Accurate modelling of battery energy storage systems (BESSs) is critical for optimising their integration into power grids with high penetration of renewable energy. Conventional stochastic models often assume constant charging and discharging efficiencies, an oversimplification that neglects the significant dependence of battery performance on its state-of-charge (SOC). This paper introduces a novel analytical model for BESS based on a discrete-time discrete-state Markov chain that explicitly incorporates SOC-dependent efficiencies and charge acceptance limitations. The BESS is modelled as a finite-state buffer subject to stochastic energy inflows and outflows, where the transition probabilities are functions of the current SOC. We derive a closed-form analytical solution for the steady-state probability distribution of the battery's charge levels. Through an illustrative numerical study, the comparative analysis demonstrates that, when charge acceptance is limited at high SOC (e.g., for State Of Health preservation), our model predicts a significant shift in operational behaviour compared to ideal or constant-efficiency models. The system's probability mass tends to concentrate in an intermediate range, a behaviour that simpler models often overlook. This has significant implications for BESS sizing and control strategies, indicating that the selected operating strategy greatly affects the appropriate usable capacity. The proposed model provides a computationally efficient and more realistic framework for analysing these dependencies.

Transition metal oxalates have been proven to be a promising electrode material for lithium-ion batteries. Here, we have designed a series of multi-phase transition metal oxalates with different structures and compositions by simply adjusting the proportions of five transition metal elements. Among them, the multi-phase mixture (MC₂O₄·2H₂O - CuC₂O₄ - MC₂O₄·2H₂O, M = Mn, Fe, Co, Ni, Cu) provides a more stable framework for the material during lithiation and delithiation, effectively alleviating the structural collapse during the cycling process. In addition, the electron transport and fast charge compensation processes of multiple electrochemically active metal pairs also contribute to the improvement of performance. Therefore, the multi-phase transition metal oxalate TMOx-2 electrode with an additional CuC₂O₄ phase exhibits high reversible capacity and long-term cycling stability. After 400 cycles at 100 and 500 mA/g, the specific discharge capacities are 827 mAh/g and 498 mAh/g, respectively. Constructing multi-metal, multi-phase systems by combining different transition metals enables control over potential, reaction pathways, and stability of high-performance electrodes.

This work presents an asymptotic analysis of lithium transport phenomena during a galvanostatic intermittent titration technique (GITT) pulse-relaxation cycle in electrodes combining composite silicon-carbon (Si-C) aggregates and graphite particles. The study demonstrates that asymptotic techniques offer both physical insight into the complex interplay of transport mechanisms—namely, lithium exchange between silicon and graphite, diffusion within active particles, and exchange between graphite and composite particles—and contribute to efficient parameter identification. A key challenge in characterising composite Si-C electrodes via GITT lies in the presence of very disparate time scales associated with the relevant transport phenomena. This fact results in a cell behaviour during the GITT test completely different with respect to homogeneous electrodes. The asymptotic framework developed here explains how the interplay among these transport phenomena affects the observed cell voltage during the experiments and why GITT tests must be adapted for reliable identification of blended electrode parameters, providing guidance for the design of such adapted experiments. Although applied here to a single pulse-relaxation cycle, the methodology is general and can be extended to other operating conditions or composite electrode systems.

As integrated circuit technology approaches its physical limits in the post-Moore era, transition metal sulfides, with atomic-scale thickness and exceptional electrical properties, have emerged as promising channel materials. The commonly occurring ripple strain, previously considered a fabrication defect to be overcome, has evolved into an actively controllable dimension with potential applications. This review first analyzes two types of formation mechanisms of ripple strain: one is a spontaneous process governed by thermodynamic fluctuations, substrate coupling, lattice mismatch, and mismatched thermal expansion coefficients; the other is based on artificial control strategies, such as substrate morphology engineering, strain transfer through flexible substrates, and field-induced modifications, with a comparison of their controllability and limitations. The paper further examines how inhomogeneous strain fields profoundly alter the optoelectronic properties of materials through multiple physical channels. In particular, interface strain coupling in heterojunction systems offers a new paradigm for band engineering and quantum state manipulation. Although challenges remain in many aspects, the development of atomically precise strain fabrication processes and robust integration strategies holds promise for ripple strain engineering, playing a key role in tunable optoelectronic devices, high-performance sensors, and on-chip quantum information processing, advancing two-dimensional materials from fundamental research to functional applications.

