The motivation stems from a well-known weakness of conventional lithium-ion batteries. Since their commercial debut in 1991, these devices have relied on flammable liquid organic carbonate electrolytes that permit uneven lithium flux and the growth of metallic dendrites, structures that can pierce the separator, trigger internal short circuits, thermal runaway, and in extreme cases fire or explosion. Solid-state electrolytes act as a physical barrier to dendrite growth and are widely regarded as the safest long-term solution. Inorganic ceramic conductors achieve superb conductivities between 10⁻³ and 10⁻² S cm⁻¹ but are brittle, hard to process at scale, and suffer from high interfacial impedance. Polymer electrolytes, by contrast, are flexible and electrode-compatible but typically conduct at a sluggish 10⁻⁷ S cm⁻¹, a gap the new work sets out to narrow using sustainable materials.

Composite polymer electrolytes, which disperse a secondary filler into a polymer host, have long been used to push conductivity upward. Fillers suppress polymer recrystallization, create amorphous regions and grain boundaries, and promote salt dissociation through Lewis acid-base interactions. Yet most polymer hosts studied to date, including polyethylene oxide, poly(methyl methacrylate), PVDF, polyacrylonitrile and poly(vinyl alcohol), derive from fossil feedstocks and are not biodegradable. Biopolymers offer a striking alternative: cellulose, chitosan, lignin and starch are abundant, renewable, nontoxic and richly decorated with polar hydroxyl and ether groups that can coordinate lithium ions and host high salt loadings. Corn starch in particular, composed of roughly 20 to 30 percent linear amylose and 70 to 80 percent branched amylopectin linked by alpha glycosidic bonds, is cheap, lightweight and compatible with ionic salts, making it an attractive host for solid electrolyte research.

The researchers fabricated their films by solution casting. Corn starch was dispersed in a dilute acetic acid solution at 80 °C, lithium perchlorate was added in concentrations from 20 to 50 weight percent, and the mixtures were stirred, cast onto Teflon dishes and dried under vacuum to yield free-standing membranes roughly 140 micrometers thick. Electrochemical impedance spectroscopy identified 40 weight percent salt as the optimum: below that limit, conductivity rose with charge carrier concentration, while above it undissociated salt accumulated and impeded ion motion. Building on that baseline, the team introduced Pluronic, a PEG-PPG-PEG triblock copolymer, at 10 to 30 weight percent, and finally dispersed graphene oxide, synthesized by the modified Hummers method, at loadings of 0.1 to 0.7 weight percent into the best plasticized formulation.

Fourier transform infrared spectroscopy revealed exactly what each additive does to the starch structure. The ratio of the crystalline band at 993 cm⁻¹ to the amorphous band at 1015 cm⁻¹, a standard order parameter, fell from 1.24 for neat starch to 0.98 with salt, then to 0.69 after Pluronic addition and to 0.65 once graphene oxide was incorporated. Peak shifts and broadening across the fingerprint region confirmed complexation between lithium ions and the starch oxygen atoms, while the gradual disappearance of the band at 1366 cm⁻¹ signaled progressive disruption of crystalline order. The result is a predominantly amorphous matrix in which polymer chain segments can move freely, a prerequisite for fast ion hopping through the electrolyte.

Perhaps the most elegant finding involves the perchlorate anion band near 623 cm⁻¹. By deconvoluting the overlapping peaks corresponding to free perchlorate and contact ion pairs, the authors quantified the fraction of dissociated salt in each film. That fraction climbed steadily as Pluronic and then graphene oxide were added, providing direct spectroscopic evidence that both additives actively break lithium-perchlorate ion pairs. Pluronic is no ordinary diluent: because its PEG and PPG segments contain ether oxygens that coordinate lithium ions, it participates directly in conduction pathways while also softening the film. Graphene oxide, with its dense surface population of hydroxyl and carboxyl groups, interacts with the salt through Lewis acid-base chemistry and creates low-energy percolation channels at the polymer-filler interface. Both effects multiply the population of mobile charge carriers.

The electrical measurements tell a consistent story. Room-temperature conductivity climbed from the salt-only baseline to 1.33 × 10⁻⁵ S cm⁻¹ at the optimal 20 weight percent Pluronic loading, and then to 3.55 × 10⁻⁵ S cm⁻¹ with 0.5 weight percent graphene oxide, roughly triple the plasticized value. Beyond 0.5 percent, graphene oxide sheets aggregate into insulating barriers that disrupt the conduction network, a phenomenon the group had documented previously in PVDF-HFP/Pluronic blend systems. Temperature-dependent impedance from 20 to 80 °C showed classic Arrhenius behavior, with conductivity reaching 6.45 × 10⁻⁴ S cm⁻¹ at 80 °C and the activation energy falling stepwise from 0.69 eV for the salt-only film to 0.67 eV with plasticizer and 0.59 eV with the nanofiller, confirming that the additives smooth the energetic landscape for lithium-ion hopping.

