The underlying problem is one of geometry and transport. In a conventional battery, the cathode is a relatively thin layer of active material coated onto a metal current collector. Increasing the thickness of that layer packs in more of the energy-storing material and reduces the relative weight and volume taken up by current collectors and separators, which is exactly what designers of long-range electric vehicles want. But as the electrode grows thicker, lithium ions must travel farther through a crowded, tortuous pore network to reach the deeper regions. Transport slows, electrochemical reactions become concentrated near the electrode surface, and a large fraction of the stored energy becomes effectively inaccessible during fast charging or discharging. The KRICT team describes this as a lithium-ion traffic jam, and their additive is designed to clear it.

The manufacturing route matters as much as the chemistry. Most electrodes today are made by a wet process: cathode active materials, binders, and other components are mixed into a solvent, coated onto the current collector, and then dried. In thick electrodes, the drying step causes the binder to migrate toward the surface, leaving an uneven distribution of components through the film. Dry electrode manufacturing eliminates the solvent and the drying stage entirely, which avoids that migration and, as the researchers note, has significant potential to reduce manufacturing costs, energy consumption, and production space by removing solvent-drying and recovery processes. Dry processing alone, however, does not solve the rising resistance to lithium-ion transport that comes with thicker electrodes, which is where the new additive comes in.

Graphitic carbon nitride is a porous, nitrogen-rich material, and the team exploited its surface chemistry in a specific way. Nitrogen atoms on the surface of the g-C3N4 particles temporarily capture and release passing lithium ions through the formation of transient lithium-nitrogen bonds. The researchers compare the effect to placing intermediate transfer hubs inside a large building: instead of a visitor struggling across the whole structure in one effort, the hubs break the journey into easier stages. In electrochemical terms, the additive helps lithium ions shed the solvent molecules of the electrolyte that surround them and enter the cathode active material more readily. The porous structure of the additive also improves electrolyte wettability, allowing the liquid electrolyte to penetrate the thick film more effectively and promoting a more uniform distribution of lithium ions throughout the electrode.

The quantitative gains reported in the study are striking. The activation energy required for lithium-ion charge transfer, the energy barrier ions must overcome to enter the cathode material, fell by 56 percent, from 49.8 to 22.1 kilojoules per mole. In a dry thick-film electrode approximately 68 micrometers thick containing just 0.5 weight percent g-C3N4, the discharge capacity measured at a high discharge rate of 3C rose by 165.9 percent, from 58.8 to 156.2 milliampere-hours per gram. Power density increased by up to 2.85 times. In pouch-type full cells, capacity retention after 600 charge-discharge cycles improved from 72.9 percent for the additive-free electrode to 81.3 percent for the electrode containing the additive, indicating that the benefit extends beyond raw rate performance to long-term durability.

Just as important as the headline numbers is the team’s finding that more additive is not automatically better. Because g-C3N4 is a poor electrical conductor, adding excessive amounts raises the overall electrical resistance of the electrode, working against the very performance the additive is meant to improve. The researchers also observed the spring-back effect, in which a compressed dry electrode partially expands over time, making the internal ion-transport pathways more tortuous and partly undoing the gains in transport efficiency. Performance, they conclude, depends on the simultaneous design of three things: the amount of additive, its positioning within the electrode, and the pore structure of the electrode itself. They describe this combined approach as an architecture-interface co-design strategy, reflected in the title of the published paper.

The dry-electrode process itself carries commercial weight. Conventional wet processing requires large volumes of solvent, energy-intensive drying ovens, and systems for solvent recovery, all of which add cost, floor space, and energy consumption to a battery plant. Removing those steps raises prospects for commercial-scale production of high-energy batteries, particularly the high-capacity cells targeted at long-range electric vehicles, where every micron of extra active material and every gram of saved inactive component translates into driving range. The KRICT team is careful, however, to note the limits of the present study: it did not directly measure actual mass-production yields or reductions in manufacturing costs, so those economic benefits remain a prospect rather than a demonstrated result.

The study also illustrates how instrumentation partnerships support modern battery research. The collaboration included Thermo Fisher Scientific Korea, a global scientific instrumentation company, alongside the university partners, and the work was supported by KRICT’s institutional research program, the Nano and Material Technology Development Program through the National Research Foundation of Korea funded by the Ministry of Science and ICT, the Technology Innovation Program funded by the Ministry of Trade, Industry and Energy, and the Global TOP Strategic Research Group Program supported by the National Research Council of Science and Technology. Dr. Moon and Dr. Suk served as corresponding authors, with Hye Ji Eun, a post-master’s researcher, as first author; the KRICT team also included Dr. Jinkyu Park, a postdoctoral researcher, and student researcher Garam Lee.

