Desirable sulfur electrochemistry strongly relies on host-guest interactions, which calls for rational designs on the surface fine structure of sulfur reservoir materials. Herein, we for the first time, explore the coordinative unsaturation in ferric hexacyanoferrate (FeHCF) for sulfur immobilization and catalyzation towards improved lithium-sulfur (Li–S) batteries. A simple ammonia etching treatment is implemented to selectively remove Fe^III–H₂O moieties, leaving vast coordinatively unsaturated Fe sites with a simultaneous establishment of considerable mesoporosity in the activated matrix (denoted as FeHCF-A). As a sulfur-host, the massive meso-scale channels endow FeHCF-A with abundant active interfaces and ion/mass transfer pathways, while more importantly, the coordinatively unsaturated Fe sites are revealed with higher adsorbability and conversion catalytic activity to polysulfides. Attributed to theses chemical and structural superiorities, the as-developed FeHCF-A enables a fast, stable, and efficient sulfur electrochemistry, e.g., good rate capability up to 5C and excellent cyclability with an ultralow decay rate of 0.024% per cycle over 500 cycles, as well as a commendable areal capacity of 4.5 mAh cm⁻² under high sulfur loading. This work affords a new and insightful perspective of coordinative chemistry for material engineering in Li–S batteries as well as other related fields.

理想的硫电化学强烈依赖于主体-客体之间的相互作用，这要求对储硫材料的表面精细结构进行合理的设计。在这里，我们第一次探索六氰合铁酸铁（FeHCF）中的配位不饱和键，用于硫的固定化和向改进的锂硫（Li-S）电池的催化作用。实施简单的氨蚀刻处理以选择性去除Fe ^III -H ₂O部分，在活化基质（表示为FeHCF-A）中同时留下大量配位不饱和的Fe位点，同时建立相当大的介孔性。作为硫的宿主，大量的中尺度通道赋予FeHCF-A丰富的活性界面和离子/质量转移途径，而更重要的是，显示出配位的不饱和Fe位具有更高的吸附能力和将催化活性转化为多硫化物。归因于这些化学和结构上的优势，新开发的FeHCF-A实现了快速，稳定和高效的硫电化学，例如，高达5C的良好速率能力和出色的可循环性，在500次循环中每循环0.024％的超低衰减率，以及值得赞扬的4.5 mAh cm ^-2面积在高硫负荷下。这项工作为锂-硫电池以及其他相关领域的材料工程提供了配位化学的新见解。