The pursuit of higher energy density through thick lithium-ion battery electrodes is fundamentally challenged by their increased susceptibility to cracking during fabrication. This work reveals that this failure stems from a pronounced size effect. As the active layer thickens, drying-induced binder migration creates a steeper gradient in porosity from top to bottom. This amplified mesostructural heterogeneity directly governs the macroscopic mechanical weakening. We developed a robust method using a soft substrate to fabricate damage-free, free-standing thick active layers for accurate tensile testing, which confirmed the systematic reduction in both modulus and strength with increasing thickness. Mesostructure-based finite element simulations establish a direct causal link, showing that the porosity gradient elevates local stress concentrations and reduces the effective load-bearing capacity. By establishing a mechanistic link between mesostructure and macroscopic performance, this study provides a critical foundation for designing high-energy-density thick electrodes.

For rheology-sensitive methods of electrode structure construction, drying-controlled slurry evolution critically governs structure formation and battery performance. This study develops a bidirectional machine-learning framework for tailoring electrode structures through rheology-optimized drying. Rheological characterization validates the accuracy of Herschel-Bulkley model in describing rheological behaviors of drying electrode slurries and quantifies the effect of drying parameters on rheological properties, thereby closing a critical knowledge gap. A coupled artificial neural network and genetic algorithm model (i.e., the machine-learning framework) establishes precise drying-rheology bidirectional mapping. The inverse-design capability accurately identifies optimal drying parameters and is validated through the mechanical imprinting of thick electrodes. Crucially, it identifies an optimal drying window where rheology-optimized properties ensure stable microstructure formation, resolving trial-and-error limitations. The maximum relative error for the preserved structure cases is merely 4%, demonstrating excellent predictive accuracy of the framework. This end-to-end workflow represents a paradigm shift from empirical iteration to a physics-informed digital design framework, enabling the efficient development of advanced high-performance electrodes.

Quantum dot doping effectively mitigates ionic diffusion limitations and mechanical degradation in battery electrodes. However, a quantitative continuum understanding of these chemo-mechanical mechanisms remains elusive. Herein, we propose an experimentally motivated continuum model, representing quantum dot doping as localized diffusivity enhancements to elucidate its regulation of ionic kinetics. Results indicate that quantum dots fundamentally redistribute local concentration gradients, significantly alleviating internal deformation mismatch. Notably, quantum dot doping reduces the peak principal stress by up to 13.7% and shrinks the high-stress region fraction from 36.7% to 4.62% during ion extraction. Parametric analysis reveals that the quantum dot volume fraction dominates chemo-mechanical improvements compared to affected-zone shape or normalized size. Furthermore, surrogate-based multi-objective optimization identifies optimal geometric design windows for stress-balanced particles. This work provides critical theoretical insights and a quantitative design framework for developing mechanically reliable and electrochemically stable defect-engineered electrodes.

Solid-state electrolytes mitigate safety risks of lithium-ion batteries but face inherent limitations in ionic conductivity and interfacial stability, whereas conventional liquid electrolytes offer high ion transport efficiency but are plagued by fundamental safety issues. In this work, we propose a paradigm-shifting concept of intelligent electrolytes capable of reversible and controllable liquid-solid transitions, thereby integrating the key advantages of both electrolyte forms while circumventing their inherent limitations. This concept is realized by introducing a liquid/solid switchable electrolyte that behaves as a fluid in the absence of a magnetic field and rapidly solidifies upon magnetic field application. In its liquid state, the liquid-solid switchable electrolyte maintains the high conductivity and stability of conventional electrolytes. Upon magnetic solidification, it delivers comprehensive safety enhancements, effectively resisting impact, leakage, and puncture. Beyond these protections, the reversible phase transition further enables self-healing of mechanical damage to the electrochemically active interface. Furthermore, the liquid-solid switchable electrolyte also enhances battery thermal safety by significantly delaying thermal runaway. This on-demand electrolyte solidification enables a paradigm shift in battery design, moving from a static materials-based approach to a dynamic, intelligent control strategy.

Optimizing electrode microstructure is critical for advancing lithium-ion battery performance. Most electrochemical simulations adopt pseudo-two-dimensional models or assume spherical particles, resulting in difficulties to capture real electrode features like irregular shapes and particle alignment. This study proposes a Voronoi-interpolation algorithm to generate heterogeneous electrodes with randomly distributed, irregular active particles. Systematic simulations reveal that in electrodes where liquid-phase lithium-ion diffusion exerts a negligible effect, particle size plays a primary role in lithiation, whereas particle shape plays a secondary role. Smaller particles show higher volume-averaged concentration and lower lithiation inhomogeneity due to shorter diffusion lengths. Irregular particles of equal volume to spheres have a larger specific surface area and shorter, wider internal diffusion paths, accelerating ion transport. The results are proved by the overpotential decomposition which identifies intraparticle concentration polarization as the key voltage loss source in these cases. However, complex particle alignment impacts liquid-phase lithium-ion transport. Particle alignment along the transport direction reduces tortuosity and facilitates liquid-phase diffusion, while perpendicular alignment increases tortuosity and blocks lithium-ion diffusion. This study shows the comprehensive influence of non-uniform electrode structure on battery performance and provides a feasible modeling approach for such works.