This study examines the cooling performance of lithium-ion (Li-ion) batteries in electric vehicles, emphasizing the importance of maintaining temperatures below 35°C to ensure efficiency and safety. A simulation-based approach is used to study battery pack cooling using a liquid coolant (deionized water) within a cold plate system, focusing on a 16-cell battery pack connected in series-parallel. A novel stereoscopic-serpentine cold plate design is implemented. The thermal response of the battery pack is evaluated under constant and worldwide harmonized light vehicles test cycle (WLTC Class 3 drive) discharge rates. The inlet temperature and inlet flow velocities of the liquid coolant are varied. The simulation results for the stereoscopic-serpentine cold plate design are compared with those for the traditional serpentine bottom cold plate design. The new design improved coolant flow and effectively reduced temperature differences in the battery pack. The findings highlight that lowering the coolant temperature is significantly more effective for reducing the battery temperature than increasing the coolant flow speed, with a 1% decrease in coolant temperature leading to a 7.1% reduction in the maximum battery temperature, compared with a mere 0.21% reduction from a 1% increase in coolant flow speed.

Black phosphorus (BP) is a layered and two-dimensional substance that has been discussed as an anode material for lithium-ion batteries (LIBs) due to its exceptionally large theoretical capacity, anisotropic electrochemical characteristics, and bandgap control. However, pristine BP suffers from problems such as significant volume expansion, capacity fading, and low coulombic efficiency. To overcome these challenges, researchers have explored BP incorporated with various nanocomposites to not only improve structural stability and conductivity of BP, but also suppress its environmental degradation and optimize its electrochemical performance. This review focuses on modification strategies such as carbon-based hybridization, metal doping, and heterostructure engineering to address these challenges. It also systematically compares the strategy of synthesis of the BP-based nanocomposites, such as high-energy ball milling machine, chemical vapor deposition, liquid exfoliation, and their combination with various reinforcements. The electrochemical behavior of these composites, such as specific capacities, rate capability, cycling stability, among others are evaluated and compared, and the results are summarized in a tabular form to make them clear. In addition, this review explains how the BP-based nanocomposites can be used to transform the LIB technology while identifying key research directions to advance the versatility of these composites in real-world applications.

The formation of a stable cathode-electrolyte interphase (CEI) is critical for the performance of lithium–sulfur (Li–S) batteries with carbonate-based electrolytes, as it suppresses parasitic polysulfide reactions and enables solid-state sulfur conversion. In nanoporous carbon hosts, the CEI together with nanopore confinement plays a key role in capacity retention and long-term cycling. Yet, its spatial formation, stability, and contribution to electrochemical performance remain poorly understood, partly due to challenges in characterization caused by beam and air sensitivity. Here, we employ cryogenic transmission electron microscopy (cryo-TEM) with electron energy loss spectroscopy and energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and electrochemical testing together with galvanostatic intermittent titration technique measurements to elucidate how carbon particle size affects CEI formation and electrochemical performance. We find that the CEI is not a uniform surface film but extends heterogeneously into the particle bulk. Mass transport during the first discharge dictates CEI development, and larger particles suffer from inactive regions due to the preferential CEI formation only in the outer regions of the particles. During extended cycling, charge transfer resistance at confined CEI/active material/carbon interfaces emerges as the dominant performance-limiting factor. These findings show that particle size controls CEI formation during initial discharge, offering guidance for designing carbon hosts from nano- to micrometer length scales in Li–S battery cathodes.

