Volcano Plot of Transition Metal Disulfides in Aqueous Zinc Ion Storage.

The rational design of cathode materials for aqueous zinc-ion batteries (AZIBs) has been guided by the principle that larger interlayer spacing facilitates greater Zn2+ storage. However, this geometric heuristic fails to explain the stark performance difference between isostructural transition metal disulfides (TMDs) like VS2 and MoS2, which possess similar spacings but vastly different capacities. Herein, we propose an electronic-structure descriptor, φ, defined as the product of the transition metal's d-band center and electronegativity. Density functional theory calculations reveal that φ strongly correlated with Zn2+ adsorption energy (R2 = 0.94). Experimental validation across six synthesized TMDs confirms a definitive volcano-type relationship between Zn2+ storage capacity and φ, while revealing no correlation with interlayer spacing. This work establishes a generalizable screening principle that prioritizes the electronic origin of host-guest interactions over traditional structural metrics, providing a new roadmap for the rational design of intercalation hosts for multivalent-ion batteries.