Ultrastable Cu²⁺ Intercalation Chemistry Based on a Niobium Sulfide Nanosheet Cathode for Advanced Aqueous Storage Devices

Exploring stable and durable cathodes for cost-effective reversible aqueous batteries is highly desirable for grid-scale energy storage applications, but significant challenges remain. Herein, we disclosed an ultrastable Cu 2+ intercalation chemistry in mass-produced exfoliated NbS 2 nanosheets to build ultralong lifespan aqueous batteries with cost advantages. Anisotropic interplanar expansion of NbS 2 lattices balanced dynamic Cu 2+ incorporation and the highly reversible redox reaction of Nb 4+ /Nb (4−δ)+ couple were illuminated by operando synchrotron X-ray diffraction and energy dispersive X-ray absorption spectroscopy, affording an extraordinary capacity of approximately 317 mAh g –1 at 1 A g –1 and a good stability of 92.2% capacity retention after 40000 cycles at 10 A g –1 . Impressively, a budget NbS 2 ||Fe hybrid ion cell involving an aqueous electrolyte/Fe-metal anode is established and provides a reliable energy supply of 225.4 Wh kg –1 at 750 W kg –1, providing insights for building advanced aqueous battery systems for large-scale applications.