The cover art highlights the article by Monja Gronenberg et al., selected as an Editor’s Choice article, “Upscaling the Electrochemical Porosification of Silicon — A Theoretical and Experimental Process Analysis”

This study addresses the fundamental challenges encountered when electro­chemical porosification of silicon is transferred from laboratory-scale experiments to industrially relevant production. The authors clarify how thermal, kinematic, geometric, and electrochemical similarities govern pore uniformity during scale-up. In particular, they present a novel inline etching tool in which silicon wafers pass over electrolyte tanks of alternating polarity, enabling porosification without mechanical backside contact. Through COMSOL-based analysis of the series-resistance network, the observed current-density fluctuations are reproduced quantitatively, providing practical design rules for improving next-generation inline etching systems.

The cover image schematically represents an industrial inline porosification process. Silicon wafers move across transparent electrolyte tanks, where alternating electrochemical regions, gas evolution, and spatial current-density distributions are visualized. The porous silicon structure shown at the upper left represents silicon in which a controlled pore network has been formed, while the color maps emphasize the importance of understanding and minimizing electrochemical inhomogeneity during scale-up.

The cover art highlights the article by Hiroshi Takida et al., selected as an Editor’s Choice article, “Tuning the Sodium Electrode Potential by Solvent Molecular Framework Engineering”

This study presents a rational strategy for tuning sodium and lithium electrode potentials through the molecular framework design of electrolyte solvents. By comparing phosphate ester, glyme, and crown ether solvents, the authors demonstrate that steric hindrance and cyclic chelation can significantly alter cation solvation structures and thereby shift electrode potentials. Notably, extending the alkyl chain from trimethyl phosphate to tripropyl phosphate upshifts the sodium electrode potential, whereas crown ether coordination stabilizes the cation and shifts the potential in the opposite direction. Machine-learning-based molecular dynamics simulations further clarify how solvent structure controls cation coordination and anion participation in the solvation shell.

The cover image schematically represents molecular framework engineering in battery electrolytes. The molecular assemblies illustrate different solvation environments surrounding alkali-metal cations, while the battery-like background emphasizes the relevance of electrolyte design to sodium-ion battery systems. The image conveys how subtle changes in solvent architecture can reorganize ion solvation and provide a new route to controlling electrode potentials beyond conventional electrolyte design.

The transition from laboratory-scale experiments to industrial-scale production frequently exposes fundamental challenges related to process similarity. In the context of silicon porosification, achieving consistent results during scale-up requires maintaining thermal, kinematic, geometric, and electrochemical (current/potential) similarities. On the example of two stages of upscaling, this work aims to elucidate the principal scaling effects that arise during the electrochemical porosification of silicon and to outline strategies for mitigating them. Through a series of representative examples, the paper highlights how process parameters, reactor geometry, and operating modes influence the resulting pore architecture and uniformity. A novel inline etching tool is presented where the wafers pass over tanks of alternating polarity. This approach has the great benefit that it does not need a backside contact; however, the alternating tank coverage leads to current density fluctuations under potentiostatic operation. A simple COMSOL simulation (Finite Element Method) of the series resistance network of the system is able to explain the fluctuations qualitatively as well as quantitatively. On this basis, design rules for the next-generation inline etching tool are suggested that would reduce the current density fluctuations from about 50 % to less than 10 %.

In this study, the lithium morphology plated on Cu substrates and the compositional changes of the solid electrolyte interphase (SEI) film during the first charging process of anode-less batteries (ALBs) were analyzed to clarify their impact on lithium plating/stripping efficiency. In the 1 mol dm⁻³ LiPF₆ in the mixed solvent of ethylene carbonate and dimethyl carbonate (STD), numerous lithium nuclei form in the early stage and subsequently grow into dendritic structures. In contrast, in STD containing tetrakis(trimethylsiloxy)titanium (STD+TMST), nucleation is suppressed and the deposited lithium develops large plate-like morphologies, greatly improving the plating/stripping efficiency. In the STD system, the overall composition of the SEI film formed on both plated lithium and the Cu substrate changes significantly during the first charging process, whereas that of the SEI film formed in STD+TMST remains nearly unchanged. Notably, the SEI films obtained at the fully charged state exhibit almost identical compositions in both electrolytes. These results indicate that the cycling stability of ALBs is determined not only by the final SEI composition but more critically by the compositional changes occurring during the first charging process.

