Synergistic Adsorption‐Catalytic Effect Based on Hierarchical Porous Structure and Lewis Acidic Cu + Sites in Cu 2 O@MXene for Boosting the Performance of RT Na–S Batteries

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Abstract
Room‐temperature sodium–sulfur (RT Na–S) batteries offer high energy density and low cost but suffer from poor conductivity, sluggish redox kinetics, and polysulfide shuttling. This study introduces a multifunctional Cu 2 O@MXene separator with a hierarchical porous structure and a 3D MXene network for fast electron transport. The hierarchical porous structure provides physical confinement, while the polar Cu─O bonds and Cu + Lewis acid centers in Cu 2 O provide chemical anchoring and catalytic sites for sodium polysulfides (NaPSs). Experimental evidence and theoretical calculations reveal that MXene serves as an electronic reservoir to protect Cu + catalytic active sites from reduction, enabling NaPSs anchoring through interfacial Cu─S and Ti─S bonds. Benefiting from this synergistic adsorption‐catalytic mechanism, the Cu 2 O@MXene interlayer enhances NaPSs confinement and accelerates sulfur redox kinetics. Consequently, Cu 2 O@MXene‐PP cells achieve 942.1 mAh g −1 after 100 cycles at 0.2 C and ultralong cycling stability of 574.9 mAh g −1 after 3500 cycles at 2 C. Under a sulfur loading of 4.65 mg cm −2 , the cell retains 3.1 mAh cm −2 after 105 cycles. Theoretical calculations further reveal that Cu 2 O@MXene enables stronger NaPSs adsorption and improves the thermodynamical favorability of the Na 2 S 2 to Na 2 S conversion. This work provides reasonable guidelines for designing Cu‐based catalytic separators in high‐performance RT Na‐S batteries.
Funding Information
  • National Natural Science Foundation of China (52072034)
  • National Natural Science Foundation of China (52372173)

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