Strengthened D‐p Orbital Hybridization Via Interlayer Coupling Enables Sulfur Redox Kinetics in Lithium‐Sulfur Batteries

ABSTRACT

The inherent wide bandgap and large d‐p band center energy difference (Δε _d‐p ) of δ‐MnO ₂ significantly impede electron transport and ion diffusion, limiting its catalytic efficiency in lithium‐sulfur (Li─S) batteries. Herein, we report an interlayer coupling strategy that intercalates cetyltrimethylammonium (CTA ⁺ ) cations into birnessite (δ‐MnO ₂ ) to simultaneously modulate the Mn 3d‐O 2p orbital hybridization and expand the Li ⁺ diffusion channels. Synchrotron X‐ray absorption fine structure (XAFS) spectroscopy combined with density functional theory (DFT) calculations reveal that the strong electrostatic interaction between CTA ⁺ and the MnO ₂ host layers narrows the d‐p band center energy difference (Δε _d‐p ) from 1.458 to 1.145 eV, substantially enhancing Mn 3d‐O 2p orbital hybridization. This optimized d‐p matching renders the Mn d‐band more compatible with the S 2p orbitals of polysulfides, synergistically optimize adsorption energies and conversion barriers. Meanwhile, the CTA ⁺ expanded interlayer afford ordered Li ⁺ diffusion channels with a high Li ⁺ transference number and uniform Li deposition. Consequently, the Li─S batteries deliver a remarkable capacity of 819.07 mAh g ^{− 1} at 3.0 C and sustain 850 cycles at 1.0 C with an capacity decay of only 0.05% per cycle. Significantly, the Li─S pouch cell equipped with a Bir(CTAB)‐separator delivers a high energy density of 305.25 Wh kg ⁻¹ .