Engineering Coral‐Inspired Gradient Porosity Composite for High‐Performance Batteries

ABSTRACT

Lithium–sulfur batteries offer high energy density but are limited by polysulfide shuttling, sluggish ion transport, and lithium‐dendrite‐induced interfacial failure. Conventional nanofibrous separators provide mechanical and thermal stability, yet strong inter‐fiber interactions cause dense restacking, low porosity, tortuous ion pathways, and severe concentration polarization. Inspired by the hierarchical porosity and mechanical resilience of coral reefs, we developed a coral‐mimetic gradient porous composite separator (APA) integrating aramid nanofibers (ANFs), methacryloxy‐functionalized polyhedral oligomeric silsesquioxane (POSS), and 2‐amino‐5‐mercapto‐1,3,4‐thiadiazole (AMT). The ANF scaffold provides mechanical strength, the POSS‐derived hybrid framework suppresses nanofiber restacking and forms continuous mesoporous ion channels, while the AMT‐functionalized surface chemically anchors lithium polysulfides. This asymmetric architecture improves electrolyte wettability, ionic conductivity, Li ⁺ transference, polysulfide confinement, and dendrite resistance. Benefitting above merits, the assembled Li–S cells with APA exhibit an initial capacity of 945 mAh g ^{− 1} at 2.0C and sustain >2000 cycles with only 0.023% capacity decay per cycle. Li||Li symmetric cells remain stable for over 4000 h under harsh conditions (10.0 mA cm ^{− 2} /10.0 mAh cm ^{− 2} ). The separator also demonstrates compatibility with LFP/Li and NCM/Li systems, highlighting the versatility of this bioinspired gradient‐architecture strategy for advanced lithium metal batteries.