Nanocellulose‐Derived Hierarchical Carbon Framework‐Supported P‐Doped MoO ₂ Nanoparticles for Optimizing Redox Kinetics in Lithium–Sulfur Batteries

Abstract The integration of nanocatalysts into the separators of lithium–sulfur batteries (LSBs) boosts the polysulfide conversion efficiency. However, the aggregation of catalyst nanoparticles diminishes the active surface area. Moreover, densely packed catalyst‐modified layers often hinder ion transport rates and impede access to the catalytic sites. To overcome these challenges, a strategy is reported for modifying commercial separators, using wood nanocellulose as a building block to construct hierarchical P‐doped MoO _2−x nanoparticles anchored on N, P co‐doped porous carbon (P‐MoO _2−x /NPC). The web‐like entangled nanocellulose forms a framework for the in situ polymerization of polyaniline, providing abundant anchoring sites for MoO ₂ nanoparticles. The addition of P atoms optimizes the d‐band center of MoO ₂ and enhances the catalytic activity of polysulfide conversion. The LSBs assembled using a P‐MoO _2−x /NPC coated polypropylene separator display an initial discharge capacity of 1621 mAh g ⁻¹ and rate performance of 774 mAh g ⁻¹ at 5 C. Even with a sulfur loading of 8.1 mg cm ⁻² and lean electrolyte conditions, the cell achieves an initial areal capacity of 11.3 mAh cm ⁻² at 0.1 C. This work provides a biopolymer nanofiber solution for constructing LSB separators with advanced electrochemical reactivity.