Turning water-based flow batteries into a truly sustainable technology hinges on recycling the organic molecules inside the battery. A redox-active organic molecule has now been developed that not only outperforms the industry-standard vanadium benchmark but also offers exceptional reusability.
Aqueous redox flow batteries are promising for large-scale grid energy storage, but their widespread implementation is hindered by the lack of anolyte materials that combine high capacity, environmental compatibility, recyclability, low cost and long-term stability. While organic anolyte molecules offer a potential sustainable solution, integrating these competing attributes within a single molecular platform remains challenging. Here we report a recyclable oligo(disulfide)-based anolyte in which robust sulfur–sulfur bonds serve as redox-active sites. The anolyte is synthesized by ring-opening polymerization of potassium-form endogenous thioctic acid, providing a scalable route to high-concentration redox-active species. Paired with a sulfonated cobalt phthalocyanine catalyst, this oligo(disulfide) anolyte delivers a capacity density of 128 Ah l−1 with a 95.5% material utilization rate at 50 mA cm−2. Using a carbon-coated sulfonated poly(ether ether ketone) membrane with a sulfur–sulfur bond concentration of 0.25 M, the battery retains 98.1% of its capacity over 2,200 cycles while maintaining an energy efficiency of approximately 70% at 100 mA cm−2. We further validate the scalability and closed-loop recyclability of this chemistry in a 63 Wh stack. Our findings establish oligo(disulfide)s as a robust, circular redox platform, providing a pathway towards more resource-efficient and sustainable grid-scale energy storage. Aqueous flow batteries are ideal for grid storage but lack sustainable, high-capacity anolytes. Here the authors report a recyclable oligo(disulfide) design that combines closed-loop recyclability with good electrochemical performance.
As an energy-efficient and scalable alternative to conventional chemical absorption, membrane-based carbon capture requires materials that simultaneously combine molecular-level thinness, precise sub-nanometre porosity and exceptional mechanical robustness—a longstanding trilemma in separation science. Here we report graphene–amorphous carbon bilayer membranes that overcome these trade-offs by way of a graphene-guided polymer conversion approach. Leveraging a super-spreading effect, we coat graphene with a uniform, ultra-smooth, polymer-derived carbon layer as thin as 2 nm, achieving a high Young’s modulus of approximately 26.8 GPa. Controlled pyrolysis of the polymer precursor generates a carbon network featuring narrowly distributed, high-precision ultramicropores. The resulting graphene–amorphous carbon membranes exhibit sharp molecular sieving (selectivity of >60 for CO2/N2, >70 for H2/CO2 and >70 for CO2/CH4) alongside an exceptional CO2 permeance of up to 5,000 gas permeation units that surpasses existing benchmarks. This combination of structural integrity and separation performance enables efficient carbon capture across varied flue gas, syngas and natural gas streams, establishing graphene–amorphous carbon membranes as a versatile, energy-efficient platform for sustainable molecular separations. Membrane-based separations offer a promising energy-efficient approach to mitigating CO2 emissions. Here the authors develop molecularly thin graphene–amorphous carbon membranes that simultaneously deliver sharp molecular sieving, high permeance and mechanical stability for selective CO2 separation.
Anthropogenic emissions are rapidly increasing atmospheric CO2 levels, with severe consequences for the global climate. Researchers have developed a carbon membrane as thin as only two molecular layers that sieves and captures CO2 with very high flux and selectivity, holding promise for climate change mitigation technologies.
