Mechanical Bonding Research Articles

Oxidative Addition of a Mechanically Entrapped C(sp)-C(sp) Bond to a Rhodium(I) Pincer Complex.

By use of a macrocyclic phosphinite pincer ligand and bulky substrate substituents, we demonstrate how the mechanical bond can be leveraged to promote the oxidative addition of an interlocked 1,3‐diyne to a rhodium(I) center. The resulting rhodium(III) bis(alkynyl) product can be trapped out by reaction with carbon monoxide or intercepted through irreversible reaction with dihydrogen, resulting in selective hydrogenolysis of the C−C σ‐bond.

Oxidative Addition of a Mechanically Entrapped C(sp)–C(sp) Bond to a Rhodium(I) Pincer Complex

AbstractBy use of a macrocyclic phosphinite pincer ligand and bulky substrate substituents, we demonstrate how the mechanical bond can be leveraged to promote the oxidative addition of an interlocked 1,3‐diyne to a rhodium(I) center. The resulting rhodium(III) bis(alkynyl) product can be trapped out by reaction with carbon monoxide or intercepted through irreversible reaction with dihydrogen, resulting in selective hydrogenolysis of the C−C σ‐bond.

Stress/Strain Behaviour of Mechanical and Adhesive Joints in Timber Façade Applications

This paper compares the stress and strain behaviour of mechanical fasteners and elastic adhesive connections in timber façade applications. Two common designs with timber cladding are introduced. The traditional façade planks and multilayer large-format solid wood panels were selected. The resistance of a reference façade section with mechanical fasteners or adhesive bond to wind suction is determined according to the recommendations of European guideline ETAG 034. The pressure/suction chamber allowing hermetic closure was used. The sample deformation was measured at 15 locations, this also allowed to determine the elongation of the adhesive layer at break. The failure loads reached with the adhesive joint exceeded 20 kN/m2 in both combinations of façade cladding. On the other hand, the sample with a large-format panel and mechanical fasteners showed the lowest failure load at 12 kN/m2. The results confirmed that bonded joints are a suitable solution for large-format cladding, whereas an increase in the number of mechanical fasteners will be a more convenient solution for façade plank applications.

Polydispersity‐Driven Printing of Conformal Solid Metal Traces on Non‐Adhering Biological Surfaces

AbstractMetals and organics possess two very dissimilar surface energies, hence, do not naturally adhere to each other. This incompatibility is exacerbated by surface roughness yet advances in wearables and bioelectronics call for their integration. Mesoscale mechanical bonds, however, transcend the necessities of surface energy matching while taking advantage of surface texture. Herein, transient carrier fluids, particle size polydispersity, and capillary‐driven autonomous size‐sorting are exploited to conformally jam undercooled liquid metal particles on textured soft substrate. The well packed undercooled metal particles are then chemically activated to induce phase change, leading to a solid electrically conductive metal trace. Static and dynamic deposition of the particles is amenable to this surface‐templated printing of conductive traces. This process allows for printing across surfaces with varying surface features like on the brain, on paper (asymmetric porosity), or across smooth and rough brain sections. By tuning particle size and slurry concentration, good particle packing is demonstrated on a multi‐scale rough surface like a rose flower. This printing method is therefore compatible with delicate (low modulus), heat sensitive, and textured substrates hence compatible with biological tissues and organic substrates.

Effect of Non-Thermal Atmospheric Pressure Plasma (NTP) and Zirconia Primer Treatment on Shear Bond Strength between Y-TZP and Resin Cement

