Fish Scale-Derived Microreactor Accelerating Polysulfide Redox for Ultrahigh-Rate Li–S Batteries

Lithium-sulfur (Li-S) batteries offer compelling advantages, including high theoretical energy density (2600 Wh kg^-1), low cost, and environmental friendliness. However, their practical application is hindered by poor cycle stability at high rates stemming from low conductivity, sluggish redox kinetics, and polysulfide shuttle effects. To address these challenges, we design a high-efficiency microreactor (HA@C-mr) composed of hydroxyapatite (HA) nanoarrays anchored on the fibrous carbon substrate fabricated from fish scales. The HA nanoarrays provide abundant active sites to facilitate Li⁺ diffusion and accelerate polysulfide lithiation, while the collagen-derived fibrous carbon matrix establishes a continuous conductive network for rapid electron transfer. When integrated into a battery separator, HA@C-mr significantly enhances polysulfide redox kinetics, yielding exceptional sulfur utilization, rate capability, and cycling stability. The Li-S battery delivers a stable capacity of 784.9 mAh g^-1 over 200 cycles at 2 C (displaying a low capacity-decay-rate of 0.104% per cycle) and maintains a reversible capacity of 615 mAh g^-1 even at an ultrahigh rate of 10 C. This work demonstrates a sustainable high-performance microreactor strategy for advancing high-rate Li-S batteries toward practical applications.