High Sulfur Loading in Hierarchical Porous Carbon Rods Constructed by Vertically Oriented Porous Graphene‐Like Nanosheets for Li‐S Batteries

Abstract

The utilization of porous carbon frameworks as hosts for sulfur loading is an important theme in current Li‐S battery research. Unfortunately, the high loading of insulating sulfur often leads to low specific capacities, poor rate properties, and rapid capacity loss. To address this challenge, a facile templating route to fabricate a novel host material, hierarchical porous carbon rods constructed by vertically oriented porous graphene‐like nanosheets (HPCR) is presented. With a high specific surface area, ultralarge pore volume, hierarchical porous structures, and ideal ion transfer pathways, HPCR is a promising candidate for high sulfur loading. When used as the active material for a sulfur cathode, the HPCR‐S composite with 78.9 wt% sulfur exhibits excellent rate performance (646 mAh g−1sulfur at 5 C) and cycling stability (700 mAh g−1sulfur after 300 cycles at 1 C). Even with a sulfur content of 88.8 wt%, the HPCR‐S composite, without any additional protective polymer coating, still delivers a good rate performance (545 mAh g−1sulfur at 3 C) and cycling stability (632 mAh g−1sulfur after 200 cycles at 1 C). More importantly, the high sulfur loading (88.8 wt%) ensures that the HPCR‐S composite has a high energy density (880 mAh cm−3cathode after 200 cycles at 1 C).

Recent Advances in Hollow Porous Carbon Materials for Lithium–Sulfur Batteries

“…Hierarchically structured HPCM can be regarded as an assembly structure of its primary HPCM units. Compared with the nano‐ or sub‐micrometer scale HPCM, the micrometer scale hierarchically structured HPCM not only inherits the structural characteristics of the primary HPCM units, but also provides additional advantages from the assembly, such as high tap density, fast charge transport, and hierarchically porous network . When used as sulfur‐hosting materials, the performance of the hierarchically structured HPCM is usually superior to the primary HPCM units.…”

“…Since sulfur was effectively encapsulated within the inner cavities of the hierarchically structured HPCF, the hierarchically structured HPCF/S composite with 71.5 wt% of sulfur exhibited the enhanced rate capability (990, 861, and 663 mAh g −1 at 1, 5, and 10 C) and cycling stability (capacity retentions of 94.4%, 95.5%, and 85.5% after 500 cycles at 1, 5, and 10 C). Recently, a similar MgO‐templated process was proposed by Zheng and co‐workers to fabricate hierarchically structured HPCN (Figure c) . Based on the hydrolyzation reaction of MgO, they developed a facile method for the controllable synthesis of layered metal hydroxide nanosheets and their derived hierarchical structures .…”

Multifunctionality of Carbon-based Frameworks in Lithium Sulfur Batteries

“…For example, Zheng et al [86] used MgO as a template to prepare porous carbon rods constructed with vertically oriented porous graphene-like nanosheets (HPCR) using chemical vapor deposition (Fig. 3).…”

“…For example, Fang et al [96] assembled a single-wall carbon nanotube Reproduced with permission from Ref. [86] (SWCNT) network electrode that was capable of achieving an ultrahigh sulfur content reaching 95 wt%. In this study, the theoretical sulfur content in the SWCNT composite was first investigated based on SWCNTs that we recoated with sulfur possessing core-shell structures.…”

Popcorn Inspired Porous Macrocellular Carbon: Rapid Puffing Fabrication from Rice and Its Applications in Lithium–Sulfur Batteries

“…The synergy between the physical confinement and chemical binding guarantees the high utilization in a working Li-S cell at a high areal sulfur loading. [54][55][56] In summary, we have proposed a facile and high-efficiency instantaneous puffing strategy for controllable fabrication of porous microcellular carbon. An in situ pressure releasing method generates abundant macropores, which afford enough space to accommodate active materials.…”