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Among various intergranular microstructures, pore spaces in SEs play a critical role in Li-metal nucleation in SEs. To realize Li-metal nuclei-free inside the SE, removing pore spaces is essential and a commonly applicable design strategy to all SEs.

The “selective and successive oxygen redox” concept is suggested as a universal reaction mechanism in Mn–Fe binary oxide cathodes, and it elucidates the oxygen (in)stability affecting the cycle retention in sodium-ion batteries.

O substitution for S in argyrodite-type sulfide-based solid electrolytes enhances the stability by suppressing reaction with H2O and decomposition. O substitution modulates the electronic structures and then improves electrochemical performance.

Phosphate doped hard carbons have shown a significant capacity increase accompanied by an additional plateau in its voltage profile. The work reveals the co-contribution of oxygen atoms in phosphate and carbon atoms for the additional Na-ion storage.

A surrogate model for dynamical behavior of dielectric elastomer actuators was proposed, the reduced-order framework was based on long short-term memory (LSTM) networks, and the combination of prop...

A design method of the opto-mechanical actuation is proposed. The system is constituted of liquid crystal photo-responsive polymer, and is subject to light-induced isomerization, leading a nematic ...

The jumping motion is adapted by Earth’s creatures to achieve rapid maneuverability and energy-efficient hurdling over uneven terrains or large obstacles. Herein, the continuous photomechanical jumping of polymer monoliths with on-demand height and angle programmability is reported. Upon exposure to actinic light, self-assembled spring-like molecular geometry of azobenzene-functionalized liquid crystalline polymers provide on-demand jumping via snap-through of non-isometric structures. The finite element method simulation quantitatively describes stress–strain responsivity of the experimental jumping. Remarkably, the maximum jumping height reaches 15.5 body length (BL) with the maximum instantaneous velocity of 880 BL s−1. We demonstrate programmable jumping height and angle by varying macroscopic geometry and light intensity profile. Finally, four continuous and directional jumping sequences are demonstrated within 5 s to overcome an obstacle.

Recurrent neural network (RNN)-based accelerated prediction was achieved for the long-term time-dependent behavior of viscoelastic composite laminated Mindlin plates subjected to arbitrary mechanical and hygrothermal loading. Time-integrated constitutive stress-strain relation was simplified via Laplace transform to a linear system to reduce the computational storage. A fast converging smooth finite element method named cell-based smoothed discrete shear gap was employed to enhance the data generation procedure for straining RNNs with a sparse mesh. This technique is applicable under varying hygrothermal conditions for real engineering structure problems with fluctuating temperature and moisture. Hence, accurate RNN-based long-term deformation prediction for laminated structures was realized using the history of environmental temperature and moisture condition.

The cross-deposition of wavy circuits is essential in the mass production of flexible devices. This article clarifies structural limitation in enhancing the maximum stretch ratio of cross-deposited...

Model updating processes are important for improving a model’s accuracy by considering experimental data. Structural system identification was achieved here by applying the degree-of-freedom-based ...

Deformations triggered by body heat are desirable in the context of shape-morphing applications because, under the majority of circumstances, the human body maintains a higher temperature than that of its surroundings. However, at present, this bioenergy-triggered action is primarily limited to soft polymeric networks. Thus, herein, the programming of body temperature-triggered deformations into rigid azobenzene-containing liquid crystalline polymers (azo-LCPs) with a glass-transition temperature of 100 °C is demonstrated. To achieve this, a mechano-assisted photo-programming strategy is used to create a metastable state with room-temperature stable residual stress, which is induced by the isomerization of azobenzene. The programmed rigid azo-LCP can undergo large-amplitude body temperature-triggered shape changes within minutes and can be regenerated without any performance degradation. By changing the programming photomasks and irradiation conditions employed, various 2D to 3D shape-morphing architectures, including folded clips, inch-worm structures, spiral structures, and snap-through motions are achieved. When programmed with polarized light, the proposed strategy results in domain-selective activation, generating designed characteristics in multi-domain azo-LCPs. The reported strategy is therefore expected to broaden the applications of azo-LCPs in the fields of biomedical and flexible microelectronic devices.

