Among the most striking contributions is a study by Myeong and colleagues that reimagines one of the most overlooked components in a lithium-ion cell: the current collector. Conventionally treated as a passive piece of aluminum foil whose only job is to conduct electrons, the current collector in this work becomes an active safety device. The researchers coated the aluminum foil with melamine polyphosphate, a flame-retardant compound, creating what they describe as a fire-extinguishing current collector. When the coating composition is properly optimized, the layer reduces the self-extinguishing time of a cell undergoing thermal runaway while preserving electrochemical performance. The significance lies in the strategy itself. Rather than reformulating the bulk electrolyte with flame-retardant additives, which can degrade cell performance, the team localized the safety functionality directly at the electrode architecture level. The current collector, in other words, becomes a multifunctional component that improves abuse tolerance without exacting a performance penalty.

Safety through structural innovation also drives a complementary contribution from Wang and co-workers, who engineered a composite solid-state electrolyte for sodium metal batteries. Their material combines a PVDF polymer matrix with a NASICON-type ceramic filler of the composition Na3.7Zr1.45Sc0.4Mg0.15Si2PO12. The optimized electrolyte establishes multiple ion-transport channels, achieving improved room-temperature ionic conductivity, a higher sodium-ion transference number, and better interfacial compatibility with the electrodes. Full cells built with this electrolyte showed strong capacity retention and long-term cycling stability. The work illustrates a broader maturation in solid-state sodium research: progress is coming less from raw conductivity improvements alone and more from careful interfacial design. It also underscores why sodium is attracting growing attention as a lower-cost alternative to lithium, both for stationary grid storage and, potentially, for transport applications.

While safety and interfaces dominate the experimental side of the collection, a different kind of breakthrough appears in the work of Tham and colleagues, who deployed high-throughput computational screening to hunt for new cathode materials for anode-free aqueous zinc batteries. Starting from a pool of more than 1,000 candidate compounds, the team systematically down-selected using a battery of criteria: thermodynamic stability, electrical conductivity, voltage window, stability in aqueous environments, and ion diffusion kinetics. The funnel narrowed to six promising compounds, including ZnNi5Zn4MnO5. The study is a textbook example of how first-principles databases and structured screening pipelines can compress years of trial-and-error experimentation into a computational search. Just as importantly, the work produced design rules linking chemical composition to electrochemical performance, rules that can guide future experimental validation and accelerate materials discovery across the emerging zinc chemistry landscape.

The computational perspective is balanced by a broader strategic assessment from Khan, whose mini-review on sodium-ion batteries frames why the technology continues to attract global investment. Sodium is abundant, inexpensive, and well suited to large-scale storage, but the review is candid about the obstacles that remain. The larger ionic radius of the sodium ion causes greater volume change during cycling, kinetics are comparatively sluggish, and the formation of a stable solid-electrolyte interphase remains problematic. Khan’s conclusion is measured: sodium-ion batteries are highly promising but still require coordinated advances in cathodes, anodes, electrolytes, and separators before reaching full commercial maturity. It is a reminder that in battery science, no single component breakthrough is sufficient; the entire cell must advance together.

Perhaps the most commercially urgent finding in the collection concerns manufacturing rather than chemistry. Lee and colleagues compared dry and wet coating methods for nickel-rich NCM811 cathodes, the high-energy layered oxide materials at the heart of many modern electric vehicle cells. Their results revealed that the coating route itself profoundly shapes surface degradation and, ultimately, cell durability. Wet coating, despite being the conventional industry approach, exposes the cathode surface to water, promoting the formation of a NiO-like surface phase. That phase accelerates cation mixing and resistance growth, quietly eroding performance over the cell’s life. Dry coating, by contrast, suppresses the unwanted phase formation and delivers better capacity retention and rate capability. The lesson is timely: as nickel content climbs in pursuit of higher energy density, the manufacturing process itself becomes as important as the material composition. Performance losses can originate not only from intrinsic material instability but from process-induced surface chemistry.