Anion doping is a promising approach for controlling material functionalities. However, precise control of anion concentration remains challenging. In this study, we experimentally evaluated the effects of reaction conditions on F concentration and distribution in topochemical F doping to La_0.6Sr_0.4CoO_3−δ thin films by simply varying F sources, reaction temperatures, and reaction times. Comparative experiments using MgF₂, BiF₃ and PVDF as F sources suggested that the equilibrium F₂ activity of the F source is the primary factor governing the F concentration in the product. Meanwhile, the choice of F source also significantly affects the homogeneity of F distribution. Temperature-dependent experiments showed that maximum F incorporation was achieved at 300 °C, while higher temperatures led to F release and decreased F concentration. Time-dependent experiments demonstrated that F concentration increases with prolonged reaction time. Notably, uniform F distribution throughout the entire film thickness (100–150 nm) was achieved within just 1-hour treatment at 240 °C when using MgF₂ as the F source, indicating that the topochemical F-doping process is governed by surface reaction kinetics rather than bulk diffusion. These findings enable precise control of anion composition in topochemical anion doping and contribute to the rational design of functional materials by anion doping.

Spherical Cu/Pt Janus micromotors were fabricated by electroless copper plating onto sulfonated polystyrene microspheres (∼1 µm diameter) followed by hemispherical platinum sputtering. The electroless plating step provided Cu deposition over the particle surface, and subsequent directional Pt sputtering yielded a hemispherical Pt localization, generating a Cu–Pt bimetallic interface with spatially defined redox asymmetry. In aqueous iodine solution, the Cu/Pt Janus particles showed active displacement without bubble formation. At iodine concentrations of 0.1 and 0.2 mM I₂, representative apparent velocities of ∼2.6 and ∼5.5 µm s⁻¹, respectively, were obtained from particle tracking, whereas no active displacement beyond Brownian-like motion was observed in the absence of iodine. The concentration-dependent motion behavior is consistent with a redox-driven asymmetric reaction field at the Cu/Pt interface, although a definitive propulsion mechanism is not conclusively established here. The present fabrication approach offers batch scalability and material versatility for the development of halogen-driven Janus micromotors as a proof-of-concept platform.

All-solid-state lithium metal batteries have attracted significant attention as next-generation batteries with the potential to achieve substantial performance improvements over conventional lithium-ion batteries. However, achieving a higher energy density requires not only improving the performance of the Li metal anode but also overcoming the challenges posed by a thinner, lighter configuration. In this study, a vacuum deposition process is employed to prepare thin Li–Mg films with thicknesses of several micrometers, which are difficult to achieve using conventional processes. Subsequently, the electrochemical properties of these thin films are evaluated in all-solid-state lithium metal batteries, and the functional role of Mg is investigated. The results reveal that the cycle life is highly dependent on the Mg content. Specifically, the Li (5 µm)–Mg (400 nm) configuration (∼7 at% Mg) exhibits the highest performance, achieving 87.7 % capacity retention after 100 cycles. Cross-sectional observations confirm uniform alloying of the prepared film. Furthermore, the optimal film exhibits a stable interface with the solid electrolyte (Li₆PS₅Cl), effectively suppressing void formation during repeated plating/stripping cycles. This improved cycling stability is attributed to increased elastic modulus of the films and the suppression of void formation, which is facilitated by the improved wettability induced by Mg.

