Vertically Aligned Mesoporous Arrays Catalyzing Long-Chain Polysulfide Conversion to Unlock High-Energy Magnesium-Sulfur Batteries.

Abstract

Rechargeable magnesium-sulfur (Mg-S) batteries are attractive for next-generation energy storage systems owing to their safety and superior volumetric energy density. Nevertheless, the underlying origins of the severe shuttle effect in Mg-S batteries remain unclear, significantly limiting improvements in their electrochemical performance. Herein, insufficient MgS₈ conversion kinetics is identified as the primary cause of the shuttle effect in Mg-S batteries. A thermally activated metal-organic framework (MOF)-derived cuprous 2,3,6,7,10,11-triphenylenehexol (Cu-HHTP-200@CNT) interlayer with vertically aligned mesoporous arrays is designed to modulate sulfur conversion kinetics. The reduced spatial hindrance within the mesopores facilitates the preconcentration of long-chain polysulfides, while coordinatively unsaturated Cu sites establish catalytic interfaces through sufficient <i>d-p</i> orbital hybridization. Consequently, the optimized S-Cu-HHTP-200@CNT configuration elevates the main discharge plateau from 1.1 to 1.6 V, achieves a high-rate performance (a power density of 4090 W kg^-1 after 500 cycles at 3 C), and maintains a capacity of 236 mAh g^-1 at -20 °C. This work highlights the critical role of electrocatalytic regulation in long-chain sulfur conversion and provides design principles for high-performance sulfur-based batteries.