Flexible Three-Dimensional-networked Iron Vanadate Nanosheet Arrays/carbon Cloths As High-Performance Cathodes for Magnesium Ion Batteries

Owing to their safety and low cost, magnesium ion batteries (MIBs) have attracted much attention in recent years. However, the sluggish diffusion dynamics of magnesium ions hampers the search for appropriate cathode materials with excellent electrochemical performance. Herein, we design and synthesize a novel flexible three-dimensional-networked composite of iron vanadate nanosheet arrays/carbon cloths (3D FeVO/CC) as a binder-free cathode for MIBs. Relative to bare FeVO nanosheets, the 3D binder-free electrode with designed architecture enables a full range of electrochemical potential, including a high specific capacity of 270 mA h g −1 and an increased life span (over 5000 cycles). Such achievable high-density energy originates from the synergistic optimization of electron and ion kinetics, while the durability benefits from the robust structure that prevents degradation in cycling. The single-phase reaction mechanism of FeVO in the magnesium ion storage process is also explored by in-situ X-ray diffraction and Raman technologies. Moreover, a flexible MIB pouch cell (3D FeVO/CC|MgNaTi 3 O 7 ) is assembled and exhibits practical application potential. This work verifies that 3D FeVO/CC is a potential candidate cathode material that can satisfy the requirements of high-performance MIBs. It also opens a new avenue to improve the electrochemical performance of cathode materials for MIBs.