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Electronic structure defines the conductivity and ion absorption characteristics of a functional electrode, significantly affecting the charge transfer capability in batteries, while it is rarely thought to be involved in mesoscopic volume and diffusion kinetics of the host lattice for promoting ion storage. Here, we first correlate the evolution in electronic structure of the Mo 6 S 8 cathode with the ability to bound volume expansion and accelerate diffusion kinetics for high-performance aqueous Cu 2+ storage. Operando synchrotron energy-dispersive X-ray absorption spectroscopy reveals that accumulative delocalized Mo 4d electrons enhance the Mo-Mo interaction with distinctly contracting and uniformizing Mo 6 clusters during the reduction of Mo 6 S 8 , which potently restrain lattice expansion and release space to promote Cu 2+ diffusion kinetics. Operando synchrotron X-ray diffraction and comprehensive characterizations further validate the structural and electrochemical properties induced by the Cu 2+ intercalation electronic structure, endowing the Mo 6 S 8 cathode a high specific capacity with small volume expansion, fast ions diffusion, and long-term cycling stability.

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.