High‐loading lithium–sulfur (Li–S) batteries suffer from poor electrochemical properties. Electrocatalysts can accelerate polysulfides conversion and suppress their migration to improve battery cyclability. However, catalysts for Li–S batteries usually lack a rational design. A d‐band tuning strategy is reported by alloying cobalt to metal sites of Ni2P to enhance the interaction between polysulfides and catalysts. A molecular or atomic level analysis reveals that Ni2Co4P3 is able to weaken the SS bonds and lower the activation energy of polysulfides conversion, which is confirmed with temperature‐dependent experiments. Ni2Co4P3 nanowires are further fabricated on a porous nickel scaffold to unfold the catalytic activity by its large surface area. Using a simple ion‐selective filtration shell, a microreactor‐like S cathode (MLSC) is constructed to realize ultrahigh S loading (25 mg cm−2). As such, a microreactor design integrates reaction and separation in one cell and can effectively address the polysulfide issues, the MLSC cell demonstrates excellent properties of cyclability and high capacity (1223 mAh g−1 at 0.1 C). More importantly, the catalyst's designs and microreactor strategies provide new approaches for addressing the complicated issues of Li–S batteries.

The slow conversion and rapid shuttling of polysulfides remain major challenges that hinder the practical application of lithium−sulfur (Li−S) batteries. Efficient catalysts are needed to accelerate the conversion and suppress the shuttling. However, the lack of a rational understanding of catalysis poses obstacles to the design of catalysts, thereby limiting the rapid development of Li−S batteries. Herein, we theoretically analyze the modulation of the electronic structure of CoP 1−x S x caused by the NiAs-to-MnP-type transition and its influence on catalytic activity. We found that the interacting d-orbitals of the active metal sites play a determining role in adsorption and catalysis, and the optimal d z 2 -, d xz -, and d yz -orbitals in an appropriately distorted five-coordinate pyramid enable higher catalytic activity compared with their parent structures. Finally, rationally designed catalysts and S were electrospun into carbonized nanofibers to form nanoreactor chains for use as cathodes. The resultant Li− S batteries exhibited superior properties over 1000 cycles with only a decay rate of 0.031% per cycle and demonstrated a high capacity of 887.4 mAh g −1 at a high S loading of 10 mg cm −2 . The structural modulation and bonding analyses in this study provide a powerful approach for the rational design of Li−S catalysts.

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