This paper presents a free vibration analysis of functionally graded Reissner-Mindlin circular plates with various supported boundaries in thermal environments. A FGM consisting of metal and ceramic was considered in the study. Based on the geometric equation, physical equation and equilibrium equation of thick plate, taking into account the transverse shearing deformation, the free vibration equation of the axisymmetric FGM moderately thick circular plates was derived in terms of the middle surface angles of rotation and lateral displacement. The material properties of the plate were assumed to vary continuously in the thickness direction according a power law. By using shooting method to solve the coupled ordinary differential equations with different boundary conditions, the natural frequencies of FGM thick circular plates were obtained numerically. The effects of material gradient property, thickness ratio and boundary conditions on the natural frequencies were discussed in detail.

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The mechanical behavior of electrode composite during the drying preparation has played a crucial role in the electrochemical performance of lithium-ion batteries (LIBs). Our work aimed at developing an integrated analysis method to study the component distribution, mechanical properties, and internal stress of composite coating in the process of electrode drying. The main influence factors of drying stress were thoroughly investigated. It was found that this present model could capture not only the heterogeneity effect of inactive ingredients but also the porosity-dependent viscoelasticity of electrode composite. Meanwhile, the calculated effective modulus and stress evolution upon drying time were in acceptable accord with the experimental data. Furthermore, the rapid solidification markedly increased the drying stress in electrodes and significantly impaired the tensile strength of electrode composite due to the highly gradient distributed constituents. However, the stress level at high drying temperature could be significantly reduced by an aqueous sodium alginate binder instead of poly(vinylidene fluoride). The obtained results will be a great help in efficiently manufacturing LIB electrodes with adequate mechanical integrity.

The drying rate would significantly affect the quality of the composite electrode after solidification. In order to clarify the underlying effect mechanism of ingredient heterogeneity in the electrode caused by the drying process on the mechanical integrity of lithium secondary batteries in service, an integrated analysis approach is developed to determine the mechanical properties and lithium diffusion-induced stress of the composite electrode with gradient distributed binder and conductive agent. A faster solidification is found to broaden the inhomogeneous extent of inactive components in the electrode coating across its thickness, markedly. As a result, it will not only enlarge the tensile stress in the brittle electrode upon electrochemical operation due to the increased effective modulus of composite near the surface, but will also impair the interfacial strength between the active layer and current collector. Moreover, a two-stage drying protocol (initially fast, followed by slow evaporation of solvent) is found to be greatly beneficial to boosting the resistance to cohesion failure and surface damage of the composite electrode, and the optimized processing parameters are proposed to obtain a robust production with high efficiency.

Surface chemistry plays a critical role in the ion structuring of ionic liquids (ILs) at the interfaces of electrodes and controls the overall energy storage performance of the system. Herein, we functionalized the gold (Au) colloid probe of an atomic force microscope with −COOH and −NH2 groups to explore the effect of different surface chemical properties on the ion structuring of an IL. Aided by colloid-probe atomic force microscopy (AFM), the ion structuring of an imidazolium IL, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]­[PF6], abbreviated as BP hereafter), on the Au electrode surface and the ion response to the change in the surface chemistry are investigated. AFM morphologies, contact angles, and approaching force–distance curves of the BP IL on the functionalized Au surfaces exhibited that the IL forms a more obvious layering structure on the −COOH-terminated Au surface (Au–COOH), while it forms heterogeneous and aggregating droplets on the −NH2 surface (Au–NH2). The formed uniform and aggregation-free ion layers in the vicinity of the Au–COOH surface are due to the π–π+ stacking interaction between the delocalized π+ electrons from the imidazolium ring in the IL [BMIM]+ cation and the localized π electrons from the sp2 carbon on the −COOH group. The in situ observation of nano-friction and torsional resonance frequency at the IL–electrode interfaces further demonstrated the ion structuring of the IL at Au–COOH, which results in a more sensitive electrochemical response associated with a faster capacitive process.