Enhanced Performance of Li–S Batteries via Dual Cathode–Interlayer Engineering: Hollow TiO2–Sulfur with Electrospun MXene–TMO Interlayers

TL;DR

This paper introduces a new strategy to improve lithium-sulfur batteries by combining a special sulfur host with a conductive interlayer, leading to better performance and longer battery life.

Contribution

The first dual-engineered Li–S cathode system combining defect-mediated sulfur hosts and catalytic interlayers is demonstrated.

Findings

The dual-engineering strategy reduces LiPS charge-transfer resistance by 93% and improves cycling stability with >81% capacity retention.

Li+ diffusion rates nearly double, and fast kinetic reactions are maintained at high scan rates.

DFT calculations confirm stronger LiPS binding and higher catalytic reactivity on hydrogen-treated TiO2 surfaces.

Abstract

Lithium–sulfur (Li–S) batteries suffer
from rapid
capacity fading due to the polysulfide (LiPS) shuttle, sluggish redox
kinetics, and the formation of insulating discharge products. Here,
we report a dual-engineering strategy that integrates a hydrogen-treated
hollow TiO2 (H–TiO2) sulfur host with
conductive poly­(vinylidene fluoride) (PVDF)-based MXene–TMO
interlayers. Hydrogen treatment introduces Ti3+/oxygen
vacancies and forms a hollow framework, imparting enhanced conductivity
to TiO2 while providing abundant active sites for sulfur
immobilization and redox catalysis. Complementarily, the best-performing
MXene–TMO interlayer, PVDF/MXene–SnO2 (PV–MS),
couples the high conductivity of MXene with the polar, catalytic activity
of SnO2, enabling efficient LiPS adsorption and accelerated
conversion. This synergy yields substantial performance improvements:
LiPS charge-transfer resistance decreases by 93% (4.5 to 0.31 Ω),
cycling stability is significantly enhanced (capacity retention >81%
compared with 64% for the reference cell), Li+ diffusion
rates nearly double, and fast kinetic reactions are maintained even
at high scan rates without diffusion limitations. Additionally, the
rate capability remains robust at high current densities. Density
functional theory (DFT) calculations further confirm this synergistic
behavior, showing that the adsorption free energy of Li2S6 follows the trend |ΔG
ads|H–TiO2
> |ΔG
ads|TiO2
> |ΔG
ads|graphene, indicating the strongest LiPS
binding and the highest catalytic reactivity on H–TiO2 surfaces. Both DFT and XPS analyses reveal a distinct dual-site
binding mechanism in H–TiO2, where Ti–S and
Ti–O–Li interactions cooperatively enhance polysulfide
anchoring, promote faster redox conversion, and improve sulfur utilization.
To the best of our knowledge, this is the first demonstration of a
dual-engineered Li–S cathode system in which defect-mediated
sulfur hosts and catalytic interlayers operate synergistically. The
resulting mechanismcontrolled sulfur release at the cathode,
shuttle suppression at the interlayer, and rapid electron/ion transport
across the interface, establishes a powerful design guideline for
achieving long-lived and high-rate Li–S batteries.

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