Biomimetic Gradient-Porous Carbon Enables Sustainable High-Loading Lithium-Sulfur Batteries by Regulating Polysulfide Chemistry.

To realize the commercial viability of lithium-sulfur (Li-S) batteries, it is imperative to substantially increase the areal sulfur loading of the cathode to achieve higher energy density. However, increasing sulfur loading inevitably deteriorates charge-transport efficiency and slows electrochemical reaction kinetics, leading to pronounced degradation in rate capability and cycling stability. To address these critical challenges, a biomimetic strategy is adopted to engineer gradient-porous nitrogen-doped carbon nanomaterials (Bio-N-CNTs) with radially graded pore architectures, enabling their use as highly effective sulfur host materials. In situ Raman spectroscopy and DFT reveal that such unique structures facilitate efficient mass transport, ion diffusion, sulfur conversion, and high sulfur loading simultaneously, as well as enable gradient confinement catalytic conversion of LiPSs. As a result, the Bio-N-CNT/S cathode exhibits a capacity decay rate of only 0.178% after 100 cycles at a 0.1 C rate. Even under high sulfur loading conditions of 8.6 mg cm-2, this cathode material maintains 71% capacity retention after 100 cycles. Additionally, a sustainable "precipitation-enrichment-reduction-regeneration" silver recovery strategy with a 93% recovery rate, enhancing economic feasibility. This work demonstrates an innovative, scalable, and sustainable biomimetic Bio-N-CNT host for practical Li-S batteries.