Switchable and Strain‐Releasable Mg‐Ion Diffusion Nanohighway Enables High‐Capacity and Long‐Life Pyrovanadate Cathode
Xiu‐Fen Ma, Hongyi Li, Xiqin Zhu, Weiwei Ren, Xie Zhang, Jiang Diao, Bing Xie, Guangsheng Huang, Jingfeng Wang, Fusheng Pan
Abstract
Abstract Rechargeable magnesium batteries (RMBs) suffer from low capacity and poor cyclability of cathode materials, which is due to the sluggish Mg 2+ diffusion kinetics and large lattice strain. Here, a layer‐interweaving mechanism in lamellar cathode to simultaneously facilitate Mg 2+ diffusion and release Mg 2+ ‐insertion strain is reported. In the Cu 3 V 2 O 7 (OH) 2 ·2H 2 O (CVOH) cathode, Mg 2+ diffusion highways are generated by the vertical interweaving of CVOH layers and V 6 O 13 layers that nucleate in CVOH during discharging, which are switchable by Mg 2+ insertion/extraction. These highways enhance the Mg 2+ diffusion coefficient by three orders of magnitude and release 50% Mg 2+ ‐insertion strain. This enables CVOH to exhibit a high capacity of 262 mAh g −1 at high current density of 250 mA g −1 in aqua, and extremely low capacity loss of 0.0004% per cycle in the activated carbon//CVOH cell. This work inspires designing the magnesiation phase transformation of electrodes to resolve both kinetic and strain issues for high‐performance RMBs.