Researchers at Qingdao University have now reported a strategy that could address these problems by controlling not only the chemical composition of a catalyst, but also the spin of the electrons involved in the reaction. In a study published in National Science Review, a team led by Prof. Hongsen Li demonstrated that adjusting the “chiral asymmetry factor” of a catalyst can regulate the spin state of its active sites. The result was faster sulfur conversion chemistry, more efficient lithium sulfide formation and decomposition, and improved performance in lithium–sulfur batteries.

The approach is based on the chiral-induced spin selectivity effect, commonly known as CISS. Chirality describes a structure that cannot be superimposed on its mirror image, much like a left hand and a right hand. When electrons move through certain chiral materials, one spin orientation can be transported more readily than the other. This produces spin-polarized electrons without requiring an external magnet. Because many electrochemical reactions involve paramagnetic or spin-sensitive intermediates, researchers have increasingly explored whether electron spin can be used as a tool for controlling catalytic activity.

Until now, however, most studies have focused on whether a catalyst is chiral or non-chiral. The Qingdao University team investigated a more precise question: does the degree of chirality matter? To explore this possibility, the researchers prepared cobalt oxide nanoparticles modified with chiral molecules. They then used an external magnetic field to progressively tune the catalysts’ chiral asymmetry factor, a measure associated with the difference in their response to left- and right-handed circularly polarized light. Circular dichroism measurements confirmed that the magnetic treatment increased this factor while leaving the catalysts’ crystal structure and overall morphology essentially unchanged.

That distinction was important because it allowed the researchers to examine the effect of chirality independently of major changes in particle size, shape, or composition. Electrochemical tests showed a direct relationship between the increased asymmetry factor and improved catalytic behavior. Catalysts with stronger chiral asymmetry facilitated faster charge transfer and accelerated the conversion of sulfur species during battery operation. They also promoted the nucleation of lithium sulfide during discharge and its decomposition during charging—two critical steps that frequently limit the efficiency of lithium–sulfur cells.

The resulting batteries displayed higher capacities, better rate performance, and stronger cycling stability than cells using non-chiral catalysts or untreated chiral catalysts. In practical terms, the optimized catalyst enabled the battery to sustain more of its stored energy when operated at higher current rates, while also retaining its performance over repeated charge–discharge cycles. These gains are particularly significant because sulfur redox reactions involve several intermediate compounds and phase changes, making the overall process much more difficult to control than the simpler intercalation reactions used in many lithium-ion batteries.

The researchers combined density functional theory calculations with spectroscopic and electrochemical analyses to explain why the effect occurs. Their calculations indicated that increasing the chiral asymmetry factor strengthened the spin polarization of cobalt sites within the catalyst. This altered the electronic structure of the cobalt oxide surface and changed the way cobalt 3d orbitals interacted with sulfur 3p orbitals. Stronger orbital coupling improved the electronic communication between the catalyst and sulfur-containing intermediates, while also lowering the calculated energy barriers for key sulfur redox steps.

According to the team, the catalyst’s improved performance did not arise simply because it adsorbed lithium polysulfides more strongly. Excessively strong adsorption can immobilize intermediates and make subsequent reactions more difficult. Instead, the enhanced spin polarization appeared to influence the reaction pathway itself, helping spin-sensitive intermediates interact more efficiently with catalytic sites. This suggests that electron spin can act as an additional control variable in electrocatalysis, alongside composition, surface structure, oxidation state, and adsorption energy.

The findings establish a quantitative connection between chirality, spin polarization, and battery activity. Rather than treating chirality as a fixed characteristic that is either present or absent, the study shows that catalytic behavior can be continuously adjusted by tuning its magnitude. Prof. Li said the work was motivated by the possibility of improving a catalyst without fundamentally changing its composition. By regulating the chiral asymmetry factor, the researchers were able to modify the spin state of catalytic sites and accelerate sulfur chemistry using a physical control strategy.

The work broadens the potential role of CISS beyond spintronics and molecular electronics, placing it within the rapidly developing field of electrochemical energy storage. If the approach can be transferred to other catalyst families and scaled for practical battery manufacturing, spin-selective catalysis could become a new design principle for high-energy batteries. Future research will need to determine how magnetic-field processing can be integrated into large-scale production and whether chiral engineering can be combined with porous structures, alternative catalytic metals, or advanced electrolytes. The same concept could also be relevant to fuel cells, electrolyzers, carbon dioxide conversion, and other technologies in which controlling the movement and spin of electrons may unlock faster and more selective chemical reactions.

Subject of Research: Chiral-induced spin selectivity and spin-state regulation in catalysts for lithium–sulfur batteries.

Article Title: Tuning the chiral asymmetry factor: A new dimension for lithium–sulfur battery catalysts.

Web References: https://doi.org/10.1093/nsr/nwag448

References: National Science Review, DOI: 10.1093/nsr/nwag448.

Image Credits: © Science China Press.

Keywords

Lithium–sulfur batteries, chiral-induced spin selectivity, CISS, chiral catalysts, spin polarization, cobalt oxide nanoparticles, sulfur redox reactions, lithium polysulfides, electrocatalysis, energy storage.

