H<sub>2</sub>O‐Mg<sup>2+</sup> Waltz‐Like Shuttle Enables High‐Capacity and Ultralong‐Life Magnesium‐Ion Batteries
Xiu‐Fen Ma, B. Zhao, Hongyu Liu, Jing Tan, Hongyi Li, Xie Zhang, Jiang Diao, Jili Yue, Guangsheng Huang, Jingfeng Wang, Fusheng Pan
Abstract
Abstract Mg‐ion batteries (MIBs) are promising next‐generation secondary batteries, but suffer from sluggish Mg 2+ migration kinetics and structural collapse of the cathode materials. Here, an H 2 O‐Mg 2+ waltz‐like shuttle mechanism in the lamellar cathode, which is realized by the coordination, adaptive rotation and flipping, and co‐migration of lattice H 2 O molecules with inserted Mg 2+ , leading to the fast Mg 2+ migration kinetics, is reported; after Mg 2+ extraction, the lattice H 2 O molecules rearrange to stabilize the lamellar structure, eliminating structural collapse of the cathode. Consequently, the demo cathode of Mg 0.75 V 10 O 24 ·nH 2 O (MVOH) exhibits a high capacity of 350 mAh g −1 at a current density of 50 mA g −1 and maintains a capacity of 70 mAh g −1 at 4 A g −1 . The full aqueous MIB based on MVOH delivers an ultralong lifespan of 5000 cycles The reported waltz‐like shuttle mechanism of lattice H 2 O provides a novel strategy to develop high‐performance cathodes for MIBs as well as other multivalent‐ion batteries.