The purpose of this study was to investigate the effect of non-thermal atmospheric pressure plasma (NTP) treatment on the sandblasting of mechanical method and zirconia primer of chemical method used to increase the bond strength between zirconia and resin cement. In this study, Y-TZP was divided into 4 groups according to the surface treatment methods as follows: Zirconia primer (Pr), NTP + Zirconia primer (NTP + Pr), Sandblasting + Zirconia primer (Sb + Pr), Sandblasting + NTP + Zirconia primer (Sb + NTP + Pr). Then, two types of resin cement (G-CEM LinkAce and Rely X-U200) were used to measure the shear bond strength (SBS) and they were divided into non-thermal cycling group and thermal cycling group for aging effect. Statistical analyses were performed using the Kruskal-Wallis test and Mann-Whitney U test. The result of the surface energy (SE), there was no significant difference among the groups (p > 0.05). As a result of the SBS test, the Sb + Pr group had a significantly higher SBS value than the other groups regardless of the resin cement type (p < 0.05), and the decrease rate after thermal cycling treatment was the lowest. On the other hand, the NTP + Pr group showed significantly lower SBS values than the other groups except for the case of using Rely X-U200 (p < 0.05), and the reduction rate after thermal cycling was the highest. The Sb + NTP + Pr group did not differ significantly from the Pr group (p > 0.05). Within the limitations of two successive studies, treatment with NTP after sandblasting used for mechanical bond strength showed a positive effect on initial SBS. However, when NTP was treated before the zirconia primer used for the chemical bond strength, it showed a negative effect on SBS compared to other treatment methods, which was noticeable after the thermal cycling treatment.

Three-Dimensional Polycatenation of a Uranium-Based Metal-Organic Cage: Structural Complexity and Radiation Detection.

The potential applications of metal-organic cages (MOCs) are mostly achieved through specific host-guest interactions within their cavities. Electronic applications would require an effective electron transport pathway, which has been extensively studied in hybrid organic-inorganic materials with extended structures. These properties have not been considered for MOCs because cage-to-cage interactions in these materials have rarely been examined and are challenging to functionalize. We report here a previously unobserved actinide-based MOC assembled from four hexagonal-bipyramidal-coordinated uranyl ions and six bidentate flexible ligands. Remarkably, each isolated cage is further interlocked with six adjacent ones through mechanical bonds, resulting in the first case of a 0D → 3D f-element polycatenated metal-organic cage, SCU-14. Long-range π-π stacking extending throughout the structure is built via polycatenation, providing a visible carrier transmission path. SCU-14 is also an extremely rare case of an intrinsically semiconductive MOC with a wide band gap of 2.61 eV. Combined with the high X-ray attenuation efficiency, SCU-14 can effectively convert X-ray photons to electrical current signals and presents a promising sensitivity of 54.93 μC Gy-1 cm-2.

Cell Interconnections in Battery Packs Using Laser-assisted Ultrasonic Wire Bonding

Abstract This paper presents the results of a series of bonding tests using a laser-assisted ultrasonic wire bonding process. Aluminium and copper wire, both 500 μm (20 mil) thick, were bonded to nickel-coated steel caps of type 21700 battery cells. Mechanical bond strength tests prove that laser-assisted wire bonding has significant advantages over room temperature wire bonding. For example, it can be used to reduce the process time with aluminium wire or to increase the bondability of copper wire on nickel-coated steel. The results show a direct relation between tool tip temperature and measured bond strength. The quality of the joints was effectively improved by heating the tool tip up to 430 °C. These advantages are the same as in classic thermosonic wire bonding, but without the major disadvantage of having to heat to whole package. The cell temperature was shown to remain safely below the critical 60 °C in any application.

Influence of rib parameters on mechanical properties and bond behavior in concrete of fiber-reinforced polymer rebar

Mechanical properties of fiber-reinforced polymer rebar and bond behavior between the fiber-reinforced polymer rebar and concrete are highly related to rib parameters, including rib depth and rib spacing. Therefore, rib parameters should be taken into account when fiber-reinforced polymer bars are used as the structure reinforcement. In this article, the tensile properties of glass-fiber-reinforced polymer rebars with different rib depths and rib spacings are tested. The influences of different rib depths and rib spacings on the bond behavior between glass-fiber-reinforced polymer rebar and concrete are investigated by pull-out test. Experimental results show that the rib depth has a distinctive effect on the ultimate tensile strength, elastic modulus, and ultimate elongation of glass-fiber-reinforced polymer rebar. The tensile strength and elastic modulus of glass-fiber-reinforced polymer rebar with shallow rib are remarkably higher than those of glass-fiber-reinforced polymer bars with deep rib. However, compared with the glass-fiber-reinforced polymer bars with shallow rib, the glass-fiber-reinforced polymer bars with deep rib contribute larger bond strength with concrete. Besides, the bond strength and basic anchorage length are predicted by taking rib depth and rib spacing into account. A modified Bertero–Popov–Eligehausen model is adopted to simulate the bond stress–slip behavior, and the ascending branch of bond stress–slip curve expressed by rib depth and rib spacing is also proposed. The calculated results are in good agreement with the test ones.

