Sub-Monolayer Wrapping Stabilizes Magnesium Ion Cathode.
basic_science · Level V
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- Record sourced from PubMed, PMID 42714343.
- Also identified by DOI 10.1002/adma.74924.
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Abstract
Rechargeable magnesium batteries (RMBs) hold promise as next-generation energy storage systems, owing to their high volumetric capacity, high safety, and abundance of Mg. However, their development is hindered by sluggish Mg ion (Mg<sup>2+</sup>) diffusion and cathode instability, especially polysulfide and transition metal dissolution. While ultrathin protection layers offer distinct advantages over conventional bulk coatings, their synthesis remains a significant challenge. Herein, we wrap a sub-monolayer MoS<sub>2</sub> on Cu<sub>1.81</sub>S cathode, where MoS<sub>2</sub> layer acts as a functional interface that regulates the local chemical environment and suppresses cathode dissolution. MoS<sub>2</sub> layer also plays an activation role by facilitating Mg adsorption and reducing migration barriers, thereby accelerating storage kinetics. Benefiting from this synergistic design, Cu<sub>1.81</sub>S@MoS<sub>2</sub> cathode exhibits enhanced cycling stability and rate performance. It delivers around 246 mAh/g after 200 cycles at 100 mA/g with a low fading rate (0.057% per cycle), maintaining around 107 mAh/g after 600 cycles at 400 mA/g with 99.1% coulombic efficiency (CE). Furthermore, with the MoS<sub>2</sub> layer, the cathode shows excellent rate capability with 106 mAh/g at 1000 mA/g and full recovery at 20 mA/g. This work highlights a feasible nanostructuring strategy to stabilize conversion-type cathodes to advance high-performance RMBs.