For the battery industry, the message is twofold. First, dry-electrode manufacturing, already attractive for its cost and environmental profile, can be made compatible with thick, high-energy cathodes if ion transport inside the film is actively engineered rather than left to chance. Second, small quantities of a well-chosen additive, here only half a percent by weight, can produce outsized improvements in rate capability and cycling life when its chemistry and placement are matched to the electrode’s pore architecture. The transient lithium-nitrogen bonding mechanism offers a template that other nitrogen-rich porous materials might follow, and the demonstrated 56 percent reduction in charge-transfer activation energy gives researchers a concrete target for future additive design. As electric vehicle makers push for cells that store more energy in the same volume and weight, solutions that clear the lithium-ion traffic jam inside thick electrodes, without adding solvent back into the factory, are likely to attract close attention from cell developers worldwide.

Subject of Research: Dry-process thick-film lithium-ion battery cathodes enhanced with graphitic carbon nitride additives for faster ion transport

Article Title: KRICT clears lithium-ion traffic jams in thick electrodes for high-capacity batteries

Article References: KRICT clears lithium-ion traffic jams in thick electrodes for high-capacity batteries. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: lithium-ion batteries, dry electrode manufacturing, graphitic carbon nitride, cathode additives, thick-film electrodes, energy density, charge transfer, electrolyte wettability, electric vehicles, KRICT, battery cycle life, pouch cells

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

The appeal of lithium-sulfur chemistry lies in its theoretical energy density, which far exceeds that of today’s lithium-ion cells because sulfur can in principle exchange two electrons per atom at a lightweight atomic mass. That promise has made Li-S batteries a favorite candidate for structural energy storage, an emerging field in which the battery itself doubles as a load-bearing component of an aircraft fuselage, a car chassis, or a robot’s limb. The problem is that sulfur cathodes are mechanically and chemically fragile. When a sulfur-loaded electrode is bent around a curved surface, the active material cracks, the interface between the cathode and the current collector delaminates, and electrical contact is progressively lost. Under repeated curvature changes and external loading, these failure modes compound, and the cell’s performance collapses.

The KAIST-led team attacked this problem at the level of materials architecture rather than cell packaging. Their starting point is ordinary woven carbon cloth, a flexible, conductive textile made of carbon fibers. Onto this fabric they grew dense arrays of nickel-cobalt precursor nanowires directly, without any polymer binder, and then converted the nanowires into nickel cobalt selenide, NiCo2Se4, through a selenization process. The result is a single monolithic scaffold in which polar, polysulfide-grabbing NiCo2Se4 surfaces are seamlessly fused to a continuous carbon-fiber network that shuttles electrons throughout the electrode. Because the nanowires are grown rather than glued, there is no weak interface between the active material and the conductive substrate, which is precisely where conventional composite cathodes tend to fail under mechanical stress.

The chemistry of the selenide coating matters as much as its mechanical integration. During discharge in a lithium-sulfur cell, sulfur is converted through a series of intermediate polysulfide species that dissolve into the electrolyte and migrate between the electrodes, a phenomenon known as the polysulfide shuttle that erodes capacity and fouls the lithium anode. Polar transition-metal compounds such as NiCo2Se4 chemically adsorb these polysulfides, anchoring them near the conductive network where they can be reconverted instead of wandering off. In comparative tests, the sulfur-loaded nanowire scaffold, designated S/NCSe@CC, showed markedly stronger polysulfide adsorption than sulfur deposited on plain carbon cloth or on a precursor-coated cloth lacking the selenide conversion, confirming that the selenide surface is the active ingredient in taming the shuttle problem.

Electrochemically, the scaffold delivered impressive numbers. At a modest rate of 0.1 C, the S/NCSe@CC cathode achieved a discharge capacity of 1,544 milliampere-hours per gram of sulfur, close to the theoretical limit of the chemistry, with a voltage polarization of only 0.13 volts between charge and discharge plateaus. Reduced charge-transfer resistance and accelerated sulfur-redox kinetics, measured against the control electrodes, indicate that the interconnected nanowire-fiber network provides both fast electron transport and efficient ionic access deep inside the electrode. In practical terms, the scaffold functions simultaneously as a current collector, a polysulfide trap, and a mechanical backbone, collapsing three functions that normally require separate layers into one integrated textile.

