Customizing Multifunctional Sulfur Host Materials Via a General Anion‐Exchange Process with Metal–Organic Solid

Fe/Co/Ni‐based discrete nanoparticles are often explored to chemically adsorb and catalytically convert polysulfides for high‐performance Li–S batteries. Herein, by manipulating the anion‐exchange process between Ni–Co acetate microcrystals and various organic anions, porous single‐ or multi‐layered hierarchically functionalized carbon nanoshells are customized. Among them, the shell‐in‐shell composite, namely C–NiCoPi@C–Ni2Co, which has an external Ni2Co‐decorated carbon nanoshell and an internal Ni3P‐anchored carbon nanoshell encapsulated within a 3D‐structured continuous NiCo‐phosphate (NiCoPi) layer, displays collective merits as a sulfur host. Particularly, compared with discrete nanoparticles, the network‐like NiCoPi layer is structurally and inherently advantageous in chemical adsorption and catalytic conversion of polysulfides, as also supported by Density Functional Theory calculations, while the metallic Ni2Co nanoparticles enable high local conductivity. Such S@C–NiCoPi@C–Ni2Co displays an initial specific capacity of 1237 mAhg–1 at 0.1 C and maintains 1010 mAhg–1 after 100 cycles; at 0.5 C, its discharge specific capacity in the 1st cycle is as high as 1038 mAhg–1 and maintains capacity retention as high as 86% after 500 cycles. This study provides a straightforward strategy in customizing multifunctional sulfur hosts for high‐performance Li–S batteries. By manipulating the anion‐exchange process between Ni–Co acetate microcrystals and various organic anions, single‐ or multi‐layered carbon nanoshells hierarchically functionalized with discrete Ni2Co, Ni3P nanoparticles, and/or 3D NiCo‐phosphate network are customized. When employed as sulfur hosts for Li–S batteries, they can not only support high local conductivity but also enable efficient chemical adsorption and catalytic conversion of polysulfides.