A multiscale modeling approach is proposed to account for the interfacial load transfer characteristics of epoxy nanocomposites. The localized stress evolutions in nanocomposites are examined with ...

Considering that the existing C1 absolute nodal coordinate formulation (ANCF) elements must satisfy C1 continuity, herein a four-node plane C0 ANCF element is proposed to overcome current limitatio...

Graphite is currently utilized as anode materials for Li-ion batteries, but it is well-known that graphite does not show good electrochemical performances as the anode material for sodium-ion batteries (SIBs). It was also reported that the low electrochemical performances of graphite originated from the larger ionic radius of the sodium ion due to the required higher strain energy for sodium-ion intercalation into graphite leading to an unstable sodium-ion intercalated graphite intercalation compound (GIC). In this work, using first-principles calculations, we introduce pillaring effects of Na n X (n = 3 and 4; X = F, Cl, or Br) halide clusters in GICs, which become electrochemically active for Na redox reactions. Specifically, to enable sodium-ion intercalation into graphite, the interlayer spacing of graphite is required to increase over 3.9 A, and Na n X halide cluster GICs maintain an expanded interlayer spacing of >3.9 A. This enlarged interlayer spacing of Na n X halide cluster GICs facilitates stable intercalation of sodium ions. Na3F, Na4Cl, and Na4Br halide clusters are identified as suitable pillar candidates for anode materials because they not only expand the interlayer spacing but also provide reasonable binding energy for intercalated sodium ions for reversible deintercalation. Based on the model analysis, theoretical capacities of Na3F, Na4Cl, and Na4Br halide cluster GICs are estimated respectively to be 186, 155, and 155 mA h g-1. These predictions would provide a rational strategy guiding the search for promising anode materials for SIBs.

The demand for large-scale design optimization and probability-based analysis is constantly increasing. In design optimization and stochastic analysis, repeated analyses are required, which impede ...

Although Ni2+/Ni4+ double redox offers the possibility of high-energy-density manganese-based spinel cathode materials for sodium-ion batteries, their poor cyclability and power density, owing to i...

In nonlinear analysis, performing iterative inverse calculation and nonlinear system construction procedures incurs expensive computational costs. This paper presents an element-wise stiffness evaluation procedure combined with hyper-reduction reduced-order modeling (HE-STEP ROM) method. The proposed approach constructs a non-intrusive reduced-order model based on an element-wise stiffness evaluation procedure (E-STEP) and hyper-reduction methods. Because the E-STEP evaluates nonlinear stiffness coefficients element-by-element using cubic polynomial, numerous number of polynomial variables are required. The number of variables directly affects the computational efficiency of the online and offline stages. Therefore, to enhance efficiency of the online/offline stages, the proposed method employs hyper-reduction method. By applying hyper-reduction, the full stiffness coefficients are approximated from the stiffness coefficients evaluated at a few sampling points. Subsequently, the number of polynomial equations and variables is prominently reduced, and the efficiency of the reduced system increases. The efficiency and accuracy of the proposed approach are validated via several structural dynamic problems with geometric and material nonlinearities.

Pump it up Carbon nanotube yarns can be used as electrochemical actuators because infiltration with ions causes a contraction in length and an expansion in diameter. Either positive or negative ions can cause this effect. Chu et al. constructed an all-solid-state muscle that eliminated the need for an electrolyte bath, which may expand the potential for its use in applications. By infiltrating the yarns with charged polymers, the fibers start partially swollen, so the length can increase through the loss of ions. It is thus possible to increase the overall stroke of the muscle. Further, these composite materials show a surprising increase in stroke with scan rate. Science , this issue p. 494

A wavy circuit is one of the structures used in flexible devices, which endure high stretch ratios during operation. In this study, we focus on the importance of the section tilting angle of the wa...