Direct-current polarization measurements using ion-blocking electrodes added a crucial safety metric. The ion transference number rose from 0.58 at 20 weight percent salt to 0.76 at 40 weight percent, then to 0.82 with Pluronic and finally to 0.90 in the fully optimized composite, indicating that ionic conduction overwhelmingly dominates over electronic leakage. Dielectric analysis reinforced the picture: both the dielectric constant and dielectric loss surged in the low-frequency regime as Pluronic and graphene oxide were added, a hallmark of increased free-ion density and enhanced electrode polarization. According to Bjerrum theory, the elevated dielectric constant also shortens the critical distance for ion-pair formation, further favoring salt dissociation, while the higher permittivity exponentially boosts charge carrier density. Electric modulus formalism, which suppresses electrode polarization, showed no relaxation peak within the measured frequency window, implying ion hopping times shorter than 1.6 × 10⁻⁷ seconds, fast dynamics for a biopolymer electrolyte.

Thermal data close the loop on practicality. Differential scanning calorimetry showed that the onset of chain fragmentation shifts downward as salt, plasticizer and filler are added, from 272 °C for the 20 weight percent salt film to about 253 °C for the optimized composite, but all samples remain comfortably above the operating temperatures of real batteries. The optimized conductivity is comparable to other reported systems such as starch/PEGMA (3.8 × 10⁻⁵ S cm⁻¹) and PEO/sepiolite nanoribbon composites (9.22 × 10⁻⁵ S cm⁻¹), though it trails ionic-liquid and chemically modified electrolytes in the 10⁻⁴ to 10⁻³ S cm⁻¹ range. The authors caution that their study was limited to structural characterization, impedance and dielectric analysis; validating the electrolyte in actual cells will require linear sweep and cyclic voltammetry to establish the electrochemical stability window, along with full-cell testing. If those trials succeed, tomorrow’s batteries could draw part of their backbone not from petrochemicals but from a crop grown on farms worldwide, a small but meaningful step toward truly sustainable energy storage.

Subject of Research: Biodegradable corn starch-based solid polymer electrolytes enhanced with lithium perchlorate, Pluronic plasticizer, and graphene oxide nanofiller for sustainable lithium-ion battery applications.

Article Title: Pluronic and graphene oxide influence the structural properties as well as the ionic conductivity and dielectric behavior of corn starch based solid electrolytes

Article References: Numan, M., Arwish, S., Khan, K. H., Shah, S. M., & Hussain, H. (2026). Pluronic and graphene oxide influence the structural properties as well as the ionic conductivity and dielectric behavior of corn starch based solid electrolytes. Discover Electrochemistry, 3(1), Article 69. https://doi.org/10.1007/s44373-026-00157-8

Image Credits: AI Generated

DOI: 10.1007/s44373-026-00157-8

Keywords: solid polymer electrolyte, corn starch, graphene oxide, Pluronic plasticizer, ionic conductivity, lithium perchlorate, dielectric behavior, biopolymer, lithium-ion batteries, FTIR spectroscopy, electrochemical impedance spectroscopy, sustainable energy storage

The motivation behind the study rests on a well-known problem in electrochemical energy storage. Supercapacitors are prized for their fast charge–discharge rates, long cycle life and high power delivery, but their performance is ultimately dictated by the electrode material. Transition metal oxides such as copper oxide and nickel oxide are attractive candidates because they are abundant, environmentally benign and rich in accessible oxidation states that support pseudocapacitive, Faradaic charge storage. Copper oxide brings high theoretical capacitance, while nickel oxide contributes strong chemical stability and a highly active Ni2+/Ni3+ redox couple. Yet both materials suffer from the same Achilles heel: modest electrical conductivity and structural degradation during repeated cycling, which erode practical performance over time.

The researchers, led by B. H. Akpeji of the Federal University of Petroleum Resources in Effurun, Delta State, attacked this limitation with a binary composite strategy. Rather than relying on either oxide alone, they combined CuO and NiO into a single heterostructured nanomaterial, betting that the interplay of the two phases would multiply electroactive sites, speed electron transport and buffer each oxide’s structural weaknesses. Their synthesis began with seeds collected in the Ukwani Local Government Area of Delta State and verified at the University of Benin herbarium under voucher number UBH-R673. A Soxhlet extraction with distilled water, run for roughly four hours, yielded a concentrated aqueous extract that was then subjected to systematic phytochemical screening.

That screening revealed a veritable chemical toolkit within the seed. Flavonoids, alkaloids, tannins, phenolic compounds, terpenoids, saponins, glycosides and reducing sugars were all present, each playing a distinct role in the nanomaterial formation that followed. Flavonoids, phenolics and alkaloids donate electrons that reduce Cu2+ and Ni2+ ions toward their oxide forms, while hydroxyl and carbonyl functional groups assist nucleation and stabilization. Tannins and saponins act as passivating agents that prevent the freshly formed nanoparticles from clumping together, a property that proved decisive for the later electrochemical results. In essence, the plant extract replaced the hazardous reducing agents and synthetic surfactants that conventional nanoparticle recipes demand.