All-solid-state batteries (ASSBs) are widely regarded as a promising next-generation energy storage technology due to their potential advantages in intrinsic safety, energy density, and operating temperature window. However, growing evidence indicates that their performance degradation and failure cannot be attributed to a single material or an isolated interface issue, but rather arise from the coupled evolution of intrinsic material instabilities, constrained solid–solid interfacial contact, and strong chemo–electro–mechanical interactions. This review systematically summarizes the failure mechanisms and fault evolution of ASSBs from the material level to the cell level. First, the chemical stability and mechanical properties of solid electrolytes and electrode materials are examined, with particular emphasis on thermodynamic instability, interfacial decomposition, and structural embrittlement under high-voltage cathodes or lithium-metal anodes. Subsequently, the formation and evolution of real contact area at solid–solid interfaces are discussed, elucidating the intrinsic links between volume-change-induced stress concentration, contact loss, and the nonlinear growth of interfacial resistance. Furthermore, the mutual reinforcement between interfacial chemical reactions and mechanical damage is analyzed, along with how these processes are amplified at the electrode scale and ultimately evolve into capacity fading and safety risks at the cell level. By integrating experimental observations, operando/three-dimensional characterization, and multiscale modeling, this work establishes a unified framework connecting materials, interfaces, and cell-level degradation, providing theoretical guidance for interfacial engineering, structural optimization, and lifetime prediction of ASSBs.

Nickel-rich layered oxide cathodes are considered highly promising candidates for next-generation lithium-ion batteries (LIBs), owing to their high energy density. Nevertheless, their practical application remains constrained by limited cycling stability and rate capability. This study explores the influence of Sc₂O₃ doping on the electrochemical performance and structural stability of LiNi_0.88Co_0.09Mn_0.03O₂ (LNCM88). Sc₂O₃ was incorporated at doping levels of 0.5, 1, and 2.5 wt%, and its effects were systematically investigated using several characterization techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). These analyses confirmed successful Sc₂O₃ incorporation without significant changes in the cathode morphology. Electrochemical characterizations showed that, although the initial capacity decreased with increasing Sc content, capacity retention and rate performance improved significantly. Notably, the sample doped with 1 wt% Sc₂O₃ demonstrated a discharge capacity of 195.1 mAh g^-1 after 100 cycles at 0.1 C, with a retention rate of approximately 93.1%. These findings highlight the efficacy of Sc₂O₃ doping as a viable strategy to enhance the electrochemical properties and commercial potential of nickel-rich layered cathodes in LIB applications. Full cell results revealed that the Sc₂O₃-doped LNCM88 delivers improved capacity retention, maintaining 83.2% at 1 C after 300 cycles, compared to only 76.4% for the undoped material under identical conditions. High-rate cycling results further demonstrate that 1 wt% Sc doping significantly enhances the durability of LNCM88, making it a promising strategy for improving the performance of nickel-rich layered cathode materials in high-power lithium-ion battery applications.

Binder-free electrodes are emerging as a transformative solution in electrochemical energy storage systems, offering direct electron transport pathways and eliminating the limitations imposed by insulating binders. In this work, we report the synthesis of nickel-cobalt phosphate dihydrate (NCP) grown directly on nickel foam using a simple hydrothermal method carried out at 180°C for 12 h. This straightforward approach yielded a distinctive flake and nanosheet morphology, resulting in abundant electroactive sites, enlarged surface area, and open channels for rapid ion diffusion. Electrochemical investigation revealed the remarkable performance of the NCP electrode. Cyclic voltammetry (CV) demonstrated a specific capacity of 118.8 C/g (215 F/g) at 5 mV/s, while galvanostatic charge-discharge (GCD) measurements confirmed a specific capacity of 98.8 C/g (178.9 F/g) at 1 A/g within a 0.55 V potential window. To evaluate practical applicability, a supercapattery device was assembled using the binder-free NCP electrode as the positive electrode and activated carbon (AC) as the negative electrode. The NCP//AC device delivered a specific capacity of 87.7 C/g at 0.5 A/g. Most notably, the device demonstrated outstanding electrochemical stability, maintaining 92.9% capacity retention after 5000 cycles at 2 A/g. These findings highlight the efficacy of the hydrothermal approach and the synergistic role of Ni and Co in stabilizing the phosphate framework. The NCP electrode, with its unique nanosheet architecture, emerges as a promising candidate for next-generation, high-performance supercapattery.

