Atomically Dispersed Fe–N<sub>4</sub> and Ni–N<sub>4</sub> Independent Sites Enable Bidirectional Sulfur Redox Electrocatalysis
Jin‐Lin Yang, Peihua Yang, Da‐Qian Cai, Zhe Wang, Hong Jin Fan
Abstract
Single-atom catalysts (SACs) with high atom utilization and outstanding catalytic selectivity are useful for improving battery performance. Herein, atomically dispersed Ni–N 4 and Fe–N 4 dual sites coanchored on porous hollow carbon nanocages (Ni–Fe–NC) are fabricated and deployed as the sulfur host for Li–S battery. The hollow and conductive carbon matrix promotes electron transfer and also accommodates volume fluctuation during cycling. Notably, the high d band center of Fe in Fe–N 4 site demonstrates strong polysulfide affinity, leading to an accelerated sulfur reduction reaction. Meanwhile, Li 2 S on the Ni–N 4 site delivers a metallic property with high S 2p electron density of states around the Femi energy level, enabling a low sulfur evolution reaction barrier. The dual catalytic effect on Ni–Fe–NC endows sulfur cathode high energy density, prolonged lifespan, and low polarization.