Enhancing the performance and cyclability of MoS2 cathodes with interspace layer engineering using polypyrrole

Abstract

Molybdenum disulfide with a layered structure shows great potential as a cathode for aqueous rechargeable zinc-ion batteries due to its adjustable structure, high capacity, and energy density. Previous studies have improved its performance by introducing metal ions to adjust layer spacing, but this approach has limitations. This study takes a different approach by incorporating conductive polymer polypyrrole (PPy) into MoS₂ layers, achieving a maximum layer spacing of 1.13 nm, which enhances zinc ion (de)intercalation kinetics and accelerates battery performance. The efficient (de)intercalation of zinc ions is facilitated by the considerable interlayer spacing, thereby significantly boosting the electrochemical performance of molybdenum disulfide. The enhanced specific capacity of PPy–MoS₂ is 404 mA h g⁻¹ at 0.1 A g⁻¹, and its performance remains constant throughout the cycle. A novel synthesis method is presented in the pre-insertion of conducting polymer strategy into the host material, which enables the utilization of MoS₂ as a cathode material for ARZIBs. Density functional theory (DFT) calculations also validate the augmented migration kinetics of Zn²⁺. A thorough understanding of the energy storage mechanism linked to the highly reversible phase that occurs between Mo⁴⁺ and Mo⁵⁺ during the intercalation and deintercalation of Zn ions is achieved through ex situ observations.