<i>In Situ</i> Regulation of Interfacial Charge Transfer and Interlayer Van der Waals Force Enables Ultrafast Aluminum-Ion Diffusion.

Abstract

The diffusion kinetics of trivalent aluminum ions in intercalated cathode materials is impeded, significantly impeding the advancement of rechargeable Al batteries. We propose a strategy for the enhancement of Al³⁺ diffusion kinetics through the incorporation of Li⁺, aimed at improving the Al-storage properties in model MoS₂ material. By modulating the Li⁺ concentration (1-8 wt %) in a room-temperature ionic-liquid electrolyte, we elucidate its correlation with the overall electrochemical performance. At 3.33 wt % Li⁺, it substantially reduces the interlayer van der Waals force by inducing a high-quality and stable phase transition and simultaneously optimizes the charge transfer at the cathode-electrolyte interface, thereby comprehensively accelerating the Al³⁺ transport. The assembled MoS₂||Al pouch battery exhibits the highest recorded electrochemical performance, achieving an initial discharge capacity of 253.1 mAh g^-1 and maintaining a high capacity of 202.3 mAh g^-1 after 200 cycles at 0.5 A g^-1. These findings provide valuable insights into the development of metal-phase insertion cathode materials in Al batteries.