Using the extract mixed with copper acetate and nickel acetate solutions in the presence of sodium hydroxide, the team observed characteristic color transitions, copper oxide turning from blue to dark black and nickel oxide to dark green, as the hydroxide intermediates dehydrated into the final oxides. The nanocomposite itself was assembled by combining equimolar CuO and NiO nanofluids and stirring them at 65 degrees Celsius for two hours before centrifugation and drying. A full characterization battery followed: UV–visible spectroscopy showed absorption peaks at 301 nanometers for CuO, 295 nanometers for NiO and 299 nanometers for the composite, with optical band gaps of 2.29, 3.21 and 2.40 electronvolts respectively. The composite’s band gap sits neatly between its parents, a hallmark of genuine electronic interaction and heterojunction formation between the two oxide phases.

Electron microscopy confirmed that the green route produced the fine, well-dispersed particles that high-performance electrodes require. The CuO nanoparticles averaged 21.0 nanometers and the NiO particles 14.9 nanometers, while the composite measured 16.2 nanometers with reduced agglomeration and enhanced dispersion. Powder X-ray diffraction reinforced the picture, resolving the monoclinic structure of CuO and the face-centered cubic phase of NiO and giving the composite a mean crystallite size of 19.18 plus or minus 5.40 nanometers, calculated from six indexed reflections using the Debye–Scherrer equation and verified statistically in SPSS. Energy-dispersive X-ray analysis confirmed the successful incorporation of copper at 47.30 weight percent, nickel at 32.10 percent and oxygen at 20.60 percent in the composite, while Fourier-transform infrared spectroscopy located the distinctive Cu–O and Ni–O lattice vibrations, with a clear band near 535 inverse centimeters signaling hybridization of the two oxide lattices.

The electrochemical payoff came in a three-electrode configuration using a glassy carbon working electrode, a platinum counter electrode and an Ag/AgCl reference in 2 molar potassium hydroxide. Cyclic voltammetry revealed reversible, Faradaic redox behavior for all three materials, but the composite’s integrated curve area was dramatically larger. Quantitatively, the CuO–NiO nanocomposite delivered a specific capacitance of 489.60 farads per gram and an energy density of 0.272 watt-hours per kilogram, against roughly 124 farads per gram and about 0.069 watt-hours per kilogram for each of the single oxides, a near fourfold leap in stored charge. Electrochemical impedance spectroscopy told the same story from another angle: the composite exhibited the lowest charge-transfer resistance of the set at 2.31 ohms, compared with 4.90 ohms for CuO and 2.34 ohms for NiO, alongside the highest double-layer capacitance at 126 microfarads, indicating faster electron-transfer kinetics, more accessible electroactive surface and superior interfacial charge storage.

The authors attribute this synergy to the heterojunction formed where the two oxides meet. Band alignment between the narrow-gap CuO and the wider-gap NiO redistributes charge at the interface, creating new electronic states that ease the movement of electrons, while the dual Cu2+/Cu3+ and Ni2+/Ni3+ redox couples multiply the sites available for reversible Faradaic reactions in the alkaline electrolyte. The phytochemical capping inherited from the seed extract adds further advantages, keeping particle sizes small, shortening ion diffusion pathways and preserving the porous, interconnected morphology that scanning electron microscopy revealed. Compared with previous CuO–NiO composites reported in the literature, some requiring controlled-atmosphere annealing or surfactants to reach similar capacitances, the raffia-mediated route achieved competitive figures with nothing more exotic than water, acetate salts, sodium hydroxide and plant chemistry.

Beyond the numbers, the study carries a broader sustainability argument. Raphia hookeri seeds are inedible and largely discarded, so converting them into functional nanomaterials adds value to agricultural waste without competing with food production, in line with circular-economy thinking and the growing field of biomass valorization. The work was funded by Nigeria’s Tertiary Education Trust Fund and conducted across the Federal University of Petroleum Resources and the University of Benin. The authors are careful to note that thermogravimetric analysis, which showed decomposition temperatures of 379, 394 and 355 degrees Celsius for CuO, NiO and the composite respectively, speaks to thermal behavior rather than long-term cycling stability, and that full-cell devices, rate capability testing and extended cycling remain the next milestones. Still, the demonstration that a humble palm seed can seed, quite literally, a fourfold capacitance improvement offers a compelling template for affordable, greener electrode manufacturing, and suggests that the future of energy storage may be growing in fields as much as it is being engineered in cleanrooms.

The choice of a hydrothermal route deserves particular attention when weighing the practical significance of this work. Hydrothermal processing, in which reactions proceed in a sealed aqueous medium under elevated temperature and pressure, is prized for producing crystalline oxides at relatively low temperatures without the need for post-synthesis calcination at extreme conditions. Coupling that method with a plant-derived extract means the reducing, nucleating and capping functions are all performed by biomolecules rather than synthetic reagents, which simplifies purification and reduces the environmental footprint of the entire workflow.

The electrochemical measurements also illustrate why pseudocapacitive metal oxides behave so differently from carbon-based double-layer electrodes. In a 2 molar potassium hydroxide electrolyte, hydroxide ions participate directly in the reversible redox reactions at the electrode surface, so the measured capacitance reflects genuine Faradaic charge transfer rather than simple electrostatic adsorption. The low solution resistance of 0.29 ohms recorded for the composite electrode indicates that the electrolyte and electrode interface offered minimal ohmic opposition, an important precondition for high-rate operation in practical devices.

