One-Step Tunable MoS2 with Enhanced Zn2+ Diffusion for High-Energy Zinc-Ion Hybrid Capacitors

Abstract

Zinc-ion hybrid capacitors (ZIHCs) offer a promising solution for large-scale energy storage, combining battery-like energy density with superior power performance. However, their development is challenged by the scarcity of suitable cathode materials, as well as poor reversibility and sluggish Zn2+ diffusion due to its large hydrated ion size and limited efficiency. To address this, a one-step, tunable synthesis approach is developed for growing MoS2 on carbon cloth via an ethylene glycol (EG) intercalation strategy, effectively transforming inactive interlayer cavities into highly active sites. Density functional theory calculations reveal that EG intercalation substantially lowers the energy barrier for hydrated Zn2+ intercalation, significantly improving Zn2+ storage capability. Experimentally, EG molecules expand the MoS2 interlayer spacing from 0.617 to 0.948 nm, creating wider diffusion channels for Zn2+ transport. The optimized EG-MoS2 exhibits a high specific capacitance of 240.5 F/g at 0.7 A/g, which is three orders of magnitude higher than that of pristine MoS2, along with exceptional rate capability. Notably, the assembled ZIHC exhibited a high energy density of 40.42 Wh kg-1 at a power density of 385 W kg-1 while demonstrating outstanding cycling stability over 5000 cycles. This work unveils a powerful strategy for engineering high-performance MoS2-based cathodes, advancing next-generation ZIHCs development.