Bond performance between FRP tubes and seawater sea sand concrete after exposure to seawater condition

In this study the durability of the bond between different fibre reinforced polymer (FRP) tubes and seawater sea sand concrete (SWSSC) under seawater condition is investigated. Concrete filled pultruded glass fibre reinforced polymer (GFRP) tubes and filament winding GFRP, carbon fibre reinforced polymer (CFRP) and basalt fibre reinforced polymer (BFRP) tubes were exposed to seawater at 25 °C and 40 °C for 1, 3 and 6 months. Push-out tests were carried out to study the bond performance of concrete filled FRP tubes (CFFT). The bond strength changes compared to the reference samples, in terms of the mechanical and chemical bonds, were calculated. The results showed that for all cases except one condition that had the same value as the reference, the maximum bond strength of the tubes increased due to the conditioning, however, the bond strength at the chemical adhesion breaking moment decreased by the conditioning. In other words, the friction coefficients of the samples increased due to conditioning, while the chemical adhesion decreased. Equations are proposed to predict the bond strength corresponding to slip initiations.

One-Pot Synthesis of a Linear [4]Catenate Using Orthogonal Metal Templation and Ring-Closing Metathesis.

The efficient synthesis of well-defined, linear oligocatenanes possessing multiple mechanical bonds remains a formidable challenge in the field of mechanically interlocked molecules. Here, a one-pot synthetic strategy is described to prepare a linear [4]catenate using orthogonal metal templation between a macrocycle precursor, composed of terpyridine and phenanthroline ligands spaced by flexible glycol linkers, and a closed phenanthroline-based molecular ring. Implementation of two simultaneous ring-closing metathesis reactions after metal complexation resulted in the formation of three mechanical bonds. The linear [4]catenate product was isolated in 55% yield as a mixture of topological diastereomers. The intermediate metal complexes and corresponding interlocked products (with and without metals) were characterized by nuclear magnetic resonance, mass spectrometry, gel permeation chromatography, and UV-vis absorption spectroscopy. We envision that this general synthetic strategy may pave the way for the synthesis of higher order linear oligocatenates/catenanes with precise molecular weights and four or more interlocking molecular rings.

Weld seam morphology and bond strength of infrared and vibration welded SLS parts of polyamide 12 as a function of the layer build-up direction and the welding process

Selective laser sintering (SLS) offers the possibility of manufacturing complex parts without tools and thus enables the cost-effective production of individualized products. In contrast to this advantage, the producible component dimension is restricted due to the dimensions of the building chamber of commercial SLS systems. Furthermore, a great amount of cost-intensive powder is necessary for the production of large SLS parts. In order to overcome these limitations, reliable joining processes, which enable high mechanical bond properties in SLS assemblies, are indispensable. Especially welding processes are suitable in this case. However, there is only limited knowledge available about the welding of SLS parts. In particular, the influence of the characteristics of the SLS process on the resulting bond quality has not been analyzed so far. Within this paper, the influence of the SLS layer build-up direction on the resulting weld seam morphology and bond strength as a function of the welding process is investigated. Infrared and vibration welding, which differ in the method of energy input into the joining zone, are used.The investigations carried out show that high weld seam strengths can be achieved in SLS assemblies for both welding processes. The resulting bond strength is thereby largely independent of the SLS build-up direction. Vibration welded SLS parts exhibit high bond strengths in the range of the base material strength. SLS joints produced via infrared welding have lower bond strengths, which is expected to be caused by an already beginning recrystallization in the generated melt layer during the changeover phase. Furthermore, the investigations show that the weld seam morphology for SLS parts deviates from the characteristic structure of polymeric weld seams, as welded SLS samples do not show the typical separated multi-layer structure. The weld seam shows a very fine spherulitic, partly optically amorphous structure. This is probably the case because of additives contained in the SLS powder (e.g. pyrogenic silicon dioxide), which have an accelerating effect on crystallization. Deformed spherulites in the transition area to the base material are only visible for vibration welded SLS specimens. Due to larger occurring spherulites within the SLS samples compared to injection molded parts, their deformation takes place over a much wider area. The analysis of the weld seam morphology further substantiates the assumption that recrystallization already begins during the changeover phase in the infrared welding process. A highly oriented area with growing spherulites can be detected in the area of the joining plane. In summary, however, it can be noted that both welding processes are well suited for joining SLS parts.