In lithium-ion batteries, the desolvation of Li⁺ is widely regarded as the activation barrier for interfacial charge-transfer reactions; however, the governing factors remain unclear. This study investigated the effect of solvent properties on charge-transfer kinetics for a Li_1.05Mn_1.95O₄ thin-film electrode using lithium bis(trifluoromethanesulfonyl)amide-based electrolytes with H₂O, tetrahydrofuran, and n-dibutyl ether. Electrochemical impedance spectroscopy revealed that the concentrated aqueous electrolyte exhibited a significantly lower charge-transfer resistance (R_ct) than the monoether-based systems, contrary to expectations based on viscosity. Analysis of Li⁺ activity indicated that the high activity in the concentrated aqueous system contributed to the reduced R_ct; however, comparisons using 1 mol dm⁻³ (1 M) electrolytes showed that neither viscosity nor Li⁺ activity alone could explain the observed trends. These results suggest that dynamic solvent properties play a critical role, and that the rapid molecular reorientation of water facilitates faster solvation and desolvation of Li⁺ at the interface.

This study makes an attempt to quantify the inhibitory effects of CO poisoning on the hydrogen evolution reaction at Pt electrode using a polarization resistance curve and its techniques. This method overcomes the limitations of traditional Tafel extrapolation, such as solution resistance interference and ambiguity in identifying linear Tafel regions. Measurements in 0.5 mol dm⁻³ H₂SO₄ solution saturated with H₂ gas poisoned by CO injection reveal that CO adsorption triggers a mechanistic transition from a reversible process (z = 2, j₀ ≈ 0.7 mA cm⁻²) to an irreversible one (z = 1) controlled by a single-electron transfer step, which were reported in previous paper [Catalysts, 11, 1322 (2021).] This paper shows that the exchange current density under the poisoned condition plummets to j₀ ≈ 10^−3.5 mA cm⁻², representing a massive loss of electrocatalytic activity by a factor of approximately 10^−3.3. The study theoretically demonstrates that the equilibrium potential for the rate-determining step aligns with that of the whole reaction. These findings highlight the polarization resistance curve technique as a useful tool for evaluating catalyst degradation and developing CO-tolerant electrocatalysts for fuel cell applications.

Sodium-ion batteries (SIBs) are promising next-generation energy-storage systems, yet their low energy density remains a major challenge. An effective strategy to utilizing low-potential anodes is tuning their electrode potentials with respective to an electrolyte potential window. Herein we propose a molecular framework design of electrolyte solvents to rationally tune sodium electrode potential (E_Na). Extending the alkyl chains of phosphate ester solvents upshifted E_Na by up to 0.32 V (tripropyl phosphate vs. trimethyl phosphate) despite similar donor numbers, indicating a dominant steric effect to weaken the Na⁺ solvation. In contrast, cyclic crown ether 15-crown-5 downshifted E_Na by 0.16 V compared to its linear counterpart (tetraglyme) via the formation of a more stable chelate coordination. Furthermore, the magnitude of these steric/structural effects depended strongly on the cation species, leading to large variations in the Na-Li electrode potential difference (ΔE_Na–Li), from 0.53 V in tripropyl phosphate to 0.10 V in 18-crown-6. Machine-learning-based molecular dynamics simulations revealed that the changes in the cation solvation structure, induced by the solvent molecular framework engineering, are responsible for the observed potential shifts. These findings establish solvent molecular framework engineering as a versatile strategy to tune electrode potentials in battery electrolytes.

There has been a growing movement to effectively utilize phenylpropanoids as biomass resources for polymer materials in pursuit of a sustainable society. Isoeugenol, an aromatic biomass resource, is expected to be a sustainable polymer feedstock from the viewpoint of availability and price. On the other hand, due to its β-substituted styrene structure, it has poor reactivity in cation/radical polymerization and is difficult to polymerize on its own. In this study, we focused on catalytic [3 + 2] cycloaddition reactions of isoeugenol and utilized it for polymerization. Specifically, we designed a bifunctional monomer consisting of two isoeugenol molecules bonded by silicon to achieve efficient polymerization using catalytic [3 + 2] cycloaddition reactions. Furthermore, the polymer was decomposable under mild conditions, and the decomposition products were suitable for chemical recycling and upcycling.