Unveiling the Interlayer-Intralayer Cooperative Diffusion Mechanism in Bimetallic Layered Cathodes for Rechargeable...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Rechargeable Mg batteries (RMBs) show promise for grid-scale energy storage.
• Limited cathode materials and slow Mg²⁺ diffusion hinder RMB development.
• Interlayer diffusion in layered cathodes for Mg²⁺ storage is underexplored.

Purpose of the Study:

• To synthesize and compare two-layered copper molybdenum sulfide (Cu₂MoS₄) cathodes for Mg²⁺ storage.
• To investigate the impact of intralayer versus intralayer/interlayer diffusion channels on Mg battery performance.
• To elucidate the role of ion transport pathway engineering in optimizing Mg²⁺ diffusion kinetics.

Main Methods:

• Synthesis of two-layered Cu₂MoS₄ (CMS-L and CMS-V) with distinct diffusion channels.
• Electrochemical evaluation including capacity, rate capability, and cyclability tests.
• Mechanism analysis and theoretical computations (e.g., DFT) to study ion diffusion.

Main Results:

• CMS-V, with 3D ion transport tunnels, outperformed CMS-L.
• CMS-V achieved a high reversible capacity (210 mAh g^-1 at 100 mA g^-1) and excellent rate capability (98 mAh g^-1 at 2 A g^-1).
• CMS-V demonstrated outstanding cyclability (77% retention after 500 cycles) due to stable Mo-S bonds and reduced diffusion barriers via interlayer-intralayer cooperative diffusion.

Conclusions:

• Multidimensional ion-transport pathway engineering is crucial for optimizing Mg-storage kinetics.
• Vertically aligned interlayer tunnels in CMS-V facilitate rapid Mg²⁺ transport.
• This study provides insights for designing advanced RMB cathode materials with enhanced performance.