The most striking result, however, concerns mechanical durability. The researchers subjected the cathode scaffold to 1,000 curvature-conditioning cycles at a bending radius of just 2.5 millimeters, an aggressive deformation that would destroy most conventional electrodes. Microscopic examination afterward showed that the nanowire-fiber integration remained intact, with no catastrophic cracking or delamination of the active layer. Even more importantly, pouch cells assembled with electrodes that had already endured this conditioning displayed discharge behavior comparable to pristine, never-bent cells. This suggests that the scaffold does not merely survive bending in a laboratory test; it can be pre-shaped into a curved geometry and still deliver full electrochemical performance once installed in a real device.

To test that idea under realistic conditions, the team assembled pouch cells and bent them around cylindrical mandrels. Cells held in the curved state retained 94.0 percent of their flat-state discharge capacity, a loss of only six percent attributable to the curvature itself. The researchers then went further, integrating the pouch cells into cylindrical, oval, and square geometries, and finally wrapping them around a drone-leg structure to mimic the kind of non-planar component a structural battery would actually inhabit. In every case the cells remained electrically operational after geometric insertion and fixation, demonstrating that the materials-to-architecture strategy holds up not just on a bending jig but in the awkward, compound-curved shapes that real engineering demands.

Why does this matter beyond the laboratory? Structural batteries promise to eliminate the dead weight of dedicated battery packs by making the airframe or chassis itself an energy store, and for lightweight platforms such as drones, eVTOL aircraft, and small satellites, every gram saved translates directly into range or payload. Lithium-sulfur chemistry is particularly attractive here because of its low areal density, but until now nobody had shown a Li-S cathode that could be reliably integrated into a non-planar structural element. The carbon-cloth substrate is itself a textile, which means it can in principle be draped, stitched, or laminated into composite structures using processes familiar to the aerospace industry, and the binder-free growth process avoids the polymer additives that add weight and creep under load.

The work also offers a template that extends beyond nickel cobalt selenide. The core insight, that a polar conversion compound grown monolithically on a flexible conductive textile can simultaneously solve the chemical and mechanical failure modes of a sulfur cathode, could be adapted to other transition-metal chalcogenides or phosphides as polysulfide hosts. The KAIST and Chalmers collaboration, which bridges mechanical engineering, materials science, and structural-battery expertise, is well positioned to push the concept toward full structural composites in which the cathode textile is embedded within a load-bearing laminate. The research was supported by the National Research Foundation of Korea and the Korean Institute for Advancement of Technology, reflecting sustained national investment in next-generation energy-storage materials.

Challenges remain before curved lithium-sulfur structural cells fly on real aircraft. The reported results focus on cathode performance and curvature tolerance; full structural-battery systems must also address lithium-metal anode stability, electrolyte containment under load, and the trade-off between mechanical stiffness and ionic transport that defines the entire structural-power field. Cycle-life data at the pouch-cell level under sustained mechanical stress will be essential, and scaling the nanowire growth process to meter-scale textiles is an open engineering question. Still, the demonstration that a Li-S pouch cell can be wrapped around a drone leg and keep working, retaining 94 percent of its capacity under cylindrical curvature, is a vivid proof of concept. It suggests a future in which the battery is not a box bolted onto a machine but a material woven into its very shape, flexible enough to follow the designer’s geometry and tough enough to carry the load.

Subject of Research: Monolithic NiCo2Se4 nanowire-carbon cloth cathode scaffolds for non-planar lithium-sulfur structural battery integration

Article Title: Monolithically integrated NiCo2Se4 nanowire–carbon cloth cathode scaffolds for non-planar lithium-sulfur structural-battery integration

Article References: Ha, J., Garai, M., Ullah, Z., Ardhi, R. E. A., Kim, C., Kim, A., Mahato, M., Kim, H. Y., Asp, L. E., & Oh, I.-K. (2026). Monolithically integrated NiCo2Se4 nanowire–carbon cloth cathode scaffolds for non-planar lithium-sulfur structural-battery integration. Advanced Composites and Hybrid Materials. https://doi.org/10.1007/s42114-026-02093-y

Image Credits: AI Generated

DOI: 10.1007/s42114-026-02093-y

Keywords: lithium-sulfur batteries, structural batteries, nickel cobalt selenide, nanowires, carbon cloth, polysulfide shuttle, flexible electrodes, energy storage, curvature tolerance, pouch cells, drone integration, KAIST