TiVCT x MXene/Chalcogenide Heterostructure-Based High-Performance Magnesium-Ion Battery as Flexible Integrated Units.

Magnesium-ion batteries (MIB) have gradually attracted attention owing to their high theoretical capacity, high safety, and low cost. A bimetallic metal-organic framework self-sacrificing template and a co-assembly strategy are used to prepare a high-performance, stable cycling NiSe 2 -CoSe 2 @TiVCT x (NCSe@TiVC) heterostructure MIB cathode that can be used as a flexible integrated unit to power future self-powered systems. Benefiting from the synergistic effect of TiVCT x MXene and NCSe, the NCSe@TiVC heterostructure electrode has a discharge-specific capacity of 136 mAh g -1 at 0.05 A g -1 and high cycling stability of over 500 cycles; the assembled pouch-cell device as flexible integrated unit exhibits good practicability. The magnesium ion storage mechanism is also validated using quantitative kinetic analysis, ex situ XRD, and XPS techniques. Density functional theory analysis indicates the most stable Mg-atom adsorption sites in the heterostructure. This study broadens the possibilities for applying the TiVCT x MXene heterostructure to energy storage materials and future self-powered flexible systems.