The thermal analysis adds a complementary dimension to the characterization. Decomposition temperatures in the range of 355 to 394 degrees Celsius indicate that the organic residues inherited from the plant extract are largely removed or stabilized well below the operating temperatures of supercapacitors, which function near ambient conditions. This suggests the phytochemical capping does not introduce thermal liabilities during normal device use, even though it may influence long-term cycling behavior in ways that only extended testing can reveal.

From a materials-design perspective, the intermediate band gap of the composite relative to its parent oxides is a useful diagnostic. It signals electronic coupling across the heterojunction rather than a mere physical mixture, which is precisely the condition needed for the interfacial charge redistribution that underpins the observed synergy. Future work building on this platform could explore varying the CuO to NiO ratio, tuning annealing conditions, or pairing the composite with biomass-derived carbon substrates to push energy density further while retaining the low-cost, waste-valorizing character that makes the approach distinctive.

Subject of Research: Green synthesis of CuO–NiO nanocomposites from Raphia hookeri seed extract for supercapacitor energy storage

Article Title: Nanocomposite materials of CuO–NiO from Raphia hookeri seed for investigation of energy storage potentials

Article References: Akpeji, B. H., Iyasele, J. U., Elemike, E. E., Okhuarobo, L. O., & Akpeji, S. A. (2026). Nanocomposite materials of CuO–NiO from Raphia hookeri seed for investigation of energy storage potentials. Discover Electrochemistry, 3(1), Article 76. https://doi.org/10.1007/s44373-026-00163-w

Image Credits: AI Generated

DOI: 10.1007/s44373-026-00163-w

Keywords: CuO–NiO nanocomposite, green synthesis, supercapacitor, Raphia hookeri seed, pseudocapacitance, transition metal oxides, phytochemicals, energy storage, electrochemical impedance spectroscopy, cyclic voltammetry, nanoparticles, biomass valorization

Sodium-ion batteries are attracting intense interest because sodium is far more abundant than lithium and is widely distributed across Earth’s crust. That abundance could help reduce raw-material costs and ease pressure on lithium supplies. Sodium-based cells also offer safety and low-temperature advantages, making them attractive for applications ranging from stationary energy storage to electric vehicles. However, their commercial progress depends on solving a major problem: many sodium-ion cathodes lose capacity rapidly after repeated charging and discharging.

The Tokyo University of Science team focused on O3-type sodium nickel manganese oxide, written chemically as O3-Na[Ni1/2Mn1/2]O2, or NNMO. This layered material begins with a favorable, stoichiometric sodium arrangement and can deliver relatively high reversible capacity. Yet sodium ions move in and out of its crystal structure during battery operation, causing large changes in the spacing and volume of the layered lattice. Over time, these repeated structural shifts can trigger cracking, phase transformations, loss of crystallinity and severe capacity fading.

To investigate how scandium works, the researchers introduced Sc3+ ions into NNMO in two ways. In the first approach, scandium was incorporated directly into the bulk crystal structure through a doping process. The resulting materials were labeled NNMSOx, with the number representing the scandium content. The researchers paid particular attention to NNMSO8, which demonstrated the strongest cycling performance among the doped compositions. In the second approach, they treated NNMO particles with a scandium isopropoxide solution and then annealed them at 800 degrees Celsius, producing a surface-modified material known as NNMO-SC800.

The difference between the two approaches became strikingly clear when the materials were tested in coin-type sodium cells. After 100 charge-discharge cycles, undoped NNMO retained only 18.6 percent of its original capacity. By comparison, NNMSO8 retained 67.8 percent, while NNMO-SC800 retained 75.4 percent. These results show that both bulk doping and surface coating can dramatically improve durability, although they do so through different chemical and structural mechanisms.

Inside the doped material, electrochemically inactive Sc3+ ions occupy positions normally associated with transition metals. Their ionic size is comparable to that of the nickel and manganese ions in the host lattice, allowing them to become part of the layered framework without simply forming a separate phase. Because scandium does not participate in the same redox reactions as the active transition metals, it helps immobilize nearby sodium ions. These relatively fixed sodium ions function like structural pillars, supporting the layers as sodium is extracted and reinserted during operation.

This internal stabilization also changes the battery’s electrochemical signature. NNMSO8 displayed a smoother charging and discharging profile than the undoped cathode. The researchers attributed this behavior to suppression of sodium-ion and vacancy ordering, a process in which sodium ions and empty sites arrange themselves into ordered patterns during cycling. Such ordering can promote abrupt structural changes and voltage plateaus. By disrupting it, scandium doping allows sodium ions to move through the cathode more smoothly while reducing the size of harmful volume fluctuations.

