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.