<scp>l</scp> -Cysteine Intercalation Inducing 1T-Rich MoS ₂ Hybrids as High-Performance Cathodes for Reversible Zinc-Ion Storage

Due to the high energy density, inherent safety, and cost-effectiveness, aqueous zinc-ion batteries (AZIBs) have been recognized as promising solution for energy storage. Compared to the 2H phase of MoS2, the metallic 1T phase counterpart holds greater potential for application in AZIBs, owing to its higher electrical conductivity and favorable two-dimensional channel structure. Herein, a facile one-step hydrothermal approach was employed to synthesize stable and 1T-rich MoS2 hybrids (MoS2-l-Cys) using l-cysteine as an intercalation modifier. This approach simultaneously induces a spontaneous phase transition from the semiconducting 2H to metallic 1T phase and expands the interlayer spacing of MoS2. The metallic 1T phase of MoS2 promotes electrons transfer, while the expanded interlayer spacing accelerates the Zn2+ ions’ diffusion kinetics and exposes more active sites. These synergistic effects collectively boost charge transfer kinetics of the Zn2+ ions’ redox reaction, thereby dramatically improving the electrochemical performance of AZIBs. Therefore, the discharge specific capacity of the MoS2-l-Cys electrode is as high as 279.0 mAh g–1 with outstanding rate capability. Furthermore, the MoS2-l-Cys electrode exhibits exceptional cycling stability, with a capacity retention of 91.4% after 1000 cycles at 4 A g–1, due to that the expanded interlayer spacing can effectively mitigate volume variations of MoS2-l-Cys during cycling. This work systematically elucidates the crucial role of l-cysteine intercalation-induced phase transition in optimizing reaction kinetics, providing a viable and effective strategy for developing MoS2-based cathodes for high-performance AZIBs.