At the system level, the collection turns to the digital frontier. Madani and colleagues present an expansive review of digital twin technologies for battery systems, charting the emergence of virtual replicas that integrate physics-based modeling, machine learning, cloud-edge computing, and battery management functions. The applications they survey span electric vehicles, stationary storage, production lines, thermal management, state estimation, predictive maintenance, fault diagnosis, and end-of-life handling. Crucially, the review frames digital twins as multiscale entities, spanning everything from cell-level materials to full packs and grid-scale systems. The authors also identify the barriers that stand in the way of widespread adoption: standardization, cybersecurity, computational load, and data quality. Their central message is one of the most important in the entire collection: future battery performance will not be determined by electrochemical materials alone, but by the intelligence of the digital infrastructure that monitors and controls batteries throughout their lifecycle.

Taken together, the papers sketch a coherent map of where the field is heading. Interfaces remain decisive, whether in nickel-rich layered oxides, sodium metal solid-state cells, or flame-retardant current collectors, because interfacial chemistry controls not only capacity fade but also safety and abuse response. Processing matters as much as composition, as the dry-versus-wet coating comparison demonstrates, with subtle differences in synthesis route producing major changes in surface phase evolution and electrochemical behavior. Sodium and zinc chemistries are gaining strategic importance, offering resource and cost advantages and pathways toward aqueous, potentially safer batteries, both benefiting from improved modeling and interface engineering. And digitalization is becoming foundational, connecting electrochemistry with sensing, prediction, and operational control to enable smarter charging, improved health estimation, and lifecycle optimization.

The overarching trajectory is unmistakable. The battery community is moving beyond isolated component optimization toward integrated design across materials, processes, architectures, and cyber-physical control. The editors argue that the future of advanced batteries will likely belong to approaches that combine these domains: safer interfaces, scalable manufacturing, chemistry-aware materials discovery, and intelligent management systems working in concert. As electrification accelerates across transport and grid storage, the cells that succeed will be those designed not as isolated electrochemical devices but as holistic systems, engineered from the atomic interface to the cloud-connected digital twin. This collection offers a strong snapshot of that transition and points toward a more integrated, application-ready era in electrochemical energy storage.

Subject of Research: Recent advances in battery and electrochemistry research spanning safety design, solid-state electrolytes, computational materials discovery, cathode processing, and digital twin systems

Article Title: Editorial: Reviews in batteries and electrochemistry volume II

Article References: Johnson, C., Kim, J. H., & Cheng, Y.-T. (2026). Editorial: Reviews in batteries and electrochemistry volume II. Frontiers in Batteries and Electrochemistry, 5, Article 1985379. https://doi.org/10.3389/fbael.2026.1985379

Image Credits: AI Generated

DOI: 10.3389/fbael.2026.1985379

Keywords: batteries, electrochemistry, lithium-ion, sodium-ion batteries, solid-state electrolytes, zinc batteries, current collector, digital twin, cathode coating, materials discovery, battery safety, energy storage

In a study published in the journal Ionics, Zhuo Wang, Xu Zhang, Long Peng, Jingwen Zhu, and Qiquan Li developed an analytical model that captures the lithiation-induced stress inside bilayered silicon/graphite electrodes, the kind of layered architectures that battery manufacturers are increasingly exploring as a pragmatic compromise between silicon’s enormous capacity and graphite’s mechanical reliability. Their work, published on 13 October 2026, provides one of the clearest mechanical pictures yet of why layer arrangement matters, and it delivers concrete design rules that electrode engineers can apply directly.

The core of the study is a mechanoelectrochemical coupling model, a mathematical framework that links the electrochemical state of charge to the mechanical stress it generates. As lithium ions flood into an electrode during charging, the active materials expand; as they are withdrawn during discharge, the materials contract. Because silicon expands far more than graphite, and because the two materials possess different elastic moduli, a bilayer electrode becomes a mechanical mismatch problem: the silicon-rich layer wants to swell while the graphite-rich layer resists, and the thin metallic current collector underneath is dragged along for the ride. The researchers’ model tracks how these competing tendencies translate into stress distributions and bending deformations across the entire electrode stack.

What the analysis revealed is that the electrode stress originates primarily from the volumetric expansion associated with the increasing state of charge, meaning that the deeper a battery is charged, the more mechanical punishment its anode endures. This is a crucial insight for battery designers, because it implies that the most damaging stresses accumulate precisely during the high-capacity operation that silicon electrodes are meant to deliver. Managing stress is therefore not an optional refinement but a fundamental requirement if silicon-based anodes are ever to reach industrial maturity, a point the authors emphasize when they describe mechanoelectrochemical coupling issues as bottlenecks hindering the industrial development of silicon-based lithium-ion batteries.

