Superior Diffusion Kinetics of Zn ²⁺ Over Monovalent Ions in MoS ₂ Nanosheets for High‐Power Supercapacitive Energy Storage

ABSTRACT Supercapacitors (SCs) are prized for their exceptional cycle life, operational stability, inherent safety, and maintainability. The electrolyte is a critical component, directly governing their electrochemical performance. This study investigates molybdenum disulfide (MoS 2 ) as a capacitive electrode material across chloride‐based electrolytes (LiCl, KCl, NaCl, ZnCl 2 ). Findings reveal that the divalent Zn 2+ ion enables significantly enhanced energy storage compared to monovalent cations. The MoS 2 electrode in the Zn 2+ ‐based electrolyte achieved a remarkably high specific capacitance of 630.5 F/g at 1 A/g, vastly outperforming LiCl, KCl, and NaCl (413.55, 281.94, and 275.73 F/g, respectively). It also demonstrated exceptional long‐term stability, retaining 97% of its initial capacitance after 10 000 charge–discharge cycles. Density functional theory (DFT) calculations corroborate these results, indicating a stronger adsorption interaction between Zn 2+ ions and the MoS 2 , which elucidates the superior charge storage. To demonstrate practical viability, an asymmetric SC (MoS 2 //CP) was assembled. This device delivered a high capacitance of 260.5 F/g at 1 A/g and maintained ∼ 93% of its capacity over 10 000 cycles within a 0.0–1.6 V voltage window. This work provides fundamental insights and a promising pathway for developing high‐performance, durable MoS 2 ‐based Zn 2+ ‐ion SCs, advancing the field of advanced energy storage solutions.