Modulation of Potential‐Limiting Steps in Lithium–Sulfur Batteries by Catalyst Synergy
Liqi Liu, Yichun Zheng, Yang Sun, Huilin Pan
Abstract
Abstract Electrocatalysis is considered to be an effective method to solve the sluggish kinetics of lithium–sulfur batteries. However, a single catalyst cannot simultaneously catalyze multi‐step sulfur reductions. And once the catalyst surface is covered by the initially deposited solid products, the subsequent catalytic activity will significantly deteriorate. Here, microporous ZIF‐67 and its derivative nano‐metallic Co 0 are used as dual‐catalyst aiming to address these drawbacks. The dual catalytic center effectively cooperates the adsorption and electron transfer for multi‐steps of sulfur reductions, transforming the potential‐limited step (Li 2 S 4 →Li 2 S 2 /Li 2 S) into a thermodynamic spontaneous reaction. ZIF‐67 first adsorbs soluble Li 2 S 4 to form a coordination structure of ZIF‐Li 2 S 4 . Then nano‐metallic Co 0 attracts uncoordinated S atoms in ZIF‐Li 2 S 4 and facilitates the breaking of S–S bonds to form transient reductive ZIF‐Li 2 S 2 and Co‐S 2 via. spontaneous electron transfer. These intermediates facilitate continuous conversion to Li 2 S with reduced formation energy, which is beneficial to the regeneration of the catalyst. As a result, the cathode with ZIF@CNTs/Co@CNFs synergetic catalyst achieves initial areal capacity of 4.7 mAh cm −2 and maintains 3.5 mAh cm −2 at low electrolyte/sulfur ratio ( E / S ) of 5 µL mg −1 . This study provides valuable guidance for improving the electrochemical performance of lithium–sulfur batteries through catalyst synergistic strategies for multi‐step reactions.