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Strategies for converting mechanical energy into electrical energy hold significant importance in diverse battery‐free and battery‐supported applications. Recent studies have demonstrated promising approaches involving the twisting of carbon nanotube yarns, which alter the intrinsic electrochemical capacitance during mechanical motion, thereby generating electrical energy in various aqueous environments. However, the fundamental mechanism of chemo–mechanical energy harvesters based on the nanoscale piezoionic effect, as well as the kinetics of both cations and anions within the system, remains to be clarified. In this study, experimental and computational approaches aimed at fundamentally understanding the piezoionic effect in nanoscale chemo–mechanical dynamics are presented. This phenomenon is analyzed using in situ Raman scattering, piezoelectrochemical impedance spectroscopy, and molecular dynamics simulations. The findings elucidate the collective contributions of cations and anions under mechanical energy inputs and demonstrate the impact of piezoionic kinetics on electrical energy outputs. By gaining a comprehensive understanding of the fundamental piezoionic effect in chemo–mechanical energy harvesting systems, significant advancements in energy sustainability across numerous practical applications are anticipated. [ABSTRACT FROM AUTHOR]

The potential of organic electrodes in lithium‐ion batteries (LIBs) is highlighted by their cost‐effectiveness and natural abundance. However, the dissolution of the active material in the electrolyte is a major obstacle to their use in LIBs. Although high‐concentration electrolytes (HCEs) have been proposed to address this issue, they face challenges such as high viscosity, poor wettability, and suboptimal ion conductivity. Hence, this study introduces diluted electrolytes as non‐solvating electrolytes to offset the physical limitations of HCEs and suppress the dissolution of organic electrodes. When a diluted electrolyte is used, perylene‐3,4,9,10‐tetracarboxylic dianhydride (PTCDA)—a notable organic electrode material—demonstrates superior capacity retention and rate performance, achieving 91% of capacity retained at 1000 mA g−1 over 1000 cycles. Through electrochemical and spectroscopic measurements and molecular dynamics simulations, the diluted electrolyte successfully inhibits and demonstrates the dissolution of the active material, preventing capacity loss and the detrimental shuttle effect. This study presents a promising strategy for achieving highly reversible organic electrode‐based LIBs through the development of nonsolvating electrolytes. [ABSTRACT FROM AUTHOR]

An intriguing mechanical seed (MS) concept that modulates (in)homogeneous Li metal growth is proposed based on an in‐depth understanding of its fundamental mechanism using unified atomistic computations. A large dataset of thermodynamic energies for Li disordered phase decouples the dual‐body interactions into three components: i) crystal‐like, ii) long, and iii) short bonds of Li─Li based on machine learning assisted by density function theory calculations. The contributions of these dual‐body interactions offer a mechanical factor for controlling the disordered‐ordered phase transition during electrochemical deposition. Macroscopic molecular dynamics simulations systematically construct the core–shell sphere and cross‐sectional models to reinforce the MS premise. The former reveals that the lower energy level of disordered phase under the moderate compression causes a slow phase kinetics, whereas the strain‐free mode exhibits a relatively fast transition. In addition, the cross‐sectional model exhibits a smooth surface landscape for the strain‐optimized case. These observations are attributed to the surface area evolutions depending on the MS conditions and elucidate the dynamic atomic displacements near the grain boundary from a local structural perspective. The proposed mechanical design concept facilitates uniform Li growth and is expected to be a global parameter in harnessing the full potential of Li metal batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effect of fluorination on photoisomerization of azobenzene are explored using multiscale simulations. • Fluorine, as an electron-withdrawing group, stabilizes the molecular orbital at diazene, correcting molecular conformations. • Stabilized molecular orbitals offer thermodynamic advantage to photoisomerization of diazene group. • Fluorination of azobenzene improves responsiveness of photoisomerization while degrading actuating force. • Effects on photoisomerization at the molecular level spatiotemporally extend to bulk-state azobenzene. The photoisomerization dynamics of azobenzene (Azo-H) and its modulation by electron-withdrawing groups (EWGs) are important for designing photophysical applications, such as artificial muscles, liquid crystal displays, and solar thermal fuels. In this study, the electron-withdrawal kinetics of fluorination and the tailoring of the photoisomerization dynamics of azobenzene were explored using theoretical multiscale simulations. First-principle calculations provide insight into the mechanical aspects of photoisomerization, whereas molecular dynamics simulations offer a time-dependent perspective. Fluorinated azobenzene (Azo-F) exhibits superior photoisomerization responsiveness owing to changes in its molecular conformation and energy states induced by the EWG. These thermodynamic advantages were influenced by the stabilization of the molecular orbitals near the diazene groups. Despite the thermodynamic advantages of Azo-F, heavy fluorine atoms reduce the actuating force and work capacity owing to their increased inertia. This study provides a comprehensive understanding of photoisomerization kinetics modulated by the local fluorination of Azo-H. [ABSTRACT FROM AUTHOR]