Mechanical behavior of waste fishing net fiber-reinforced cementitious composites subjected to direct tension

In this study, we investigated the mechanical behavior of waste fishing net (WFN) fiber-reinforced cementitious composites (FRCCs) subjected to direct tension to evaluate the possibility of using WFN fibers as reinforcement in cementitious composites. Three different WFN fibers, two commercial (C) polypropylene (PP) fibers, and two fiber volumes (0.5 and 1.0%) were considered as test variables to explore the effect of adding WFN fiber to a cement mortar. As the fiber volume was increased, both the compressive and first cracking strengths decreased, while the post-cracking strength increased. Reinforced samples (WFN3-FRCCs) with a 0.5% fiber volume exhibited the highest compressive strength, while those with a fiber volume of 1.0% had the highest post-cracking strength. The compressive and post-cracking strengths of WFN3-FRCCs were 6–10% and 2–13% higher than those of C-FRCCs, respectively. Therefore, WFN-fibers consisting of twisted yarns, which generate mechanical bonds during fiber pull-out, are appropriate for reinforcing cement mortar, thereby improving their strength and ductility under tensile loads.

Retinal Anatomy, Mechanisms of Retinal Adhesion, Retinal Tears, and Pathogenetic Mechanisms of Retinal Detachment

Retinal detachment (RD) is the separation of the retinal pigment epithelium (RPE) and the neurosensorial layer of the retina. To ensure visual function, these two subunits must be in close contact with each other, but there is no mechanical bond between them. In the formation of this connection, mainly the adhesive forces due to RPE metabolism, interfotoreseptic matrix, and some pressure gradients are involved. Against these factors, the retina is also exposed to opposing forces. The most common cause of retinal tear is the posterior vitreous detachment (PVD). Retinal injuries are divided into subgroups as atrophic holes, retinal tears, and retinal dialysis. Lattice degeneration, degenerative retinoschisis, and peripheral cystoid degeneration are predisposing to the development of RD.

Effect of Substrate's Heat Treatment on Microstructure and Mechanical Properties TLP Bonding of Dissimilar X-45/FSX-414 Cobalt Based Superalloys

In this study, a dissimilar joint of cobalt based superalloys X-45 and FSX-414 has been created under the standard heat treatment conditions with the nickel-based BNi-9 interlayer with the thickness of 50 μm by the transient liquid phase bonding process. Solution heat treatment (1150 °C/4 h) was used for bonding and the aging heat treatment (980 °C/4 h) for the homogenization of the bond. Optical metallography, Field Emission Scanning Electron Microscope with Energy Dispersive X-ray Spectroscopy, Differential scanning calorimetry, micro-hardness test and shear strength test were used for the characterization of microstructural and mechanical evolution in base metals and bonds. The solution heat treatment leads to the dissolution of a part of the M23C6 and M6C carbides in the substrate of superalloys, which due to the aging heat treatment secondary and fine carbides M23C6 precipitate in the substrate and help strengthen the superalloys. The diffusion of the boron from the molten interlayer to the base metals resulted in the complete isothermal solidification and a nickel-based single-phase solid solution has been developed. Cobalt-chromium-tungsten-molybdenum-based carboborides precipitation with high hardness in the vicinity of the isothermal solidification zone and in base metals results in the non-homogeneity of microhardness profile along the bonding area. Homogenization heat treatment did not have an effect on the omission of these precipitations, but by more uniform redistribution of the alloying elements strengthen solid solution that could increase shear strength from 655 to 688 MPa, which is somewhat equivalent to the shear strength of the 45-X alloy and also 93% of the shear strength of the FSX-414 alloy.