Activated carbon (AC) materials, characterized by their high surface area, diverse pore structure, and excellent electrical conductivity, have proven to be highly efficient and versatile options for applications in electrochemical energy storage. This investigation explores the most recent advancements in the synthesis and application of AC materials and their use in novel hydrogen storage and supercapacitor solutions. Carbon-based electrodes demonstrate outstanding electrochemical performance in supercapacitors, characterized by their high capacitance, rapid charge-discharge cycles, and long life span. Through surface modifications and the incorporation of metal nanoparticles, AC materials exhibit notable adsorption potential for hydrogen storage, demonstrating enhanced hydrogen absorption properties. Maximizing the performance of AC electrodes requires a critical examination of the interplay between pore size distribution, surface kinetics, and material processing. This analysis provides a detailed and comprehensive examination of the current challenges and prospective strategies for improving the energy storage and hydrogen storage capabilities of AC materials, focusing on their structural and chemical characteristics. The findings underscore the promise of AC materials as viable and sustainable options in the transition to clean energy technologies.

Solid polymer electrolytes (SPEs) offer a compelling path toward next-generation all-solid-state batteries (ASSBs), but their practical application remains constrained by low ionic conductivity and poor interfacial stability. These limitations arise from the intrinsically low dielectric constant of polymer matrices that fail to effectively dissociate lithium salts. Meanwhile, the disordered ion pathways induce tortuous migration routes and nonuniform current density at electrode interfaces. This perspective introduces the concept of programming ionic transport, which integrates ferroelectric liquid crystals (LCs), dielectric field engineering, and process-programmed assembly to overcome these challenges. Ferroelectric LCs offer a unique combination of high dielectric anisotropy and programmable molecular order, enabling the creation of low-tortuosity ion highways with built-in polarization fields. The spontaneous polarization of ferroelectric nematic phases can generate local electric fields that actively repel anions and guide lithium ions, potentially overcoming the limitations of conventional SPEs. To translate this molecular order into macroscopic device function, we highlight the critical role of advanced manufacturing techniques. Process-programmed assembly, including shear-induced alignment in 3D printing and electrospinning, provides a direct means to control alignment of LCs into designed architectures. The integration of material design and digital fabrication enables electrolytes with graded dielectric properties, hierarchical ion transport networks, and customized device geometries for ASSBs. We outline a roadmap for the future development of ASSBs that moves beyond facilitated ion transport toward actively programmed ion transport.

Sustainable energy storage devices are intensively sought with the goal to produce nontoxic and easily recycling devices with minimum to zero environmental impact. Porous carbon materials made from biomass waste in combination with the use of green solvent like deep eutectic solvent (DES) make the perfect combination to produce sustainable supercapacitors. In this work, a bio-compatible DES composed of betaine and urea is used in combination with a sodium perchlorate (NaClO₄) solution (20% water content) to form hybrid DES electrolyte with improved ionic conductivity, reduced viscosity and enhanced electrochemical performances. This hybrid DES was used as electrolyte in a symmetric supercapacitor employing porous activated carbon derived from spent grains. The carbon material was prepared via a one-step carbonization and activation process at 900°C, resulting in a hierarchical porous structure with interconnected sheet-like morphology, exhibiting high specific surface area of 1828 m² g^-1 and a total pore volume of 1.06 cm³ g^-1. Electrochemical testing in aqueous 1 M H₂SO₄ revealed a specific capacitance of 253 F g^-1 at 0.25 A g^-1, with 54.5% retention at 10 A g^-1, demonstrating excellent rate capability. Furthermore, using hybrid DES electrolyte, the symmetric device demonstrated excellent operating voltage of 2.6 V with an energy density up to 53.8 Wh kg^-1 and a maximum power density of 9.8 kW kg^-1, along with 78% capacitance retention after 10,000 cycles. These findings highlight the potential of green, non-toxic and low-cost modified Betaine: Urea DES electrolytes in the development of high-performance, sustainable supercapacitors using biomass-derived carbon materials.

