Catalyzing Desolvation at Cathode‐Electrolyte Interface Enabling High‐Performance Magnesium‐Ion Batteries

Abstract Magnesium ion batteries (MIBs) are expected to be the promising candidates in the post‐lithium‐ion era with high safety, low cost and almost dendrite‐free nature. However, the sluggish diffusion kinetics and strong solvation capability of the strongly polarized Mg 2+ are seriously limiting the specific capacity and lifespan of MIBs. In this work, catalytic desolvation is introduced into MIBs for the first time by modifying vanadium pentoxide (V 2 O 5 ) with molybdenum disulfide quantum dots (MQDs), and it is demonstrated via density function theory (DFT) calculations that MQDs can effectively lower the desolvation energy barrier of Mg 2+ , and therefore catalyze the dissociation of Mg 2+ ‐1,2‐Dimethoxyethane (Mg 2+ ‐DME) bonds and release free electrolyte cations, finally contributing to a fast diffusion kinetics within the cathode. Meanwhile, the local interlayer expansion can also increase the layer spacing of V 2 O 5 and speed up the magnesiation/demagnesiation kinetics. Benefiting from the structural configuration, MIBs exhibit superb reversible capacity (≈300 mAh g −1 at 50 mA g −1 ) and unparalleled cycling stability (15 000 cycles at 2 A g −1 with a capacity of ≈70 mAh g −1 ). This approach based on catalytic reactions to regulate the desolvation behavior of the whole interface provides a new idea and reference for the development of high‐performance MIBs.