Breaking new ground, researchers have unveiled a high-voltage anode-free sodium–sulfur battery that operates in the impressive realm of 3.6 volts, ushering in a new paradigm for Na–S energy storage. This innovative battery design features a high-valence sulfur/sulfur tetrachloride (S/SCl_4) cathode chemistry combined with an anode-free configuration, fundamentally altering the battery architecture and performance metrics. The anode-free design notably eliminates the need for pre-loaded metallic sodium, addressing safety concerns and material inefficiencies characterizing earlier Na–S systems.

Central to this breakthrough is the incorporation of sodium dicyanamide (NaDCA) within a non-flammable chloroaluminate electrolyte. The NaDCA additive serves dual functions: it facilitates the reversible conversion between sulfur and SCl_4 in the cathode, while concurrently promoting efficient sodium plating and stripping at the anode interface. This dual functionality is critical, enabling unprecedented cycling reversibility and stability, cornerstones for practical battery deployment.

The performance statistics are nothing short of remarkable. Calculations based on the total mass of both cathode and anode materials reveal that this battery can achieve maximum energy and power densities of 1,198 watt-hours per kilogram and 23,773 watts per kilogram, respectively. These figures place the Na–S battery on a competitive pedestal comparable to, or even exceeding, that of many lithium-based technologies, but at a potentially lower cost and greater material availability.

Further enhancing the cathode kinetics, the team introduced a bismuth-coordinated covalent organic framework (Bi-COF) catalyst into the sulfur cathode at a loading of just 8 weight percent. This catalytic incorporation significantly accelerates the S/SCl_4 redox conversion, delivering a discharge capacity staggering at 1,206 milliamp-hours per gram when considering the combined sulfur and catalyst mass. This improvement in capacity translates to a considerable jump in the maximum energy density, now calculated at 2,021 watt-hours per kilogram, remarkably bolstering overall battery efficacy.

Operational stability is critical for any energy storage system, and the anode-free Na–S battery demonstrates impressive cycle life along with consistent coulombic efficiencies. The non-flammable chloroaluminate electrolyte not only enhances safety but also supports robust sodium deposition and dissolution processes, curtailing dendrite formation and thereby mitigating risks associated with short circuits and capacity fade. This aspect of the design is pivotal for real-world applications where safety is non-negotiable.

In terms of economic viability, the researchers estimate a production cost of approximately US$5.03 per kilowatt-hour, a figure that sharply undercuts many existing lithium-ion battery production costs. This affordability arises from the use of abundant materials and simpler cell architecture, making the technology especially suited for grid-level energy storage where cost-per-unit energy capacity governs adoption.

Scalability, often the Achilles’ heel of novel battery chemistries, is another standout attribute of this Na–S system. The anode-free approach simplifies cell assembly, reduces material waste, and enables compatibility with existing manufacturing infrastructure. This means that the transition from laboratory-scale prototypes to commercial-scale production can be expedited, fostering quicker market penetration.

Beyond grid applications, the compact and high-energy nature of these batteries holds promise for wearable electronics, where both energy density and safety are paramount. The elimination of metallic sodium anodes reduces the weight and risks associated with mechanical flexing and accidental puncture, enhancing the appeal for portable devices.

This pioneering work directly challenges the entrenched notion that sodium-based batteries must inherently compromise on voltage and safety. By leveraging innovative electrolyte formulations, advanced cathode chemistry including halogenated sulfur species, and catalytic strategies, the research unlocks new chemistry landscapes that redefine what is achievable in Na–S battery technology.

Overall, this cutting-edge development represents a watershed moment, highlighting the potential of high-voltage Na–S batteries as a viable, sustainable alternative to lithium-ion systems. Its amalgamation of high energy and power densities, safety, low cost, and scalability constitute a blueprint for next-generation energy storage innovations poised to impact grid stability and portable electronics profoundly.

These findings elevate the sodium–sulfur battery from the realm of theoretical interest to practical feasibility, igniting excitement within the energy materials community. The future of sustainable energy storage could well be illuminated by the glow of a high-voltage, anode-free Na–S battery — an elegant synergy of material science, electrochemistry, and engineering ingenuity.

Subject of Research: Development of high-voltage, anode-free sodium–sulfur batteries using sulfur/sulfur tetrachloride cathodes and sodium dicyanamide electrolyte.

Article Title: High-voltage anode-free sodium–sulfur batteries.

Article References:
Geng, S., Yuan, B., Zhao, X. et al. High-voltage anode-free sodium–sulfur batteries. Nature 649, 353–359 (2026). https://doi.org/10.1038/s41586-025-09867-2

Image Credits: AI Generated

DOI: 10.1038/s41586-025-09867-2

Keywords: Sodium–sulfur batteries, anode-free configuration, high-voltage cathode chemistry, sodium dicyanamide, chloroaluminate electrolyte, bismuth-coordinated covalent organic framework, energy density, power density, sustainable energy storage, grid storage, wearable electronics.