The overall efficiency of electrocatalysis is governed by the microscopic mechanistic pathways, whose precise engineering remains a fundamental challenge. In this work, we report a noble-metal-free FeCrNi multi-principal element alloy catalyst featuring a supra-nanoscale crystalline/amorphous dual-phase structure, fabricated through controlled cooling during magnetic sputtering deposition. The catalyst delivers exceptional oxygen evolution reaction (OER) performance in alkaline media, achieving an ultralow overpotential of 363 mV at an industrial-level current density of 1 A cm-2 and maintaining robust stability for over 1000 h at 200 mA cm-2. Through integrated operando analyses, including distribution of relaxation times (DRT) analysis from in situ staircase potential electrochemical impedance spectroscopy, differential electrochemical mass spectrometry, attenuated total reflection surface-enhanced infrared spectroscopy, and in situ Raman, we reveal that the dual-phase structure promotes the in situ formation of FeNiOOH intermediates. These intermediates significantly enhance charge-transfer kinetics and optimize the adsorption-desorption behavior, thereby driving a mechanistic shift from the conventional adsorbate evolution mechanism (AEM) to the more kinetically favorable oxide path mechanism (OPM). Density functional theory (DFT) calculations further confirm that the FeNiOOH intermediate stabilizes *O-O* species with reduced energy barriers, facilitating the OPM pathway. Our work demonstrates a practical strategy for boosting OER performance by activating the OPM route through the rational design of crystalline/amorphous dual-phase active sites.

This study proposes a pre-strain optimization strategy for carbon fiber structural lithium-ion battery (SLIB) composites to inhibit the interfacial debonding between carbon fibers and solid-state electrolytes due to fiber lithiation. Through an analytical shear-lag model and finite element simulations, it is demonstrated that applying tensile pre-strain to carbon fibers before electrode assembly effectively reduces the interfacial shear stress, thereby suppressing debonding. However, the excessive pre-strain can induce the interfacial damage in the unlithiated state, necessitating careful control of the pre-strain within a feasible range. This range is influenced by electrode material properties and geometric parameters. Specifically, the electrodes with the higher solid-state electrolyte elastic modulus and larger electrolyte volume fraction exhibit more significant interfacial damage, making pre-strain application increasingly critical. However, these conditions also impose stricter constraints on the feasible pre-strain range. By elucidating the interplay between pre-strain, material properties, and geometric factors, this study provides valuable insights for optimizing the design of carbon fiber SLIBs.

The recently reported silicon/graphite(Si/Gr)composite electrode with a layered structure is a promising approach to achieve high capacity and stable cycling of Si-based electrodes in lithium-ion batteries.However,there is still a need to clarify why particular layered structures are effective and why others are ineffective or even detrimental.In this work,an unreported mechanism dominated by the porosity evolution of electrodes is proposed for the degradation behavior of layered Si/Gr electrodes.First,the effect of layering sequence on the overall electrode performance is investigated experimentally,and the results suggest that the cycling performance of the silicon-on-graphite(SG)electrode is much superior to that of the graphite-on-silicon electrode.To explain this phenomenon,a coupled mechanical-electrochemical porous electrode model is developed,in which the porosity is affected by the silicon expansion and the local constraints.The modeling results suggest that the weaker constraint of the silicon layer in the SG electrode leads to a more insignificant decrease in porosity,and consequently,the more stable cycling performance.The findings of this work provide new insights into the structural design of Si-based electrodes.

This paper investigates the interfacial debonding along the fiber-electrolyte interface induced by fiber lithiation in carbon fiber structure batteries using a shear-lag model, with the model validated through finite element simulations. The results demonstrate that as lithiation progresses, the interface transitio00ns from a purely elastic state to a cohesive damage phase, ultimately leading to interfacial debonding. Once debonding initiates, cracks propagate rapidly along the fiber-electrolyte interface, impeding ion and electron transport and significantly degrading the electrochemical performance and load-bearing capacity of the battery. To mitigate interfacial debonding, this study systematically examines the impacts of electrode length, modulus of carbon fiber and solid-state electrolyte, and cross-sectional size ratio. The findings indicate that electrode length and carbon fiber modulus have limited impacts on interfacial debonding, while reducing the modulus of solid-state electrolyte effectively decreases shear stress at the interface, thereby inhibiting debonding. Furthermore, a smaller cross-sectional size ratio alleviates interfacial stress, reducing the possibility of debonding. This research offers theoretical insights for the design of carbon fiber-based batteries, particularly in enhancing their structural stability and performance under electromechanical coupling environment.