In extreme ultraviolet lithography (EUVL), the non-uniformity of patterned surface roughness of contact holes results in pattern failures such as bridging or missing holes, which affects production yield. In this study, we propose a multiscale model for reproducing 10–35 nm contact hole patterns based on the photo-chemical reactions in a photoresist (PR). To determine the heterogeneous spatial distribution of the resist components at the mesoscopic level, we employed a coarse-graining (CG) strategy for the PR. Additionally, we constructed a statistical model to obtain the novel acid/base distributions using existing MD data. The chemical reaction kinetics were reproduced via the finite difference method (FDM). We predicted resulting hole-patterned surfaces according to the target hole size. The variability in interfacial surface roughness among the holes, which is quantified by local critical dimension uniformity (LCDU), increased with decreasing target hole size, which is consistent with experimental reports. By investigating the photochemistry in the PR at the molecular level, we confirmed that the decrease in the chemical gradient due to the increase in relative acid diffusivity to hole size caused the LCDU and hole-failure probability trends. The diffusivity control enhanced this interpretation further, resulting in mitigation of CD variability in the 10 nm contact holes.

Solid-state batteries (SSBs) have attracted significant interest owing to their relatively high energy density and nonflammability. LiNi0.5Mn1.5O4 (LNMO) is a promising candidate for cathodes in SSBs because of its high working voltage of 5 V (vs. Li/Li+). However, the inadequate durability of LNMO prevents it from being commercially viable. Although LNMO is known to be stabilized by doping with Mg rather than transition metal atoms, the stabilization mechanism of Mg-doped LNMO is not well understood yet. Here, we examine the stabilization mechanism of a Mg-doped LNMO structure using first-principles calculations. We show that the doped Mg atoms act as pillars in the LNMO structure and effectively mitigate lattice misfits of the interfaces during two-phase reactions without affecting the redox reaction. In addition, the doped Mg atoms lower the phase transition barrier in the biphasic region, thereby alleviating sudden structural shifts, which are accompanied by abrupt phase transitions. Consequently, Mg-doped LNMO undergoes less destructive reactions than pristine LNMO and therefore, less cyclability degradation. Additionally, a solid-solution reaction, which has a higher thermodynamic phase stability than the biphasic reaction, occurs in the later part of the delithiation process only when Mg atoms are doped into pristine LNMO. Mg doping also mitigates Ni ion migration that leads to capacity fading through the blocking of Li ion diffusion and acceleration of Mn dissolution. The doped Mg atoms efficiently improve the cycle performance of LNMO. Our findings are useful for the development of long-lasting cathode materials and spinel structures.

In this study, we present improved power characteristics and suppressed phase transition by incorporating elemental doping into a P2-type cathode of sodium ion batteries. A Cu-doped Fe–Mn based P2-type Na0.67Cu0.125Fe0.375Mn0.5O2 cathode was designed based on the calculations of the electronic structure and then examined experimentally. Using first principles, we introduced instrinsic p-type conductivity by elemental doping with Cu. Introduction of Cu generated electron holes above the Fermi level in the electronic structure, which is typical of p-type semiconductors. Charge analyses suggested that the hole generation was driven primarily by the greater reduced characteristics of Cu as compared with those of Fe and Mn. In addition, introduction of Cu retaining high reduced property also suppressed phase transition from the P2 to Z phase by Fe migration to empty Na layers mainly. Electrochemical experiments revealed improved power characteristics upon the introduction of p-type conductivity. This could be attributed to the increase in the electronic conductivity by hole generation in the valence band. This study suggests that the introduction of p-type conductivity could be a rational tactic for the development of promising cathode materials for high performance sodium ion batteries.

In extreme ultraviolet lithography (EUVL), a photoacid generator (PAG) blended photoresist (PR) is used to transfer the blueprint from the mask to the wafer. The photoacids are predominantly activated by photo-triggered secondary electron attachment in EUVL, which is distinct from the direct electron excitation of PAG in conventional deep ultraviolet resists. However, uncontrolled acid dispersion causes excessive deprotection and serious damage to the residual pattern. A quencher base compound was introduced in the PR to confine the acid diffusion, but the molecular level description of the acid ↔ quencher interaction and the resulting influence on the pattern image remains elusive. We examine the quencher effect that neutralizes the acid and impedes the deprotection in the masked region, leading to the enhancement of the line edge roughness (LER) of the pattern. In addition, we investigated the loading effect of the quencher and predicted the optimal concentration of the quencher for the best LER, consistent with experimental reports. The LER optimum along the quencher concentration is interpreted by the reciprocal relationship between the acid-blocking effect at the line edge of the pattern (positive) and the acid trapping behavior in the exposure domain (negative). The variations in the deprotection homogeneity clearly demonstrate the negative impact of the acid trap phenomenon on the chemical reaction according to the quencher's loading. In multiscale modeling, PAG dissociation energy curve calculated from density functional theory (DFT) is applied to molecular dynamics (MD) simulation to reproduce the indirect photochemical activation in EUVL. The sequential multiscale framework (DFT-MD-finite difference method) also reproduces acid/base diffusion, neutralization, deprotection kinetics, and pattern morphology in EUV resist at the molecular level.