The team systematically examined how two architectural variables, the relative position of the graphite- and silicon-based active layers and the thickness ratio between them, influence the stress landscape. For single-sided bilayer electrodes, they compared configurations in which the silicon-based layer sits above the graphite-based layer versus the reverse arrangement. The results were striking. Placing the silicon-based layer on top, a configuration the researchers designate Architecture II, produces increased bending deformation of the whole electrode. Somewhat counterintuitively, this configuration slightly lowers the compressive stress within the active layers themselves, but it comes at a hidden cost: a significant increase in stress within the current collector, the thin metallic foil that carries electrons in and out of the electrode.

That last finding may prove to be the study’s most consequential contribution. Current collectors are rarely the focus of electrode design conversations, yet they are the structural backbone of the entire assembly. If a particular layer arrangement offloads stress from the active materials only to concentrate it in the collector, the electrode may fail in a different and equally destructive way, through collector wrinkling, delamination, or fracture. The researchers’ model makes these hidden trade-offs visible, allowing designers to see that the mechanical budget of an electrode cannot be optimized layer by layer in isolation; the whole stack, including the collector, must be considered as a coupled system.

The picture changes for symmetric double-sided bilayer electrodes, in which active layers coat both faces of the current collector. Here, the researchers found that the sequence of the active layers has no significant effect on the electrode stress, a result that simplifies design choices considerably for double-sided architectures. However, a second lever proved powerful: increasing the thickness ratio of the graphite-based layer to the silicon-based layer effectively mitigates stress, particularly within the current collector. In other words, giving graphite the lion’s share of the thickness acts as a mechanical buffer, absorbing and distributing the deformation that the silicon layer would otherwise impose on the fragile collector beneath.

These conclusions arrive at a moment when layered and gradient silicon/graphite electrodes are attracting intense attention across the battery research community. Recent work has explored dual-layer hybrid graphite anodes for fast charging, gradient silicon distributions for energy- and power-dense cells, and porosity-engineered layered composites, all converging on the same idea: spatially organizing silicon within the electrode can dramatically improve performance. What the Zhongyuan team adds is a rigorous analytical treatment of the mechanical consequences, complementing electrochemical studies that focus on capacity, rate capability, and cycling life. By grounding architecture decisions in stress analysis, their model helps explain why some layered designs succeed in the laboratory while others fail prematurely.

The study also builds on a rich mechanistic literature. Prior experimental work has measured strains in composite battery electrodes during cycling and documented the interplay between electrochemical reactions and mechanical responses in silicon-graphite anodes, including its impact on degradation. First-principles studies have shown that the elastic properties of lithiated silicon and graphite themselves evolve with lithium concentration, with silicon softening as it lithiates and graphite stiffening during intercalation. The new analytical model incorporates this mechanoelectrochemical reality, evaluating how stress evolves as the state of charge climbs, rather than treating the electrode as a static structure. That dynamic perspective is essential for a component that may swell and relax hundreds of times over its service life.

From a mechanical perspective, the researchers distilled their numerical evaluation of the analytical solution into several electrode design strategies, offering manufacturers a practical playbook. For single-sided coatings, the message is to think carefully before stacking silicon on top, since the apparent relief in active-layer stress is offset by collector stress amplification and greater bending. For double-sided coatings, the message is more encouraging: layer order matters little, but deliberately weighting the graphite layer’s thickness relative to the silicon layer can meaningfully reduce the stresses that threaten the collector. As the industry races toward higher-energy-density cells, such rules of thumb, grounded in quantitative stress analysis rather than trial and error, could shorten the path from laboratory concept to factory floor. The work was supported by the Key Projects of Science and Technology of Henan Province and the Young Backbone Teacher program of Zhongyuan University of Technology, and it underscores a broader truth about the energy transition: sometimes the breakthrough is not a new material, but a smarter way to arrange the ones we already have.