In silicon/graphite (Si/Gr) composite electrodes for lithium-ion batteries, which have recently garnered significant attention, the competitive (de)lithiation between Si and Gr is recognized as crucial for understanding the internal electrochemical processes. In this work, an in-situ method to characterize this competitive behavior is proposed, utilizing a self-developed electrode curvature measurement system. After validating the parallel electrode configuration and the model battery, curvature measurements are simultaneously conducted on the parallel Si and Gr cantilevered electrodes throughout electrochemical cycling. Subsequently, by calibrating the correlation between capacity and curvature of the Gr electrode, the capacity evolution of Si and Gr within the Si/Gr electrode is determined, shedding light on the underlying competitive (de)lithiation behavior. During lithiation, the process transitions from "Si-dominant" to "Gr-dominant" and eventually reaching a "synchronous" stage. For delithiation, it moves from "Gr-dominant" to "Si-dominant". The method proposed in this work, based on the measurement of macroscopic electrode deformation, offers a novel perspective for characterizing competitive (de)lithiation in electrodes with multiphase active materials.

Electric vehicles (EVs) have garnered significant attention as a vital driver of economic growth and environmental sustainability. Nevertheless, ensuring the safety of high-energy batteries is now a top priority that cannot be overlooked during large-scale applications. This paper proposes an innovative active protection and cooling integrated battery module using smart materials, magneto-sensitive shear thickening fluid (MSTF), which is specifically designed to address safety threats posed by lithium-ion batteries (LIBs) exposed to harsh mechanical and environmental conditions. The theoretical framework introduces a novel approach for harnessing the smoothed-particle hydrodynamics (SPH) methodology that incorporates the intricate interplay of non-Newtonian fluid behavior, capturing the fluid-structure coupling inherent to the MSTF. This approach is further advanced by adopting an enhanced Herschel-Bulkley (H-B) model to encapsulate the intricate rheology of the MSTF under the influence of the magnetorheological effect (MRE) and shear thickening (ST) behavior. Numerical simulation results show that in the case of cooling, the MSTF is an effective cooling medium for rapidly reducing the temperature. In terms of mechanical abuse, the MSTF solidifies through actively applying the magnetic field during mechanical compression and impact within the battery module, resulting in 66% and 61.7% reductions in the maximum stress within the battery jellyroll, and 31.1% and 23% reductions in the reaction force, respectively. This mechanism effectively lowers the risk of short-circuit failure. The groundbreaking concepts unveiled in this paper for active protection battery modules are anticipated to be a valuable technological breakthrough in the areas of EV safety and lightweight/integrated design.

The largely bending bilayer electrode model battery has been widely used to measure the mechanical properties of composite electrode materials. The assumption used in the method that lithium is uniformly distributed in the active layer lacks quantitative evaluation, and the uniformity of concentration distribution is crucial for accurate in-situ measurements of concentration-related material properties and stress in bilayer electrodes. Therefore, this paper proposes a mechanical-electrochemical coupled model to study the lithium concentration distribution in the active layer during lithiation. This model includes lithium concentration diffusion and active layer deformation. By comparing experimental and simulated curvature evolution of the active layer during lithiation and delithiation, the reliability of this simulation model is verified. We then derive the precise concentration distribution inside the active layer and suggest using relative error to quantitatively evaluate the uniformity of lithium concentration in the active layer. Results show that a low relative error in lithium concentration can be achieved in the middle region of the active layer. Additionally, the effects of different rates and geometric parameters on the lithium concentration distribution in the active layer are discussed. Results indicate that reduced rates, thinner active layers, shorter active layer lengths, and increased spacing between the working and counter electrodes can lead to a more uniform distribution of lithium concentration in the active layer. These insights help improve experimental methods and equipment, promoting uniform distribution of lithium in the active layer and enhancing measurement accuracy.

It is still highly desired and challengeable to design H2S sensor with high selectivity and sensitivity due to its toxicity and new application in biomarkers like monitoring halitosis. Here, we reported a novel confined structure as highly sensitive and selective H2S gas sensor. The sensing material was prepared with a HKUST-1 templated method by atomic layer deposition (ALD) ZnO decorated on HKUST-1 and calcination. The gas sensor exhibits a high gas sensitivity (Ra/Rg = 2.67 @ 2 ppm) with excellent selectivity to H2S. Furthermore, the obtained sensor shows ppb-level detection ability (Ra/Rg = 1.13 @ 0.1 ppm). Apart from releasing electrons by the oxidization of H2S on oxygen vacancies with adsorbed oxygen species O2− on ZnO surface (Langmuir-Hinshelwood mechanism), the Cu was proved to be the active sites, and would react with surficial S species. The suggestion was confirmed by operando XAS (X-ray adsorption spectrum) measurements combined with DFT calculations (Mars-van Krevelen mechanism). This work provides valuable insights for developing efficient sensing materials and understanding the sensing mechanism.