Heterogeneous Mediator Enabling Three‐Dimensional Growth of Lithium Sulfide for High‐Performance Lithium–Sulfur Batteries

• Published in: Energy & environmental materials (Hoboken, N.J.) Vol. 5; no. 4; pp. 1214 - 1221
• Main Authors: Tian, Da, Song, Xueqin, Qiu, Yue, Sun, Xun, Jiang, Bo, Zhao, Chenghao, Zhang, Yu, Xu, Xianzhu, Fan, Lishuang, Zhang, Naiqing
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.10.2022; State Keys Laboratory of Urban Water Resource and Environment,Harbin Institute of Technology,Harbin 150001,China; School of Chemistry and Chemical Engineering,Harbin Institute of Technology,Harbin 150001,China%Academy of Fundamental and Interdisciplinary Sciences,Harbin Institute of Technology,Harbin 150001,China%Academy of Fundamental and Interdisciplinary Sciences,Harbin Institute of Technology,Harbin 150001,China
• Subjects: Anodic protection; Computer applications; Deposition; electrocatalysis; Electrodes; Electrolytes; Electrolytic cells; Graphene; Insulation; Lithium; lithium sulfide nucleation; Lithium sulfur batteries; polysulfide redox reaction; shuttle effect; Sulfides; Sulfur; shuttle effect; polysulfide redox reaction; lithium-sulfur batteries; electrocatalysis; lithium sulfide nucleation
• ISSN: 2575-0356; 2575-0348; 2575-0356
• DOI: 10.1002/eem2.12236

Two‐dimensional (2D) deposition regime of insulating lithium sulfide (Li2S) is a major obstacle to achieve high reversible capacity in the conventional glyme‐based lithium–sulfur (Li–S) batteries as it leads to rapid loss of active electrode surface and low sulfur utilization. Achieving three‐dimensional (3D) growth of Li2S is therefore considered to be necessary, but the available strategies are mainly based on the electrolyte manipulations, which inevitably lead to added complexity of the electrode–electrolyte compatibility and, in particular, instability of the lithium anode. In this work, we have developed a heterogeneous polysulfide mediator composed of discrete Mo5N6 anchored on graphene, which functions on the cathode side, to regulate the deposition mode of Li2S. Mo5N6 can efficiently boost the formation of Li2S as demonstrated by a series of experimental and computational results. More importantly, the discrete distribution of Mo5N6 nucleants on graphene postpones the merging of adjacent Li2S nuclei to promote their isotropic growth. Thus, 3D deposits of Li2S is guided by the heterogeneous mediator. Benefiting from these unique superiorities, Li–S cells with high rate capability of 954 mAh g−1 at 2 C and long cycle life exceeding 1000 cycles are realized without advanced lithium anode protection. A heterogeneous polysulfide mediator composed of discrete Mo5N6 anchored on graphene is developed to regulate the deposition mode of Li2S. Mo5N6 efficiently boosts the formation of Li2S and the discrete distribution of Mo5N6 nucleants on graphene postpones the merging of adjacent Li2S nuclei to promote their isotropic growth.