Highly dispersed metallic active centers supported on two-dimensional conductive carbon materials hold great promise for energy-conversion applications; however, their structurally controllable synthesis remains challenging. Herein, we propose a template-assisted assembly strategy using ZnO as a structure-directing template to construct a branched porous carbon framework embedded with FeNi alloy species. Unlike conventional hard templates that merely create pores, the ZnO template creates a favorable microenvironment for CNT growth and simultaneously generates abundant mesopores upon its removal. Through coordination interactions between folic acid and Fe/Ni ions, two-dimensional confined precursors are first formed. This branched architecture, conceptually described as a porous carbon reactor, integrates a high specific surface area, efficient electron/ion transport pathways, and densely distributed catalytic active sites. As a result, the optimized catalyst exhibits excellent bifunctional ORR/OER activity in alkaline media, with a small potential gap (ΔE = 0.67 V). The assembled rechargeable zinc-air battery delivers a high peak power density of 239 mW cm^–2 together with outstanding cycling stability (over 200 h). This work provides a new paradigm for designing noble-metal-free electrocatalysts through template-guided assembly.

Against the backdrop of the rapid development of green and sustainable electrochemical energy storage technologies, aqueous zinc-ion batteries (AZIBs) have attracted significant attention as next-generation energy storage candidates due to their high theoretical capacity, exceptional safety, cost-effectiveness, and environmental friendliness. However, Zn anodes suffer from dendrite growth and side reactions such as hydrogen evolution, corrosion, and passivation, leading to low Coulombic efficiency and limited cycle life, hindering the commercialization of AZIBs. Recently, polymer materials have been widely employed to address these issues through the construction of polymer-based interfacial protective layers or polymer electrolytes, demonstrating broad application prospects. The attractiveness of polymer materials lies in their tunable functional groups, highly designable molecular structures, flexibility, and facile processability. These features allow polymers to shield the Zn anode from direct electrolyte contact, suppressing water-induced side reactions. Moreover, by homogenizing the interfacial electric field and regulating Zn²⁺ transport, polymer-based components promote uniform and dense Zn deposition, significantly improving cycling stability and reversibility of Zn anodes. This review systematically summarizes recent advances in polymer-based Zn anode protection strategies, classifying polymers by their functional groups and discussing the design principles, working mechanisms, and optimization approaches of polymer-based interfacial layers or electrolytes. Finally, forward-looking perspectives are proposed regarding the key challenges currently faced and future development directions, such as the molecular structure design of high-performance polymers and the construction of multifunctional synergistic interfaces.

Electrochemical impedance spectroscopy (EIS) is highly sensitive to interfacial processes in solid-state batteries (SSBs) but can be difficult to interpret in real time. Here we pair in situ EIS with machine learning (ML) to create a lightweight, interpretable diagnostic framework. By encoding spectra into feature vectors and training tree-based multi-output regressors, we achieve real-time predictions of state of charge and cycle index with R² >0.99. Feature-importance analysis links dominant mid- and low-frequency responses to cathode and anode degradation, respectively. Remarkably, retraining on only five key features maintains sub-percent accuracy, enabling millisecond-scale, impedance-based monitoring suitable for embedded solid-state battery management systems.