Dynamics of poly[n]catenane melts.

Inspired by advances in the chemical synthesis of interlocking polymer architectures, extensive molecular dynamics simulations have been conducted to study the dynamical properties of poly[n]catenanes-polymers composed entirely of interlocking rings-in the melt state. Both the degree of polymerization (number of links) and the number of beads per ring are systematically varied, and the results are compared to linear and ring polymers. A simple Rouse-like model is presented, and its analytical solution suggests a decomposition of the dynamics into "ring-like" and "linear-like" regimes at short and long times, respectively. In agreement with this picture, multiple sub-diffusive regimes are observed in the monomer mean-squared-displacements even though interchain entanglement is not prevalent in the system. However, the Rouse-type model does not account for the topological effects of the mechanical bonds, which significantly alter the dynamics at intermediate length scales both within the rings and at the chain segment scales. The stress relaxation in the system is extremely rapid and may be conveniently separated into ring-like and linear-like contributions, again in agreement with the Rouse picture. However, the viscosity has a non-monotonic dependence on the ring size for long chains, which disagrees strongly with theoretical predictions. This unexpected observation cannot be explained in terms of chain disentanglement and is inconsistent with other measures of polymer relaxation. Possible mechanisms for this behavior are proposed and implications for materials design are discussed.

Electrochemical Switching of a Fluorescent Molecular Rotor Embedded within a Bistable Rotaxane.

We report how the nanoconfined environment, introduced by the mechanical bonds within an electrochemically switchable bistable [2]rotaxane, controls the rotation of a fluorescent molecular rotor, namely, an 8-phenyl-substituted boron dipyrromethene (BODIPY). The electrochemical switching of the bistable [2]rotaxane induces changes in the ground-state coconformation and in the corresponding excited-state properties of the BODIPY rotor. In the starting redox state, when no external potential is applied, the cyclobis(paraquat-p-phenylene) (CBPQT4+) ring component encircles the tetrathiafulvalene (TTF) unit on the dumbbell component, leaving the BODIPY rotor unhindered and exhibiting low fluorescence. Upon oxidation of the TTF unit to a TTF2+ dication, the CBPQT4+ ring is forced toward the molecular rotor, leading to an increased energy barrier for the excited state to rotate the rotor into the state with a high nonradiative rate constant, resulting in an overall 3.4-fold fluorescence enhancement. On the other hand, when the solvent polarity is high enough to stabilize the excited charge-transfer state between the BODIPY rotor and the CBPQT4+ ring, movement of the ring toward the BODIPY rotor produces an unexpectedly strong fluorescence signal decrease as the result of photoinduced electron transfer from the BODIPY rotor to the CBPQT4+ ring. The nanoconfinement effect introduced by mechanical bonding can effectively lead to modulation of the physicochemical properties as observed in this bistable [2]rotaxane. On account of the straightforward synthetic strategy and the facile modulation of switchable electrochromic behavior, our approach could pave the way for the development of new stimuli-responsive materials based on mechanically interlocked molecules for future electro-optical applications, such as sensors, molecular memories, and molecular logic gates.