Subject of Research: Mechanoelectrochemical stress modeling of bilayered silicon/graphite electrodes in lithium-ion batteries

Article Title: Effects of bilayered architecture design on the mechanical stability of silicon/graphite-based electrodes for lithium-ion batteries

Article References: Wang, Z., Zhang, X., Peng, L., Zhu, J., & Li, Q. (2026). Effects of bilayered architecture design on the mechanical stability of silicon/graphite-based electrodes for lithium-ion batteries. Ionics. https://doi.org/10.1007/s11581-026-07582-0

Image Credits: AI Generated

DOI: 10.1007/s11581-026-07582-0

Keywords: lithium-ion batteries, silicon anode, graphite, bilayer electrode, lithiation-induced stress, mechanoelectrochemistry, current collector, electrode architecture, volumetric expansion, battery degradation, analytical modeling, energy storage

The appeal of the anode-free design is easy to grasp. In a conventional sodium metal battery, a foil of metallic sodium is preloaded into the cell, adding weight, volume, cost, and hazard. In the anode-free version, the anode is simply a bare current collector, usually copper or aluminum, and the sodium that plates onto it during charging is extracted in situ from the cathode. Strip the sodium back during discharge and the cycle repeats. In principle this maximizes both gravimetric and volumetric energy density, because the cell carries no excess anode mass whatsoever. Current pouch-cell prototypes deliver roughly 200 to 210 watt-hours per kilogram at the cell level, still 20 to 30 percent below commercial lithium-ion cells, but the headroom is real if the chemistry can be tamed.

The problem is that sodium is a difficult metal to plate reversibly. Compared with lithium, sodium ions bind more weakly to substrates, carry a larger ionic radius, and behave differently in solution, all of which conspire to produce higher nucleation overpotentials and three-dimensional, mossy deposits rather than compact films. Where lithium nucleates with an overpotential of roughly 10 millivolts, sodium often demands more than 50. The solid electrolyte interphase that forms on sodium is typically soft and organic-rich, fracturing repeatedly as the metal expands and contracts, exposing fresh sodium to the electrolyte each time. Each fracture consumes both sodium and electrolyte irreversibly. In a cell with a sodium reservoir these losses are buffered; in an anode-free cell they are fatal.

The review’s authors formalize this with an inventory balance that deserves to become standard practice in the field. They divide the sodium in a cycled cell into three categories: reversible sodium that remains electrically connected and can be stripped again; dead sodium, which is metallic but electronically isolated or entombed in insulating interphase; and chemically bound sodium, consumed into interphase phases and electrolyte decomposition products. Coulombic efficiency, the metric nearly every paper reports, captures only the sum of the last two. Because dead sodium is in principle partially recoverable while chemically bound sodium is not, the two loss channels respond to entirely different design levers. The authors propose that reporting the three terms separately, using techniques such as sodium-23 nuclear magnetic resonance, titration gas chromatography, and X-ray photoelectron spectroscopy, would finally let researchers identify which failure pathway dominates in a given system rather than inferring it.

The arithmetic of efficiency is brutal. Working from the retention relation that multiplies initial Coulombic efficiency by the average efficiency raised to the power of cycle number, the authors derive minimum efficiency targets for practical operation. To retain 80 percent of capacity over 500 cycles with a first-cycle efficiency of 90 percent, a cell must sustain an average Coulombic efficiency of at least 99.98 percent. Even at a perfect first cycle, 500 cycles demand 99.96 percent. A cell averaging 99.7 percent, which sounds excellent, reaches the same retention threshold after only about 74 cycles. Measured against these criteria, fewer than 13 percent of reported studies achieve efficiencies above 99.7 percent under lean-electrolyte conditions, and the gap between the state of the art and commercial viability amounts to nearly a sevenfold reduction in sodium loss per cycle.

What makes this gap worse is that most laboratory numbers are collected under conditions that flatter the chemistry. More than 80 percent of reported systems operate below 2 milliamp-hours per square centimeter of areal capacity, while the industrial benchmark is at least 3. Coin cells are typically flooded with 30 to 50 microliters of electrolyte, corresponding to more than 10 grams per ampere-hour, whereas industrial cells require 3 or less. When chemistries that shine in coin cells are translated into multilayer pouch cells, a consistent penalty emerges: efficiencies above 99.9 percent often fall to 99.0 to 99.5 percent, driven by edge plating at cell perimeters, uneven stack pressure, tab corrosion, and electrolyte starvation. Of twenty-four representative systems surveyed, only one simultaneously satisfies both the lean-electrolyte and high-areal-capacity thresholds. The review’s blunt conclusion is that anode-free sodium batteries are integration-limited, not materials-limited.

