Phase Inversion-Enabled Polymer Scaffold Engineering for Ultrahigh-Loading Sulfurized Polyacrylonitrile Cathodes in Lithium-Sulfur Batteries.

Lithium-sulfur batteries are promising candidates for next-generation energy storage due to their high theoretical capacity and low cost. However, structural instability, polysulfide shuttling, and sluggish ion transport hinder the development of thick sulfur cathodes with high areal loading. Sulfurized polyacrylonitrile (SPAN) mitigates polysulfide shuttling via a quasi-solid conversion mechanism; however, volume changes and limited ion transport remain challenging, particularly in thick electrodes. Here, a phase inversion-engineered polymer scaffold is developed to fabricate mechanically robust, ion-permeable, high-loading SPAN cathodes. By tuning polymer crystallinity and pore architecture via temperature-controlled nonsolvent-induced phase inversion, a hierarchical, low-tortuosity transport network is achieved, enabling balanced ionic conduction, electronic percolation, and mechanical integrity. The optimized cathode delivers a specific capacity of 1263.68 mAh/g of sulfur at 2 C with 90.83% capacity retention over 500 cycles and presents an ultrahigh electrode loading of 62.95 mg/cm2, achieving 12.73 mAh/cm2. This work demonstrates that phase inversion-enabled scaffold engineering is a scalable strategy for fabricating ultrahigh-loading electrodes.