This study suggests a critical factor that regulates (in)homogeneous growth based on an in‐depth understanding of three alkali metal ((AM): Li, Na, and K) models using unified‐multiscale atomistic calculations. The importance of AM disordered phases as a transition state is covered with a thermodynamic energy dataset using density functional theory (DFT) calculations, which indicates that the disordered‐phase energy level (DPEL) plays a decisive role in controlling the degree of non‐homogeneity during electrochemical deposition. Using the DFT‐assisted machine learning method, the DPEL‐related cohesive energy is investigated to understand in depth the energy level of disordered phase. Reliable molecular dynamics (MD) simulations systematically compare AM growth during charging. The results illustrate severely fluctuating morphologies including sharp tips in Li metal, whereas Na and K metals showed smooth surfaces. Finally, the transition state thermodynamics are explored using cross‐sectional AM growth models. Metallic Li is preferentially adsorbed on its crystalline phase rather than on grain boundaries comprising disordered phases, resulting in severe dendritic Li growth. However, these characteristics are rarely observed for K metal during the entire deposition process. Based on the growth mechanisms of the three types of AM models, DPEL poses a potentially universal design strategy for facilitating homogeneous lithium‐metal dendrite growth. [ABSTRACT FROM AUTHOR]

Effective adhesion between AlO x and SiO x is important for protective coatings and high-k films under extreme operating conditions. Here, we study the chemo-mechanical behavior of the AlO x /SiO x interface and its delamination mechanism using all-atom reactive molecular dynamics simulations. The structure of the interface is examined by the formation of bridge oxygen and the distribution of nanopores. The cleavage of ionic bonds during delamination and the resulting adhesion strength of the system are quantified using pull-out simulations. The results reveal the dependence of the nanopores and ionic bond formation on the oxide structure. The ionic bond density at the interface increases as the oxidation of the aluminum surface proceeds, which directly increases the adhesion strength with SiO x. In particular, the global coordination distribution in the homogeneously grown oxide inhibits the formation of nanopores inside the aluminum substrate and contributes to extremely high adhesion strength. This reveals a fundamental relationship between physicochemical parameters and engineering mechanics for hetero-oxide structure design. [Display omitted] [ABSTRACT FROM AUTHOR]

In the design and manufacturing of ultra-fine grained materials, it is important to understand the competitive relationship between grain growth and intergranular bonding under thermal loads. The key is to understand the mechanisms by which the load transfer is initiated between the surfaces of the glassy disordered phase, at the atomic level. In this regard, the initiation of load transfer through the glassy disordered phase during the binding of Y 2 O 3 nanoparticles was investigated in silico. Multiscale analysis combining quantum mechanics and classical molecular dynamics simulations showed that the disordered phase structure between Y 2 O 3 nanoparticles exhibits high resistance to shear deformation. However, yttrium cations and oxygen anions exhibit opposing mechanical roles within the disordered phase. The steric deformation exhibited by anion-biased electronic structures with perpendicular O 2 p and Y 4 d – O 2 p overlap allows the yttrium cation to contribute to the phase transition, while the oxygen anion directly participates in load transfer. The analysis of phase transition kinetics, including the experience of transition states, provides the composition and distribution of the energy levels of the disordered phase, thereby explaining the origin of the differences in the roles of atomic species. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A multi-scale analysis method for the plasma spray coating process is developed. • The mechanical properties of films are predicted through DSMC and MD simulations. • The increase in powder feed let the sprayed particle have an oblique incidence angle. • The oblique incident trajectory reduces the ionic bond density on the Y-O-Al network. In this study, we proposed a multiscale analysis method that integrates the direct simulation Monte Carlo (DSMC) method and all-atom molecular dynamics (MD) simulation to comprehend the process of unsteady plasma spray coating of yttria nanoparticles (YNPs) on an alumina substrate. The correlation between the increase in the powder feed rate and growth mechanism of the film microstructure was obtained by solving the collisions of the sprayed YNPs and corresponding spatial trajectories. The results showed that higher powder feed rates form a wider spray cone angle, and a reduction in spray distance increased the probability of powder impinging normal to the substrate. This also explained the changes in the interfacial adhesion and hardness of the films with the powder feed rate and spray distance observed in the experiments. In particular, vertically incident YNPs not only constituted the densest bulk layer, but also contributed to strong adhesion by increasing the probability of generating Y-O-Al binding structures at the interface. The findings were the first to examine the complexity of chemo-mechanical behavior between spatial particle trajectories and facing material, thus throwing light on an important factor in the quality of sprayed ceramic coatings. [ABSTRACT FROM AUTHOR]