Switchable and Strain-Releasable Mg-Ion Diffusion Nanohighway Enables High-Capacity and Long-Life Pyrovanadate Cathode.

Rechargeable magnesium batteries (RMBs) suffer from low capacity and poor cyclability of cathode materials, which is due to the sluggish Mg diffusion kinetics and large lattice strain. Here, a layer-interweaving mechanism in lamellar cathode to simultaneously facilitate Mg diffusion and release Mg -insertion strain is reported. In the Cu V O (OH) ·2H O (CVOH) cathode, Mg diffusion highways are generated by the vertical interweaving of CVOH layers and V O layers that nucleate in CVOH during discharging, which are switchable by Mg insertion/extraction.