Research Output
Articles
Publication Date: 2025
International Journal of Mechanical Sciences (00207403)290
Solid-state batteries are promising candidates for the next-generation energy storage technology, as they circumvent the cyclic stability and safety issues of the traditional liquid-electrolyte Li-ion technology. Solid electrolytes are less reactive and enable using Li-metal anodes, increasing the energy density of battery cells. However, Li dendrites nucleating at pores, grain boundaries, and cracks, particularly when the current density exceeds a critical level, have been found to penetrate the solid electrolyte, resulting in short circuit and battery failure. While existing fracture mechanics-based models of dendrite usually examine Li-filled cracks, recent experiments have shown that a Li dendrite formed inside a crack can induce fracture growth well before filling it. This work aims to develop a model for this largely unexplained behaviour by considering a Li dendrite as it grows inside a crack from an initially small nucleus. The model couples solid electrolyte deformation, stress-driven Li diffusion along the dendrite-electrolyte interface, and stress-dependent Butler-Volmer kinetics of Li deposition into the crack. A finite element formulation developed for solving the governing equations is applied to two types of solid electrolytes to examine simultaneous evolution of the stress profile, dendrite thickness profile, dendrite length, and the stress intensity factor. By considering a realistic range of model parameters, it is shown that dendrite thickening, as compared to lengthening, promoted by a lower interfacial diffusivity, a higher interfacial resistance, and a higher applied current density, can mediate crack growth before dendrite fills the crack. Both assumptions and predictions of the model are discussed with reference to the existing literature, and model predictions are compared to the experiments. © 2025
Publication Date: 2023
Journal of the Mechanics and Physics of Solids (00225096)174
Point defect distribution in the vicinity of discontinuities plays important role in the transport properties of nonstoichiometric ionic solids. Here, considering dopants and oxygen vacancies as the major point defects in doped ceria, we develop a Monte Carlo model to examine how the stress field of edge dislocations affect point defect distribution in their surroundings. Point defects are considered to interact with the elastic stress field of dislocations due to their misfit volume, and the electrostatic interaction between the point defects is also taken into account. In contrast with a prevalent theory of chemo-mechanical equilibrium in solid solutions, the model developed here is consistent with classical elasticity in that the point defects do not interact through their self-stress fields. Stress effects both on the defect distribution, and on the electric potential, are examined for a single dislocation as well as a periodic array of like dislocations. In agreement with previous atomistic simulations, the model predicts that electrostatic interactions drive enrichment or depletion of defects of both types on either the compressive or tensile side of edge dislocations depending on the ionic radius of the dopant. The stress field of an array of like dislocations periodic in the direction of the Burgers vector is shown to result in different bulk defect concentrations and bulk electric potentials on the opposite sides of the array, whereas for an array with repeat direction normal to the Burgers vector, defect enrichment and depletion emerge in alternate regions limited to the vicinity of the dislocations. © 2023 Elsevier Ltd
Publication Date: 2023
Construction and Building Materials (09500618)369
The cement production process produces enormous amounts of carbon dioxide (CO2). Hence, using new types of cement, like ternary cement, which contains calcined clay, limestone, and cement clinker, can significantly reduce the CO2 emissions of the cement industry and even increase the mechanical properties and durability of samples. This paper investigates the cement mortar's mechanical and durability characteristics, containing ceramic waste powder (CWP) and limestone powder (LSP) as partial cement substitution. Samples with 5, 10, and 15 % LSP and 10, 20, and 30 % (by weight of cement) CWP as cement substitutes were produced. The mortar specimen tests were performed after 7, 28, and 90 days of curing in the water pool, then compressive strength and alkali-silica reaction (ASR) tests were evaluated. Furthermore, setting time test, thermogravimetric analyses, X-ray diffraction analyses, and scanning electron microscopy (SEM) of cement paste were carried out. The ternary cement mortar containing 10 % CWP and 15 % LSP has the highest compressive strength. Also, the ternary cement mortar containing 30 % CWP and 15 % LSP shows the lowest compressive strength (decreased by 8.5 % compared to the reference sample). In addition, the mix containing 20 % CWP and 15 % LSP has a lower ASR value than the control sample (52 % less). Eventually, SEM images showed the reference sample and the specimen containing 30 % CWP and 15 % LSP have the lowest and highest pores and cavities, respectively. © 2023 Elsevier Ltd
