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.