Construction of solid solution sulfide embedded in MXene@N-doped carbon dual protection matrix for advanced aluminum ion batteries

Abstract

Engineering intriguing cathode electrode with desirable kinetics behaviors is imperative for boosting aluminum storage systems. Here, a MXene and N-doped carbon dually protected Ni 0.6 Co 0.4 S solid solution (Ni 0.6 Co 0.4 S@MXene@NC) composite is reported as the cathode material for AIBs. The dissolution of Ni into CoS lattice leads to the electronic rearrangement, tuning its binding interaction with the Al 3+ and modifying the Al 3+ diffusion barrier. Consequently, the Ni 0.6 Co 0.4 S renders the high overall Al 3+ adsorbability, and contributes to fast Al 3+ diffusion kinetics. Additionally, the robust MXene@NC protective shell not only provides faster electron transfer pathway, but also contributes to high chemical and structural stability, attributed to the inhibition of active species dissolution and favorable tolerance to volume change. This novel design enables the Ni 0.6 Co 0.4 S@MXene@NC composite a high initial discharge capacity of 481.2 mA h g −1 at 400 mA g −1 . Even at 1000 mA g −1 , the capacity still maintains at 125.2 mA h g −1 after 300 cycles. Meanwhile, the investigation of reaction mechanism reveals that the cell involves the intercalation of Al 3+ into Ni 0.6 Co 0.4 S to generate Al l Ni m Co n S and elemental Ni and Co. This work propels the process of enhancement of electrochemical performance for AIBs via smart designing and constructing cathode materials. • MXene and N-doped carbon confined Ni 0.6 Co 0.4 S (Ni 0.6 Co 0.4 S@MXene@NC) was prepared. • The incorporation of Ni into CoS improves the Al 3+ diffusion kinetics in AIBs. • MXene can prevent the dissolution of Ni 0.6 Co 0.4 S towards the electrolyte. • Ni 0.6 Co 0.4 S@MXene@NC exhibits enhanced aluminum storage performance.