanced colorimetric nanoprobes, enabling highly sensitive and specific detection of engineered CTCs. Overall, this approach adeptly circumvents challenges associated with biomarker bias, offering a robust method for non-invasive cancer diagnostics.

Solid-state electrolytes (SSEs) with high ionic conductivity, superior electrochemical stability, and mechanical durability are safe and reliable for solid-state lithium (Li) batteries. However, most existing SSEs suffer from limited mechanical resilience and poor interface contact, impeding their practical deployment. Here, an in situ phase separation strategy is proposed to construct a class of elastomeric solid-state electrolytes with bicontinuous architecture. The rigid phase ensures high ionic conductivity (7.8×10-4 S cm-1 at 25 °C), while the elastic phase provides excellent elastic restorability (82%) and strong interface contact (adhesion energy ≈43.9J m-2). This bicontinuous structure endows the material with superior stretchability (1800%), fatigue resistance, and puncture strength, while maintaining interface contact, keeping mechanical integrity of the battery structure during cycling, and restraining the dendrite growth. Consequently, symmetric batteries exhibit no short-circuiting even after 2000 h of operation, and Li-metal batteries demonstrate high specific capacity. Solid-state Li-O2 batteries fabricated with the P(BA-SN)-IL electrolyte also exhibit good cycling performance (500 cycles), and the Li-O2 pouch cell achieves stable cycling and superior feasibility under various abuse tests, including bending and squeezing. The bicontinuous-structured elastomer electrolytes present a highly promising strategy for enabling safe operation of high-energy solid-state batteries.

Adhesion and friction in viscoelastic rough contacts

Decoupling surface stiffness from surface chemistry: Impact on bacterial adhesion and retention under shear conditions.

Adhesive contact of elastic spherical shells: Non-monotonic thickness dependence of pull-off force

Abstract This work re-examines the frictionless adhesive contact between a spherical indenter and a supported incompressible elastic layer within the framework of Johnson–Kendall–Roberts (JKR) adhesion theory. Two typical interfacial conditions between the layer and the underlying rigid support are considered: perfectly bonded and free to slide. Based on the recently established non-adhesive contact solution, explicit parametric relationships between external load, depth and contact radius are derived for layers of arbitrary thickness. In particular, the influence of layer thickness on the critical contact responses at the moments of zero-external load and pull-off detachment is presented. It is demonstrated that our general solution can completely quantify the transition from the classical half-space-based JKR theory to the asymptotic solution where contact radius significantly exceeds layer thickness. Excellent agreement with the results of boundary element simulations validates the proposed explicit extended JKR model. Superior to existing semi-analytical approaches requiring intensive numerical calculations and the asymptotic solutions valid in limited ranges, the explicit formulas developed are simpler yet sufficiently accurate in the general thickness range, providing convenient theoretical tools for practical indentation analysis of soft films and thin biological materials.

Polyethylene (PE) films are widely used as waterproofing materials on the surfaces of metal pipelines. Poor adhesion of PE films to a metal substrate reduces durability, leading to shorter service life and higher economic costs. The current research aims to study the modification of PE films in atmospheric pressure gliding arc plasma (GAP). The adhesion properties of the modified films were investigated using the contact angle method and adhesion work calculations. During the modification process, the GAP treatment duration and deflector nozzle angle of attack were optimized to 10 s and 135°, respectively. It was established that the adhesion work increased from 62.1 to 141.3 mJ/m2 after 10 s GAP modification compared to untreated PE. GAP modifying of PE films for 30 s or more is impractical, as the increase in the adhesion work ceases after that. It was found that surface roughness Rmax increased by up to 4.1 times after 10 s GAP modification compared with nontreated PE. The PE films acquired hydrophilic properties after plasma modification, due to changes in the polymer surface’s chemical structure. The results of IR spectroscopy studies indicated oxidation of the film surface, an increase in the concentration of surface polar groups (-COOH, OH, C=O), and the formation of double bonds (C=C), which led to improved adhesive properties. A study of the electret properties showed that the observed decline and subsequent stabilization of values occurred within the first 24 h. Mechanical tests indicated improved performance of the GAP-modified PE films compared to the non-treated ones in the PE–mastic–PE and PE–mastic–steel systems. Due to their enhanced contact properties, the modified PE films are of interest as a base material for creating waterproofing materials.