The coated material followed a different path. In NNMO-SC800, scandium was found mainly at the particle surface, where it formed a phase resembling O3-NaScO2. This protective layer did not substantially alter the crystal structure inside the cathode. Instead, it acted as a barrier between the active electrode and the electrolyte, suppressing parasitic reactions that gradually consume active sodium, damage the surface and accelerate interfacial degradation. The coating therefore improved cycling stability without producing the smoother voltage profile observed in the bulk-doped material.

Tests in full sodium-ion cells further demonstrated the practical significance of the findings. The researchers paired the modified cathodes with hard-carbon anodes and operated the cells for 300 cycles. The full cell using NNMSO8 retained 71.4 percent of its initial capacity, while the cell using NNMO-SC800 retained an impressive 91.2 percent. The results suggest that surface protection is especially powerful for preserving capacity over extended operation, while bulk doping provides important resistance to structural collapse. Neither strategy alone solved every degradation pathway: coating could not fully prevent long-term loss of crystallinity, and doping did not completely eliminate capacity fading.

The researchers say the most promising future direction may be to combine both approaches, creating cathodes that are reinforced internally and protected externally. Scandium provides an exceptionally clear model for understanding how these mechanisms operate, but its cost and limited availability make it unlikely to be the final commercial solution. The next challenge will be to identify more abundant elements that can reproduce scandium’s ability to stabilize sodium-ion battery structures and protect their surfaces. If successful, this design principle could help transform sodium-ion batteries into longer-lasting, lower-cost alternatives for the rapidly expanding energy-storage market.

Subject of Research: Not applicable

Article Title: Scandium doping and coating for improving O3-NaNi1/2Mn1/2O2 electrode in sodium battery

News Publication Date: 8 August 2026

Web References: https://www.tus.ac.jp/en/mediarelations/

References: Small, DOI: 10.1002/smll.75049

Image Credits: Professor Shinichi Komaba and Associate Professor Shinichi Kumakura, Tokyo University of Science, Japan

Keywords

Sodium-ion batteries, scandium doping, surface coating, cathode materials, energy storage, battery technology, electrochemistry, electric vehicles, sustainable energy, materials science

Researchers at Zhengzhou University, spearheaded by Professors Jianhua Zhu and Yijun Cao, alongside collaborators including Run Ren and Ling Zhang, have recently unveiled a revolutionary strategy that addresses this knowledge gap and materially enhances HC anode performance. Their breakthrough lies in the design and synthesis of hard carbon structures featuring rationally engineered closed pores controlled on the nanoscale. This nano-space confinement method effectively governs the heterogeneous nucleation and growth of quasi-metallic sodium clusters within the anode’s graphitic pores, unlocking previously inaccessible sodium storage capacity while enhancing the rate capabilities critical for fast charging.

Traditional hard carbon anodes conventionally possess a network of closed pores, but only a fraction—approximately 60%—of these pores actively participate in sodium ion storage during battery operation. This limited utilization, combined with a well-documented trade-off between capacity achieved at the plateau region of the charge-discharge profile and the electrode’s rate performance, has constrained the adoption of SIBs in high-demand applications. The strategy introduced by the Zhengzhou team overcomes this bottleneck by coupling intercalation processes with pore filling in a stage-wise manner. The resulting mechanism allows for rapid ion transport reminiscent of supercapacitors while retaining the high capacity characteristic of intercalation-based storage.

At the core of this innovation is the meticulous synthesis of hard carbon materials through the controlled crosslinking of resorcinol-hexamethylenetetramine resins, followed by a carefully calibrated pyrolysis process at elevated temperatures. Through computational modeling using density functional theory (DFT) and ab initio molecular dynamics simulations, the researchers demonstrated that sodium storage behavior is fundamentally linked to the size and geometry of nanoconfined spaces within the anode. Decreasing the size of these nanocavities lowers the energy barrier for nucleation of sodium clusters; however, even small cavities alone cannot fully explain the charge storage unless the process of sodium-ion intercalation into narrow pore orifices (specifically within the 0.4 to 0.6 nm range) is incorporated.

This cleverly engineered pore size distribution enables a stepwise, pre-nucleation mechanism, where initial intercalation into the smallest pores activates the growth of sodium cluster formation in progressively larger pore volumes—up to approximately 2 nanometers in diameter—while maintaining a positive electrode potential (V > 0). The interconnected graphitic defects and localized disorder within the carbon matrix provide diffusion pathways that facilitate ion movement across the bulk material. This intricate pore architecture and its associated transport dynamics underpin the observed enhancements in both capacity and rate performance.

Experimental validation of these design principles yielded remarkable results. The optimized HC-1300 electrode exhibited a reversible sodium storage capacity approaching 500 milliamp-hours per gram (mAh g⁻¹), a figure that substantially exceeds earlier reports for hard carbon anodes. Even at ultrahigh current densities of 2000 mA g⁻¹, the electrode maintained 344 mAh g⁻¹, demonstrating exceptional rate capability. Furthermore, the material preserved 83.3% of its capacity after 1,000 charge-discharge cycles at 500 mA g⁻¹, confirming its excellent cycling stability. An equally impressive reversible capacity of 388.5 mAh g⁻¹ was achieved at an elevated areal loading of 3.7 mg cm⁻², marking strides toward practical, device-level implementation.

