Intercalation Engineering Synthesizes MoS₂ Cathodes Rich in the 1T Phase To Achieve Stable Cycling for Aqueous Aluminum-Ion Batteries.

Abstract

The 1T-phase MoS₂ is a highly attractive cathode candidate for aqueous aluminum-ion batteries (AAIBs) due to its metallic conductivity, impressive theoretical specific capacity, and tunable interlayer spacing. However, its thermodynamic instability under ambient conditions hinders direct synthesis and limits practical applications. In this study, 1T-phase-rich MoS₂ nanoflowers were successfully fabricated via an intercalation strategy, resulting in a structure of alternating monolayer carbon and 1T-phase MoS₂. This architecture significantly increases the interlayer spacing, reduces the ion diffusion barrier, and enhances the ion transport kinetics. The incorporation of monolayer carbon further improves the electrical conductivity and structural stability. Electrochemical measurements reveal that, after 150 cycles under a current density of 0.4 A g^-1, the electrode retains a discharge capacity of 209.12 mAh g^-1 alongside a Coulombic efficiency exceeding 90%, indicating excellent Al-ion storage performance. Ex situ characterization elucidates the reaction mechanism and phase evolution of MoS₂ during battery operation, while density functional theory (DFT) calculations confirm that monolayer carbon promotes rapid reaction kinetics and reduces the ion diffusion energy barrier. The study provides valuable guidance for the design of MoS₂-based cathodes, advancing their development and application in AAIBs.