Interlayer‐Expanded MoS 2 Containing Structural Water with Enhanced Magnesium Diffusion Kinetics and Durability

Abstract One obstacle that hinders the development of rechargeable magnesium batteries (RMBs) is the limited selection of cathode materials with decent Mg diffusion kinetics due to the highly polarizing nature of divalent Mg 2+ . To promote Mg 2+ diffusion kinetics, water molecules (H 2 O) are incorporated into the gaps of MoS 2 with enlarged interlayer spacing through an electrochemically assisted method. Owing to the charge shielding effect of crystal H 2 O, the electrostatic interaction between Mg 2+ and host frameworks is weakened, thus hydrous MoS 2 (H−MoS 2 ) delivers a Mg diffusion rate three times faster than that of MoS 2 before hydration. The facilitated Mg diffusion kinetics in H−MoS 2 ensure a high capacity of 190.3 mAh g −1 at 20 mA g −1 , accompanied by excellent rate performance (75.1 mAh g −1 retains at 500 mA g −1 ). Additionally, crystal H 2 O plays the role of pillars, endowing that the layered structure of H−MoS 2 retains stable during repetitive Mg intercalation, thus 91.2 % of initial capacity is retained after 300 cycles.