Beyond the anode itself, the team incorporated HC-1300 into full sodium-ion battery cells, pairing it with a Na₃V₂(PO₄)₃ cathode within coin-type configurations. These full cells delivered an average operating voltage of 3.25 volts and a normalized capacity of 447 mAh g⁻¹ based on the anode mass at a moderate current of 50 mA g⁻¹. Notably, the cells retained 83.9% of their initial capacity after 200 cycles, attesting to the compatibility and robustness of the integrated battery architecture.

Scaling up to practical energy storage devices, the researchers fabricated pouch cells incorporating commercial Na₄Fe₃(PO₄)₂P₂O₇ cathodes paired with their advanced HC anodes. These Na-ion pouch batteries achieved an impressive energy density of 147.4 watt-hours per kilogram (Wh kg⁻¹), rivaling or exceeding existing sodium-ion battery technologies. Additionally, the cells exhibited remarkable endurance, with a minimal capacity fade rate of merely 0.064% per cycle sustained over 700 cycles at 2000 mA charging current—a promising indication for long-term application in grid storage, electric vehicles, and portable electronics.

The success of this nano-space confinement approach can be attributed to the rational manipulation of the metallic sodium phase formation within hard carbon’s closed pores. By guiding nucleation and growth processes with precision, the researchers have devised a coupled intercalation and pore-filling storage mechanism, resulting in significantly enhanced sodium utilization. This discovery not only pushes the performance boundaries of sodium-ion batteries, positioning them closer to lithium-ion benchmarks, but also provides a versatile design platform that can be extended to other energy storage materials characterized by confined nanospaces.

Looking forward, the principles elucidated in this research set the stage for a new family of intercalation-pore filling materials, combining the high energy density of battery chemistries with the rapid charge-discharge capabilities traditionally associated with supercapacitors. The embedded nano-space confinement concept and stage-wise sodium cluster growth model offer a roadmap for developing next-generation SIBs that marry safety, cost-effectiveness, and high-rate performance.

This innovative work opens new horizons for fundamental and applied battery research, underscoring the vital role of precise nanoscale engineering in overcoming the intrinsic challenges of energy storage materials. As sodium-ion technologies continue to mature, breakthroughs such as this will be essential in enabling the widespread adoption of sustainable battery systems capable of meeting the accelerating demands of renewable energy integration, electric transportation, and portable power.

The Zhengzhou University team’s efforts represent a significant leap forward in hard carbon anode optimization, demonstrating how multi-disciplinary approaches integrating experimental synthesis, advanced characterization, and theoretical modeling can unlock hidden potential in established materials. Their findings hold valuable implications not only for academia but also for industry stakeholders pursuing commercially viable, high-performance sodium-ion batteries tailored for diverse energy storage applications worldwide.

Stay tuned as this pioneering research inspires future innovations that bring us closer to realizing the full promise of sodium-ion battery technology.

Subject of Research: Sodium-ion battery anode materials; nano-space confinement effects in hard carbons; high-capacity and high-rate sodium storage mechanisms.

Article Title: Nano‑Space Confinement Drives Rational Closed Pore Design in Hard Carbons for High‑Capacity and High‑Rate Sodium Storage

News Publication Date: 21-May-2026

Web References: DOI:10.1007/s40820-026-02223-7

Image Credits: Run Ren, Ling Zhang, Jianhua Zhu, Yunfeng Chao, Junlin Guo, Yijun Cao, Xiaobo Ji, Xinwei Cui

Layered sodium manganese oxides, especially those with a chemical formula near Na₂/₃MnO₂, have attracted considerable attention as cathodes for sodium-ion batteries. These materials stand out because they do not rely on rare-earth metals, thus offering a more sustainable and cost-effective pathway. Initially, sodium manganese oxides deliver high capacities, but they suffer from rapid capacity fading when subjected to the mechanical and chemical stresses of cycling. This fading is fundamentally linked to changes in the crystal structure caused by the sodium ions moving in and out of the lattice, which triggers complex oxidation state changes and distortions in the manganese ions themselves.

During battery operation, the Mn ions in Na₂/₃MnO₂ toggle between oxidation states Mn³⁺ and Mn⁴⁺ as sodium ions are inserted or extracted. Particularly, the presence of Mn³⁺ leads to a well-known structural effect called the Jahn-Teller distortion, where the Mn-centered octahedra become distorted to reduce their electronic energy. This structural distortion can be localized or cooperative, but in either case, these repeated lattice distortions generate cumulative strain. Such mechanical stress undermines the crystallinity of the cathode material, promotes microstructural defects, and accelerates capacity degradation, posing a persistent challenge to the advancement of high-performance sodium-ion batteries.

In pioneering research conducted by a team led by Professor Shinichi Komaba at the Tokyo University of Science, significant progress has been made in understanding and mitigating these issues through selective doping. Their recent study focused on the effects of scandium (Sc) doping on different polytypes of Na₂/₃MnO₂, specifically the P2 and P’2 structural variants. Each polytype exhibits distinct behaviors: while the P2 variant is characterized by localized Jahn-Teller distortions, the P’2 polytype features a cooperative distortion where the distorted MnO₆ units align in a long-range order, with different implications for material stability.

