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Utilizing marine waste and resources for eco‐friendly building materials is pivotal in promoting sustainable development in island and coastal construction industries. Among the potential alternatives, coral sand as well as sea sand stands out as a promising material. This research seeks to explore the potential of coral/sea sand as a fine aggregate in the creation of environmentally sustainable marine engineered geopolymer composites. An assessment was conducted on the influence of varying proportions of coral sand, meant as a substitute for sea sand, on the flowability, drying shrinkage, mechanical properties, and microstructure of the marine engineered geopolymer composites. The findings indicate that as coral sand replaces sea sand, flowability and drying shrinkage decrease, while compressive strength experiences an initial rise followed by a decline. Encouragingly, a combination of coral and sea sands enhances tensile ductility. Overall, a 20 wt.% coral sand mixture yields optimal results, with the compressive strength is 54.4 Mpa and the tensile strain capacity is 2.397% after 28 days. Moreover, microscopic tests reveal changes in hydration products and pore structure. Our research delves into the potential of coral/sea sand as a fine aggregate in the creation of environmentally sustainable marine engineered geopolymer composites. [ABSTRACT FROM AUTHOR]

Co9S8 has been regarded as a desirable anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity. However, lithium (Li) insertion caused large volume expansion, and subsequent pulverization and capacity decay are the major challenges for its practical applications in commercial LIBs. In this work, we design an Au@Co9S8 yolk-shell nanoparticle (NP) anode and use in-situ transmission electron microscopy to study the structural, morphological, and chemical evolutions in the NPs during lithiation. Our experimental results reveal that Li insertion leads to the volume expansion of the lithiated Co9S8 shell dominantly in the outward direction, and the conversion reaction between Li and Co9S8 induces the formation of a two-phase shell with metallic Co clusters dispersed in the as-formed Li2S matrix. With corroboration of chemo-mechanical simulations, we elucidate that the lithiation-generated comparative softer phase together with the inner stiffer unlithiated Co9S8 phase contributes to the outward only deformation pattern. In addition, the insulating nature of the as-formed Li2S results in an unexpected non-reactive Au yolk during lithiation. Our findings elucidate the significance of considering the dynamical phase transformations of active materials (i.e., Co9S8) for LIBs and provide valuable insights into the rational design of new generation high-performance LIBs. [ABSTRACT FROM AUTHOR]

Polymer networks usually have many entanglements as well as a finite extensibility due to the uncrossability and the full stretching of the network chains. In this paper, the nonaffine model proposed by Davidson and Goulbourne is adopted to characterize the influence of entanglements and finite extensibility of the polymer chains on the mechanical behavior of hydrogels. The Davidson-Goulbourne model only contains three material parameters and has a simpler mathematical form than the Edwards-Vilgis slip-link model, which is the only model that has been adopted to characterize the influence of entanglements on the swelling deformation of polymeric gels so far. Some benchmark problems such as free swelling, constrained swelling, uniaxial tension, equibiaxial tension in the immersed state and uniaxial compression in the isolated state are analyzed, respectively, based on the new constitutive equations. The results show that entanglements as well as chain extensibility have important influences on the mechanical response of hydrogels. [ABSTRACT FROM AUTHOR]

Layer-structured vanadium oxide (V 2 O 5 ) nanoribbons with efficient electron transport and short lithium ion insertion lengths are promising candidates for high-performance lithium-ion battery applications. Despite the extensive investigation of its electrochemical properties, the chemical and structural evolution during lithiation-delithiation processes has rarely been characterized in real time. Herein, the lithiation-delithiation behaviors of V 2 O 5 nanoribbons are probed by in situ transmission electron microscopy. We reveal that the V 2 O 5 nanoribbons exhibit high lithiation speed (0.8 nm/s) without retardation along the [010] direction and can be fully lithiated to the Li 3 V 2 O 5 phase. Fully reversible retraction of lithium is observed in these V 2 O 5 nanoribbons during delithiation. The lithiation process accompanying the coherent strain is further simulated by our phase field model. The simulation results reveal that the specific rough lithiation interface between the V 2 O 5 and Li 3 V 2 O 5 phases originates from the lithiation inhomogeneity.