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

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 d–p 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.