Electron-injection-engineering induced dual-phase MoO 2.8 F 0.2 /MoO 2.4 F 0.6 heterostructure for magnesium storage.

Rechargeable magnesium batteries (RMBs) have received increased attention due to their high volumetric capacity and safety. Nevertheless, the sluggish diffusion kinetics of highly polarized Mg 2+ in host lattices severely hinders the development of RMBs. Herein, we report an electron injection strategy for modulating the Mo 4d-orbital splitting manner and first fabricate a dual-phase MoO 2.8 F 0.2 /MoO 2.4 F 0.6 heterostructure to accelerate Mg 2+ diffusion. The electron injection strategy triggers weak Jahn-Teller distortion in MoO 6 octahedra and reorganization of the Mo 4d-orbital, leading to a partial phase transition from orthorhombic phase MoO 2.8 F 0.2 to cubic phase MoO 2.4 F 0.6 . As a result, the designed heterostructure generates a built-in electric field, simultaneously improving its electronic conductivity and ionic diffusivity by at least one order of magnitude compared to MoO 2.8 F 0.2 and MoO 2.4 F 0.6 . Importantly, the assembled MoO 2.8 F 0.2 /MoO 2.4 F 0.6 //Mg full cell exhibits a remarkable reversible capacity of 172.5 mAh g -1 at 0.1 A g -1 , pushing forward the orbital-scale manipulation for high-performance RMBs.