HighlightsWhat are the main findings?Composite oxidation mechanism.The ways in which surface oxidation affects the friction performance of current-carrying components.What are the implications of the main findings?These results provided an in-depth understanding of the oxidation mechanisms of friction pairs in complex atmospheric environments.Oxidation is a critical factor contributing to material wear and the degradation of conductive performance during current-carrying tribological processes. The present study investigated the composite oxidation mechanisms that occurred during current-carrying rolling in mixed atmospheres containing O2 and H2O vapor. The results obtained in a dry N2/O2 mixture, humid N2, and humid N2/O2 mixture indicated that the oxidation mechanisms on current-carrying rolling surfaces involved thermal oxidation, tribo-oxidation, and anodic oxidation. XPS analysis confirmed that the primary oxidation product was CuO. Conductive atomic force microscopy (C-AFM) revealed that surface oxidation caused a significant reduction in conductive α-spots, leading to an increase in contact resistance. Contact resistance exhibited a quasi-linear relationship with the surface CuO content. Contact angle measurements and adhesion tests showed that the enhanced hydrophilicity of the oxidized surface and the resulting high adhesion contributed to an increase in the macroscopic friction coefficient. In humid N2/O2 with 50% relative humidity (RH), the friction coefficient rapidly exceeded 0.8 when the O2 content surpassed 25%. Wear morphology analysis demonstrated that this abrupt increase in the friction coefficient induced fatigue wear on the surface. Overall, the present study elucidated the composite oxidation mechanisms during current-carrying rolling and clarified the pathways through which oxidation affected current-carrying tribological performance. These findings may contribute to improved failure analysis and the safe, reliable operation of electrical contact pairs.

Enhanced macromolecule bioavailability in rats and pigs using an in situ forming synthetic epithelial lining.

Relation between contact area and adhesion behaviour between viscoelastic food systems and processing surfaces – influence of rheology and contact time

A high-efficiency versatile adhesive contact model for layered media

Abstract With the increasing miniaturization of mechanical systems and the prevalence of rough surfaces in engineering applications, understanding and accurately characterizing the contact response at small scales has become crucial. This review article provides a comprehensive analysis of two significant aspects in the field of contact mechanics: the size-dependent response of single asperity due to strain gradients and surface effects, and the contact behavior of rough surfaces. The former forms the foundation for the latter analysis, as real surfaces are inherently rough and contact occurs at discrete asperities. At the microscale, strain gradients play a dominant role, as classical continuum mechanics fails to account for the intrinsic material length. Further downscaling to the nanoscale highlights the importance of surface effects due to the large surface-to-bulk ratio. The first section examines these distinct size-dependent effects and their implications for contact mechanics across different scales. The second section further focuses on the contact of rough surfaces, highlighting incremental contact models, contact behavior at large contact fraction where asperity interactions are significant, adhesive rough contact in soft materials, and experimental advances that improve the understanding and validation of these models. Together, these two topics underscore the need for refined theoretical and experimental approaches to accurately model and predict the contact behavior at small scales and with realistic multiscale roughness.

A semi-analytical numerical method for solving size-dependent three-dimensional adhesive contact of dissimilar elastic materials

ABSTRACT We develop new continuum contact model for the micro-scale sliding frictional and adhesive coupling contact problem of the conducting cylindrical indenter on the exponentially functionally graded piezoelectric materials (FGPM) layered half-plane. This model can explain the sliding friction contact behavior with adhesion effects. First, based on the displacement components and the electrical potential equations of the sliding frictional contact problem, the governing equations of the problem have been derived by using the Maugis type of adhesion theory and the extended Amonton’s law of friction. Second, the present problem could be reduced into a set of coupled Cauchy singular integral equations and two displacement difference equations, which can be numerically discretized and solved by a newly developed algorithm. Finally, numerical examples are presented to demonstrate the effectiveness of the method. The effects of the gradient index, the friction coefficient, the adhesive stress, the work of adhesion and the electric charge on the surface electromechanical response of FGPM were carried out systemically. The motivation for this approach is the adsorption behavior of a gecko type micro crawling robot, which can generate frictional forces under tensile normal loads.

Pull-off force prediction in viscoelastic adhesive Hertzian contact by physics augmented machine learning

ABSTRACT Purpose To evaluate the aetiology, demographic profile, clinical features, and outcomes in cases of refractory bacterial keratitis. Methods This is a retrospective observational study in which 41 eyes of 40 patients diagnosed with bacterial keratitis, with no improvement after medical therapy, were evaluated. The inclusion criteria were as follows: (a) culture-proven bacterial keratitis; (b) antibiotic usage of ≥6-weeks; (c) No surgery within 8-weeks of diagnosis. The exclusion criteria were as follows: (a) other causes of microbial keratitis and (b) surgical intervention in non-responding keratitis within 8-weeks. Results Forty-one eyes of 40 patients were analysed in this study. Thirty eyes (73.2%) had an ulcer area of about 15–20 mm2. The visual acuity varied from 0 logMAR in ulcers with small size to no light perception due to the nature of the corneal infiltrate. Common risk factors noted in the patients were systemic comorbidities like uncontrolled diabetes mellitus, glaucoma, and ocular surface disorders. Staphylococci were the predominant organisms, found in 21 (51.2%) eyes. Twenty-two surgical interventions were performed including one eye which had to undergo evisceration. This included eight tissue adhesive and bandage contact lens application (TA+BCL), five intracameral antibiotic injections, five therapeutic penetrating keratoplasty (Th.PK). Conclusion Various factors can contribute to the development of non-healing or refractory corneal ulcers including systemic conditions, ocular factors, and the characteristics of the infecting organism. Identification of these factors can aid in early diagnosis and prompt management of the condition.