Oxygen-redox reactions (ORRs) in Na-based transition metal (TM) layered oxides have attracted a great deal of attention as a means of overcoming the intrinsic low energy density of the cathodes of sodium-ion batteries (SIBs), because their activities occur above ≈4.0 V versus Na+/Na and deliver extra capacity beyond the TM-based redox contribution. Intriguingly, Mn-based binary-layered oxides (e.g., Na1−x[Mn1−yNiy]O2), have recently been re-examined to elucidate the ORR involvement that had been assigned to the Ni3+/Ni4+ redox couple. Accordingly, Na1−x[Mn1/2Fe1/2]O2, a representative abundant cathode, was reinvestigated in detail using first-principles calculations to unlock veiled ORRs upon charging. First, the charge variations of Mn, Fe, and O showed that a typical Mn3+/Mn4+ cationic redox is a principal factor in charge compensation for 0.25 ≤ x ≤ 0.5 in Na1−x[Mn1/2Fe1/2]O2, whereas a dominant ORR contributes to the charge compensation with the partial Fe redox for a value above x = 0.5. Second, the ORR is selective depending on the oxygen site coordinates with Fe-rich (2Fe–O–Mn) or Mn-rich (Fe–O–2Mn) environments. Third, the Fe–O chemical bonding features reveal that the Jahn–Teller distortion determines the priority of the oxygen redox reaction ≈4.0 V. Along these lines, our findings provide insights into directions in utilizing the veiled oxygen redox reaction of Nax[Mn1−yFey]O2 binary oxides.

Spherical secondary particles for cathode active materials have been highlighted owing to their superior electrochemical performance compared to other types. However, they suffer from micro-cracking, which is a crucial factor of electrochemical performance degradation, owing to the highly anisotropic mechanical deformation of primary particles during cycling. In particular, anisotropy is significant for Ni–Mn binary layered oxides, which utilize oxygen redox reactions and suffer severe structural variations occurring in sodium-ion batteries (SIBs). To elucidate the intrinsic origins, we focused on the anisotropic structure distortion of Ni–Mn binary-layered oxides and their correspondence with the Ni redox picture using first-principles calculations. Analysis of the atomic-scale structure indicated that opposite deformation in the lattice parameters is observed for both Na1−xMnO2 and Na1−x[Mn1/2Ni1/2]O2 (NMO and NMNO); contraction occurs on the ab plane whereas expansion (0.25 ≤ x ≤ 0.75) and contraction occur (0.75 ≤ x ≤ 1.0) on the c lattice direction upon desodiation. Notably, the mechanical anisotropy of the Ni–Mn binary-layered oxide is accelerated attributable to the dual contraction of Ni ionic radii owing to Ni2+/Ni4+ double redox and the suppression of contraction of the transition metal layer because of the Jahn–Teller distortion. Therefore, we established that the shape of the radially oriented secondary particle could alleviate the impact of the anisotropic distortion from primary particles, resulting in a stabilized cycle performance. Thus, adjusting the shape of the secondary particle is a suitable approach for alleviating the anisotropic features of the primary particles, thus enhancing cycle stability with oxygen redox and fast charging for further advances in lithium-ion batteries (LIBs) or SIBs.

Oxygen redox (OR) reactions in sodium layered oxide cathodes have been studied intensively to harness their full potential in achieving high energy density for sodium-ion batteries (SIBs). However, OR triggers a large hysteretic voltage during discharge after the first charge process for OR-based oxides, and its intrinsic origin is unclear. Therefore, in this study, an in-depth reinvestigation on the fundamentals of the reaction mechanism in Na[Li