Building a robust artificial composite interphase layer is a promising approach for stabilizing lithium-metal anode, however, fully exploiting the synergistic effects of composite structures and developing scalable manufacturing methods are the keys to optimizing battery performance and promoting practical applications. Here, we propose a ternary heterostructural gradient design, and develop a universal chemical metathesis to in-situ constructing a gradient LiCl-LiF-LiIn composite interphase layer onto lithium-metal. This composite layer exhibits an interpenetrated gradient structure with controllable morphology and thickness. The modified electrode shows a plat and dense interface layer, with its structure presenting a heterogeneous, vertically oriented components, which bears low interfacial impedance, rapid Li-ion diffusion dynamics and high electrochemical stability, thus enabling fast charge-transfer and uniform Li plating/stripping, finally suppressing side-reactions and Li-dendrites. Consequently, the lithium electrode cyclability can be markedly enhanced. Symmetric cells of modified lithium electrode achieve 1600 h stable cycling at 1 mA cm^-2 current density, and asymmetric cells coupled with high-loading LiFePO₄ or LiNi_0.8Co_0.1Mn_0.1O₂ cathodes show significantly improved cycle-life (500 cycles of modified Li//LiFePO₄ vs. 205 cycles of bare Li//LiFePO₄, and 300 cycles of modified Li//LiNi_0.8Co_0.1Mn_0.1O₂ vs. 128 cycles of bare Li//LiNi_0.8Co_0.1Mn_0.1O₂). This gradient heterostructural concept would invoke a paradigm shift to future lithium-electrode interface technologies.

Understanding and predicting battery cycle life is crucial for the reliable operation of lithium-ion cells, particularly under fast-charging conditions. Conventional prognostic methods predominantly rely on electrochemical measurements such as capacity fade and internal resistance, which often require specialized testing protocols and limit practical applicability. In this work, we investigate temperature as a non-electrochemical and readily accessible signal that encodes degradation-related information during battery cycling. Motivated by a physically grounded hypothesis informed by density functional theory, we relate the accumulation of internal resistance to increased heat generation, which manifests as characteristic temperature behavior over cycling. Using a large open-source dataset comprising 96,700 cycles of commercial LiFePO₄/graphite cells subjected to diverse fast-charging protocols, we systematically analyze the relationships among temperature, discharge capacity, internal resistance, and cycle life. Temperature features are extracted separately from charge and discharge temperature curves, and data-driven cycle life prediction models based on a gradient boosting machine (GBM) framework are developed. Models using discharge-derived temperature features significantly outperform those based solely on charge-derived features, while combining charge and discharge features yields the highest predictive accuracy. Shapley value analysis further reveals the dominant contribution of discharge-related temperature features to model predictions. These results demonstrate that appropriately processed temperature data can provide a practical, non-electrochemical pathway for battery cycle life prediction without reliance on electrochemical diagnostics.

The growing demand for lithium calls for integrated strategies that combine resource recovery with sustainable material synthesis. Here, we demonstrate a patented chemicals-free circular approach that converts real spent lithium-ion battery black mass into functional lithium–aluminum layered double hydroxide (Li/Al-LDH). The process integrates a 5-min microwave-assisted carbothermic treatment, water-only leaching, and spontaneous precipitation, enabling the formation of crystalline Li/Al-LDHs alongside high-purity Li₂CO₃ without the use of added chemical reagents. Structural characterization by synchrotron pair distribution function analysis, XRD, and SEM confirms the formation of phase-pure LDHs with a hierarchical nanosheet-based morphology and an exceptionally high surface area (more than 400 m² g^-1). Preliminary adsorption–desorption experiments demonstrate the ability of the synthesized Li/Al-LDHs to reversibly exchange lithium ions, supporting their potential application as sorbents for lithium recovery from aqueous systems. The sustainability analysis reveals a reduction of 60%–90% in environmental impacts, including embodied energy and carbon footprint, compared to conventional LDH synthesis routes. This work establishes for the first time a direct link between battery recycling and lithium extraction technologies, providing a scalable pathway toward a circular and low-carbon lithium economy.