Hierarchical Rambutan‐Like CNTs‐Assembled N−Co−C@rGO Composite as Sulfur Immobilizer for High‐Performance Lithium‐Sulfur Batteries

Abstract

The design of efficient sulfur‐host materials is of great significance to enhance the conductivity of lithium‐sulfur (Li−S) batteries and inhibit the shuttle effect of polysulfides. Hence, a nitrogen and cobalt co‐doped graphitized carbon (N−Co−C)‐coated reduced graphene oxide (rGO) with plenty of carbon nanotubes (CNTs) was rationally designed. The composite had abundant multiple adsorptive and electrocatalytic sites to provide strong chemical trapping for polysulfides and simultaneously propel their electrochemical kinetics. The densely grafted small‐diameter CNTs could shorten the ion‐diffusion pathways and maintain the structural stability of the electrode materials. Meanwhile, abundant pore structures could provide enough volume for sulfur impregnation and physical adsorption of polysulfides. Owing to these favorable features, the as‐prepared rambutan‐like S/N−Co−C@rGO‐CNTs (S/NCoC@G‐CNTs) composite demonstrated excellent electrochemical performance with a high initial specific capacity of 1225.8 mAh g−1 at 0.2 C and high rate performance of 632.5 mAh g−1 at 5.0 C and possessed decent areal capacity under high raised sulfur loading of up to 5 mg cm−2.

Recent progress in metal–organic framework/graphene-derived materials for energy storage and conversion: design, preparation, and application

“…225 Furthermore, Co,N-codoped porous carbon hosts showed enhanced LSB performance. [226][227][228][229] For example, Wang et al fabricated a free-standing sulfur host consisting of Co,N-co-doped porous carbon nanocages on 3D rGO (Co/N-PCN@rGO) through pyrolyzation of ZIF-67@rGO followed by acid leaching. 226 Aer being penetrated by sulfur, the obtained cathode manifested a high discharge capability and an extremely low capacity decay rate, which was better than that of most reported carbon-sulfur-based cathodes.…”

Recent Progress on Zeolitic Imidazolate Frameworks and Their Derivatives in Alkali Metal–Chalcogen Batteries

“…Graphene not only improves electrical conductivity but also exposes an abundance of active sites for redox reactions. [ 54,121,122 ] For instance, Yin et al. fabricated the RGO‐wrapped ZIF‐67‐derived Co/N‐codoped carbon polyhedra via a carbonization process ( Figure 7 a) and then used them as sulfur immobilizers.…”

“…reported a hierarchical rambutan‐like CNT‐assembled N‐Co‐C@RGO composite as a sulfur immobilizer based on thermal annealing of a ZIF‐67@RGO precursor. [ 122 ] Considering the physicochemical confinement of intermediates and catalytic properties of N‐Co‐C species, the Li–S batteries delivered 1225.8 mAh g −1 at 0.2 C and 632.5 mAh g −1 at 5.0 C, respectively, and good areal capacity under a sulfur loading of 5.0 mg cm −2 .…”

“…Graphene not only improves electrical conductivity but also exposes an abundance of active sites for redox reactions. [54,121,122] For instance, Yin et al fabricated the RGO-wrapped ZIF-67-derived Co/N-codoped carbon polyhedra via a carbonization process (Figure 7a) and then used them as sulfur immobilizers. [121] In addition to the merits of ZIF-derived materials themselves, RGO sheets acted as barriers to prevent the dissolution and shuttling of polysulfides and alleviated the volume expansion of sulfur during cycling.…”

Advanced Battery Materials Research at Nazarbayev University: Review

“…Moreover, transition metal compounds used in other electrochemical reactions as electrocatalysts can facilitate the conversion of LiPSs to lithium sulfides and vice versa. In this way, the role of metal oxides such as Mg 0.6 Ni 0.4 O [1,3,4], ZnO [5,6], Fe/Co 3 O 4 [7] Co 3 O 4-x [8], Fe 3 O 4 [9], TiO 2 [10] and TiO 2-x [11] as sulfur and LiPSs carriers and the role of Ni [12,13], Co [14] and Fe [7] electrocatalysts and hetero-structured materials were investigated.…”