Nitrogen‐Doped Graphene‐Supported Mixed Transition‐Metal Oxide Porous Particles to Confine Polysulfides for Lithium–Sulfur Batteries

• Published in: Advanced energy materials Vol. 8; no. 22
• Main Authors: Sun, Qian, Xi, Baojuan, Li, Jiang‐Ying, Mao, Hongzhi, Ma, Xiaojian, Liang, Jianwen, Feng, Jinkui, Xiong, Shenglin
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 06.08.2018
• Subjects: Atomic structure; Batteries; Bonding strength; Cathodes; Chemical bonds; chemical confinement; Graphene; Hydrothermal treatment; Lithium; Li–S batteries; Nanostructure; Nitrogen; nitrogen‐doped reduced graphene oxides; Organic chemistry; Polysulfides; Refluxing; Structural stability; Sulfur; ZnCo2O4 nanocubes
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.201800595

The intricate charge–discharge reactions and bad conductivity nature of sulfur determine the extreme importance of cathode engineering for Li–S batteries. Herein, spinel ZnCo2O4 porous particles@N‐doped reduced graphene oxide (ZnCo2O4@N‐RGO) are prepared via the combined procedures of refluxing and hydrothermal treatment, consisting of interconnected uniform ZnCo2O4 nanocubes with an average size of 5 nm anchored on graphene nanosheets. The as‐obtained composite can act as an inimitable cathode scaffold to suppress the shuttling of polysulfides by chemical confinement of ZnCo2O4 and N‐RGO for the first time, as demonstrated by the adsorption energy of ZnCo2O4 to Li2S4 via the strong chemical bonding between Zn or Co and S. The RGO nanosheets with a relatively high specific surface area provide a good conductive network and structural stability. The introduction of doped N atoms and numerous ZnCo2O4 porous nanoparticles can inhibit the transfer of lithium polysulfides between the cathode and anode. Due to the unique structural and compositional features, the as‐obtained hybrid materials with the high sulfur loading of 71% and even 82% still deliver high specific capacity, good rate capability, and enhanced cycling stability with exceptionally high initial Coulombic efficiency, which displays a high utilization of sulfur. A unique ZnCo2O4 porous particles@N‐doped reduced graphene oxide (ZnCo2O4@N‐RGO) hybrid is composed of interconnected spinel ZnCo2O4 nanocubes anchored on graphene nanosheets. Due to the advantages of the ZnCo2O4@N‐RGO hybrid with a high electrical conductivity and strong immobilization/blocking ability for polysulfides, the ZnCo2O4@N‐RGO‐based electrode displays high sulfur utilization, long cycling life, and high rate performance in Li–S batteries.