Microstructural Characterization of HVOF-Sprayed Ni on Polished and Oxidized Stainless Steel Substrates

In the present study, microstructural analysis was carried out to investigate the effect of substrate surface chemistry on splat formation. Ni powder was sprayed onto stainless steel substrates exhibiting two different surface conditions (polished and oxidized) by high-velocity oxy-fuel (HVOF) thermal spray. X-ray photoelectron spectroscopy (XPS) was employed to investigate the chemical state of the surfaces which indicated the presence of the adsorbates on the oxidized substrate. Single splats of different morphologies from both samples were examined using a range of characterization techniques including scanning electron microscopy (SEM), focused ion beam (FIB) microscopy and transmission electron microscopy (TEM) and energy-dispersive x-ray spectroscopy (EDS) interfaced to both SEM and TEM. This provided information on the particle solidification behavior and splat formation mechanism following impact on substrates with distinct surface conditions. The results showed the effect of oxidized surface adsorbates on splat morphology, pore formation and splat–substrate interactions. These microstructural findings, aided by theoretical models, revealed that a mixture of mechanical and metallurgical bonds exists between the splats and both substrates.

(Invited) The Mechanical Bond As a New Tool to Revisit Old Problems in Swnt Chemistry

The chemical mofidication of SWNTs typically aims at modifying their surface properties (to make them more processible, or to improve interface with other materials) and/or their electronic properties (to fine tune them for specific applications). Both covalent and supramolecular strategies have been explored towards those ends.[1] We will present strategies towards the synthesis of mechanically interlocked derivatives of SWNTs (MINTs), which are rotaxane-type materials in which the SWNTs are threaded through organic macrocycles, so that they are interfaced through mechanical bonds (see image, for a cartoon and a HRTEM of a MINT).[2] With the synthetic strategies established, we will focus on the the effect of the mechanical bond on the properties of SWNTs and show that such effect is unique, and clearly different from the noninterlocked, supramolecular compounds.[3] More specifically, we will report how to use the mechanical bond to improve the interface between SWNTs and polymeric materials, to achieve significantly improved mechanical properties.[4] We will also show that the organic macrocycles can be used to modulate the electronic properties of SWNTs, which in turn influence their catalytic properties.[5] [1] Rao, R.; Pint, C. L.; Islam, A. E.; Weatherup, R. S.; Hofmann, S.; Meshot, E. R.; Wu, F.; Zhou, C.; Dee, N.; Amama, P. B.; Carpena-Nuñez, J.; Shi, W.; Plata, D. L.; Penev, E. S.; Yakobson, B. I.; Balbuena, P. B.; Bichara, C.; Futaba, D. N.; Noda, S.; Shin, H.; Kim, K. S.; Simard, B.; Mirri, F.; Pasquali, M.; Fornasiero, F.; Kauppinen, E. I.; Arnold, M.; Cola, B. A.; Nikolaev, P.; Arepalli, S.; Cheng, H.-M.; Zakharov, D. N.; Stach, E. A.; Zhang, J.; Wei, F.; Terrones, M.; Geohegan, D. B.; Maruyama, B.; Maruyama, S.; Li, Y.; Adams, W. W.; Hart, A. J. Carbon Nanotubes and Related Nanomaterials: Critical Advances and Challenges for Synthesis toward Mainstream Commercial Applications. ACS Nano 2018, 12, (12), 11756-11784. [2] a) de Juan, A.; Pouillon, Y.; Ruiz-Gonzalez, L.; Torres-Pardo, A.; Casado, S.; Martin, N.; Rubio, A.; Perez, E. M. Mechanically Interlocked Single-Wall Carbon Nanotubes. Angew. Chem., Int. Ed. 2014, 53, 5394-5400; b) Lopez-Moreno, A.; Perez, E. M. Pyrene-based mechanically interlocked SWNTs. Chem. Commun. 2015, 51, 5421-5424; Leret, S.; Pouillon, Y.; Casado, S.; Navio, C.; Rubio, A.; Perez, E. M. Bimodal supramolecular functionalization of carbon nanotubes triggered by covalent bond formation. Chem. Sci. 2017, 8, 1927-1935; c) de Juan-Fernandez, L.; Munich, P. W.; Puthiyedath, A.; Nieto-Ortega, B.; Casado, S.; Ruiz-Gonzalez, L.; Perez, E. M.; Guldi, D. M. Interfacing porphyrins and carbon nanotubes through mechanical links. Chem Sci 2018, 9 (33), 6779-6784; d) For reviews, see: Perez, E. M. Putting Rings around Carbon Nanotubes. Chem. Eur. J. 2017, 23 (52), 12681-12689; Mena-Hernando, S.; Perez, E. M., Mechanically interlocked materials. Rotaxanes and catenanes beyond the small molecule. Chem. Soc. Rev. 2019, 48, 5016-5032. [3] Martinez-Perinan, E.; de Juan, A.; Pouillon, Y.; Schierl, C.; Strauss, V.; Martin, N.; Rubio, A.; Guldi, D. M.; Lorenzo, E.; Perez, E. M. The mechanical bond on carbon nanotubes: diameter-selective functionalization and effects on physical properties. Nanoscale 2016, 8 (17), 9254-9264. [4] Lopez-Moreno, A.; Nieto-Ortega, B.; Moffa, M.; de Juan, A.; Bernal, M. M.; Fernandez-Blazquez, J. P.; Vilatela, J. J.; Pisignano, D.; Perez, E. M. Threading through Macrocycles Enhances the Performance of Carbon Nanotubes as Polymer Fillers. ACS Nano 2016, 10 (8), 8012-8018. [5] Blanco, M.; Nieto-Ortega, B.; de Juan, A.; Vera-Hidalgo, M.; López-Moreno, A.; Casado, S.; González, L. R.; Sawada, H.; González-Calbet, J. M.; Pérez, E. M. Positive and negative regulation of carbon nanotube catalysts through encapsulation within macrocycles. Nat. Commun. 2018, 9 (1), 2671. Figure 1