Through detailed experimental analyses, the research revealed that Sc doping has a transformative impact specifically on the P’2 polytype structure. By incorporating scandium ions modestly—approximately 8% substitution for manganese—the team demonstrated that the cathode material undergoes significant modulation in particle size distribution and crystal growth processes. More importantly, scandium doping preserves the cooperative Jahn-Teller distortion inherent in the P’2 structure while enhancing its overall structural integrity, thereby stabilizing the electrode at an atomic level during cycling. This delicate balance leads to remarkable improvements in capacity retention and resistance to mechanical degradation.

Beyond structural effects, Sc doping also influences the interfacial chemistry between the cathode and electrolyte. The researchers observed that the scandium-doped cathodes exhibited suppressed side reactions with liquid electrolytes and increased resistance to moisture-induced damage. This was attributed to the formation of a more stable cathode-electrolyte interface layer, which acts as a protective barrier preventing deleterious degradation processes commonly associated with long-term battery operation. Such interface engineering is crucial for enhancing practical battery lifetimes and performance consistency.

Electrochemical testing in sodium half-cells further substantiated the benefits of scandium doping. The 8% Sc-doped P’2 Na₂/₃[Mn₁₋ₓScₓ]O₂ electrodes demonstrated a drastic improvement in cycling stability compared to undoped counterparts, maintaining much of their initial capacity over extended cycling periods. Intriguingly, this enhancement was not observed in the P2 polytype, suggesting that the synergistic effect between Sc doping and cooperative Jahn-Teller distortion is fundamental to the observed performance gains. Additionally, doping with other rare-earth or trivalent metal ions such as ytterbium and aluminum failed to replicate these beneficial effects, underscoring the unique role of scandium in this system.

The team also explored the impact of pre-cycling—the practice of conditioning electrode materials through initial cycles to stabilize their structures and interfaces. This method further boosted the capacity retention of the Sc-doped P’2 electrodes, demonstrating that combining doping strategies with electrochemical conditioning could be a powerful approach to prolong battery life. Building on these findings, full coin-cell sodium-ion batteries were fabricated using the optimized Sc-doped cathode. These cells exhibited an impressive 60% capacity retention after 300 charge-discharge cycles, marking a significant step toward the practical viability of sodium-ion battery technology.

Professor Komaba emphasizes the broader implications of their work: “While scandium is a relatively costly element, our study validates its utility in advancing sodium-ion batteries. Importantly, the mechanistic insights we have uncovered open avenues for designing longer-lasting and higher-performance energy storage devices.” Beyond sodium-ion batteries, their findings propose a novel strategy to enhance the structural robustness of layered metal oxide materials where lattice distortions often limit performance. This could influence the development of various battery chemistries reliant on similar cathode architectures.

Overall, this breakthrough highlights the power of precise chemical modification—in this case, using Sc doping—to contend with intrinsic material challenges in sodium-ion battery electrodes. It represents a leap forward in overcoming structural degradation mechanisms that have long stifled the practical deployment of these promising batteries. As global energy demands intensify and resource sustainability takes center stage, innovations like these bring sodium-ion batteries closer to commercial reality, offering an alternative that balances cost, performance, and environmental impact.

The study’s findings are set to be published in the prestigious journal Advanced Materials on September 12, 2025, offering the scientific community both a detailed experimental framework and new perspectives on electrode design. As researchers worldwide pursue energy storage breakthroughs, the work from Tokyo University of Science underscores the importance of fundamental materials chemistry and interfacial engineering in creating the next generation of safe, efficient, and durable batteries.

It is clear that through targeted doping strategies and a deep understanding of the interplay between crystal structure and electrochemical behavior, the limitations of sodium-ion batteries can be addressed. Scandium’s unique ability to maintain cooperative Jahn-Teller distortions while modulating crystal growth and stabilizing interfaces exemplifies how subtle atomic-level changes can lead to substantial performance enhancements. Such advances echo the ongoing evolution of battery science toward ever more sophisticated materials tailored to meet tomorrow’s energy needs.

Subject of Research:
Not applicable

Article Title:
Unique Impacts of Scandium Doping on Electrode Performance of P’2- and P2-type Na₂/₃MnO₂

News Publication Date:
12-Sep-2025

References:
DOI: 10.1002/adma.202511719

Image Credits:
Professor Shinichi Komaba from Tokyo University of Science, Japan

Keywords:
Batteries, Electrochemistry, Electrochemical cells, Physical sciences, Earth sciences, Materials science, Chemical engineering

Single-atom catalysts, which feature isolated metal atoms dispersed on substrates, have been celebrated for their ability to maximize catalytic efficiency and atom utilization. Traditional thinking posits that the activity of these SACs for HER is mainly governed by the strength with which hydrogen atoms adsorb to the metal centers. The rationale being, hydrogen binding energy serves as a predictor for the energy barriers involved in proton-electron transfer steps that culminate in molecular hydrogen release. However, this research observes that this simplistic descriptor fails to account for the complex reality of surface interactions, especially under realistic operating conditions where various adsorbate species influence the catalytic environment.

