GA, UNITED STATES, February 11, 2026 /EINPresswire.com/ — Sodium-ion batteries are rising as a promising different to lithium-based methods for large-scale power storage, however their power density has lengthy been restricted by the shallow redox exercise of iron in layered oxide cathodes. A brand new supplies design technique now demonstrates that iron can contribute way more cost than beforehand thought. By intentionally altering the stability of transition metals, researchers unlocked a a lot deeper iron redox response, enabling considerably larger reversible capability and power density. The redesigned cathode combines enhanced electrochemical exercise with structural stability, wide-temperature operability, and improved sturdiness, providing a sensible pathway towards next-generation sodium-ion batteries with efficiency ranges as soon as thought-about unattainable.
Layered transition-metal oxides are among the many most promising cathode supplies for sodium-ion batteries due to their excessive theoretical capability and low value. Nonetheless, standard designs depend on strict compositional symmetry to take care of cost stability, which unintentionally suppresses iron redox exercise. Consequently, iron usually contributes little to power storage, leaving battery efficiency constrained. Makes an attempt to boost capability by adjusting metallic ratios or rising working voltage typically set off structural instability or irreversible reactions, undermining long-term efficiency. Based mostly on these challenges, it turns into essential to discover new design methods that essentially improve iron redox exercise whereas preserving structural integrity.
In a examine revealed in Carbon Vitality in 2025, researchers from Tianjin College of Expertise and Shanghai Jiao Tong College report a valence-engineering technique that essentially redefines how iron participates in sodium-ion battery cathodes. By deliberately breaking standard transition-metal stoichiometric symmetry, the group designed a layered sodium oxide materials by which iron undergoes an unusually deep and reversible redox course of. This strategy delivers considerably larger capability and power density than benchmark cathodes, whereas sustaining structural stability throughout a large working temperature vary.
The researchers developed a layered sodium oxide cathode with a intentionally imbalanced ratio of nickel, iron, and manganese, reshaping iron’s native digital atmosphere. Superior theoretical calculations revealed that this configuration lowers the efficient cost on iron atoms and raises their 3d orbital power, making iron way more electrochemically energetic. Experimentally, iron was proven to reversibly cycle between unusually high and low oxidation states, transferring greater than twice as many electrons per iron atom in contrast with standard supplies.
This deep iron redox instantly translated into electrochemical features. The brand new cathode delivered a reversible capability exceeding 180 mAh g⁻¹ and achieved an power density near 600 Wh kg⁻¹—among the many highest reported for layered sodium-ion cathodes. Importantly, these features didn’t come on the expense of stability. In situ structural analyses revealed a extremely reversible phase-transition pathway with minimal quantity change, successfully suppressing microcracking and mechanical degradation.
The fabric additionally demonstrated sturdy efficiency throughout temperatures starting from sub-zero circumstances to elevated warmth, highlighting its adaptability for real-world purposes. Collectively, these outcomes present that iron—lengthy thought-about a weak contributor in sodium-ion batteries—can change into a dominant cost service when its redox depth is correctly unlocked.
“This work challenges the long-standing assumption that iron redox in layered sodium cathodes is intrinsically restricted,” an unbiased battery supplies professional commented. “By rethinking cost stability on the atomic degree, the researchers display that iron can ship way more capability than beforehand believed, with out sacrificing structural stability. That is significantly vital for sodium-ion batteries, the place cost-effective and earth-abundant components are important. The examine supplies a transparent design precept that might affect the event of high-energy cathodes effectively past this particular system.”
The findings open new alternatives for sodium-ion batteries in grid-scale power storage, renewable-energy buffering, and low-cost electrical mobility. By maximizing the contribution of iron—an plentiful and cheap component—the valence-engineering technique reduces reliance on pricey or scarce metals whereas concurrently bettering power density. The demonstrated air stability, scalable synthesis, and profitable full-cell efficiency additional strengthen the case for sensible deployment. Extra broadly, the idea of unlocking hidden redox depth by way of electronic-structure design might encourage related advances in different battery chemistries, accelerating the transition towards safer, extra sustainable, and high-performance power storage applied sciences.
References
DOI
10.1002/cey2.70142
Unique Supply URL
https://doi.org/10.1002/cey2.70142
Funding info
This work was supported by the Nationwide Pure Science Basis of China (Grant Nos. 52202282, 52402054, 22471283, and 52202327) and Pure Science Basis of Tianjin Metropolis (Grant Nos. 22JCYBJC00040, 24JCQNJC00970).
Lucy Wang
BioDesign Analysis
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