Highly stable magnesium-ion-based dual-ion batteries based on insoluble small-molecule organic anode material

Magnesium-ion batteries (MIBs) are promising candidates for large-scale energy storage applications owing to their high volumetric capacity, low cost, and no dendritic hazards. However, the development of the MIBs is restricted owing to the obstacles of incompatibility between Mg metal and conventional electrolytes as well as the lack of suitable cathode materials with fast ion reaction kinetics, which lead to low working voltage, poor rate performance and unsatisfied cycling stability. In this work, a magnesium-ion based dual-ion battery (Mg-DIB) is constructed, using 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) as organic anode, expanded graphite (EG) with high potential and fast anion diffusion kinetics as cathode, and ionic liquid as electrolyte. The PTCDI was demonstrated to go through threefold coordination mechanism and hydrogen bond formation during Mg-ion insertion, which shows good insolubility in organic electrolytes and good structural stability. As a result, the Mg-DIB was demonstrated to exhibit a reversible discharge capacity of 57.7 ​mAh g−1 at 2C in the voltage range of 1–4 ​V, and good cycling stability with capacity retention of 95.7% after 500 cycles at 5C, which present a new way to design high-performance MIBs and other energy storage devices.

Effect of silicate modulus on tensile properties and microstructure of waterproof coating based on polymer and sodium silicate-activated GGBS

Abstract This paper investigated a novel and environmentally-friendly waterproof coating produced by the organic (i.e., styrene-acrylate copolymer) and inorganic (i.e., waterglass and ground granulated blast-furnace slag (GGBS)) compounds. The good cohesion of polymer and sodium silicate-activated GGBS can provide good mechanical properties, and this material also shows a better environmental benefit as no cement was used for coating. In this work, an appropriate proportion of polymer, waterglass and GGBS was given, and the effect of silicate modulus on the macro-performances and microstructures of the waterproof coating was studied. The optimal silicate modulus was 1.75, and the corresponding tensile strength and breaking elongation were 2.20 MPa and 90.48%, respectively. Furthermore, the waterproof coating also exhibited favorable tensile properties, flexibility or water impermeability after subjected to high temperature, alkali, water immersion, low temperature and high water pressure. This new waterproof coating exhibited the favorable tensile properties owing to (i) appropriate reaction rate, (ii) high degree of polymerization of C-S-H gel, (iii) high content of C-S-H gel and CaCO3 crystal, (iv) high reaction degree between emulsion and sodium silicate-activated GGBS, (v) nano-sized CaCO3 crystals and mechanical bond between the CaCO3 particles.