That said, the toolbox of interventions is expanding rapidly, and the review organizes it by function rather than by material class. Electrolyte engineering has moved from empirical salt-solvent mixing toward mechanism-guided control: weakly solvating dual-salt systems, high-entropy sole-solvent formulations, zeolite molecular-sieve films that impose geometric confinement on solvation clusters, and nano-silica suspensions that immobilize reactive anions all steer interphase chemistry toward inorganic-rich, mechanically robust layers. On the current collector side, fluorinated carbon scaffolds act as built-in fluorine donors that seed sodium fluoride-rich interphases, with one fluorinated carbon nanotube collector sustaining over 99.9 percent efficiency across 800 cycles at 3 milliamp-hours per square centimeter. Alloy coatings of indium, tin-copper intermetallics, and high-entropy alloy nanolayers lower nucleation barriers, while three-dimensional porous hosts redistribute ion flux and buffer the mechanical stress of plating. Sodium sits at roughly 80 percent of its melting point at room temperature, so it creeps plastically under modest pressure, which means controlled stack compression between 0.1 and 0.4 megapascals can close voids and restore contact to otherwise disconnected deposits, a lever lithium does not offer so readily.

The cathode side, often neglected in anode-free discussions, turns out to be a coupled problem rather than an isolated one. At operating voltages above roughly 4.0 volts, layered oxide cathodes accelerate electrolyte oxidation and dissolve transition metals, and X-ray photoelectron spectroscopy has directly detected nickel and iron species on the cycled sodium anode, proof that cathode degradation migrates across the cell and poisons the interphase where sodium plates. Electrolytes that form thin, inorganic-rich cathode-electrolyte interphases suppress this crossover, and several pouch cells have now operated up to 4.3 volts across temperatures from minus 40 to 60 degrees Celsius with cell-level energies exceeding 200 watt-hours per kilogram. The design lesson is that the two interphases must be chemically aligned: stabilizing one while ignoring the other simply relocates the failure.

Manufacturing economics add a final layer of constraint. Sodium itself is cheap, but the supporting ecosystem is not. Fluorinated imide salts cost five to six times more than the incumbent sodium hexafluorophosphate, and projected cell manufacturing costs of 80 to 120 dollars per kilowatt-hour erode the cost advantage that motivates sodium chemistry in the first place. Sodium’s extreme moisture sensitivity demands dry rooms with dew points near minus 60 degrees Celsius, capital costs 50 to 100 percent higher than conventional lithium-ion lines, yet fewer than 5 percent of studies even report humidity tolerance. A technology-readiness assessment across 36 strategies finds that only three reach prototype demonstration level, and those tend to be the ones using commercially compatible materials and processes rather than exotic syntheses.

The review closes with a roadmap that reads less like a wish list and more like an audit. Short-term priorities through 2026 center on standardized pouch-cell protocols with controlled pressure, lean electrolyte dosing, and humidity-controlled filling. The mid-term focuses on electrolyte-interphase co-design validated at the ampere-hour scale, and the long term points toward solid-state anode-free cells for grid and mobility applications. The authors also propose a coordinated Battery300 initiative, modeled on the U.S. Department of Energy’s Battery500 program, to unify evaluation standards around targets of at least 300 watt-hours per kilogram, efficiency above 99.95 percent in pouch cells, and open benchmarking databases. Their underlying message is clear and slightly uncomfortable for the field: the path to practical anode-free sodium batteries runs not through another record-breaking coin cell, but through measurement conventions, inventory accounting, and the patient, unglamorous work of making every component survive contact with every other one.

Subject of Research: Anode-free sodium metal battery design, failure mechanisms, and system-level integration for practical energy storage

Article Title: Anode‐Free Sodium Metal Batteries: From Materials Design to System‐Level Integration

Article References: Hussain, H., Ali, S., Ali, M., Aman, S., Ali, M., Naseer, U., Farooq, S., Mahmood, A., He, S., Jiang, Y., & Yousaf, M. (2026). Anode‐Free Sodium Metal Batteries: From Materials Design to System‐Level Integration. Advanced Science, Article e77874. https://doi.org/10.1002/advs.77874

Image Credits: AI Generated

DOI: 10.1002/advs.77874

Keywords: sodium batteries, anode-free, solid electrolyte interphase, Coulombic efficiency, current collector, electrolyte engineering, dead sodium, pouch cells, energy density, battery manufacturing, solid-state electrolytes, machine learning