Interlayer-Expanded MoS₂ Containing Structural Water with Enhanced Magnesium Diffusion Kinetics and Durability

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 Mg²⁺. To promote Mg²⁺ diffusion kinetics, water molecules (H₂O) are incorporated into the gaps of MoS₂ with enlarged interlayer spacing through an electrochemically assisted method. Owing to the charge shielding effect of crystal H₂O, the electrostatic interaction between Mg²⁺ and host frameworks is weakened, thus hydrous MoS₂ (H−MoS₂) delivers a Mg diffusion rate three times faster than that of MoS₂ before hydration. The facilitated Mg diffusion kinetics in H−MoS₂ 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 H₂O plays the role of pillars, endowing that the layered structure of H−MoS₂ retains stable during repetitive Mg intercalation, thus 91.2 % of initial capacity is retained after 300 cycles.