A major hurdle in SAC design and HER performance is the phenomenon of site poisoning by reactive adsorbates such as hydroxyl radicals (HO) and oxygen radicals (O). These species can adhere to the active metal centers, interfering with the adsorption and reaction dynamics of hydrogen intermediates, thus suppressing catalytic activity. The study highlights that ignoring these poisoning effects leads to misleading predictions and suboptimal catalyst designs. Such insights emphasize the necessity to consider the adsorption coverage and the dynamic interfacial chemistry surrounding SACs, beyond just hydrogen-metal interactions.

Delving deeper into this complex interplay, the researchers employed advanced experimental techniques and theoretical modeling that simulated realistic adsorption environments. They discovered that hydrogen binding energy, calculated with a proper understanding of the adsorbate landscape, can serve as a more reliable predictor of catalytic activity. Intriguingly, when metal sites are compromised by poisoning, neighboring coordinating atoms—often nitrogen in metal-nitrogen-carbon (M-N-C) frameworks—can step in as alternative active sites. These adjacent nitrogen atoms offer an alternate pathway for HER, effectively circumventing the deactivation caused by adsorbate poisoning and maintaining catalytic performance.

This dual-site activity concept challenges the orthodox single-site framework and provides a more nuanced understanding of SAC behavior. The idea that non-metal coordinating atoms may significantly contribute to catalysis underlines the importance of holistic catalyst design strategies that integrate the entire local atomic environment. Such approaches could lead to enhanced catalyst durability and activity, especially in harsh conditions that involve aggressive adsorbates.

Another critical takeaway from this work is the refined use of catalytic descriptors. Historically, HBE was often regarded as the sole descriptor for SAC HER activity. The novel approach advanced by the research combined hydrogen binding energy with Gibbs free energy calculations to develop composite descriptors that better predicted spontaneous and efficient hydrogen evolution. This multidimensional descriptor provides a more predictive framework for tailoring catalysts that perform optimally across a wider range of pH conditions, surpassing the limitations previously imposed by HBE-only models.

The implications of this methodology extend into the design of next-generation catalysts specifically tailored for alkaline and other challenging environments. Alkaline conditions have been notoriously difficult for HER catalysts due to enhanced poisoning and different reaction kinetics. By considering HO* poisoning effects and enabling nitrogen sites as active centers, new classes of single-atom and dual-atom catalysts can be engineered with superior resistance to degradation and higher catalytic turnover.

The research team further underscores that their experimental approach is supported by the creation of an extensive catalyst database via the Digital Catalysis Platform. This platform aggregates key computational and experimental data sets, offering unparalleled access to the scientific community and accelerating the pace of discovery by enabling researchers worldwide to benchmark, validate, and build upon these findings.

Fundamentally, this study moves the catalytic science community toward a more realistic and comprehensive view of catalyst surface phenomena. It signals the diminishing supremacy of simplistic design rules and calls for a paradigm shift where intricate adsorbate interactions, poisoning dynamics, and multi-site catalysis are integrated into catalyst optimization strategies. As the race for more efficient and economic hydrogen production intensifies globally, these insights could prove instrumental in overcoming the kinetic bottlenecks that hinder scale-up and widespread adoption.

Moreover, the broader context of this advancement aligns well with Japan’s World Premier International Research Center Initiative (WPI), which aims to foster innovative research environments. Based at Tohoku University’s Advanced Institute for Materials Research, the Hao Li Lab exemplifies the international and interdisciplinary collaboration needed to tackle the multifaceted challenges in energy materials research. Their success typifies how cutting-edge fundamental science can fuel applied technological breakthroughs.

Looking ahead, the enhanced understanding of surface adsorbate dynamics and site cooperation in SACs sets the stage not only for improved HER catalysts but possibly for a wide range of electrochemical transformations, including CO2 reduction and nitrogen fixation. The principle of leveraging adjacent non-metal sites to bypass poisoning effects ignites fresh ideas for designing multifunctional catalysts that could revolutionize sustainable chemical production.

In essence, this work dismantles the dogma that hydrogen binding energy alone dictates hydrogen evolution efficacy on single-atom catalysts. It pioneers a holistic framework incorporating adsorbate coverage, poisoning resistance, and alternative active sites that collectively define catalytic success. For the clean energy community and catalysis scientists worldwide, this could mark a turning point, charting new pathways toward designing robust, efficient, and versatile catalysts indispensable for a green hydrogen economy.

Subject of Research: Hydrogen Evolution Reaction and Single-Atom Catalysts with Adsorbate Poisoning Dynamics

Article Title: Hydrogen Binding Energy Is Insufficient for Describing Hydrogen Evolution on Single-Atom Catalysts

News Publication Date: 20-Mar-2025

Web References: https://www.jsps.go.jp/english/e-toplevel/index.html, http://dx.doi.org/10.1002/anie.202425402

Image Credits: Hao Li et al.

Keywords

Catalysis, Active sites, Metals, Water molecules