Strategy for capacity boosting in aluminum-ion batteries: controlling the interlayer spacing

Al-ion batteries (AIBs) have attracted increasing attention due to their three-electron reactions, abundant raw materials, and inherent safety. They employ cathodes such as graphite-based compounds and metal dichalcogenides, among which molybdenum disulfide (MoS₂) stands out with its unique layered structure, enhancing AIB capacity. Notably, its 6.2 Å interlayer spacing enables rapid ion diffusion, insertion, and extraction. However, few studies have explored the relationship between areal capacity and interlayer spacing in layered MoS₂ for AIBs. Herein, interlayer-controlled MoS₂ was synthesized via amine intercalation to enhance ion transport. The resulting n-butylamine-intercalated MoS₂ exhibited a larger interlayer spacing of 10.1 Å and achieved ∼ 15-fold higher areal capacity than bulk MoS₂. Moreover, it maintained 75 % of its initial capacity after 6000 cycles at 1.12 mA cm⁻², demonstrating excellent long-term stability. These findings contribute to high-performance AIB development using transition-metal sulfide cathodes.